Neuroscientist: 7 Habits To Protect Your Brain & Reduce Dementia Risk | Dr. Tommy Wood

Dr. Rangan Chatterjee 0:00 The framing I thought would be quite fun and useful for people is basically around the common mistakes-

Dr. Tommy Wood 0:07 Mm

Dr. Rangan Chatterjee 0:07 ... people make when it comes to brain health, and longevity, and health span. Mistake number one: we neglect how much our perception of aging impacts how well we age. And in your latest book, which I love, you quote the Ohio Longitudinal Study of Aging.

Dr. Tommy Wood 0:29 Mm.

Dr. Rangan Chatterjee 0:29 And you write that those with a more positive perception of aging were found to live on average seven and a half years longer. What's going on?

Dr. Tommy Wood 0:40 There's several things going on, and it's difficult to tease them all apart in a study like this. But essentially what they did is they asked people how they felt about the process of aging. So they asked them to rate on a scale of, you know, one to five, how do you feel about questions like when I get older or when people get older, they become less useful. Things, you know, things like that. And those who had a higher level of the positive perception of aging tended to live longer, like I said, seven and a half years longer on average. And then you have to adjust for other things like age and health status and some other things. And some of it could be what we call, uh, reverse causality, right? So if you're already feeling like you're experiencing the process of aging, you're, uh, you've lost some of your health, um, then you might feel more negative about aging.

Dr. Rangan Chatterjee 1:28 Yeah.

Dr. Tommy Wood 1:28 And it's the health that's really driving it rather than your perception. So some of that is certainly playing a role, but I do think that having, um, a positive out- like, outlook on the processes of aging will then allow you to continue to engage in the world in a positive manner that then drives a whole host of benefits. And we know that mindset and how we feel about our own health and our wellbeing are important drivers of our physiology-

Dr. Rangan Chatterjee 1:58 Mm

Dr. Tommy Wood 1:58 ... and important predictors of our long-term health. So some of that re- reverse causality is possible there too. But we do know that how you feel about the future and how you feel about your health, and then aging as part of that, is going to change both how you interact with the world and change your physiology. And I, I think that that's what we're seeing some, some of in, in, in that particular study. Um, and where this then becomes really interesting to me is when we think about this idea of chasing longevity in particular, then

Dr. Tommy Wood 2:30 inherent in that is y- some idea that, um, aging is bad, right? Because i- in order to fight against aging, you have to think that aging is inherently detrimental. Um, and yes, we, we, we know that with aging you will lose some function. It just, it is what it is. We can't prevent it entirely. But if you have a negative perception of that, then when you start to see aging happen, regardless of your efforts, I think that could then have an even worse effect on your psychology and mindset because you've kind of internalized this idea that aging is bad. When with aging could come a whole bunch of changes in, say, cognitive function and other aspects of personality that may be beneficial. But we might miss out on that-

Dr. Rangan Chatterjee 3:24 Mm

Dr. Tommy Wood 3:24 ... if our primary focus is on preventing it entirely because we think that it's bad.

Dr. Rangan Chatterjee 3:30 When we think about changes that we can make to help increase our health span, we can think about individual changes that we can make.

Dr. Tommy Wood 3:38 Mm.

Dr. Rangan Chatterjee 3:39 But we also need to think about, I guess, collective changes and the influence that culture and society has on us. So if we're constantly being surrounded by a message that aging is bad-

Dr. Tommy Wood 3:53 Mm

Dr. Rangan Chatterjee 3:54 ... how can you, um, fight the aging process? Stop the aging process. It kind of undermines like a central truth, which is you're actually aging from the minute you're born.

Dr. Tommy Wood 4:06 Yeah. [laughs]

Dr. Rangan Chatterjee 4:07 Right? It is just a truth of life. And we see this... I think I mentioned to this in maybe one of your previous appearances, that there's quite a, a bit of research showing that cultures where women aging is seen as a good thing-

Dr. Tommy Wood 4:23 Mm

Dr. Rangan Chatterjee 4:23 ... report less menopausal symptoms.

Dr. Tommy Wood 4:27 I think that a lot of what we experience, we know, um, is based on how our culture sees these processes, uh, of aging. And I really enjoy... There was a, actually a very recent paper that came out, um, uh, called Humans Peak in Midlife. Um, and actually talking about the fact that when you look at just individual factors, and we're talking about, you know, cognition and, and personality here primarily, then you might look at something like how quickly can you process complex information and maybe do some kind of non-verbal reasoning, something like that. Yes, that peaks early in life, 20s and 30s, and then on average tends to decline. Um, but that's one very narrow idea of cognitive function, right? So when you look across a whole different range of things that the brain does, and they sort of had various scales and ways to integrate all these different things, you think about the fact that, um, other things increase over time, and maybe even into our 60s and 70s. Things like, um, crystallized intelligence, which is a fancy word for wisdom, but also emotional intelligence and, um, and like moral reasoning, right? On average, a 20-year-old probably isn't as good at sort of like thinking about the moral big picture as a 40, 50, 60-year-old because they have more experience. They've kind of integrated all these different things. So, um, when you look across all those different, um, factors, then on average people sort of tend to peak somewhere between 55 and 65. Sort of like you have-

Dr. Rangan Chatterjee 5:57 Mm-hmm

Dr. Tommy Wood 5:57 ... you still have a good cognitive function, plus you've built, um- ... other aspects of wisdom and emotional intelligence and sort of how they integrate and, like, that's actually when people tend to peak, and so, like, that's after the menopausal transition in women, and obviously it's, you know, si- a, a similar age is seen in men. So we can continue to grow cognitively, emotionally, um, and see benefits from that, you know, much later maybe than, than people might otherwise think.

Dr. Rangan Chatterjee 6:25 Yeah. What's the practical take-home then for an individual? Is it a bit like gratitude, where if you focus on what you lack-

Dr. Tommy Wood 6:35 Mm

Dr. Rangan Chatterjee 6:35 ... you lose what you have?

Dr. Tommy Wood 6:36 Yeah. I, I think maybe it's worth just talking for a minute on, on the, the process of, of aging and what, what aging is, and there are lots of different theories of what, of what aging is. Um, and so, like, one is actually the developmental theory of aging, which is that aging is the continuation of developmental processes that caused growth earlier in life, and then as they sort of continue decades later, they actually drive a, a functional decline. Although, what I would argue, and this is, right, the major point, point of, um, my book as well, is that it, it might be that we stop giving the body inputs that maintain function, uh, and then that's why function declines. And that would make sense with development, because development is all about building function, uh, relative to inputs.

Dr. Rangan Chatterjee 7:22 Mm-hmm.

Dr. Tommy Wood 7:23 So if you stop giving those inputs, then function declines because the body is trying to match function to, to whatever it is that you're, you're, you're doing. So that would fit with the developmental theory of aging. But there are other theories like the information theory, where, you know, damage accumulates and, you know, DNA, uh, doesn't replicate as well, and then, uh, the, that kind of drives these aging processes. But regardless of, you know, what aging actually is, which people don't actually agree on what aging is, um, the... One thing that most people do agree on is that we c- we, we may not be able to slow aging down, but we can accelerate aging, right? And that's, uh, by not sleeping and eating a poor quality diet and not moving and, you know, not being socially connected. So when we're thinking about, um, aging in general, know that the best place to start is just do those things that I just mentioned, the things that you talk about all the time, because by not doing those things, you could accelerate the process of aging. You probably can't slow aging down, or at least at this point we're not sure how much we can slow aging down. So then if you tick those kind of boxes, those big boxes that, uh, I think each of us can do in our own way and can have a big impact even with relatively minimal effort, then the rest is just acknowledging and understanding that, yeah, things will change over time. But you also see, you know, with this kind of idea that, uh, humans peak in midlife, you actually tend to see an increase in, um, satisfaction with life-

Dr. Rangan Chatterjee 8:49 Mm

Dr. Tommy Wood 8:49 ... and happiness as you get older, and that's probably a, um, a downstream effect of all these things kind of integrating and coming together. So the, maybe the main takeaway is in that kind of middle portion as you transition into sort of mid and later life, just don't, maybe don't fight it as much, because then it's just a... It increases distress without, um, you know, any kind of major benefit of it. And so, so it's just ac- acknowledging that it's happening, acknowledging that, um, actually there is some, there's some benefit to it, and at the same time you're, you're doing, um... You know, you're kind of covering your bases so that you're not kind of accelerating any kind of biological process associated with aging. But, but I think just knowing that it happens and knowing that actually there's some net benefit to it is, is probably a starting point, because then you're not constantly fighting your biology, which is gonna win out at some point.

Dr. Rangan Chatterjee 9:42 Yeah. It's interesting. It makes me think of the stress response, and I guess a more spiritual or philosophical explanation of stress is to do with resistance.

Dr. Tommy Wood 9:53 Mm.

Dr. Rangan Chatterjee 9:53 Right? If you resist what is happening, that is what is creating the stress.

Dr. Tommy Wood 9:59 Yeah.

Dr. Rangan Chatterjee 10:00 The more you can accept and not resist, the less stress you are going to experience. And I guess we could bring that argument in here and go, if you're trying to resist the aging process to a degree... We're not saying don't do the things-

Dr. Tommy Wood 10:13 Yeah

Dr. Rangan Chatterjee 10:13 ... that are gonna help you age well.

Dr. Tommy Wood 10:15 Yeah.

Dr. Rangan Chatterjee 10:16 But the more you resist the fact that your hair's going gray-

Dr. Tommy Wood 10:19 Mm

Dr. Rangan Chatterjee 10:19 ... and that you're not gonna run probably-

Dr. Tommy Wood 10:23 [laughs]

Dr. Rangan Chatterjee 10:23 ... your 5K PB at 70.

Dr. Tommy Wood 10:26 Yeah.

Dr. Rangan Chatterjee 10:27 And that's okay.

Dr. Tommy Wood 10:27 Yeah.

Dr. Rangan Chatterjee 10:28 Yeah.

Dr. Tommy Wood 10:29 Just not essentially wasting mental and physical energy in resisting something that will happen to all of us, um, because then you may be more likely to see the benefits-

Dr. Rangan Chatterjee 10:40 Yeah

Dr. Tommy Wood 10:41 ... of the things that will happen as we change over time.

Dr. Rangan Chatterjee 10:43 Before we move to mistake number two, I've heard you talk before, Tommy, about how we perceive stress changes-

Dr. Tommy Wood 10:53 Mm

Dr. Rangan Chatterjee 10:53 ... the physiological stress response.

Dr. Tommy Wood 10:55 Yeah.

Dr. Rangan Chatterjee 10:56 And I think,

Dr. Rangan Chatterjee 10:57 you know, we're, we're broadly talking about mindset here and how the right mindset as we age can potentially help us live longer, improve our brain health, and improve the quality of our lives, right? So talk to me a little bit about stress, maybe from a less philosophical lens-

Dr. Tommy Wood 11:12 [laughs]

Dr. Rangan Chatterjee 11:12 ... and a more scientific lens.

Dr. Tommy Wood 11:13 Yeah.

Dr. Rangan Chatterjee 11:14 What it is and how reframing that stress in particular ways can change the way that our bodies respond.

Dr. Tommy Wood 11:23 Yeah. So where we've gotten to right now, and y- there's actually been a lot of it in the last couple of years, where people are talking about, right, stress is inherently bad in all situations regardless of what's happening, and fundamentally, that just is not true. The stress response is incredibly important, and it's also a general response to the outside environment changing and your body realizing, "I need to do something in response to this thing that's outside of me." That's essentially all the stress response is. Um, and that might be ... psychological, it might be physical. Um, but the initial response, you release adrenaline, cortisol, heart rate goes up, blood sugar goes up. Your body is diverting resources to allow you to respond to this change in the environment. And it's, it's why, um, historically, like the, sort of like the, the kind of the father of the modern stress response, right, is Hans Selye. Yeah. Right? And he called it general adaptation syndrome initially. And I quite like that because it's like this is your body signaling that adaptation is required. So when you're focused and learning and maybe failing, and we've talked about the, the importance of failure before for building cognitive function and building skills, it's stressful. Your heart rate goes up. You release, um, stress hormones like noradrenaline- Mm ... in the brain. But it's your brain diverting resources to say, "Hey, I need to change my structure and my functioning so that I can adapt to this thing that I'm being exposed to." And, right, exercise is the same. If you did, um, somebody's, you know, blood pressure and measured their heart rate and measured their glucose and cortisol, right? Measured that in you after a paddle game, you'd be like, "God, paddle is terrible," right? Just look how stressful it is for your body. But as a result, your body adapts, right? Resting heart rate improves. Inflammation improves. Um, strength and speed and power- Mm ... uh, improve. Uh, VO2 max improves. And that's driven by this stress response. So the first thing that I hope that people realize is that stress is useful. Mm. It's your body's signal to adapt to some change. Yes, chronic stress where it then starts to impact sleep, and it impairs your ability to adapt, which can, which can happen if, if, you know, a stressor isn't, you know, removed or relieved or you, you're unable to- Mm ... process that stress. Yes, it can be maladaptive or problematic, but in the moment, stress is actually incredibly beneficial. Um, and then we know, kind of to get to your question, we know that how we think about stress affects how we respond to it. So most of this, uh, work is, is, is done, has been done by Alia Crum. She's at Stanford. She, um, work... As, as a PhD student, she worked with Adam Langer, who I know we both, um- Love ... love, love her work. And so it's very much in a si- like Alia's work is very much in a similar vein, but has obviously taken it and, uh, built, built a, an amazing career in her own right. Um, and what she researches or one of the things she researches is this idea that stress is enhancing. Um, and they've done randomized controlled trials where you take a group of people, and one group you say, "Just think about how terrible stress is," right? Um, it sort of... It breaks you down. It impairs your decision-making, right? It's just, you know, just really, really bad for you. Stress is debilitating, right? It, it, it prevents you from being able to perform at your best. In another group, they sort of show them videos, and they prime them with this idea that stress is enhancing. Think about all the amazing people who've performed- Mm ... under incredible stress. So you might talk about Winston Churchill or Abraham Lincoln or S- uh, Sully Sullenberger who landed the plane in the, in the, in the Hudson, you know, famously. Think about all the times that- Yeah ... you've performed under stress. Like think about how amazing you can be even when you're stressed. And then you put them in a stressful situation, um, and there are experimental ways to do this. One is called the Trier Social Stress Test, where there are different versions of it. But essentially you go into a room, and there's a panel of people in front of you, and they're like, "You have to speak for five minutes on this topic that you haven't prepared at all." And while you do that, the audience just sits there completely impassively just like staring at you, which is like very str- very stressful. Um, and what you see is that those... you know, both groups, they get stressed, right? Cortisol goes up the same in both. But you see a few, um, other things that happen in those who, um, are told that stress is enhancing. So you, you see other hormones increasing at the same time. So one of them is, is DHEA, which is a, a steroid hormone. And that... Like DHEA is part of that adaptation process. It kind of, um, helps to facilitate growth, um, and the, you know, the, the building and the adaptation of- Mm ... of tissues. And that goes up in the stress is enhancing group, whereas it doesn't in the stress is debilitating group. There have been other studies by other groups that looked at hormonal responses to stressful situations, and they found that those who release more DHEA when stressed tend to make better decisions under stress. Um, it may not be the DHEA. It may be this sort of like whole physiological kind of setup- Mm ... of, of thinking that stress is enhancing that you can then... um, or, you know, being that, in that kind of situation where you don't necessarily think stress is debilitating that allows you to make better de- uh, better decisions under stress. But this is very interesting that not only does your mindset change your physiology in response to stress, but it may also then change your ability to perform under stress. So I think some of this just requires us to, to acknowledge, hey, stress is actually good. Mm. It's a good thing. First of all, it's for survival, but it's also for growth and adaptation and, you know, making us bigger and stronger and smarter. Um, and then acknowledging and thinking about the fact that, yeah, actually, we, I probably can perform un- under stress. Um, and then in doing that, you will perform better- Yeah ... under stress. Yeah. Okay, let's get to point two, okay? [laughs] So mistake number one about having the wrong mindset. Mistake number two, and again, I've started with these on purpose because I don't think they're spoken about enough, focusing on solo health habits at the expense of social connection. Mm-hmm. And I guess the point I'm trying to make here is if we consume all the health podcasts and hear

Dr. Rangan Chatterjee 18:06 The list of things that we could be doing, and perhaps should be doing, to optimize our health and longevity, you could end up living quite an isolated life. If you were gonna get your five hours of zone two, and do your Norwegian 4x4, and, um, never eat out late, and all this kind of stuff, you could find yourself spending a lot of time by yourself. Yes, you've optimized certain metrics, but potentially at the expense of social connection.

