How Different Diets Impact Your Health | Dr. Christopher Gardner

Andrew Huberman 0:00 Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life. (instrumental music) I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. My guest today is Dr. Christopher Gardner. Dr. Christopher Gardner is a professor of medicine and director of nutrition studies at Stanford University. Dr. Gardner has conducted groundbreaking research on dietary interventions for over 25 years, focusing on what dietary interventions reduce weight and inflammation and for generally improving physical health. He is known for doing extremely well-controlled studies of nutrition where calories, macronutrients, so protein, fat, and carbohydrates, and food quality are matched between the different groups and not simply comparing one intervention to the so-called standard American diet as so many other nutrition studies do. As such, his work has been published in prestigious journals, such as the Journal of the American Medical Association and the New England Journal of Medicine. Today we discuss several important nutritional controversies, and we examine what the science actually tells us. First, we explore protein requirements, how much protein we actually need, and do those needs change based on activity levels, age, and health status. And I should say that even though we started out with rather discrepant stance on this, we converge on an answer that I think will be satisfying at least to most people, and then you can tailor that answer to your unique needs. We then examine the ongoing debate between vegetarian, vegan, and omnivore diets for optimal health, and we dive into whether plant proteins are truly inferior to animal proteins as is often claimed. We also discuss the role of fiber in the diet and the emerging science on fermented foods and their powerful anti-inflammatory effects. Throughout today's conversation, we focus on food quality and not just macronutrient ratios or calories and how those can impact health outcomes. As you'll hear, Dr. Gardner and I don't agree on every nutritional recommendation, particularly how much protein people need and the discrepancy in views about animal-based proteins versus plant-based proteins. But by the end, I do believe that we converge on themes that everyone, regardless of their dietary preference, ought to be able to benefit from. As always, we provide you with science-based, actionable information that you can apply to your daily life. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero-cost-to-consumer information about science and science-related tools to the general public. In keeping with that theme, this episode does include sponsors. And now for my conversation with Dr. Christopher Gardner.

Andrew Huberman 2:32 Professor Christopher Gardner, so nice to meet you and to have you here.

Christopher Gardner 2:36 Happy to be here off Stanford campus talking to you.

Andrew Huberman 2:39 That's right. Even though we've both been there a very long time-

Christopher Gardner 2:41 (laughs)

Andrew Huberman 2:41 ... it is a big place, and so, uh, we haven't had the chance to interact directly. But of course I know who you are, and I'm very familiar with much of your work, but you'll tell us about more of it today. To kick things off, I want to know, is it possible that even though all human beings are, I presume, the same species, that some of us might thrive perhaps on one form of diet and others might thrive perhaps on a different form of diet? In other words, how do we justify talking about the, quote-unquote, "best diet" for a given age demographic, level of activity, et cetera? If one were to look at social media or even just the history of nutrition in this country, one can almost reflexively lean on the idea that, you know, maybe we all need something different and some experimentation and discovery is needed. So do we need different diets or is there a best diet?

Christopher Gardner 3:40 So there isn't one best diet, and I don't think we need different diets. We're just incredibly resilient, and we can do crazy wild things. So the way I start my human nutrition class at Berkeley with students is in the very first class, I point out that Tarahumara Indians who are like world-class ultra-marathon runners, mostly corn and beans, like total carb. And then you can look at the Alaskan Inuits who for centuries lived on whale and blubber and polar bear and things like that. So that was like total fat and total carb, and they thrived. There's really no diabetes, no heart disease, no cancer, but eating all their local indigenous diets. You know, Michael Pollan has a great quote on this, the author of Omnivore's Dilemma, and he says, you know, if you really look around the world, it is amazing how much variety there is in a diet that people can thrive on except the one that doesn't work is the American diet, the standard American diet, because it's full of processed, packaged food. And the sad thing is that the Tarahumara Indians now eat a lot of crap, and the Alaskan people and the Inuits now have a lot of packaged processed food shipped in. And the world's all sort of, um, centering on an unhealthy diet that is convenient, and it's inexpensive, and it's available, and it's addictively tasty, and it's problematic. So no, there is not one best diet. It's incredible how resilient we are, so I'd love to get into that.