Dr. Tommy Wood 18:36 Yeah. I, I think that this is, in particular, a risk for those who are very hyper-focused on, on this area. And, and I, I don't think a- any of us needs to go very far to see examples of this in popular media, social media, where people who are trying to push, say, the edges of longevity, essentially live indoors by, [laughs] by themselves, um, with a very perfected sleep schedule, food schedule, supplement schedule. And it's very possible that they'll live a little longer. I don't think they're gonna live 20 years longer. But I, I, I think that it's possible they could undo, or even go in the other direction because by being so hyper-focused on optimizing everything, which I think is a misnomer in the first place, um, you miss out on this core part of human biology, physiology, which is the conne- which is the connection to others. Um, and we know that is health promoting and health driving, um, as well as just being a part of how h- humans evolved. So, so one of my, um, my favorite stories around this goes back to Charles Darwin because when we think about Darwin, we think about evolution, we think about survival of the fittest. Although survival of the fittest was not his term. It was coined by somebody else later. But this idea that, like,

Dr. Tommy Wood 20:06 it's every species or individual for themselves, and it's just, like, this battle to survive and reproduce-

Dr. Rangan Chatterjee 20:13 Mm-hmm

Dr. Tommy Wood 20:13 ... and, right, that's, that's, that's how you, that's how you win. Um, but 12 years after he wrote On the Origin of Species, which is, like, the, you know, the, the set of essays that kind of came... the, the, that founded this theory of evolution. Um, supposedly Darwin thought, well, actually, survival of the fittest as an idea doesn't explain human evolution.

Dr. Rangan Chatterjee 20:36 Mm.

Dr. Tommy Wood 20:37 And so he wrote another, um, set of, of texts called The Descent of Man, and essentially came up with this idea instead that, um, the group that was the most, he called them sympathetic, the, like, the, the group of humans that were most sympathetic, we would, we would call it empathy now, that looked after each other the most, that cared for each other the most, actually they would be the ones that would, that would survive, and that, that kind of better explained human evolution. And then Dacher Keltner, uh, sort of mu- much later, um, e- ended up calling this survival of the kindest.

Dr. Rangan Chatterjee 21:10 Yeah.

Dr. Tommy Wood 21:10 Um, and there's now a huge amount of, uh, science to show that when we act proso- socially, like, we connect with others, and particularly when we're helping others, um, and this is where some of those ideas of why, like, purpose and meaning can have such a big effect on our health. You can see, again, physiological responses. So you see activation of the vagal nerve and, um, like heart rate variability, uh, improves, and, you know, stress responses decrease, and all these things that we know are, again, tied to, to long-term health. Um, and so I think that there's this... or we know there's this core requirement of our biology to be connected with others, and especially to act in, in the benefit of others or the benefit of things outside of ourselves. Um, and I think we miss out on that when we're so hyper-focused on optimizing everything for ourselves individually. Um, and I've seen this a ton with k- you know, clients, uh, that I've worked with over the years where they, you know, they stop going out. They stop seeing friends. They stop having meals in restaurants because they're so worried about the food that they'll eat or whether they won't get to bed in time. Um, you know, everything else will kind of fall out of kilter because they're n- they're, they're not at home to kind of get their, their perfect routine. Um, and I think their, their health suffers because of it. And, like, there's a, there's almost... I, I imagine everybody who works in our, in our fields, right? I, I don't see patients clinically. I haven't, uh, for, for a long time. But, you know, when you've worked with people as a health coach, everybody has a story of the person who essentially gave up their diet and gave up their exercise [laughs] and just started hanging out with their mates again, and all of their health problems imp- uh, im- improved. Um, and yeah, you know, those are maybe e- exceptions to the rule because, you know, those aspects of lifestyle still do matter a lot. But I think there's this critical importance of social connection that we lose out on when we, when we're so hyper-focused on, you know, getting everything else perfect.

Dr. Rangan Chatterjee 23:07 Yeah. Your book, Tommy, The Stimulated Mind, which you know how much I love it. You know how much I want people to get it-

Dr. Tommy Wood 23:14 [laughs]

Dr. Rangan Chatterjee 23:14 ... 'cause I think it's one of the books of the year. It's absolutely fantastic. There's two studies in that book that I wrote, I, I sort of wrote down-

Dr. Tommy Wood 23:22 Mm

Dr. Rangan Chatterjee 23:22 ... to discuss with you, which relates to this topic, right? A Japanese study of 9,000 adults greater than 65 years old, more frequent social contact was associated with higher brain volumes-

Dr. Tommy Wood 23:36 Mm

Dr. Rangan Chatterjee 23:37 ... and less age-related white matter injury. And then you also spoke about the 2025 World Happiness Report, showing that one of the strongest predictors of well-being across 142 countries was the number of meals per week people share with others. I mean, this is huge, right? Because a- as we're, we're talking about here, you can solo optimize, but you miss out on all of the social inputs. And if we go back to your three S model, which I'd love you to just briefly summarize-

Dr. Tommy Wood 24:07 Mm

Dr. Rangan Chatterjee 24:07 ... for people who've, you know, come to you for the first time. Well, when we think about stimulating the brain- Yeah, it can be learning new things, for sure.

Dr. Tommy Wood 24:18 Mm.

Dr. Rangan Chatterjee 24:18 But you can also argue that having conversations with other human beings, being around other human beings, well, that's also an important stimulus-

Dr. Tommy Wood 24:28 Mm

Dr. Rangan Chatterjee 24:28 ... for the brain, isn't it?

Dr. Tommy Wood 24:29 Yeah. So, so I think it's maybe worth first thinking about what's the point of living longer and maintaining cognitive function for long periods of time, right? Because I don't think it's to stay at home by yourself for more time, right?

Dr. Rangan Chatterjee 24:47 More, more Netflix watching by yourself, mate?

Dr. Tommy Wood 24:50 [laughs] Yeah. Is that-

Dr. Rangan Chatterjee 24:51 You don't think that's why we evolved?

Dr. Tommy Wood 24:52 [laughs] I mean, you know, I absolutely love a good, uh-

Dr. Rangan Chatterjee 24:57 Netflix binge

Dr. Tommy Wood 24:57 ... Netflix binge, of course. Um, but for the vast majority of people... And, and actually, yes, the, the sort of, the extreme optimizers and biohackers, I, I think it's, it's almost like theater. It's interesting. Um, I'm glad people are doing it because, you know, maybe we'll, we'll... I'm, I'm sure we'll find out some-

Dr. Rangan Chatterjee 25:17 Yeah

Dr. Tommy Wood 25:17 ... some useful stuff. Um, but the vast majority of people don't want to just live longer. They want to get to 80-something and be in good health for the majority of that time.

Dr. Rangan Chatterjee 25:30 Yeah.

Dr. Tommy Wood 25:30 And why do they want to do that? Because they want to spend time with family and friends. That's like, that's what it boils down to. So it's the spending time with people that, that is the primary motivator for all of this in the first place, right? So you don't wanna miss out on that in the pursuit of it because you'll n- you'll never actually get the thing that you're trying to live longer for in the first place. Um, so I, I think that for most of us, that should kind of like frame why are we even doing this in the first place. Um, to kind of... to go to the, the three S model. So, um, this is kind of, um, my idea of, of how we bring together all these different aspects of lifestyle and the environment that affect cognitive function. But it's actually the, the same, the same principles work for physical function and, you know, med- many other aspects of our health. And so the three S's are stimulus, supply, and support. So stimulus being how, essentially how we're using our brains. The idea, um, is that how we use our brains is the primary determinant of how our brains function, just like the, uh, how we use our bodies is the primary determinant of how our bodies function. Um, and that could be, you know, learning, skill building, languages, music but of course, like social interaction. And, and there are, um, many examples where there's an outsized benefit from something that includes doing it with other people, uh, be that volunteering or sports, you know, dancing. And like similarly, languages, music often happen with o- with other people, right? That's why, that's why you do it, um, is to play with other people or, uh, perform in front of other people or to kind of do something communally. And so that kind of is the driver of adaptation, building structure and function in the brain. And then you kind of activate networks in the brain. Um, in order for those networks to do what you're asking them to do, you need a supply of various things. So that's our second S. So it's, uh, blood supply, um, energy supply, and then nutrient supply. So these things come from physical health, cardiovascular health, um, diet quality. And then like we were kind of talking about earlier, right, we know that stimulus drives some version of a stress response. This drives adaptation. So that brings us to our third S, support. And at- most adaptation happens during sleep, but essentially during periods of rest. So that's the, the kind of major part of support. Um, but then we can support adaptation in other ways. Hormonal status is important, as well as avoiding, you know, and other kind of aspects of physical health that sort of support adaptation. And then, uh, avoiding things that impair that process, so alcohol, smoking, certain environmental exposures that, that can kind of increase inflammation or oxidative stress, and which, some of which I think we'll get to today. So that's kind of, that's kind of the three S's. But so many of... Like, the, the overall goal of thinking about the three S model, and then many of the primary inputs in the stimulus bucket come from things that either we learn and do with other people or where we can... we want to express them and use those skills and abilities with other people. Um, or cognitive functions, be able to, you know, play with our grandkids or, uh, you know, um, do any kind of, uh, sort of sport or other activity, um, with them. And that's why we're trying to maintain function in the first place. So I really think that, um, that part of human connection is, is critical to all of this. And I will say that, um, I wrote a paper on this with my colleague Josh Turknett a few, a few years ago, talking about how the sort of potentially the primary driver of loss of function with age, and this was focusing on cognitive function, was s- stopping doing the things that maintain function, right? Stopping stimulating the brain. Um, and then when I spoke to my friend Julian Abel-

Dr. Rangan Chatterjee 29:23 Yeah

Dr. Tommy Wood 29:23 ... who is, um, you know, famous for his work in compassionate communities and, um, you know, the importance of social connection on health, his response was like, was, "Yes, this is great, but of course it's all driven by the human need for social connection," because so much of this happens through our connections with other people. And I... You know, he's absolutely right. That is sort of like fundamental to, to so much of this.

Dr. Rangan Chatterjee 29:45 DO HEALTH is a preventative health app I've created to help you understand when your health is starting to move in the wrong direction. 46% of our members have discovered they had an elevated cardiovascular risk they had no idea about, and over 25% have found out they had suboptimal homocysteine levels, which is really important because elevated homocysteine levels are linked to an increased risk of Alzheimer's and heart attacks And it's actually really simple to bring down. DO HEALTH takes everything I've learnt about health over the past 25 years and makes it personal to you. An initial blood test screens you for over 50 biomarkers, but then we zero in on the 11 core markers that relate to your metabolic health. And as you may know, poor metabolic health sits at the heart of many of the chronic diseases that affect us, including heart attacks, strokes, and dementia. Every four months, you retest your blood to see what's changing and what's not, and in between, you have unlimited coaching with our in-app Coach Joy, and together, we help you build a plan that's personalized to you. If you wanna start your own DO HEALTH journey, you can do so right now. All you have to do is scan the QR code on screen or go to the link in the description box below. If you're feeling stressed or as if life is a bit overwhelming, I've put together a free guide to help. It contains three practical tools I've seen help the most when stress starts to build. Now, it's important to recognize that a little bit of stress is normal, but when it accumulates, it can start to have negative consequences for our health and happiness. That's when these simple techniques can make a real difference. I explain all of them in my guide, Break Free from Stress, and it's yours for free today. Simply scan the QR code on screen or tap the first link in the description box below, and I'll send it immediately to your inbox. With a few small changes, you can feel a little calmer right away. Can we say that social isolation is a form of stress?

Dr. Tommy Wood 32:07 So yes, on multiple levels. We, we see in controlled studies that being socially isolated increases stress responses, which you can, you know, measure through things like heart rate variability and cortisol levels. And there are studies where they've done this. For instance, NASA and other space agencies around the world have wondered, how will people do if we sp- if we send them to Mars, right? So there have been some Mars simulation, uh, projects where you put people either on their own or in a very small group in a, in a tight confined space, um, for an extended period of time. And even that for just weeks significantly increases stress responses. We know it's inherently stressful. Even, even if there are other people there, it's y- you're relatively isolated-

Dr. Rangan Chatterjee 32:54 Mm

Dr. Tommy Wood 32:54 ... because there's only one or two other people. Um, and we also know that when you look at p- when you look sort of across a big population, those who are more social isolated, particularly those who feel lonely, they have other markers of, of, um, a hi- a heightened stress response. So you can measure these stress responses in people who are isolated in a vari- variety

Dr. Tommy Wood 33:17 of different ways, either experimentally or just as part of their, you know, unfortunately, where, where they are in the world right now. Um, on the other side, you can also see a response or changes in the brain with social isolation that look like the removal of stimulus and accelerated brain aging. So when you look at the areas of the brain that are m- the human brain that are most driven by the environment and are most driven by experience and sort of interaction with the world around you, th- they're also responsible for some of our most complex cognitive functions. Um, areas like, uh, the, the prefrontal cortex, the lateral parietal lobe, the, the lateral temporal lobes are kind of like the front and sides of the brain, essentially, which are responsible for things like decision-making, focus and attention, memory, language, you know, uh, vision or visual processing, social cognition, things like that. These areas of the brain are essentially completely undeveloped at birth. They are... Their development is driven by the environment and how you engage with it, um, during childhood and then, uh, early adulthood. But these are also the areas of the brain that are most susceptible to the processes of aging, particularly the removal of stimuli, right? Um, I, I mentioned earlier that p- part of the reason why I think our brains age is because we stop doing the things that help-

Dr. Rangan Chatterjee 34:38 Mm

Dr. Tommy Wood 34:38 ... build these functions in the first place, interacting with other people, learning skills, focusing on stuff, um, you know, kind of doing complex, um, activities. And those areas of the brain that I just mentioned, when you look at people who are socially isolated, those areas of the brain are the areas of the brain that tend to either get smaller or tend to lose function.

Dr. Rangan Chatterjee 35:00 Mm.

Dr. Tommy Wood 35:00 And they've done studies where you look at, yeah, so people from those like sort of, uh, simulated Mars trip studies or people who, um, were, uh, polar explorers, right, on their own off, you know, on some snowy glacier for months on end, or, uh, in, uh, prisoners who are placed in solitary confinement. Those same areas of the brain that I mentioned tend to lose structure and function as a result of that loss of social input. So not only is, uh, social isolation and loneliness, not only are they inherently stressful, you're also removing a critical input that maintains these really important structures in our brains.

Dr. Rangan Chatterjee 35:39 Even if you're a polar explorer, right, and you're getting stimulated by all kinds of things in your environment, and, you know, you have to be vigilant and all k- all kinds of stuff, right? Even with that kind of stimulation, you're missing out on a very important part of stimulation or stimulation for the human brain. And it made me think, the brain needs stimulation, and this, I guess, fits in with the second mistake of focusing on solo health habits at the expense of social connection. Let's say you're an 80-year-old and you live by yourself, okay? And you've heard Tommy Wood or you've read your book and you go, "Yeah, I need to stimulate my brain." So you are ... learning new skills on your computer, you're competing at chess online with other people, but you're doing it all in isolation

Dr. Tommy Wood 36:27 Mm-hmm

Dr. Rangan Chatterjee 36:27 So you're giving it a lot of stimulus, but it's individual stimulus as opposed to social stimulus. Can we say then, or, or do- can we hypothesize that even with all that stimulus, you are still missing a significant primary stimulus that the brain needs, which is social connection?