Andrew Huberman 5:08 Great. Well, there's so many facets to what we call diet or nutrition. You know, there's the macronutrients, protein, fats, and carbohydrates. There are micronutrients. There's how many calories are in there. There's how it was sourced. There's how that sourcing impacts the environment. There are just so many lenses to look at this issue through. I would like to know because of what you just told us that people prior to food making its way around the world from different cultures to other cultures, food largely centered on what was grown and hunted and harvested locally.

Christopher Gardner 5:40 Yep.

Andrew Huberman 5:40 Is it possible that even though people have dispersed across the planet, sort of going back to this first question, that there is a, um, quote-unquote "best diet," meaning not that we could adapt to any diet, but that for some of us high meat, high fat, maybe even high, let's say, high protein, high fiber, just to make it a little bit, um, less extreme, high protein, high fiber, low starch is better, and in, for people that are descendants of people with genes from another, another part of the world that, um, high starch, high fiber, lower protein would be advisable?

Christopher Gardner 6:17 For me, the best way to answer that is people come up to me quite often and say something like, "Professor Gardner, I, I know you're all into whole food, plant-based diets, and I, I was vegan, I was vegetarian, I was trying that, and, uh, I, I had some health issues and I switched to be more fat and more meat. And I'm, I'm almost embarrassed to be asking you this, 'cause my doctor told me I shouldn't do this either, but all my health issues have cleaned up. I'm looking really good." And I have a whole nother cadre of folks who are eating a lot of meat and a lot of fat, and they said, "I went vegan, I went low fat vegan and all my health issues cleaned up, and I'm much better now than I was before." And it's really hard to look someone in the eye who's doing something wildly different and say, "Well, you're wrong. You're lying." I mean, clearly these people were really probing for the diet that was best for them, and they, they were following some advice that they thought was good and they kept following it and it wasn't working. They tried something counter to that and it worked better, and they're trying to rationalize that and deal with that. So I am sure that there are different diets for different people, um, but at the end of the day, it's just not the packaged processed food that the whole world is leaning towards.

Andrew Huberman 7:32 I really appreciate that answer because, uh, as somebody who's tried various diets, uh, I never had any serious health issues, thank goodness, um, but I know what I thrive on. I'm an omnivore, um, not that people need to know this, but I like to eat meat, fish, chicken, eggs, lots of fruits and vegetables. I eat very little starch. I wouldn't say I'm low carb because I eat a lot of fruits and vegetables, um, and some limited amounts of starch, but having tried many, many different things, including vegetarian diet, lacto-ovo vegetarian many year- many years ago, and more extreme keto-type diets that, uh, lean more heavily on meat as opposed to the way perhaps keto should be done, which we'll talk about, I've just found this works really well for me. So I fully embrace the idea that different people thrive on different diets. How is it that's true? Meaning do you think this is because of genetic, uh, you know, our inheritance of genes from people that, you know, came from different parts of the world? And, uh, to what extent can a different diet passed through generations have epigenetic effects? Maybe I thrive on that and somebody else thrives on something different because of where their ancestors are from and what they've been eating for the last maybe even 300 years. That's not long for a, uh, an evolutionary event to take place, but some things can happen in 300 years.

Christopher Gardner 8:54 So really the only classic example that's cl- well-established is lactose intolerance and lactase and northern Europeans developing the ability to continue making the enzyme lactase to break apart the molecule lactose well into adult life. So the majority of the world is lactose intolerant, and if we could just do that for a minute. So when you're a newborn infant and you're having breast milk, you are getting lactose in your mom's milk, and then once you are weaned off the breast, most people in the world stop making lactase, that enzyme. And so I'm sure everybody listening to this knows someone who's lactose intolerant and either buys lactose, uh, lactase milk or avoids milk and avoids dairy because of the GI disorders. So it really is fascinating that some northern Europeans at some point had enough cows and dairy and ate it that they developed the ability to keep making this enzyme later in life, whereas the rest of the planet didn't. And it's not really hard cut and dry, so there's actually people who are lactose intolerant who can still tolerate some milk. There's a lot of people who can't digest it, and to be honest, it doesn't really make much sense. If you look at mammals around the planet, all the mammals, right? Mammalian breast tissue bre- breast milk, so they're all drinking the mom's breast milk until they get weaned off for food. No other mammal on the planet drinks the breast milk of another mammal to thrive later in life. So humans are the only ones who do it. It's really mostly cow milk, and it's kind of frigging bizarre, but it works for a lot of people. And so that is the classic example of so, sort of overcoming genes over the course of evolution, but I don't know many like that, so I don't have a better example of can people who evolved from Africans versus Asians versus Scandinavians do anything different than that? That's the only example I've got, but could be possible.

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Andrew Huberman 13:50 What do you say to all these people who have, uh, wheat allergies or gluten-

Christopher Gardner 13:54 Ugh.

Andrew Huberman 13:55 ... gluten reactions?

Christopher Gardner 13:56 Yeah.

Andrew Huberman 13:56 And, and I want to be really careful here and distinguish between full-blown, um, wheat or gluten-intolerant, versus people that just don't feel good when they do this.

Christopher Gardner 14:06 Yeah.

Andrew Huberman 14:06 I, I recently took a blood test that, that revealed to me I have a mild wheat, um, I wouldn't say allergic reaction because they didn't do the allergy test, but I, I have antibodies against it, um, and dairy. And it's true, I don't like drinking milk, it makes me feel lousy. I get all, you know, um mucusy-

Christopher Gardner 14:22 Yeah.

Andrew Huberman 14:22 ... and, uh, and puffy. And, um... But I like some sourdough bread. I'm sure there's wheat in a lot of sourdough bread out there. Some yes-

Christopher Gardner 14:29 Yeah.

Andrew Huberman 14:29 ... some no. And I can eat Parmesan cheese and feel fine. But I know people that even though they're not clinically diagnosed as gluten-intolerant, they feel absolutely dreadful when they have any kind of gluten. So what we're trying to do here, I guess, is, um, there's the science, uh, which we'll get into, and then there's people's experience.

Christopher Gardner 14:49 Yeah.

Andrew Huberman 14:50 And as you pointed out, people can't get around their own experience, and they probably shouldn't, right? I think, um, the whole world is done listening to people tell them that their experience isn't real.

Christopher Gardner 14:59 Right.

Andrew Huberman 14:59 (laughs) And that's what a lot of, I think, the, um, confusion in the world of nutrition is about.

Christopher Gardner 15:05 Totally respect that. Let me do the wheat thing, but let me go back to lactose intolerance for just a minute. So I had an opportunity to work with a guy who, um, raises, uh, raw milk products in California, and he was convinced this raw milk would heal lots of people of lots of things.

Andrew Huberman 15:21 Define raw milk. No pasteurization?

Christopher Gardner 15:22 Yeah. No pasteurization, which drives-

Andrew Huberman 15:24 Might as well just be drinking out of the udder like, yeah.