Dr. Tommy Wood 36:51 The way that I would answer it is that if that person feels lonely or feels that beyond what they're currently doing, they lack some kind of purpose or meaning, then yes, I, I think-

Dr. Rangan Chatterjee 37:09 Mm

Dr. Tommy Wood 37:09 ... there's more to be gained. If that life is incredibly fulfilling to them-

Dr. Rangan Chatterjee 37:14 Yeah

Dr. Tommy Wood 37:14 ... which for some people it will be, then no, I couldn't say, "Well, you have to go out-

Dr. Rangan Chatterjee 37:19 Yeah

Dr. Tommy Wood 37:19 ... and make friends," right? So I, I think some of it is gonna come down to, like, fundamentally, how do you feel about the kind of setup and your current connection to other people? Because often when you talk about social connection, and q- and rightly so, some people will say, this is directed at extroverts who like-

Dr. Rangan Chatterjee 37:39 Yeah

Dr. Tommy Wood 37:39 ... to spend time with other people, right?

Dr. Rangan Chatterjee 37:40 I was, I was literally gonna bring that up.

Dr. Tommy Wood 37:41 Yeah, yeah.

Dr. Rangan Chatterjee 37:41 Exactly.

Dr. Tommy Wood 37:42 Um, and you can be connected to a lot of people and still feel lonely. Um, and some people, um, only need a very small amount of, of human connection to feel like th- you know, they're getting everything they need. Um, my friend, uh, Dr. Ben, uh, Ryan, who wrote a, uh, wrote an excellent book called Why Brains Need Friends, you know, talks about, um, you know, a, a, a flower in a pot. And like some people, the, the soil in the pot needs a lot of watering, right? It needs a lot of social connection for them to feel kind of fulfilled. But, like, some people are a succulent or a cactus, right? They only need a little bit, and they'll... and they, the- they feel just fine. And, like, wherever you are on that spectrum is absolutely fine, as long as you're getting what you need to feel like you're connected, to feel like you're supported, to not feel lonely, to feel like you have, you know, some kind of... you know, your life has some meaning, you know, outside of-

Dr. Rangan Chatterjee 38:31 Mm-hmm

Dr. Tommy Wood 38:31 ... ju- just yourself. So I wanna make that very clear, that it will come down to how you feel about the situation.

Dr. Rangan Chatterjee 38:38 Yeah. That's a really important point, and I think for those people who were pushing back when they heard-

Dr. Tommy Wood 38:42 Yeah

Dr. Rangan Chatterjee 38:43 ... social connection, I think that hopefully appeases people-

Dr. Tommy Wood 38:45 Yeah

Dr. Rangan Chatterjee 38:45 ... and, and helps clara- clarify things. Okay, we've done two of these mistakes so far, mindset and this solo health habit focus at the expense of social connection.

Dr. Rangan Chatterjee 38:56 Um, I wanna go to some areas that I think we haven't spoken about before.

Dr. Tommy Wood 39:02 Mm-hmm.

Dr. Rangan Chatterjee 39:02 One is blood pressure. So I would say mistake number three that I think gets made a lot is ignoring high blood pressure. Do you agree with that statement, Dr. Wood?

Dr. Tommy Wood 39:11 Yeah, uh, yes. Um, and I didn't necessarily realize it until I was doing the research for my book, but the evidence for blood pressure management and dementia risk is actually incredibly strong. It's one of the few interventions where we have multiple randomized controlled trials that have been put into meta-analyses to show that if you address this risk factor, you see a significant reduction in dementia. Um, most of the other things we talk about come from big population studies, observational studies. Yes, we're pretty sure that that connection is there, and if you, you modify this ris- risk factor, you'll see, you'll see benefit. But blood pressure actually has really high quality evidence. So, um, when... When we talk about blood pressure normally, we're, we're usually thinking about heart health, right, and, you know, heart disease risk, and it's obviously important there too. Um, but if I've learned one thing over the, over the past few years is that even when people are taking cardiovascular disease risk fairly seriously, it's not as much of a motivator for behavior change as we might hope. Um, whereas when we think about this in terms of our brains-

Dr. Rangan Chatterjee 40:28 Yeah

Dr. Tommy Wood 40:28 ... often that's the... right? Somebody wouldn't maybe worry about their blood pressure. "Oh, it's a little bit high. Hmm-

Dr. Rangan Chatterjee 40:33 Mm

Dr. Tommy Wood 40:33 ... it's, it's, it's probably fine." Um, when you then realize that this is a, you know, a, a critical risk factor for the majority of dementias, both Alzheimer's disease and vascular dementia, which have a lot of overlap, and, and between them, they make up 70% to 90% of dementias. Often that's the key maybe to, for, for people to think about it, but we don't really think about the, the brain when we think about blood pressure. But, um, we know that once your, uh, blood pressure goes, you know, much above sort of 120 over 80, and you really once you get into the sort of the metabolic syndrome le- uh, criteria level of blood pressure, which is usually 1, over 130 over 85, you see a significant increase in the risk of dementia, and if you can reduce it, um, you see a significantly reduced, uh, risk of dementia. And the sort of the, the average benefit is if you can get your systolic blood pressure down by about 10 points, you see a significant benefit in terms of your dementia risk. So, um, there are multiple ways to do that. Um, right? We know we can do it through physical activity. We can do it through other, uh, you know, other lifestyle changes to improve metabolic health. But these studies are with blood pressure medications, and you see significant benefit in terms of dementia risk. So if you need a blood pressure medication, uh, or your blood pressure is high and is not fully controlled, you know, I, I think that is something that we really should take seriously.

Dr. Rangan Chatterjee 41:49 Yeah. I guess one of the problems with, or, or potential problems with, uh, blood pressure is that people often don't feel-

Dr. Tommy Wood 42:00 Hmm

Dr. Rangan Chatterjee 42:00 ... anything wrong.

Dr. Tommy Wood 42:03 Yeah.

Dr. Rangan Chatterjee 42:04 They used to call it the silent killer, right?

Dr. Tommy Wood 42:05 Yeah.

Dr. Rangan Chatterjee 42:05 I think.

Dr. Tommy Wood 42:06 Yeah, yeah.

Dr. Rangan Chatterjee 42:06 Certainly in medical school, I'm pretty sure that's what we used to get taught, that it's just going on in the background. I'm literally at the moment trialing the Hilo bands. I think it's the- To my knowledge, it's one of the only FDA-approved continuous blood pressure monitors

Dr. Tommy Wood 42:22 Hmm. Yeah

Dr. Rangan Chatterjee 42:22 The goal is that that is telling you more accurately, whilst you're going about your everyday life, what actually is my blood pressure doing?

Dr. Tommy Wood 42:31 Yeah.

Dr. Rangan Chatterjee 42:31 Um, but of course, you know, there are 24-hour monitors that you can get on the NHS. So there's, there's all kinds of ways, but I guess the, the message you're sort of, I guess, trying to give people around brain health is get your blood pressure checked.

Dr. Tommy Wood 42:44 Yeah. And we've now gotten to a point where you could go to Boots and a blood pressure mon- right, was it 20 or 30 quid?

Dr. Rangan Chatterjee 42:53 Yeah.

Dr. Tommy Wood 42:53 It's probably not that much anymore.

Dr. Rangan Chatterjee 42:53 Probably not anymore.

Dr. Tommy Wood 42:55 And if you do it two or three times a day at home, um, or you could even get it, you know, your GP could prescribe it for you o- on the NHS-

Dr. Rangan Chatterjee 43:02 Mm

Dr. Tommy Wood 43:02 ... right? So you might not even have to pay for it yourself. Um, but just like, like you said, having some, some idea, you know, what's it in the morning, what's, you know, in the afternoon, take it two or three times a day, um, that's gonna give you a much better picture. Plus, you get used to having your blood pressure taken, so you'll have less of that kind of anxiety of, you know, that feels kind of weird and, you know-

Dr. Rangan Chatterjee 43:20 Yeah

Dr. Tommy Wood 43:20 ... getting stressed about what it might be. Um, and I think now it's gotten to a point where blood, you know, relatively regular blood pressure monitoring is, is something that's easy for all of us to do and, and, and, you know, we, we should be doing.

Dr. Rangan Chatterjee 43:33 Yeah. I think that's a good segue to get into the fourth mistake, uh, which is not doing any form of blood testing-

Dr. Tommy Wood 43:42 Mm

Dr. Rangan Chatterjee 43:42 ... until, maybe until you get sick, right? Before we just jump there, though, I guess this is related to blood pressure. I mentioned earlier on in this conversation that over the last 12 months, I have taken up paddle.

Dr. Tommy Wood 43:56 Hmm.

Dr. Rangan Chatterjee 43:58 One thing I've noticed since I started playing, and you've got to bear in mind, it wasn't as if I was sedentary beforehand.

Dr. Tommy Wood 44:04 Mm.

Dr. Rangan Chatterjee 44:04 I was already, I would say, pretty healthy before I started playing paddle. My resting heart rate has gone down by about four beats, right? That is significant. We never covered resting heart rate before. There is a linkage here with blood pressure, of course.

Dr. Tommy Wood 44:20 Mm.

Dr. Rangan Chatterjee 44:20 But, you know, as well as being a brain health expert, you're a performance coach for Formula One drivers and a lot of high-level athletes. What is the benefit of a resting heart rate going down in this context?

Dr. Tommy Wood 44:32 Yeah. The... There are several metrics that you can sort of track physiologically that do seem to correlate with longevity, chronic disease risk, you know, heart dis- you know, heart disease risk in particular. Um, and resting heart rate is, is one of them. Um, heart rate var- variability is another. And I imagine if your resting heart rate has dropped, your heart rate variability-

Dr. Rangan Chatterjee 44:57 That has also gone up

Dr. Tommy Wood 44:58 ... has also certainly gone up. Yeah. Um, and then, um, resting respiratory rate is another one that, that maybe we don't appreciate, uh, as much, uh, which is basically, you know, how many breaths you take a minute. Um, and th- that also seems to be a good predictor of, uh, you know, stress burden and other things, as well as being, you know, related to some aspects of, of, um, long- long-term health. And when your resting heart rate is lower, your heart is essentially more efficient, right, to, to get blood around the body. And we know that those who have a lower resting heart rate tend to be fitter. They tend to live longer. They tend to, you know, have fewer chronic diseases, less, less heart disease. And that's probably a combination of, yeah, improved fitness, uh, decreased, uh, decreased stress responses and, you know, all those kind of things, uh, are, are related to that. So having lower, lower resting heart rate, uh, is absolutely, um, like a, a, a measure of better sort of like overall health and fitness. Like you said, in, in this context, there are times-

Dr. Rangan Chatterjee 45:56 Yeah

Dr. Tommy Wood 45:56 ... when low resting heart rate can, can be a bad thing. You have later risk of things like, um, heart disease-

Dr. Rangan Chatterjee 46:01 Yeah

Dr. Tommy Wood 46:01 ... heart failure. Um, and so by improving efficiency and improving heart function, um, you're decreasing the risk of that happening long term.

Dr. Rangan Chatterjee 46:10 Yeah. And almost certainly, had I been tracking my blood pressure, which I was not-

Dr. Tommy Wood 46:15 Mm

Dr. Rangan Chatterjee 46:15 ... I might also have seen that come down as a consequence, right? Because these things, of course, don't work in isolation.

Dr. Tommy Wood 46:23 Mm.

Dr. Rangan Chatterjee 46:23 Let's get to that mistake number four, you know, this, this idea of not doing any form of blood testing until you get sick. And, and I guess underpinning this as a mistake is an idea that I don't think is widely known with the public.

Dr. Tommy Wood 46:39 Mm-hmm.

Dr. Rangan Chatterjee 46:39 And, and, you know, I, I'd very much appreciate your take on this, which is this idea that the bulk of our medical education, and I would say certainly here in the UK, the way the NHS is, broadly speaking, set up is to diagnose disease-

Dr. Tommy Wood 46:55 Mm

Dr. Rangan Chatterjee 46:55 ... and treat it, okay? And I think it can do that exceptionally well. The creation of health is a little bit different from the diagnosis and treatment of disease.

Dr. Tommy Wood 47:08 Mm.

Dr. Rangan Chatterjee 47:08 And one of my frustrations over the last couple of decades or so has been that we in medicine, and maybe we could argue there's no resource for that within medicine, but for whatever reason, I feel that people are allowed to deteriorate somewhat, not quite get into a disease category, but deteriorate and say everything's fine until actually something happens where we go, "Oh, no, you've got type 2 diabetes."

Dr. Tommy Wood 47:41 Hmm.

Dr. Rangan Chatterjee 47:41 "Let's talk about metformin and insulin and sulfonylureas,"

Dr. Rangan Chatterjee 47:44 and all that kind of stuff, right? So this idea that HbA1c, for example, your average blood sugar marker, here in the UK, at 6.0 on, in old money, um, it becomes prediabetes. At 6.5, you're called a type 2 diabetic. But that does not mean that 5.7 and 5.8 and 5.9 is fine.

Dr. Tommy Wood 48:13 Hmm.

Dr. Rangan Chatterjee 48:14 And many people in the UK, if you go and get an HbA1c test from your doctor, you're told that's normal. Now, there's a resource issue within the NHS, I accept. At the same time, I think our approach to prevention is a little prehistoric. It's, it's kind of a 20th century approach, even though we're now at 2026, we're in the 21st century. And so I believe it's much better if we were able to track certain metrics and start to see when things start to go wrong.

Dr. Tommy Wood 48:51 Mm.

Dr. Rangan Chatterjee 48:52 So we can say, "Hey, listen, you're not pre-diabetic, but you're not where you were a year ago. You're on the way. Uh, would you like some help in making some changes which will perhaps stop this process?" Right?

Dr. Tommy Wood 49:05 Mm.

Dr. Rangan Chatterjee 49:05 So do you have any sort of thoughts on that, initially, at least?

Dr. Tommy Wood 49:08 I completely agree with you. This is relevant to pretty much any chronic disease.

Dr. Rangan Chatterjee 49:14 Yeah.

Dr. Tommy Wood 49:14 It's relevant to, we've talked about blood pressure, it's relevant to blood tests. I mentioned cognitive tests, um, previously, or like just in passing earlier because nowadays you can't get a cognitive test from a neurologist or an old age psychiatrist or who- whoever, whoever would be doing it until somebody suspects you have cognitive impairment. There had to be some trajectory of decline, but we'd no i- no idea where you started, no idea how long that took, no idea how long you've, or like how much function you've lost in order to get to the point where somebody diagnoses you with, say, mild cognitive impairment from a, from a cognitive function test, um, because we, we don't track these things over time. The, a charity that I work with, Food for the Brain, that has an online cognitive function test that people can do for free if they're interested, but more importantly, they just got a big, uh, Invent UK grant to try and develop it so that it can be used in the NHS.

Dr. Rangan Chatterjee 50:04 Mm.

Dr. Tommy Wood 50:04 Hopefully so that people will do it more regularly, um, and then they can track their own function over time. Um, but this relates, this relates to everything.

Dr. Rangan Chatterjee 50:14 Why I think it's so important, right, is because if you were doing an annual cognitive test, you may realize at 48, "Hey, listen, at 45 I was scoring here. At 48, I've just gone down a bit. Jesus. Hey, Doc, what, what can I do here?"

Dr. Tommy Wood 50:31 Mm-hmm.