Christopher Gardner 15:26 Yeah. Which drives some health professionals crazy, 'cause at a large scale, you could get listeria and other issues from this if, if the whole thing wasn't properly hygienic. Okay. So anyway, some of his claims seemed outlandish, and quite a few of them would be hard to test, like cancer or some chronic disease. You'd have to wait decades to see that happen. But at one point he said, "And raw milk cures lactose intolerance." And I thought, "That seems friggin' wild." So I mean, how would that happen? And for me... So I am a nutrition interventionist. That is like my superpower. I love designing trials to answer questions, but usually in a couple months or a year, not in 40 or 50 years. And I thought of all the claims that you have, lactose intolerance sets on in hours. So if you wanted to know if this worked or not, you'd know right away. So I said, "I will do this." So this is like the most inexpensive study that I have ever run. I'm going to find people who are lactose intolerant and I'm going to give them your raw milk, some commercial milk, and soy milk as sort of an extra control here. And all we're going to test for is symptoms, and we actually had to have some focus groups upfront. Uh, most of my studies are done in a way that I think this is going to help you, but I'm not sure. In this particular study, if you're going to do all three harms, I know I'm going to hurt you. You're lactose intolerant. I'm going to ask you to drink cow's milk. I need you to have GI distress so that I can see if on the raw milk you don't, and compared to the soy milk, you won't. So in our focus groups, we asked... I usually don't pay people to be in our studies. I usually give them all the results of the studies and they like that. But I said, "I'm going to hurt you, so how much would I have to pay you?" And they said yeah, and I said, "How much?" And they said, "Well, 250 bucks would be okay, depending on how long this thing is." And we sort of talked about the duration, and it had an interesting design. So there's a standard test for lactose intolerance. It's objective. It's a hydrogen breath test. And so you have to drink 16 ounces of milk in one setting, fairly fast, and then you (exhales) every half hour, breathe into a tube, capture the gas, and put it into this breathalyzer. And it'll tell you if there's hydrogen there. And if you have not digested the lactose, it'll go to your colon. The microbes will eat it up. It'll generate hydrogen, you'll absorb that, and you'll exhale it. So it's a very objective test of whether you are or aren't digesting your lactose. So they said, "Yeah, we would do this if the dose after we did the test was four ounces of milk one day, and then eight, 12, 16, 20, 24." And I said, "It's only going to be a week, and you can stop whenever the symptoms are intolerable. I don't want you to be in pain for this. You're not kicked out of the study. I'm really curious what dose it would take for you to react to this. And on the soy milk, you won't react at all. There's no lactose. So it'll just be this question between the cow milk, the commercial one, and the raw milk." So the first part of this study was recruiting. And so we had to say, "To be eligible for this study, you have to fail the hydrogen breath test and you have to complain about symptoms. So you have to be intolerant, and objectively, not subjectively, fail this thing." And so we ended up with 16 people in the study. It wasn't a big deal. They did all three arms.And 50% of the people who swore they were lactose intolerant failed the breath test, like their hydrogen didn't go up after they drank 16 ounces of milk.

Andrew Huberman 18:53 But did any of them feel lousy?

Christopher Gardner 18:55 Yes. And so I couldn't look at them and say, "Sorry, you're not lactose intolerant, you're lying to me." I had to say, "You have failed our test. Our inclusion/exclusion criteria meant that you have to feel these symptoms and you have to have this response." Interestingly, so we had Asian, Black, Hispanic, white, it was all the Caucasians that failed the test that said they had symptoms and didn't pass the hydrogen breath test and show that their hydrogen went up. Which pretty much parallels lactose intolerance is usually in non-Caucasians. So I'm sort of leading up to this point of they had symptoms, they complained, they attributed it to lactose intolerance, but technically they weren't. Something else was bothering 'em, maybe it was small intestinal bacterial overgrowth, the SIBO. Now flip that to wheat.

Andrew Huberman 19:49 Uh, before, before you do, because I just asked-

Christopher Gardner 19:51 (laughs)

Andrew Huberman 19:51 ... I wanna know did raw milk help?

Christopher Gardner 19:52 Oh, oh.

Andrew Huberman 19:53 So I just have to know.

Christopher Gardner 19:54 Okay, that's not fair.

Andrew Huberman 19:55 No?

Christopher Gardner 19:55 No, not at all. So they had the-

Andrew Huberman 19:57 Okay.

Christopher Gardner 19:57 ... same exact symptoms on the raw milk as the conventional. Sorry, that was like the punchline of the whole story is it didn't help at all. It was absolutely identical, but it was a really easy test to study definitively. 16 people might not seem like a lot of people, but because GI disorder is so easy to detect, you either had diarrhea and gas or not.

Andrew Huberman 20:20 Mm-hmm.