Dr. Rangan Chatterjee 50:31 So it might motivate people to start these changes earlier.

Dr. Tommy Wood 50:36 Yeah, absolutely. I think that's the case for, for many, you know, very basic blood tests, just like it was, just like it is for blood pressure. We have to have diagnostic cutoffs like the ones you mentioned for pre-diabetes and type 2 diabetes when, when it comes to blood sugar. You have to have some decision-making point where you-

Dr. Rangan Chatterjee 50:53 Sure

Dr. Tommy Wood 50:53 ... then say, "Right, this is the, this is ... Right now it's time to treat with medication." I completely understand why, why we have those. That's very important. But blood sugar is a, is a good example, so HbA1c, because two people can have the same HbA1c but have very different blood glucose or blood sugar-

Dr. Rangan Chatterjee 51:12 Mm

Dr. Tommy Wood 51:12 ... trajectories or experiences over, over the day. Because HbA1c is affected by many other things-

Dr. Rangan Chatterjee 51:18 Mm

Dr. Tommy Wood 51:18 ... including the life of your red blood cells, and there's some genetic components as well. So what they do is they say, "Your HbA1c is this. Your average blood glucose was this." But actually there's m- a huge amount of error in that, right?

Dr. Rangan Chatterjee 51:32 Mm.

Dr. Tommy Wood 51:32 Two people with the same HbA1c can have very different average glucose levels, and one may be problematic, but the other may not be. And so where HbA1c is most useful is tracking your own changes-

Dr. Rangan Chatterjee 51:43 Yeah

Dr. Tommy Wood 51:43 ... over time. So but again, you can't do that unt- unless you have a baseline. What was my HbA1c when I was young, healthy, everything was good, right? Because for some people, that might be close, might be not that far from a pre-diabetic cutoff. For, from other people it, for other people it may, may be much lower. And then it's watching that change over time, and when it does start to change, realizing, oh, maybe, maybe now's the time or, you know, I shou- I should be doing something to intervene.

Dr. Rangan Chatterjee 52:08 Yeah. This is one of the reasons that I have created something called DO HEALTH here in the UK initially. And the, the truth is I, I never had any aspirations to do something like this, a health app, a preventative health app to help people get on top of their health early. But what I realized, Tommy, is that I've been talking about this stuff with the public now for maybe 12 or 13 years.

Dr. Tommy Wood 52:33 Mm.

Dr. Rangan Chatterjee 52:33 And people were saying, "Yeah, Dr. Chatterjee, I get all this, but I'm going to my doctor and I, I, I can't get this."

Dr. Tommy Wood 52:39 Yeah.

Dr. Rangan Chatterjee 52:40 Right? "And some of the tests that you talk about, like fasting insulin or homocysteine, I just can't get. I might be able to get an A1c-

Dr. Tommy Wood 52:47 Mm

Dr. Rangan Chatterjee 52:48 ... but I can't get it regularly. I can't track it."

Dr. Tommy Wood 52:50 Yeah.

Dr. Rangan Chatterjee 52:51 And I've been wanting the NHS to do this in the UK for years.

Dr. Tommy Wood 52:56 Mm.

Dr. Rangan Chatterjee 52:56 I mean, my, my honest hope with DO HEALTH is that within a few years we'll approved the case that the NHS take it-

Dr. Tommy Wood 53:05 Mm

Dr. Rangan Chatterjee 53:05 ... and go, "Actually, we wanna roll this out. Let's see what actually happens." But this idea that if you can empower people early, you can see certain things early, you can actually do something about it, and there's, you know, there's coaching built in and all this kind of stuff which, so it's not just do it, it's like let's find out where your current state of health is. Let's help you make changes, and then let's recheck to see if those changes actually made a difference.

Dr. Tommy Wood 53:31 Mm-hmm.

Dr. Rangan Chatterjee 53:31 I don't wanna go through all the tests that we're doing, but two I th- I'd love your take on, and, and I really pushed

Dr. Rangan Chatterjee 53:37 hard for these two because you can't really get these easily on the NHS, is fasting insulin-

Dr. Tommy Wood 53:42 Mm

Dr. Rangan Chatterjee 53:43 ... and homocysteine.

Dr. Tommy Wood 53:44 Mm-hmm. Both are very important. Um, homocysteine, w- we'll start with. So homocysteine is a, is a marker related to methylation in the, in the body, uh, particularly related to the status of, um, B vitamins related to methylation. So B12, folate, B6, and riboflavin for, for most people potent- you know, um, that there may be a genetic component as, uh, there, there as well. So the two most impo- the two most important, um, are B12 and, and, and folate. And we know that having elevated homocysteine is associated with a higher risk of, um, cardiovascular disease, but also in particular dementia. So, um- It also influences the trajectory of cognitive decline. So those who have, um, elevated homocysteine have, um, a more rapid rate of brain atrophy, right? Their brain shrinks faster, and they lose, um, co- uh, cognitive function faster, or their cognitive decline ... or their cognitive function declines more rapidly. Um, the sort of the threshold based on the randomized controlled trials that, that have been done is probably somewhere around 10 or 11. So ideally, you'd get your homocysteine below 10. You definitely want it below 13 because that's, that's considered elevated, and, and you'd see a, a more, uh, rapid cognitive decline associated with that. And then the, the intervention that you would do is, you know, supplement with B vitamins or make sure that you get enough B vitamins, uh, i- in your diet. Um, the proportion of people who have very high, um, homocysteine has come down a bit in countries that have started to fortify white flour with folic acid. So in, in the ... There's big population, uh, studies done in the US where they started to fortify flour with folic acid in 1998. Um, the proportion ... The number of people who had elevated homocysteine did decrease, uh, after that. So just we know that getting more of this in the diet definitely, uh, brings homocysteine down. Randomized controlled trials have used, uh, folate and B12, uh, s- and then s- plus or minus B6 as well. Um, and we also know, uh, people, in particular people who have MTHFR polymorphisms, they have elevated homocysteine if they don't get enough riboflavin. But by enough, I just mean the, the recommended daily allowance.

Dr. Rangan Chatterjee 56:11 Uh, Tommy, I know what you mean when you say that, but-

Dr. Tommy Wood 56:12 Yeah

Dr. Rangan Chatterjee 56:12 ... a lot of people will hear MTHFR polymorphism-

Dr. Tommy Wood 56:15 Yes. Uh-huh

Dr. Rangan Chatterjee 56:16 ... and go, say, "Come again?"

Dr. Tommy Wood 56:17 [laughs]

Dr. Rangan Chatterjee 56:18 Right? So could you d- could you just try and explain-

Dr. Tommy Wood 56:20 Absolutely

Dr. Rangan Chatterjee 56:20 ... uh, in layman's terms what that means?

Dr. Tommy Wood 56:22 Yeah. So unfortunately, um, you'll actually ... You know, I, I imagine a lot of people who've, who listen to this podcast will have heard about MTHFR. It's a, it's a gene, a methylenetetrahydrofolate reductase, um, there'll be a test later, um, that, that is in- involved in this sort of methylation pathway int- in- into, uh, which is essentially ... Well, what methylation is, maybe let's, let's talk about that. Methylation is this process of moving, um, carbons with some hydrogens attached. There's one carbon with three, three hydrogens is a, a, a methyl group, moving them around the body. And when you move methyl groups, you turn on genes, you activate proteins, you ... It's, it's like this really important signaling molecule that we use to kind of control biological processes. Um, and there are ... You know, the, the B vitamins are involved in kind of providing the, the m- the methyl groups for our body to do that, just to kind of move these signals around to turn things on and off. Um, and so one of the, the enzymes in that pathway, MTHFR, it's very common. Most of us have a polymorphism, which is just a slightly different genetic code that makes this enzyme-

Dr. Rangan Chatterjee 57:37 Mm

Dr. Tommy Wood 57:37 ... that just changes how that enzyme functions a little bit. Um, and we're often ... You know, if you go out into the world and you look up M- MTHFR, it's, uh, usually, like, sold as this disastrous thing, like your body can't do these methylation processes, and you need all these fancy supplements to overcome it. None, none of that is true. And so if you go out and see a bunch of doom and gloom around MTHFR, I would ignore the vast majority of it because most of us, actually the majority of people, have, you know, one of these polymorphisms that changes activity a little bit. But what these polymorphisms do, and they absolutely have some kind of benefit, right? Because, you know, most of them, most of us have at least one, um, is it changes how that enzyme binds to a cofactor, a cofactor being the thing that just allows that enzyme to run. Um, and that cofactor is made from riboflavin, which is vitamin B2. Um, and there are studies, randomized controlled trials that show that if you just get enough riboflavin, um, which you can find in whole grains and liver and things like that, um, then, then it's not, then it's not an issue. So for most people, if you go out and you kind of see what's on the internet, you'll be told that things like homocysteine and methylation are driven by your genetics. They're not. They are largely determined by nutrient status-

Dr. Rangan Chatterjee 59:02 Mm

Dr. Tommy Wood 59:02 ... just getting enough B vitamins. Um, so if you, if you just get the recommended daily allowance, you've ticked that box. Um, but if you do measure homocysteine and it's elevated, then the other B vitamins, um, are a great place to start. There are some other things that you can think about, um, as well, but, you know, those core B vitamins are really the, the, the main drivers.

Dr. Rangan Chatterjee 59:23 This just highlights something that has happened in the last 24 hours. So one of my really good mates has just done their DO HEALTH blood tests, and he texts me yesterday, say, "Mate, I've got my results, and I'm loving it, loving the whole thing, and the app, and the explanations." And I said, "Mate, if you're open to sharing, um, send me them, and I can give you some advice if you want." Now, we ... You know, he gets advice on the app anyway, but his homocysteine was 15.

Dr. Tommy Wood 59:51 Mm.

Dr. Rangan Chatterjee 59:52 Okay? Now, now, why I, why I'm so passionate about this, Tommy, is that you've already mentioned, and I don't know if we've covered before or not, but this idea that e- elevated homocysteine can increase your risk of cognitive decline as you get older.

Dr. Tommy Wood 1:00:07 Mm-hmm.

Dr. Rangan Chatterjee 1:00:09 He has a family member who has got dementia.

Dr. Tommy Wood 1:00:12 Mm-hmm.

Dr. Rangan Chatterjee 1:00:14 Now, it could well be for this individual that this elevated homocysteine is increasing his risk of cognitive decline like some family members of his. I'm being very careful so it's not possible to identify who this person is I'm talking about, okay? And so what's really interesting is if you don't have your homocysteine checked-

Dr. Tommy Wood 1:00:39 Mm

Dr. Rangan Chatterjee 1:00:39 ... which is the norm at the moment, I would say, in the NHS, then you don't know a critical piece of information that is actually quite easy to address.

Dr. Tommy Wood 1:00:50 Yeah.

Dr. Rangan Chatterjee 1:00:50 I said to him, "Listen, mate, you can try it with diet. If that doesn't work, it's quite easy with relatively simple supplementation of B vitamins and folates to bring that down." I said, "At the same time, mate, you've gotta be... You've gotta understand that your omega-3 status is also important here, you know?"

Dr. Tommy Wood 1:01:08 Yeah.

Dr. Rangan Chatterjee 1:01:09 But the point is, is that that piece of information will directly impact his behavior.

Dr. Tommy Wood 1:01:15 Mm.

Dr. Rangan Chatterjee 1:01:15 And when he rechecks the bloods in four months, we will know has that made a difference. If it has, great. Have we brought it down under 13, but ideally under 11, under 10? And that is a meaningful piece of the picture in terms of his risk of getting dementia in the future. So when I think about prevention, one of the things that led to me doing all the work to try and create this is to go, well, there is another model out

Dr. Rangan Chatterjee 1:01:43 there for, for prevention that doesn't currently exist. But any comments at all on what I just said about homocysteine and, and sort of my friend and how he can meaningfully reduce his risk of getting sick in the future?

Dr. Tommy Wood 1:01:53 Yeah. One of... So one of the reasons why homocysteine isn't routinely measured, um, is because homocysteine had a moment 20 years ago, uh, in cardiovascular disease and, and neurological disease or neurodegenerative disease prevention. And then there were some trials where they gave people vi- B vitamins, and they didn't really see much of an effect. And so everybody, like, if you speak to neurologists now, most of them will say, "Oh, well, we looked at homocysteine, and we tried it, and the supplements don't work." Now, the critical part of that then-

Dr. Rangan Chatterjee 1:02:30 Yeah

Dr. Tommy Wood 1:02:30 ... is what you mentioned about omega-3s, and this has now been replicated in multiple clinical trials. And it, it actually makes perfect sense that if you take a person and they have insufficient levels of one B vitamin, they're pro- or one vitamin, one nutrient, they're probably gonna be insufficient in others, right? Not everybody, but in general, um, these things don't come one at a time. And when we've done, um,

Dr. Tommy Wood 1:03:01 clinical trials in the past, we haven't looked at a full picture of somebody's nutrient status and kind of addressed multiple things at the same time. We're just like, we just... Uh, we've done the same thing with omega-3s actually. This person's at high risk of dementia. We give them omega-3s. Does it decrease their dementia risk? Nah, it doesn't seem to have a big effect in most clinical trials because we didn't check whether this person needed more omega-3s in the first place or not. Plus, nutrients don't act one at a time.

Dr. Rangan Chatterjee 1:03:26 Yeah.

Dr. Tommy Wood 1:03:26 Right? Um, in order for, to, like, a send a, to send a signal in the brain, you need, uh, B vitamins, right, for mitochondrial functions, right, to, to, for your, for your brain to make the energy to send the signal in the first place. And then, um, you need to send that signal down a long kind of arm of the neuron. We call an axon. And it's got this sort of wrapping of fat around it to kind of, uh, allow that signal to be transmitted faster called myelin. And then it's like iron status is really-

Dr. Rangan Chatterjee 1:03:55 Mm

Dr. Tommy Wood 1:03:55 ... critical for myelin. And then you get to the end, um, of... And you're trying to send the signal. And if it's like a, a serotonin, uh, neuron, um, right, then we need vitamin D in order to make that serotonin in the first place. And we need omega-3s to kind of sit at the end of that, um, neuron at the synapse that sends the signal to the next neuron. Um, we need, like, DHA, which is a long-chain omega-3, kind of concentrates there 'cause it's really-

Dr. Rangan Chatterjee 1:04:20 Mm

Dr. Tommy Wood 1:04:20 ... important to kind of make the, the little, um, sort of envelopes or vesicles of, of neurotransmitters to send them, right? So you need all of those things for that to happen at its kind of best.

Dr. Rangan Chatterjee 1:04:32 Mm.

Dr. Tommy Wood 1:04:33 Um, and so for this reason, when you look at sort of multicomponent interventions, or you look at the status of multiple nutrients, you see that they interact. So the first time this was found, uh, this was the VITA-COG study run by, uh, by David Smith, um, at the University of Oxford.

Dr. Rangan Chatterjee 1:04:51 Yeah.

Dr. Tommy Wood 1:04:52 And this was the first study to show that if you have people with high homocysteine and you give them B vitamins, you slow their rate of, um, brain atrophy and cognitive decline, but only if they have adequate omega-3 status. Um, that's now been replicated in multiple clinical trials, that you can't just address one or the other. You need B, B vitamins, and you need omega-3s. Um, so this is one of... You know, thinking about this as, like, a single variable nutrient-

Dr. Rangan Chatterjee 1:05:17 Mm

Dr. Tommy Wood 1:05:17 ... problem is one of the reasons why it's hard to get a homocysteine test today because those previous trials didn't kind of address this full, this, this full picture. Um, but-

Dr. Rangan Chatterjee 1:05:27 But that's the kind of hangover of the kind of reductionist approach to health that we've taken, right?

Dr. Tommy Wood 1:05:34 Yeah.

Dr. Rangan Chatterjee 1:05:34 Which, which is, is obviously how we test pharmaceutical interventions. You know, you get 100 people, 50 get the drug, 50 don't. Is there a difference?

Dr. Tommy Wood 1:05:42 Yeah.

Dr. Rangan Chatterjee 1:05:43 But of course, as you're saying, you know, and, and I love the VITA-COG trial, this idea that, yeah, lower the homocysteine, and it will lower your risk of cognitive decline if you have sufficient omega-3.

Dr. Tommy Wood 1:05:57 Yeah.

Dr. Rangan Chatterjee 1:05:57 If you don't, it won't.

Dr. Tommy Wood 1:05:58 Yeah.

Dr. Rangan Chatterjee 1:05:59 I think it's very, very empowering, which is why I told my buddy. I said, like, I said, "Yeah, omega-3 needs to be there as well, right?"

Dr. Tommy Wood 1:06:05 Yeah.

Dr. Rangan Chatterjee 1:06:05 So of course, testing omega-3 is a little bit harder.

Dr. Tommy Wood 1:06:08 Yeah.

Dr. Rangan Chatterjee 1:06:08 Do you think people need that? Or if they're... I guess if you're, if you're eating fatty fish two to three times a week, do you really need an omega-3 test?

Dr. Tommy Wood 1:06:17 Yeah.

Dr. Rangan Chatterjee 1:06:17 Maybe if you're vegan, it's a good idea. You know, how do you think about this?

Dr. Tommy Wood 1:06:20 Yeah. It, it's an important question because very quickly we can accumulate a large, you know, bill of tests, right?

Dr. Rangan Chatterjee 1:06:29 Yeah.

Dr. Tommy Wood 1:06:29 A large costs for, for all these tests. But I, I will say that, so Food for the Brain, the charity that I mentioned, does have an at home blood test called the DRIFT test that includes HbA1c, vitamin D, homocysteine, and omega-3 status. Um, you have to, you have to, you have to pay for it. It's Some of them are 100 and £200, so it's not cheap. Um, and I'm not saying that everybody needs to do that test, but if somebody wants to test-

Dr. Rangan Chatterjee 1:06:55 Yeah

Dr. Tommy Wood 1:06:55 ... omega-3s, right, that, that is an option. Um, the... When you then think about testing omega-3 status, dementia risk, if you're regularly eating fatty fish, cold water fish, sardines, mackerel, salmon, um, two or three times a week, you probably don't need-

Dr. Rangan Chatterjee 1:07:16 Yeah

Dr. Tommy Wood 1:07:16 ... you probably don't need to test. Um, equally, if you're not doing those things and you'd rather just, you know, take a high quality fish oil or omega-3 supplement, I think that's fine too. And often, um, you know, w- when I talk about this, yes, uh, those who are vegetarian or vegan, they certainly have questions I would recommend, uh, like an algal, you know, an-

Dr. Rangan Chatterjee 1:07:38 Yeah

Dr. Tommy Wood 1:07:38 ... an algae-based, uh, omega-3 supplement. So it's, you know, it's not, um, an, an animal-based sup- supplement, but you, you, you can still get those fats in your diet and then, you know, you take, you know, one to two grams of, of omega-3s a day. That's probably gonna cover your bases. That's gonna, you know, that's... I think that's gonna be enough for most people.

Dr. Rangan Chatterjee 1:07:57 Yeah. W- we, on DO HEALTH, we don't actually test omega-3.

Dr. Tommy Wood 1:07:59 Mm.

Dr. Rangan Chatterjee 1:08:00 Um, maybe it's something we'll bring in at some point. In fact, one thing I was very clear on is that over-testing is a massive problem.

Dr. Tommy Wood 1:08:08 Yeah.

Dr. Rangan Chatterjee 1:08:08 You know, one thing I've... I know in America there's loads of companies now who are doing, you know, we're gonna do 200 biomarkers, we're gonna do 400, we're gonna do 600, right? And I get that. One thing clinical practice has taught me is that too much data and too much information becomes very, very confusing. So our focus really is on what I call the 11 core biomarkers, which are, I think, 11 biomarkers which have a really good amount of evidence-

Dr. Tommy Wood 1:08:35 Mm-hmm

Dr. Rangan Chatterjee 1:08:35 ... and science behind them, which are all to do essentially with metabolic health.

Dr. Tommy Wood 1:08:39 Yeah.

Dr. Rangan Chatterjee 1:08:40 And interestingly enough, and I, I can't remember the exact statistic, just on homocysteine, Tommy, I think so far the few thousand people who've gone through, I think over 25, might even be over 30% of people have got elevated homocysteine, which is quite interesting.

Dr. Tommy Wood 1:08:55 Yeah. There's been some recent discussion about where these blood tests fit in, in dementia prevention in particular. So, um, I think last time we talked about the Lancet, uh, Commission-

Dr. Rangan Chatterjee 1:09:07 Yeah

Dr. Tommy Wood 1:09:07 ... report on dementia prevention run by Professor Jill Livingston. They identified 14 modifiable fac- uh, risk factors for dementia, estimated that 45% of dementias may be preventable if-

Dr. Rangan Chatterjee 1:09:17 But, but diet wasn't in that, was it?

Dr. Tommy Wood 1:09:18 So-

Dr. Rangan Chatterjee 1:09:18 In those 14, I don't think

Dr. Tommy Wood 1:09:19 ... no, no, it, it wasn't. Um, and so there were-

Dr. Rangan Chatterjee 1:09:22 Interesting

Dr. Tommy Wood 1:09:22 ... there were actually letters written to The Lancet where it was published, and then there was... This was actually discussed in the sort of popular media as well, that B vitamins and omega-3 status weren't discussed, you know, even though we have some fairly good evidence for those. Um, I absolutely don't wanna put, like, words in people's mouths, but there was some discussion as to whether insufficiencies in B vitamins and omega-3s were common enough that it was worth kind of, you know, building an evidence base around them. But, like, I think you're right that particularly as people get older, 10 to 20% of individuals at least may have elevated homocysteine. So that's, like, a significant chunk. Um, uh, you know, previous analyses done, uh, by other groups suggested that potentially up to 20% of cases of dementia were related to elevated homocysteine and, uh, low levels of omega-3s. So that's, you know, even if, even if it's not 20%, it's still a meaningful-

Dr. Rangan Chatterjee 1:10:17 Significant, yeah

Dr. Tommy Wood 1:10:18 ... it's a, it's a meaningful, uh, contribution to, to future risk. So, um, yeah, I, I think to, to kind of go to your original point about, like, what's it worth testing, I also agree that just, like, more testing isn't, isn't always the answer, and I do agree with this idea that if you're doing a test, you should be answering a specific question. Like, why am I doing this test? So, um, rather than just, like, doing a scattergun, um, test everything, and right in, in, in medicine, we have this idea of a, a pre-test probability. Like, how likely is it that you're gonna find something that you... and that you can address it?

Dr. Rangan Chatterjee 1:10:54 Yeah.

Dr. Tommy Wood 1:10:54 Um, and I think that's really important. So we focus on metabolic health. Uh, we know that the vast majority of adults have at least one, um, risk factor for metabolic disease-

Dr. Rangan Chatterjee 1:11:07 Yeah

Dr. Tommy Wood 1:11:07 ... right? So it's very likely that you're gonna find, um, some kind of modifiable metabolic health risk factor.

Dr. Rangan Chatterjee 1:11:13 And that's why we focus on metabolic health, and, uh, had a criteria when choosing the 11 that there's got to be a good evidence base behind them, and we've got to be able to do something with the results.

Dr. Tommy Wood 1:11:23 Yeah.

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Dr. Rangan Chatterjee 1:12:35 30 free days to establish your own meditation practice. All you have to do is click on the QR code on screen or go to thewayapp.com/livemore to get started. I guess- In answering some of the stuff around homocysteine and omega-3s, we, we've slipped into mistake number five-

Dr. Tommy Wood 1:12:57 [laughs]

Dr. Rangan Chatterjee 1:12:57 ... which is, uh, thinking all supplements are a waste of money.

Dr. Tommy Wood 1:13:01 Uh-huh.

Dr. Rangan Chatterjee 1:13:01 Okay. So again, the framing here is that Tommy's been on this show four times in the past, so this is appearance number five. If you haven't heard the first four, please go and listen to them. They're a wealth of information. The whole point of today is to go through common mistakes that people often make when it comes to, uh, brain health and longevity. We've done four so far. We've covered mindset, social connection, high blood pressure, and sort of testing. The fifth one, which I think relates to what we've just been talking about, is this idea about, you know, supplements. Thinking all of them are a waste of money I think is a common mistake.

Dr. Tommy Wood 1:13:37 Mm.

Dr. Rangan Chatterjee 1:13:37 You've already mentioned the potential benefits of B vitamins and omega-3s. Uh, I wanna go through some other supplements with you to get your take on them, but I wonder if it's worth talking about the COSMOS trial-

Dr. Tommy Wood 1:13:48 Yeah

Dr. Rangan Chatterjee 1:13:49 ... and what your take is on that trial, 'cause I thought it was really quite illuminating.

Dr. Tommy Wood 1:13:53 Yeah. So the, the COSMOS trial was a, a recent trial run in the United States. Thousands of people, it was a massive trial, um, older adults, um, randomized into four different groups. So they had a control group, um, and then they had a group that took a basic multivitamin. Uh, Centrum Silver was the multivitamin. It, it, Centrum Silver essentially just has 100% of your RDA of, like, the basic vitamins. Um, another group got a cocoa flavanol supplement. So cocoa flavanols are, like, the, the polyph- like the antioxidant polyphenols that are in cocoa. You know, you s- you have similar compounds in coffee, tea, chocolate, uh, berries, uh, for example, like the things that make berries sort of purple and, and red. Um, and then one group got both, right? So we call it, like, a two-by-two design. Um, and what they found was that in the two groups that got the multivitamin, there was a significant reduction in estimations of brain age and cognitive function such that, you know, on average, people's brains acted as, as if they were two years younger. So you kind of saw this slowed-

Dr. Rangan Chatterjee 1:15:05 Mm.

Dr. Tommy Wood 1:15:06 ... slowing of brain aging by taking, uh, a multivitamin. And this is the most basic multivitamin. Like, you go to Boots and you get an over 50s multivitamin. That's essentially what it is. Um, and I'll, I'll, I'll also say this about the VITACOG study. The VITACO... You know, often when we're sold supplements and vitamins we're like, "You have to have this fancy version, and this bioavailable version is gonna cost, you know, X amount of money." The best evidence that we have for multivitamins, for B vitamins is the most basic version-

Dr. Rangan Chatterjee 1:15:34 Mm

Dr. Tommy Wood 1:15:34 ... you know, the essend- you know, the essentials version, you know, some folic acid and-

Dr. Rangan Chatterjee 1:15:38 Mm

Dr. Tommy Wood 1:15:38 ... cyanocobalamin. And fol- These, like, those are f- a form of B12. It's like the cheap-

Dr. Rangan Chatterjee 1:15:42 Mm

Dr. Tommy Wood 1:15:42 ... the cheap version of B12. That's what showed benefit in VITACOG, just like the most basic low, essentially low dose-

Dr. Rangan Chatterjee 1:15:50 Mm

Dr. Tommy Wood 1:15:50 ... multivitamins showed, showed benefit in COSMOS. And there may actually be a thing where your massive doses could potentially be detrimental, whereas, you know, uh, COSMOS just gave you... You hit 100% of your RDA, you've got your bases covered. That's it.

Dr. Rangan Chatterjee 1:16:04 Mm.

Dr. Tommy Wood 1:16:04 And that showed benefit. Um, in the, the, the sort of the cocoa flavanol, um, supplement was a little bit more nuanced, where benefits were largely seen in groups that had low diet quality. So if you're getting few, like, plant polyphenol antioxidants 'cause you don't eat many fruits and vegetables, um, or drink much coffee or tea, because actually, actually coffee is the most, for most people is their primary source of antioxidants in their, in their diet. Um, if, if you had a low quality diet, you know, lots of processed foods, just, like, processed fats and, and, and carbohydrates, and few nutrients, so a nutrient poor diet, then taking the cocoa flavanol supplement was beneficial. If you already... If you have a high quality, nutrient-dense, varied diet, it didn't seem to have as much of an, as much of an effect, res- which I, which I think makes sense.

Dr. Rangan Chatterjee 1:16:53 Yeah. There's often been a negative view with doctors around supplements-

Dr. Tommy Wood 1:17:00 Mm

Dr. Rangan Chatterjee 1:17:00 ... possibly because the industry has been unregulated.

Dr. Tommy Wood 1:17:04 Yeah.

Dr. Rangan Chatterjee 1:17:04 Right? Which, which I, which I get, but the truth is is that I have seen so many patients over the years where the right supplement can be game changing.

Dr. Tommy Wood 1:17:12 Mm.

Dr. Rangan Chatterjee 1:17:13 But I think the COSMOS trial just showed us that actually for, across a broad population, there can be a benefit with the brain for a multivitamin and mineral-

Dr. Tommy Wood 1:17:22 Yeah. Yeah

Dr. Rangan Chatterjee 1:17:22 ... okay? So we think is a, a really good take home.

Dr. Tommy Wood 1:17:24 Mm-hmm.

Dr. Rangan Chatterjee 1:17:25 We've covered B vitamins and omega-3. The supplement of the moment, um, [laughs] is of course creatine.

Dr. Tommy Wood 1:17:33 Uh-huh.

Dr. Rangan Chatterjee 1:17:33 Okay? You take creatine every day. Should the listener also take creatine every day?

Dr. Tommy Wood 1:17:43 I recently heard this nice idea for how to think about supplements that I hadn't really heard before. This is from, um... It was actually, it was, it was on a panel with, uh, Jeff Bland, who, you know-

Dr. Rangan Chatterjee 1:17:55 Oh, yeah

Dr. Tommy Wood 1:17:55 ... many people call him, you know, the father of functional medicine. And the first thing that he said we should think about not is will, could this work for me, is, is it safe? Because if it, if it's safe, then you can try it with very little risk.

Dr. Rangan Chatterjee 1:18:12 Yeah.

Dr. Tommy Wood 1:18:13 Right? If we don't have good safety data, then the will it work for me becomes much m- much riskier.

Dr. Rangan Chatterjee 1:18:20 Yeah.

Dr. Tommy Wood 1:18:20 Right? And so-

Dr. Rangan Chatterjee 1:18:22 So chemotherapy, right?

Dr. Tommy Wood 1:18:23 Yes.

Dr. Rangan Chatterjee 1:18:24 And it, it's like you want really good evidence that this is going to help you before you expose yourself to the downsides.

Dr. Tommy Wood 1:18:30 Yeah, because we, because there are a lot of downsides, right?

Dr. Rangan Chatterjee 1:18:34 Yeah.

Dr. Tommy Wood 1:18:34 Um, and so I think that for most people, um, you know, uh, uh, a very basic level of B vitamin supplement, right, we know it's gonna be safe.

Dr. Tommy Wood 1:18:45 If you're not taking, you know, massive, massive doses, you're just gonna pee out any extra.

Dr. Rangan Chatterjee 1:18:49 Yeah.

Dr. Tommy Wood 1:18:49 Like, worth potentially trying, especially if you've got some markers to kind of suggest that you, you could take it. Vitamin D, trickier, because, um, again, in very high doses, a fat-soluble vitamin, you don't wanna, you know, overdose on vitamin D. There's some, some downsides there. Uh, but we know in people who are vitamin D deficient, absolutely. Well, you, you said it's prescribed on the NHS for people who are deficient. We know it's important. ... brain health, bone health, et cetera. Then you come to things like creatine. One of the reasons why I think it's actually okay that creatine is the supplement at the moment is because we know it is incredibly safe. Um, it's been tested in probably thousands of clinical trials at this point, randomized control trials for various people in various conditions. Uh, low doses, high doses, years at a time. Uh, recent meta-analysis, uh, found essentially no side effects with creatine compared to placebo on, on, on average. Um, and that's probably because it's something that we can get from the diet. Um, maybe not quite at the doses that some people might take, but, you know, close. Um, so we know, you know, assuming that you're getting a high quality source, it's not contaminate- contaminated, that kind of stuff, all right. So you would ... You want a, um, a reputable supplement maker. Hopefully, they've done something we call third-party testing.