Christopher Gardner 20:20 It was very... We're very proud of that tiny little paper, tiny little study we did. Although this raw milk company still on their website says they cure lactose intolerance. So this is-

Andrew Huberman 20:31 Oh, well, a different issue all together.

Christopher Gardner 20:33 So let's not go there, but let's flip that to wheat because-

Andrew Huberman 20:35 Mm-hmm.

Christopher Gardner 20:36 ... so my concern in the world of wheat and gluten intolerance is, yeah, it's amazing how many people feel some distress, and if they were tested you might find out that they're not clinically gluten intolerant, or I'm sure that's a continuum. But I think this actually has to do with our food supply. So in a lot of foods that we grow, historically there were multiple brands of, or types of bananas and corn and wheat, et cetera, and in the US we pretty much grow one kind of corn and one kind of wheat, mono cropping, massive amounts. And, and Americans in particular, of all the grains that people eat around the world, Americans eat wheat. I actually had to do a paper one time where we were sort of trying to determine how much protein came from different sources, how many f- how much from meat, how much from dairy, how much from grains, and I was very intrigued to see that this USDA database said, "Here's our value of protein from grains." And by grains we mean wheat and oats and rice and quinoa and everything, with a little footnote that said, "Because 90% of the grains Americans eat is wheat, we basically just used the wheat value for this and we didn't use the others." And I thought, "Oh my god, with rice and oats and everything else out there, 90% of the grains Americans eat is wheat?" And, but think about it, bagels, pastry, breakfast toast, um, the real, breakfast-

Andrew Huberman 22:04 Even pizza crust.

Christopher Gardner 22:05 Pizza crust.

Andrew Huberman 22:06 Yeah. Yeah.

Christopher Gardner 22:06 They... We eat an insane amount of wheat. So one of my favorite, um, graphics, and sorry, maybe we'll, we'll get into this later, sort of looking at the types of carbs, fats, and proteins that people in the US eat, and I'll have more details if you wanna do this later, but 50% of what Americans eat for carbs is carbs, and 40% is crappy carbs, added sugar and refined grains, which is mostly refined wheat, and 10% is healthy carbs. And so I think what Americans are eating, and I think the gluten intolerance has to do with wheat being such a predominant grain source when it doesn't need to be, and very little variety in the wheat. I know there's actually some folks out there that are trying to bring back sort of some heritage, um, versions of different wheat grains, kamut and, uh, alt- uh, buckwheat, and, uh, what are some of the other ones? Uh, farro and wheat berries. I actually make a kick-ass wheat berry salad if you wanna get into that later. But of all this refined wheat that we're eating, to your point, I, I think, God, isn't that amazing that so many people are now coming up with gluten intolerance? What is going on? I think it's 'cause we eat so much wheat, so much refined wheat, and it's really just one kind. I have heard... I don't know if you've had this experience, I've had Europeans come and say, you know, "I ate a lot of bread in Europe and I come here and I, I'm like gluten intolerant. And then I go back to Europe and I, I can have bread again." And I, I th- I don't know this, so I'm not a-

Andrew Huberman 23:45 Yeah.

Christopher Gardner 23:45 ... food scientist, but I think that's part of it.

Andrew Huberman 23:47 Yeah. My, uh... Very interesting, and I know a lot of people listening are c- are extremely curious about this issue of real versus not clinically diagnosed food allergies, but just negative experiences with food. So how many people are actually gluten intolerant? Um, you hear about celiac disease-

Christopher Gardner 24:05 Yeah.

Andrew Huberman 24:05 I mean, people also now know what the names of these things, so they just kinda throw them out there, um, whether or not they have them or not. And how many people do you think actually struggle with a wheat intolerance? Like a wheat sensitivity? Seems like there's, uh, millions and millions of people.

Christopher Gardner 24:20 Yeah. Not my area of expertise. Don't... Really can't speak to this effectively. Do know that for a, a basic nutrition class that I teach, I was looking at a, a survey of celiac disease and, and testing people for it, and even like half the population with full-blown celiac disease didn't know they had it-

Andrew Huberman 24:38 Mm-hmm.