Dr. Rangan Chatterjee 1:20:04 Yeah.

Dr. Tommy Wood 1:20:04 It's been tested for, um, impurities. They can send you a certificate to show that they've done that. Every, every good supplement some company will be able to do that. But we know that creatine is incredibly safe, even in sort of like frail older populations. Um, so then we might say, "Well, is there a possibility that it might benefit me?" So creatine has been, um, used for decades as a supplement in, like, sports performance.

Dr. Rangan Chatterjee 1:20:27 Mm-hmm.

Dr. Tommy Wood 1:20:28 Particular- particularly strength and power. Um, it helps you do an extra rep or two, uh, in the gym, and then if you do that over time, you can build more muscle, you can build more strength. Um, the effect isn't huge, but it is statistically significant and meaningful, right? It's not, it's not magic, but it helps you do a little bit more work in the gym, and that compounds over time. Um, it's become of particular interest in the brain world recently because there have been some studies to show that, or actually several different studies to show that it might help, particularly in what we could call or what I might call cognitively degraded states. So something has happened that's affected cognition or mood, and then creatine may, may be of some benefit there. So for the average person who thinks that their brain is working really well, there might not be that much of an effect. And so when you look at, um, meta-analyses, studies of many studies of creatine, it tends to benefit older people, and particularly is beneficial for memory. That's, that's kind of where it's been shown to, to, to have some benefit. Um, in other populations, there's some evidence ... Um, there's actually better evidence in, like, kids with concussions, but there's some evidence that taking creatine after, like, a, a, a traumatic brain injury may help with some elements of recovery. Um, in the, the, the kind of the, the really flashy study that got a lot of, um, press recently was in individuals who were sleep deprived, and they took a high dose of creatine.

Dr. Rangan Chatterjee 1:21:56 Mm.

Dr. Tommy Wood 1:21:56 Uh, it was kind of the equivalent of sort of 20 to 30 grams of creatine when maybe a standard dose is, like, 5 to 10 grams. And they saw, uh, saw that the people maintained brain energetics. You can do a brain scan.

Dr. Rangan Chatterjee 1:22:07 Mm.

Dr. Tommy Wood 1:22:07 You can measure energy, sort of pro- uh, the production of a certain energy metabolites in the brain, and that was ... And cognitive function was retained better when sleep deprived when taking creatine. This was just, like, a single night of sleep de-

Dr. Rangan Chatterjee 1:22:21 Mm

Dr. Tommy Wood 1:22:21 ... sleep deprivation. And there was an older study in rugby players actually that showed that when they were sleep deprived, taking creatine, actually at a, a, a lower dose, sort of 5 to 10 grams, helped to maintain rugby specific skills when they were sleep deprived. Similar to caffeine actually, 'cause they also did use caffeine in that study as a comparison. Um, so in those kind of settings when s- sleep deprived, maybe creatine can help to maintain some elements-

Dr. Rangan Chatterjee 1:22:45 Mm

Dr. Tommy Wood 1:22:45 ... of cognitive function. Um, and then there are a few randomized controlled trials now, um, although some people have suggested that, you know, they were done in countries where maybe the quality of the science isn't as good as in the UK or the US. So some people have kind of questioned the quality of these trials. But it's been shown two or three times that in individuals with depression, um, suppli- you know, adding creatine to, say a medication regimen if they've rec- if they haven't had full, you know, uh, remission of symptoms, um, may, may improve, like, symptoms of, like, mood and wellbeing or, or, or, or depression symptoms and, and again, sort of a, a five gram kind of dose. So lots of different pockets of things suggesting that creatine may be beneficial for the brain, uh, across a wide range of doses. A lot of people are now saying that you need to take a very high dose for it to benefit the brain, but I don't think we've seen that from the studies. I think we've seen benefit even at sort of a standard lower dose.

Dr. Rangan Chatterjee 1:23:43 Which is 5 to 10 grams.

Dr. Tommy Wood 1:23:44 Which is 5 to 10 grams. Um, the ... And the reason why they say that is because when you look at studies of creatine, like increasing creatine levels in the brain, that takes longer and higher doses, but you may actually see benefits of creatine before you're seeing increases of be- of, of, like, creatine levels in the brain, if that makes sense, right?

Dr. Rangan Chatterjee 1:24:06 Yeah.

Dr. Tommy Wood 1:24:06 You don't need to be saturating the brain with creatine to see benefit for the brain, 'cause it could be having other, other effects. Um, there was one study in individual with Alzheimer's disease where they gave them creatine and saw some improvements in cognitive function. However, um, there wasn't a control group.

Dr. Rangan Chatterjee 1:24:24 Mm-hmm.

Dr. Tommy Wood 1:24:25 And we know that when you enroll people with, even with cognitive decline in a study, they tend to do better. They get better at the test. They, they ... Even though, you know, their, some of their cognitive function may be impaired, they do better at the c- test the second time. They start to feel a bit be- feel a bit better. There's a placebo effect of being part of a trial.

Dr. Rangan Chatterjee 1:24:47 Mm.

Dr. Tommy Wood 1:24:47 Connecting with other people is kind of stimulating in its own way. So I tend to not include that trial when I, when I say there may be some benefits-

Dr. Rangan Chatterjee 1:24:55 Mm

Dr. Tommy Wood 1:24:55 ... for creatine for the brain, just because it was, you know, no control group. We know in cognitive ... in, in studies that look at cognitive function-

Dr. Rangan Chatterjee 1:25:03 Mm

Dr. Tommy Wood 1:25:04 ... it's re- you know, it's really hard to, to look at the effect of an intervention without having a control group.

Dr. Rangan Chatterjee 1:25:09 Mm.

Dr. Tommy Wood 1:25:09 Because you get better at the test. There's significant placebo effects, things like that. Um, so but if you're somebody who- ... identifies with any of those things that I mentioned, right? Sleep deprivation, maybe some issues with memory when you're older. You know, you know, maybe you're, you have been diagnosed with depression, and you, you have had some benefit from a medication, but you might consider adding creatine on, which is what, uh, some of these studies have done. Then I think it's worth trying. Um, we know it's safe, it's cheap. Um, it's not, again, it's not gonna be a panacea. It's not gonna be magic. But, you know, I, I think we're starting to see more and more evidence that it may have some benefits for the brain.

Dr. Rangan Chatterjee 1:25:51 Are you happy to share why you specifically choose to take it?

Dr. Tommy Wood 1:25:54 Yeah. I mainly take it from a performance standpoint. So I train for and compete in Strongman, and so I, I, I definitely can tell, um, that I, uh, just a little bit, little bit stronger, you know, little bit faster, uh, in the gym when, when, when I'm taking it. I, I find creatine to be mildly stimulating for me, and that is the case for, for some people. Like, um, like I kinda mentioned, that rugby player study, right? Seeing similar benefits with creatine versus caffeine-

Dr. Rangan Chatterjee 1:26:23 Yeah

Dr. Tommy Wood 1:26:23 ... in the setting of sleep deprivation. Um, and so I definitely notice that if I take it later at night, I don't, I don't sleep as well. And so f- for the same reason, I do feel like I get a bit of a cognitive boost from it, it, when I take it in the morning. But some of it might be the placebo, right? I kind of m- maybe expect some of that. But it could be that if you do get a, a mild stimulating effect from it, whereas caffeine can s- can often, like, overstimulate people, where... So say if you, if you had several espressos before you played padel, you might be sweaty, anxious. You, like, you don't, you don't quite have the accuracy-

Dr. Rangan Chatterjee 1:26:59 Yeah

Dr. Tommy Wood 1:26:59 ... because, right, you're, you're sort of overstimulated. Um, creatine could give us sort of like a mild stimulating effect, and it doesn't happen to everybody, but tho- those who experience it, you know, if you're one of those people, maybe it's useful then. Um, but in terms of sort of the, the strength and the power effects and the fact that, um, you know, padel is more of a sort of aerobic cardio type sport, um, it's less likely to give you that kind of performance benefit. But there's a possibility-

Dr. Rangan Chatterjee 1:27:25 Yeah

Dr. Tommy Wood 1:27:25 ... that in some people there may be some kind of cognitive effect.

Dr. Rangan Chatterjee 1:27:27 And then bringing it back to the start, if you bring up mindset, right? And so there's good science on creatine, but if you also believe-

Dr. Tommy Wood 1:27:34 Yeah

Dr. Rangan Chatterjee 1:27:34 ... that taking it is helping you and making you sharper, it's hard not to make [laughs] the case-

Dr. Tommy Wood 1:27:39 Yeah

Dr. Rangan Chatterjee 1:27:40 ... that that is going to do something as well-

Dr. Tommy Wood 1:27:42 Yeah

Dr. Rangan Chatterjee 1:27:42 ... which is, I guess, the kind of hidden glue with all this stuff.

Dr. Tommy Wood 1:27:46 [laughs]

Dr. Rangan Chatterjee 1:27:46 If you believe something's helping you, it, it possibly-

Dr. Tommy Wood 1:27:49 It probably will.

Dr. Rangan Chatterjee 1:27:49 It probably will.

Dr. Tommy Wood 1:27:50 Yeah.

Dr. Rangan Chatterjee 1:27:51 Yeah. Okay. We've got to five mistakes so far. We're not gonna get to 11, but I think the two I would like to get to, 'cause we haven't talked about them before, is number one, neglecting oral health.

Dr. Tommy Wood 1:28:00 Mm.

Dr. Rangan Chatterjee 1:28:01 And number two, ignoring the toxic load of the modern world. Okay. Slightly inflammatory-

Dr. Tommy Wood 1:28:06 [laughs]

Dr. Rangan Chatterjee 1:28:06 ... but I'm talking about things like microplastics and should we filter our water, and that kind of stuff.

Dr. Tommy Wood 1:28:10 Mm-hmm.

Dr. Rangan Chatterjee 1:28:11 So perhaps we can sort of zoom through oral health.

Dr. Tommy Wood 1:28:13 Yeah.

Dr. Rangan Chatterjee 1:28:13 You know, uh, point number six. What's the relationship between oral health and brain health and oral health and longevity?

Dr. Tommy Wood 1:28:21 Hmm. It's been known for maybe 10 or 20 years at this point that there is a connection between oral health and cardiovascular health. Um, that was pro- I think that was probably found first. Um, in fact, there are ... Some of the bacteria that you get when you have gum disease or what we call, um ... So, so gum disease has two stages. The first is gingivitis, and then if it starts to affect kind of the underli- underlying bone, then it would be called periodontitis. Um, but w- I think we can call it just gum disease more, more broadly. Um, and some of the bacteria that tend to overgrow in the setting of, of, of gum disease, things like, um, Pseudomonas gingivalis and, uh, Streptococcus mutans, um, you can

Dr. Tommy Wood 1:29:12 find those bacteria in atherosclerotic plaques in, in the heart, which we know sort of trigger, trigger heart disease. Um, and some of the thought is that because you sort of, like, have all this inflammation, um, around the gum disease and, you know, you know, bleeding and things like that, that actually those bacteria can get from the mouth into the bloodstream and then can trigger systemic inflammation, um, might, might trigger-

Dr. Rangan Chatterjee 1:29:34 Hmm

Dr. Tommy Wood 1:29:35 ... the, the formation of some of these, uh, uh, plaques in, in, in heart disease. And they've actually been found in amyloid plaques in the brain of, of certain in- individuals. And some people, um, argue that one of the reasons why we accumulate amyloid is, you know, one of the parts of, um, kind of the process of developing Alzheimer's disease, um, is because it has antimicrobial effects. So it's accumulating around-

Dr. Rangan Chatterjee 1:29:59 Hmm

Dr. Tommy Wood 1:29:59 ... say, bacteria that, that might have gotten into the brain. And one way that that happens or c- and does seem to happen is, is through, um, through gum disease. This doesn't mean that if you have gum disease you're definitely gonna get dementia, right?

Dr. Rangan Chatterjee 1:30:11 Right.

Dr. Tommy Wood 1:30:11 We're all, we're all talking about what increases and decreases risk. So there are several studies that show that having gum disease is associated with increased risk of dementia, um, in, you know, multiple sort of perspective as in sort of like you follow people over time-

Dr. Rangan Chatterjee 1:30:25 Yeah

Dr. Tommy Wood 1:30:26 ... um, studies. And then in at least one study, uh, they also found that in people who have gum disease, those who get treatment for that gum disease, something like scaling and root planing, which your dentist, uh, would do, um, they then decrease their risk of, uh, dementia over the next several years compared to those who don't get treatment. Um, there have been other studies that show that the amount of antibodies you have circulating in your blood against those bacteria that tend to sort of accumulate because of, of gum disease, the more antibodies you have kind of suggesting that you've had a higher exposure, um, they, those people tend to have a higher risk of dementia as well. So, like, from multiple different directions it seems that, uh, gum disease, uh, is associated with increased risk of dementia, and then there's also some evidence that if we treat that gum disease, that risk of dementia is decreased.

Dr. Rangan Chatterjee 1:31:15 Yeah.

Dr. Rangan Chatterjee 1:31:16 Basically, don't ignore going to the dentist. [laughs]

Dr. Tommy Wood 1:31:19 Yeah, don't ignore-

Dr. Rangan Chatterjee 1:31:19 Don't ignore-

Dr. Tommy Wood 1:31:19 ... going to the dentist. Yeah

Dr. Rangan Chatterjee 1:31:20 ... your oral health.

Dr. Tommy Wood 1:31:21 Yeah.

Dr. Rangan Chatterjee 1:31:21 And in terms of Xylitol gum, are you a fan?

Dr. Tommy Wood 1:31:24 So, uh, yes, and, um- The ... My favorite story about xylitol is actually a, um, a, a colleague of mine, uh, Greg Valentine, who I work with at, at the University of Washington. He's run several clinical trials. He's still running clinical trials looking at this. Um, but his work is looking at ways to decrease preterm birth. Um, so this nothing to do with dementia, although people who are born preterm do actually have an increased risk of dementia, so it could sort of have this full kind of life-

Dr. Rangan Chatterjee 1:31:57 Mm

Dr. Tommy Wood 1:31:57 ... lifespan effect. Um, but we know that, um, having gum disease is a risk factor for preterm birth because it creates this inflammatory effect, um, that ... And we know that chronic inflammation is a potential trigger-

Dr. Rangan Chatterjee 1:32:14 Mm

Dr. Tommy Wood 1:32:14 ... for preterm birth, so babies being born too soon. Uh, the more preterm you're born, the higher your risk of both death but also neurodevelopmental impairment, um, multiple long-term health issues. Obviously, not everybody born preterm experiences those, but it's just on average. Um, so he's run, uh, multiple clinical trials. He's running them in the US right now, but the, the clinical trials he ran already are in Malawi, um, in Africa. Malawi has the highest rates of preterm birth in the world, and the majority of pregnant women in Malawi have gum disease.

Dr. Rangan Chatterjee 1:32:47 Mm-hmm.

Dr. Tommy Wood 1:32:47 Um, and so one trial that they did was this large cluster-randomized trial where they had different villages in Malawi, and they sort of, they gave them xyl- they gave them, some of the villages, xylitol gum, um, to chew, like, three times a day throughout the, the, the last chunk of pregnancy. Um, and they saw significant improvements in gum disease and a statistically significant reduction in preterm birth rates, which to me-

Dr. Rangan Chatterjee 1:33:11 Wow

Dr. Tommy Wood 1:33:12 ... is just, like, m- mind-boggling. Um-

Dr. Rangan Chatterjee 1:33:15 Amazing

Dr. Tommy Wood 1:33:15 ... and, right, the, the, the design of the trial wasn't perfect. They didn't have a placebo gum and that kind of stuff. Those are the trials he's running right now. But, like, even that you would see that kind of effect is just incredible to me. Um, and so we know that chewing xylitol gum or using xylitol mouthwashes can address the oral microbiome, and it's really the microbiome that kind of ... And an imbalance in the microbiome that drives a lot of gum disease, um, without having negative, um, effects. So other types of mouthwashes, for example, like a alcohol-based or a chlorhexidine-based mouthwash, they can actually get rid of good bacteria that you want-

Dr. Rangan Chatterjee 1:33:52 Yeah

Dr. Tommy Wood 1:33:52 ... uh, in your mouth, whereas xylitol seems to particularly kind of decrease the ones that maybe we would like a little bit less of. So if you do have gum disease, I ... Absolutely go to your dentist, have it addressed, whatever they suggest. But, you know, xylitol, xylitol gum is, is one thing that you could try at the same time.

Dr. Rangan Chatterjee 1:34:11 Yeah. Okay.

Dr. Rangan Chatterjee 1:34:13 Very, very important message. Okay. Final mistake for this conversation-

Dr. Tommy Wood 1:34:18 [laughs]

Dr. Rangan Chatterjee 1:34:18 ... right, is mistake number seven, ignoring the toxic load in the modern world. Now, I don't wanna scare people, okay, 'cause I think one of the problems with health these days is people get quite scared.

Dr. Tommy Wood 1:34:27 Uh-huh.

Dr. Rangan Chatterjee 1:34:27 And I think we've gotta be careful not to do that. But I think a few things that people often talk about and worry about are microplastics, should people be filtering their water or not-

Dr. Tommy Wood 1:34:39 Mm

Dr. Rangan Chatterjee 1:34:39 ... in your view, and air pollution, uh, inside and outside. So I wonder if we can just sort of talk about these themes, uh, and how they relate to people's lives.

Dr. Tommy Wood 1:34:50 Yes. So the, the issue with all of these is that there's, um, absolutely some important signal, um, and y- a- as it relates to these exposures and, and our health. But there's also a huge amount of kind of hyperbole, and it's overblown, and there's a ton of scaremongering. But there is sort of like ... But, but in the middle of those, I think there is a, a way for us to navigate it fairly reasonably without sort of being overly stressed about, uh, w- what it might mean or, you know, overselling the effects of these things on our health. So I think we can go through them one by one.

Dr. Tommy Wood 1:35:34 Um, microplastics have certainly gotten a lot of press recently. Um, and these are essentially the breakdown products of plastics that, you know, we use for s- packaging for food or, um, you know, utensils or other things. So, so our primary, our primary exposure is from the food that we eat. Um, you can get a l- ... There's some from, like, skincare products and things like that. Um, but there, there have been some recent studies that suggest that maybe our primary exposure is through food, food and drink. Um, and a couple of years ago, there was this study that said, you know, the average human consumes a credit card's worth of plastics a week [laughs] or, or something. Um, and then everybody lo- lost their minds. Um, the, the ... Then some, some more recent studies, they got a lot less press, [laughs] um, went back, and they redid the calculations, and they were like, "We estimate that this is out by, like, several orders of magnitude." It's like not ... It's, like, a fraction of 1% of the amount that they said previously. So, like, yeah-

Dr. Rangan Chatterjee 1:36:42 The dec- the decimal place went in the wrong spot. [laughs]

Dr. Tommy Wood 1:36:43 The, the decimal place was, like, miles out, um, like, sever- like ... I, I can't remember exactly how, how many. It was, like, six or seven places in the wrong place. Like, it was, it was a ... It was, it was huge, the, the difference. Um, and so that's one part is, yes, we do consume these things, but the amount that we've been told we're c- we're consuming is probably a lot less than, than, than we've been told. Um, then the next part is there have been studies that have looked at microplastics in the body, um, in, right, tissues of people who've dis- who are deceased and, like, looked at them in, um, say, artery plaques, looked at them in the brain, and, and, you know, they've, they've, they've looked at them in, uh, like, testicles and other organs and, and basically suggested that, um- In those who have a higher disease burden, say higher heart disease burden or higher dementia burden, they have higher... So, like people who have a higher dementia burden or people with dementia have more microplastics in their brain.

Dr. Rangan Chatterjee 1:37:46 Mm.

Dr. Tommy Wood 1:37:48 Um, this is certainly possible, but there's a few reasons why I'm not yet certain it's like the thing that we have to worry about. So the first is that we know that vascular disease, so issues with blood vessels, are present in most people with dementia. If you have issues with blood vessels in the brain, blood flow is going to be slower. You're more likely to accumulate-

Dr. Rangan Chatterjee 1:38:17 Yeah

Dr. Tommy Wood 1:38:17 ... microplastics that, that might be in your bloodstream. So the dementia is probably driven at least partly by the blood flow issue, the, the, the, the, you know, vascular disease.

Dr. Rangan Chatterjee 1:38:29 Mm.

Dr. Tommy Wood 1:38:29 And then microplastics just kind of accumulate, uh, uh, you know, they come along for the ride. Um, we also have a big issue in terms of how microplastics are measured in these studies. So when you, when you take tissues and then you m- try and measure the amount of microplastics in them, the typical way you do that is through something called pyrolysis, which is essentially just a fancy word for heating something up a lot.

Dr. Rangan Chatterjee 1:38:59 Mm.

Dr. Tommy Wood 1:39:00 Um, and so what they do is they, they essentially, um, vaporize the plastics and then measure it in something called, um, a mass spectrometer. Um, the problem is that that doesn't work very well in tissues that have a high fat content, like the brain in particular. Because when you vaporize fat tissue, it looks like plastic. Um, the... It breaks down into the same compounds as plastics do. So there have been some papers that say that, you know, particularly in tissues that have a f- high fat content like the brain, pyrolysis is not a valid way to measure microplastics. So it could be that when we're seeing high microplastics in some of these studies, it's actually just an error in the measurement, right? Because of the method that's being used. So I think that some of that is overblown, too. So some of the exposure's overblown. Um, maybe some of like what we're measuring in tissues is, is, is overblown. However, we do know that some of the compounds that come in plastic, some of the plasticizers, uh, phthalates, uh, bisphenols, right? Um, people have heard of BPA, right, with the lining of cans. Um, and there are many other breakdown products of plastics.

Dr. Rangan Chatterjee 1:40:13 Yeah.

Dr. Tommy Wood 1:40:13 Right? They are certainly linked to, uh, some changes in cognitive function, issues with neurodevelopment in kids, um, higher risk, higher rates of heart disease. Um, so these things aren't, you know, completely benign. Um, and so like I, I think we're gonna end up down this middle road where we're like, yes, some of it's probably overblown, or at least we don't have the data to be, you know, really say that it's this primary driver. But we also know that then, that they're not benign, and we should try and minimize our exposure where we can. Um, there was a recent, um, trial where they, uh, randomized, uh, individuals to multiple different groups where they changed different plastic exposures and then tracked their sort of levels, it was levels in the urine of these different-

Dr. Rangan Chatterjee 1:40:54 Mm

Dr. Tommy Wood 1:40:54 ... of different plastic breakdown, um, compounds. And the biggest driver seemed to be the food. So they, so they, uh, gave people the... So they, they stopped them, uh, using canned, uh, uh, or reduced their canned foods, reduced, uh, storage, um, of foods in plastic.

Dr. Rangan Chatterjee 1:41:12 In plastic.

Dr. Tommy Wood 1:41:12 Yeah. Reduced, uh, uh, plastic utensil use. So, you know, if you're, if you're kind of like stirring a pot and you've got a, a, a plastic spoon, right? Swapping it for a metal spoon or a wooden spoon, and then they reduced the number of foods that were just stored in plastic, right? So, you know, they actually controlled a lot of the food production process so that at no point were, were, were foods kind of, uh, stored in plastic for long periods of time. So, you know, you go to the supermarket and you're getting your, your veggies kind of loose, and you're just throwing them in your basket rather than kind of packaging them up and stuff or, you know, and getting things that are... uh, that you can buy loose rather than things that are sort of like pre-chopped and stored in plastic, that kind of stuff. Um, I would say that if you're, um, going to avoid foods and then not replace them with other similar healthy foods that aren't stored in plastic, I would rather you eat those foods, right? So if your... If the reason why you get... you, you can eat vegetables is because you get them frozen and they come in a plastic bag, but they're already pre-prepared and it's really easy to prepare them and you can just throw them in a pot and then make, make dinner quickly, do that, right?

Dr. Rangan Chatterjee 1:42:19 Mm.

Dr. Tommy Wood 1:42:19 Uh, that is, has a, a much bigger signal in terms of benefit.

Dr. Rangan Chatterjee 1:42:23 Mm.

Dr. Tommy Wood 1:42:24 But if you can, you know, don't s- you know, don't store your leftovers in plastic, get a wooden spoon, um, minimize the amount of foods that you get that, that are kind of stored in plastic or, right? W- wherever that's possible. Um, drink, uh, fewer drinks out of plastic bottles or cans. Um, then do that. So wherever you can start to move that needle a little bit, just decrease your exposure, I think that's gonna be beneficial. But-

Dr. Rangan Chatterjee 1:42:51 Yeah

Dr. Tommy Wood 1:42:53 ... you know what? If, if the reason you eat beans is because beans come in cans, I would still eat those beans, right?

Dr. Rangan Chatterjee 1:42:58 Yeah.

Dr. Tommy Wood 1:42:58 Because we know that they have a lot of, of, a lot of health benefits. So it's all about just reducing your exposure where you can, rather than being really, really concerned about all the different ways that, that you, you might be exposed.

Dr. Rangan Chatterjee 1:43:08 Yeah. I think that's a reassuring message. I, I guess importantly, I guess we can probably make the case, I think, that a thousand years ago, humans probably weren't being exposed-

Dr. Tommy Wood 1:43:20 Mm

Dr. Rangan Chatterjee 1:43:20 ... to plastics in this way.

Dr. Tommy Wood 1:43:22 Yeah.

Dr. Rangan Chatterjee 1:43:22 So it's a, it's a new thing, so of course we have to see how the research plays out-

Dr. Tommy Wood 1:43:27 Mm

Dr. Rangan Chatterjee 1:43:27 ... and if we're gonna learn more things. Remember when Dale Bredesen came on recently to talk about dementia risk and, you know, brain health? Um- You know, he was, w- you know, at some point we spoke about microplastics, and I think to be fair to Dale, he said, "Look, we, we don't know the full story yet."

Dr. Tommy Wood 1:43:45 Yeah.

Dr. Rangan Chatterjee 1:43:46 I, I said to him, "Have you seen enough to make you at least reduce-

Dr. Tommy Wood 1:43:50 Hmm

Dr. Rangan Chatterjee 1:43:50 ... how many microplastics you're exposed to?" He goes, "Yeah."

Dr. Tommy Wood 1:43:54 Yeah.

Dr. Rangan Chatterjee 1:43:54 "So wherever possible, I try not to." And I guess that's the approach I've taken-

Dr. Tommy Wood 1:43:57 Hmm

Dr. Rangan Chatterjee 1:43:57 ... for a couple of years. I'm, you know, I try, you know, it's, it's very rare for me to drink out of a plastic water bottle now-

Dr. Tommy Wood 1:44:04 Yeah

Dr. Rangan Chatterjee 1:44:04 ... unless I'm on a plane-

Dr. Tommy Wood 1:44:05 Yeah

Dr. Rangan Chatterjee 1:44:05 ... for eight hours and actually have, you know, I'm thirsty, right?

Dr. Tommy Wood 1:44:07 Yeah, yeah.

Dr. Rangan Chatterjee 1:44:08 Um, I personally no longer, and haven't done this for a while, will get a takeout coffee in a, um, in one of those containers.

Dr. Tommy Wood 1:44:16 Yeah.

Dr. Rangan Chatterjee 1:44:16 You know, because the heat and that, how that interacts with the cups. Again, for me, in my life, that's not that difficult to do.

Dr. Tommy Wood 1:44:26 Yeah.

Dr. Rangan Chatterjee 1:44:27 Um, you know, and, you know, uh, certainly at home, we, we don't store in plastic anymore. We store in, in glass containers when we overcook food and that kind of stuff. So I think there's a lot of practical things people can do without necessarily worrying, but I guess time will tell-

Dr. Tommy Wood 1:44:42 Yeah

Dr. Rangan Chatterjee 1:44:42 ... uh, with the science how much of an impact this is having on health.

Dr. Tommy Wood 1:44:46 Yeah.

Dr. Rangan Chatterjee 1:44:47 Okay. And I'm sure we could talk for an hour on plastics-

Dr. Tommy Wood 1:44:49 Yeah [laughs]

Dr. Rangan Chatterjee 1:44:49 ... but let's leave

Dr. Rangan Chatterjee 1:44:50 it there on plastics. What's your take on filtering, uh, drinking water?

Dr. Tommy Wood 1:44:54 Yeah. So I, I'd start by saying that, you know, luckily for I imagine everybody listening to this podcast are, are of, like, water supply is very safe, right? And so the in-

Dr. Rangan Chatterjee 1:45:06 In, in many countries.

Dr. Tommy Wood 1:45:07 Yeah. In, in the, in, uh, in the vast majority of countries, not, not, not all, but, right, I'd, I, I would expect that w- wherever you're listening to this, your, your water supply is, is, is safe, and it's, it's not ... it shouldn't be a primary concern. However, um, we do know that, for example, you know, several pipes in the UK and the US still contain lead, right? And so there are several places where you drink the, the tap water, and there's a, a, a significant amount of, of lead in it. Um, we also know that there are other things ending up in the water that are very hard to remove, like, uh, the PFAs, um, and the, like, the, you know, the forever chemicals. Um-

Dr. Rangan Chatterjee 1:45:43 And plastics

Dr. Tommy Wood 1:45:44 And pla- and pla- and plastics

Dr. Rangan Chatterjee 1:45:45 Microplastics.

Dr. Tommy Wood 1:45:46 Yeah. The, the, so, uh, phthalates and things like that can, can end up in the wa- in the water as well. Um, and we know that these have, we know that these have some potentially negative heal- hea- health effects. Um, so the way that I've approached this is that I do, I do filter my water. I have an in-fridge, uh, filter. You can, uh, get, um, a jug filter, although, um, the main thing with a jug filter [laughs] is just remember to replace it. Because I know there are people who have a jug filter, and then it's in there for a year, and then it starts to grow stuff and, right. You've, you've probably undone the good work of filter- of filtering your water. Um, right.

Dr. Rangan Chatterjee 1:46:23 You're probably adding your own contaminants.

Dr. Tommy Wood 1:46:24 Yeah, exactly. [laughs] And, right, and then you can scale that up to under, you know, some people have ... you know, you can get under- under sink filters and stuff like that. But the ... I, I think about it very similarly to, to how I think about microplastics, and actually, this is how I think about this, like, um, whole topic in general, is that wherever, where- whatever you're able to do, do that, and you're almost certainly decreasing your exposure o- over time, right? So, um, most jug filters will do a decent job of decreasing things like lead if there is lead in your water, or they'll do a, a decent job of decreasing phthalates and other things if, if they are, if they are in your water. Um, and all of this stuff integrates over time, right? So if you just continuously do that, you'll be decreasing your exposure over time, and it's sort of like a, other than, you know, remembering to change your filter, it's kind of like a set it and forget it thing. It's low, low risk, high potential for benefit, not particularly, um, cost-intensive depending on which fil- you know, filtration system you, you go for. So I, that's, that's generally how, how, how I approach it. There's probably a, a level of water filter that each of us could do. I, I, I don't think you have to do it, but if we're trying to think about something that might give us benefit over long periods of time, it's low risk, relatively low cost. I think, um, I, I think it's, uh, uh, worth considering.