Christopher Gardner 24:39 ... and were consuming wheat. And so even if you have it-... there's a range of response. You could have and just think, "Oh, my stomach's grumbling. Huh. Doesn't bother me that much." Whereas you have some people who don't have full-blown celiac and they have some gluten intolerance, and a small amount bothers them. So even in, in there, there's some wiggle room that's hard to explain where you can't look somebody in the eye and say, "Sorry, I've diagnosed you. You don't have this." So it is really important for people to, to acknowledge and own what they feel and to look into it.

Andrew Huberman 25:12 Let's talk about processed foods. That gets a lot of attention nowadays and there are, I think we need to parse what we mean by processed foods. I'll just ask this in a very direct way. There are the so-called food additives, the dyes, the binders, the other things that are in, um, processed foods. We should talk about that. There's also the issue of caloric density relative to macro and micronutrients, right? A lot of calories, but not a lot of nutrition, so to speak.

Christopher Gardner 25:40 Sure.

Andrew Huberman 25:40 And then, there are probably 10 other things about what processed food is and what it isn't. Like, tends to be low-fiber, high-calorie, low-fiber, for instance. So let's start with these food additives. This is very, um, much in the, in the media space now, and it's controversial. The dyes, like they just banned another red dye-

Christopher Gardner 26:00 Yeah.

Andrew Huberman 26:00 ... number 40, I think it was, but the fact I can't remember which one just tells you that there are a lot of them. What about these dyes? How bad are these dyes? That was on the basis of a rat, or, or rodent study rather. How much does f- do food dyes concern you as somebody who's spent so much time in this, uh, studying this stuff? Um, nutrition?