Dr. Rangan Chatterjee 1:47:41 Yeah. I think all these things, you know, it just depends. Some people get very triggered over water filtration, go, "The tap water's completely safe."

Dr. Tommy Wood 1:47:49 Yeah.

Dr. Rangan Chatterjee 1:47:49 And it's like, yeah, compared to, you know, many countries around the world, it, it, it probably is, certainly here in the UK, you know. And I think that's fine. And if you are looking to just do a little bit extra, as I certainly am, you know, it's one of those things I didn't do till about three years ago-

Dr. Tommy Wood 1:48:09 Right

Dr. Rangan Chatterjee 1:48:09 ... I don't think. You know? So I lived most of my life drinking tap water.

Dr. Tommy Wood 1:48:12 Yeah.

Dr. Rangan Chatterjee 1:48:13 Um, and I think I'm doing fine. And as I learn more, I think, "Hey, you know what? It's not that much of a heavy lift to have a water filter at home."

Dr. Tommy Wood 1:48:24 Yeah.

Dr. Rangan Chatterjee 1:48:25 So I've got something, I think, I think it's called Aquatru.

Dr. Tommy Wood 1:48:28 Hmm.

Dr. Rangan Chatterjee 1:48:28 It's a reverse osmosis filter.

Dr. Tommy Wood 1:48:30 Yeah.

Dr. Rangan Chatterjee 1:48:30 Bought it about two, three years ago. It reminds you when your filter needs changing.

Dr. Tommy Wood 1:48:34 Yeah.

Dr. Rangan Chatterjee 1:48:35 You know, it's just, we have a habit now in the house that we fill it up, and you pop it on, and it, you know. But yeah, it, it is ... mate, you could call it hassle if you want, 'cause it takes out lots of good stuff as well.

Dr. Tommy Wood 1:48:47 Yeah. It takes out minerals.

Dr. Rangan Chatterjee 1:48:48 Takes all the bad ... takes all the minerals.

Dr. Tommy Wood 1:48:49 Yeah, yeah.

Dr. Rangan Chatterjee 1:48:49 So we have to put some drops to remineralize it. Now, someone might call that a faff. Uh, it possibly was a faff three years ago when I first started doing it. Now, it's just the new norm.

Dr. Tommy Wood 1:48:59 Yeah.

Dr. Rangan Chatterjee 1:49:00 Which is what we do. And so I, I think that's what, one thing I always like about what you told me, it's a very practical, nuanced approach, which is, you know, really at its heart trying not to scare people and go, "Yes, things are changing in the world. It is harder to eat nutrient-dense food. It is ... We have been exposed to all kinds of new things now which weren't in our evolutionary history." At the same time, going back to point number one about mindset, worrying about this stuff ain't gonna help you that much.

Dr. Tommy Wood 1:49:26 Yeah.

Dr. Rangan Chatterjee 1:49:26 It's, you know, what can you feel that you have an element of control over? What's your take on, uh, sauna use-

Dr. Tommy Wood 1:49:33 Hmm

Dr. Rangan Chatterjee 1:49:34 ... filtering out microplastics? 'Cause I think there's quite a

Dr. Rangan Chatterjee 1:49:37 lot of noise emerging now that that could be a good way of removing it from our system.

Dr. Tommy Wood 1:49:41 Yeah. So you do Definitely sweat out some of these, uh, compounds that you get, um-

Dr. Rangan Chatterjee 1:49:48 So exercise, of course, would do that as well

Dr. Tommy Wood 1:49:50 ... Yeah. So, uh, yeah, s- so, so I, I think that sweating is important. Um, it is a, a detoxification pathway in the most important sense, right? It's one of the ways, right? Just like with our liver and our kidneys, it's one of the ways that we ex- ex-

Dr. Rangan Chatterjee 1:50:04 Yeah

Dr. Tommy Wood 1:50:04 ... excrete things that our body doesn't want, um, inside.

Dr. Rangan Chatterjee 1:50:07 Urine, feces, skin.

Dr. Tommy Wood 1:50:08 Yeah, yeah.

Dr. Rangan Chatterjee 1:50:09 Right? It's-

Dr. Tommy Wood 1:50:09 Or sweat

Dr. Rangan Chatterjee 1:50:10 ... exactly. Yeah.

Dr. Tommy Wood 1:50:10 Yes. So, um, I do think sweating is probably beneficial. We know that some of these compounds can be excrete- excrete- excreted in sweat. Um, exercise that causes you to sweat is free, right? So I, I don't... And actually, many of the benefits of sauna, particularly dry, you know, dry saunas, sort of like a Finnish hot, hot sauna, um, many of the benefits of sauna actually overlap very significantly with aerobic exercise. Uh, the, the pathways that get activated, right, the sweating. Um, so yes, I think sauna is, is, is a possible intervention, but I don't think everybody needs to sauna. If you've got one and you enjoy it, great.

Dr. Rangan Chatterjee 1:50:48 Yeah.

Dr. Tommy Wood 1:50:48 But equally, you could go f- you could go for a jog. Go play paddle, and you're probably, you know-

Dr. Rangan Chatterjee 1:50:53 Yeah

Dr. Tommy Wood 1:50:53 ... you're sweating out, uh, uh, in, in, in, in, in a similar way. So yes, I would think about sweating. Um, but however you achieve that sweating, um, I think matters a lot less.

Dr. Rangan Chatterjee 1:51:04 That's a great message. However you achieve your sweating-

Dr. Tommy Wood 1:51:07 [laughs]

Dr. Rangan Chatterjee 1:51:07 ... it's up, it's up to you.

Dr. Tommy Wood 1:51:08 Yeah.

Dr. Rangan Chatterjee 1:51:08 You know, you choose the activity you want.

Dr. Tommy Wood 1:51:09 Absolutely, yeah.

Dr. Rangan Chatterjee 1:51:10 Okay. Um, and because I mentioned it, let's just touch on

Dr. Rangan Chatterjee 1:51:15 pollution in the air.

Dr. Tommy Wood 1:51:16 Yeah.

Dr. Rangan Chatterjee 1:51:16 Because when, when I think about it, I think about controllables and uncontrollables.

Dr. Tommy Wood 1:51:19 Mm-hmm.

Dr. Rangan Chatterjee 1:51:19 Okay?

Dr. Tommy Wood 1:51:20 Yeah.

Dr. Rangan Chatterjee 1:51:20 So we know that air pollution from planes and cars and diesel and stuff can negatively impact human health and increase risk of dementia.

Dr. Tommy Wood 1:51:31 Yeah.

Dr. Rangan Chatterjee 1:51:32 But there's also the pollution inside our home. Again, I don't think we've covered this before, Tommy, so I think we have covered the big levers a lot.

Dr. Tommy Wood 1:51:40 Mm-hmm.

Dr. Rangan Chatterjee 1:51:40 So, um, yeah, external air pollution, I know there's a link to B vitamins and how we can attenuate our risk.

Dr. Tommy Wood 1:51:46 Yeah.

Dr. Rangan Chatterjee 1:51:46 So what's your sort of top-level take on, uh, pollutants in the air?

Dr. Tommy Wood 1:51:50 Yeah, so it, it, it's very similar to, to, to the others. Um, yeah, well, I guess we can touch upon that, that, the, the B vitamin study. Uh, this was done, um, a- actually at the University of Washington, where I work. Um, and they looked at air pollution exposure. So it's particularly, people might have heard of, uh, PM2.5. It's like the two, like, two and a half micron. That's the size particles that are released from, you know, cars and roads and, and things like that, um, that seem to be... There were, there were other aspects of air pollution a- as well that are linked to human health, but the, but they're, they're kind of the most frequently studied and, you know, associated with increased risk of, um, heart attacks and de- and dementia. So this study looked at dementia, and they found that those who had good B vitamin status, if they were exposed to high levels of air pollution, they had... that sort of mitigated the risk of, of, of, of dementia. Of course, this is not a randomized control trial, but, um, it's thought that exposure to air pollution increases homocysteine, which we were talking about earlier. And so, um, if you measure your homocysteine level and it's high, and then you supplement with B vitamins and it comes down, if it was the air pollution that's driving that, you've maybe offset a lot of the risk from the air pollution-

Dr. Rangan Chatterjee 1:53:02 Mm

Dr. Tommy Wood 1:53:02 ... you know, by supplementing with B vitamins. So I think that, that makes sense. So it's just another reason to maybe consider getting enough B vitamins in your diet. Um, then the, you know, a lot of the sort of inside air, um, well, it's, it- it's obviously connected to the outside air. But because where you've got closed windows, you know, things sort of like accumulate, um, o- o- over time. And so often the, um... If you, if you look at things like the Environmental Protection Agency in the US, they sort of have this big part on their website about how indoor air quality is often worse than outdoor-

Dr. Rangan Chatterjee 1:53:35 Mm

Dr. Tommy Wood 1:53:35 ... air quality, um, for, for that reason. And so I think that, again, uh, if you, especially if you live somewhere, right, you live near a main road or... So I live in Washington State, in Seattle. In the summer, we have lots of wildfires. Like, often the, like, the, the air outside is filled with smoke.

Dr. Rangan Chatterjee 1:53:56 Mm.

Dr. Tommy Wood 1:53:56 The house smells of smoke. Um-

Dr. Rangan Chatterjee 1:53:57 Wow

Dr. Tommy Wood 1:53:58 ... and we know that's linked to poor health, you know, uh, e- effects in, in the local population. Like, several studies have shown that. So I think in those kinds of settings, if you do h- have high exposure to air pollution, then I would consider getting an air purifier i- in the rooms that you spend, uh, a lot of time. Um, and there was one recent study, uh, where they actually did a randomized control trial of air purifiers in people who have high, um, exposure to air pollution, and they sh- they saw that having an air purifier on signi- it, it significantly reduced blood pressure. So again, a meaningful, um, intervention that's kind of like a set it and forget it thing in people who have high exposure or high risk, you know, definitely, you know, something worth considering. Um, but again, right, we can't... You know, it's, it's often very ha- It, it... There aren't many people who can just move because they have a lot of air pollution, right?

Dr. Rangan Chatterjee 1:54:52 Yeah.

Dr. Tommy Wood 1:54:52 So, um, I think that if you can address that by just, you know, if you're spending... If there are rooms you spend a lot of time in, say, the bedroom, get an air purifier. Um, again, over time, you're dramatically decreasing, uh, your, your exposure with a relatively simple, um, intervention.

Dr. Rangan Chatterjee 1:55:09 Yeah. And of course, something we have covered before is the socioeconomic sort of, um, input here in the sense that, you know, in, in many places in the world, your socioeconomic status hugely influences how polluted [laughs] your environment is.

Dr. Tommy Wood 1:55:27 Yeah, where, where you can live. Yeah, yeah.

Dr. Rangan Chatterjee 1:55:28 Right? So, you know, the, the, the, the middle classes and the wealthier people can live out in the suburbs-

Dr. Tommy Wood 1:55:34 Mm

Dr. Rangan Chatterjee 1:55:34 ... and have, um, less busy roads around them-

Dr. Tommy Wood 1:55:37 Yeah

Dr. Rangan Chatterjee 1:55:37 ... et cetera, et cetera. So I think we always acknowledge that. I think it's always important-

Dr. Tommy Wood 1:55:41 Mm

Dr. Rangan Chatterjee 1:55:41 ... to acknowledge that, that everyone has a different ability to make changes. Uh, Tommy, uh, I, I, I loved chatting to you. You know, as you know, you're, you're one of the doctors and the health commentators who I respect the most. I love your, your balanced, nuanced, but also open-minded approach to health. Um, I think the book, uh,

Dr. Rangan Chatterjee 1:56:02 The Stimulated Mind, is fantastic, and, uh, I really would encourage people to, to pick it up and take a look at it. I know we haven't covered some of the interventions we covered before in today's show.

Dr. Tommy Wood 1:56:13 Mm.

Dr. Rangan Chatterjee 1:56:14 But I guess just to finish off, for that person who has been listening to us talk, and throughout the conversation has realized that they've neglected their brain health-

Dr. Tommy Wood 1:56:28 Mm

Dr. Rangan Chatterjee 1:56:28 ... for a number of years, maybe decades, and is wondering, well, you know, maybe it's too late. Maybe there's nothing I can do. Um, what would your final words for that individual be?

Dr. Tommy Wood 1:56:40 I would say that, um, it's never too late to start, and we ha- actually have really good evidence for that. Um, I talked to the, uh, you know, I mentioned the Lancet Commission report again. The first time they published that report in 2020, they even said that on the front page of The Lancet, like, the one of the world's premier medical journals. It's never too late, um, uh, to, to, to start thinking about dementia prevention, and that's because they were focusing on dementia. Uh, but then your brain health more, more broadly. Um, studies in individuals in their 60s, 70s, 80s, they start an exercise program. They start with some dietary change. They start to improve. They do some cognitive training, some... or, like, some kind of, you know, they start language or dance classes or, you know, a musical instrument or, you know, they start to improve their sleep. You, you start to see benefits, you know, even at the, you know, those later ages. So know that start wherever you are, and even just starting with one thing can have significant benefits. Is it taking more steps a day or getting an extra 15 minutes of sleep or volunteering for something, right? 'Cause you, 'cause you sort of, um, connected to the stuff that we talked about in terms of, uh, in terms of social connection. Is it just, like, getting an air filter and a water filter, and those are just... That's, that's all, all you can do right now, but you set it and forget it or, you know, you start a, a B vitamin s- supplement. Um, th- these things we know have significant impact with, through very high quality trials regardless of the age that you're at. Um, and by starting one thing, sort of like the whole system, we talked about the 3S model, that whole system shifts in your favor. And yes, maybe you have to... You, you would ideally make multiple changes over time, but these things, you know, just, just one, one thing is the place to start and then build from there.

Dr. Rangan Chatterjee 1:58:32 Yeah, very, very empowering message. I just wanna highlight your key message from the last couple of appearances on my show about learning a new thing. Give your brain a reason to grow and adapt. And I think since our last conversation, which was only a few months ago, Tommy, um, these are some of the comments that came in on the back of that.

Dr. Tommy Wood 1:58:53 Oh.

Dr. Rangan Chatterjee 1:58:53 Artie has told us she started playing netball and paddle.

Dr. Tommy Wood 1:58:56 Cool.

Dr. Rangan Chatterjee 1:58:57 Laura started figure skating. Lynn started reformer Pilates. Dorothy started tap dancing classes. Sosie started a heels dancing class. Heather started playing pickleball. Louise started ballet after a recent Parkinson's diagnosis, and Daryl started playing table tennis and badminton, and honestly, that's all because of the information you shared on my show. So I think you're doing wonderful work, Tommy. Um, thank you for sharing your research so generously with us all, and, uh, I look forward to number six-

Dr. Tommy Wood 1:59:30 [laughs]

Dr. Rangan Chatterjee 1:59:30 ... at some point in the future.

Dr. Tommy Wood 1:59:32 Um, thanks so much for sharing those with me. That's, that's, um, so, so cool. I'm so glad that people are just finding, like you, you said right at the beginning, you know, find something that you enjoy, right? You do it because, um, do it because it's fun, right? And then oh yeah, it just happens to have all these other sort of health benefits on, on the side. So, like, pick something that... You know, any of those things are fantastic. I'm so, I'm so happy people are doing it. Um, I really appreciate, uh, your time as always, and thank you for having me on.

Dr. Rangan Chatterjee 1:59:57 If you enjoyed that conversation, then I think you are really going to enjoy this one.

Speaker 2:00:02 I've been a cardiologist for 30 years, and I've tried everything. But when I tried fasting, I started seeing changes. People began to lose weight. Blood pressures came down. Diabetes got reversed.