Christopher Gardner 26:20 Don't concern me more than any of the other things that are in the packaged processed foods, and partly because those are almost impossible to study. So in my world, if somebody says this thing is a concern, a health concern or health benefit, I have to think, "How would I study that and what is the outcome?" So really, my world is, "What is the exposure and what is the outcome? Can I get funded to do that?" And if the outcome is heart disease or cancer or diabetes, I immediately write it off. I can't wait till somebody dies or goes to the hospital. I won't be able to publish my paper and I won't be able to keep my job at Stanford. I have to publish quicker. So most of my career has been very cardio-metabolic oriented. So I can move somebody's blood cholesterol, blood glucose, inflammatory markers, insulin in weeks, and sometimes say, "Oh my God, how come you didn't do this for years?" I said, "Well, 'cause most of the effect happened in the first two weeks. I did it for eight weeks or I did it for six months." But really, the effect plateaued in weeks if it was the cardio-metabolic risk factor here. So if you want to ask me what a dye does, I'd have to randomize people to sort of get the exposure or not, so the same food with or without the dye, and I would have to have an outcome. And there's really not many outcomes. Um, your cholesterol wouldn't move. Your blood glucose wouldn't move. If it was the same for everything except the dye, those measures would not move. So the idea is you give it to a rat in a huge dose and you see if they get cancer, and it makes metabolic sense that creates a plausibility that this is a carcinogen, but it's really hard to test and think of, you just said you couldn't tr- keep track of how many red dyes there were or blue dyes or yellow dyes combined with emulsifiers and gelling agents and colorants and, uh, anti- uh, or glazing agents. There's a list. So there's NOVA classification put together by Carlos Monteiro from Brazil, is like the hot topic in the world of ultra-processed food. So for the last decade, if you will look, papers coming out every month talking about ultra-processed, and if you look at that paper, it's the NOVA classification. So an interesting thing, just to make this clear a- and we can stop if this is too far down the rabbit hole, but the NOVA classification is agnostic to nutrition. He doesn't care how much fat or cholesterol or fiber is in there. His whole point in making this was there's something beyond that. I know we're worried about lack of fiber, too much saturated fat, something else, but isn't there something to the colorants and the flavorants and the gelling agents, et cetera that could be separate from all this? And it- and he, in his analyses said, "If I, if I parse that out in the data that I'm looking at, that has an additive effect to all these other things." And he's made a big case for it, and people are publishing papers on it all the time. Um, the American Heart Association has a scientific advisory on this, and I've seen the table, it's in our advisory. There's 150 different molecules in this list that come into the different categories, and if you look through the whole list, you would be a little shocked. So for one thing, turmeric is in the list of colorants, so technically, turmeric could move you into the ultra-processed category, but turmeric is full of curcumin and people are really excited about the possible health benefits of turmeric. Pectin is in there. People have used pectin for years to make jams and jellies and things like that. And there's some horrific names that you can't even pronounce in this thing, which I've looked for in foods, and I can't find many of the horrifically named things in any real foods that people eat. Anyway, there's 150 chemicals in this list and it's really intuitively appealing. It's like there must be something beyond just these nutrients. Oh my God, the food industry is out of whack here. And if we could put up- pull in one other term, it's GRAS, generally recognized as safe. And so decades and decades ago, the FDA said, "Wow, there's a lot of these things that the food industry is putting in foods. To do an appropriate test to see if this would harm humans i- is really not feasible." You... Plus, in my world, I can't really do studies where I'm gonna harm people, but I need you to sign up and your staff and I'm gonna randomize you to see who I hurt first, and once I know who I hurt, I'll know if I need to remove this from the food. So they'll do it in mice or they'll do it in rats or they'll do it in a Petri dish to see if it's plausible, and at one point-... there were 800 of these grass items, and I think it's grown to 10,000. There's a whole bunch of ingredients that the food industry can put into foods because of this grass sort of byline, uh, this, this option that's certainly problematic. So we have th- the NOVA list of these additives kind... He calls them cosmetic additives. So let's pause just for a minute to think of that name. So the cosmetic means it's to make the food look good if you're gonna go buy it on the shelf. I mean, think just for a minute of an emulsifier. If you went to buy something and it was separated on the shelf and you thought, "Wow, I don't really want that. It looks like it's half this and half the other thing." If we- let's say it was a salad dressing. I would want the salad dressing to look all homogenized, like somebody shook it up, and I don't wanna buy the... I don't wanna put the parts on my salad. I wanna put the salad dressing. So the cosmetic additives are to make it look good, and that's why we have dyes. "Oh, I don't think I want to buy that gray thing, but I would buy the red or the yellow or the... whatever color it is." So those different additives are going in to make it look more appealing, or feel more appealing, uh, or smell more appealing instead of just being food. So it does make sense that this is sort of we've gone too far. We have this incredible food system that makes inexpensive food very a bit available for a lot of people 24/7, and we just went too far. It's too available. It's too inexpensive. It's too stable on the grocery shelf, uh, placed there so that, like three months from now, no bugs have eaten it, it hasn't gone bad. Isn't that good economically that it hasn't gone bad, but isn't it a little scary that the bugs don't even want to eat it? 'Cause they can tell there's no nutrition in here. So yeah, the processed food issue is very interesting. It's fascinating that RFK Jr. is... wants to handle this, and a lot of us are really excited that somebody would like to take a real firm stance here, 'cause it is out of whack.

Andrew Huberman 33:05 That's super informative, and I appreciate it for several reasons. Uh, one that I'd like to highlight in particular is, uh, now several times you've described that to do a proper study, you need to manipulate variables one at a time. Uh, you just can't do the sorts of studies that one would like to do where you manipulate 10, 20, 40, 100 variables of dyes and colors and... in people and do that in a reasonable amount of time. As you mentioned, either people would all be dead, or, um, there'd be no more funding, uh, for the government for any purpose of, uh, for a study after a study like that was done. It's just too expensive, too time-consuming.

Andrew Huberman 33:44 The other thing is given what you just told us about these additives, wouldn't it just make the most sense to just ban them all?

Christopher Gardner 33:53 Yep, it sure would, and that would wipe out 60% of what's in a grocery store right now. And if somebody went in to buy food for their family and 60% of the food was gone and we hadn't replaced it with food that is more nutritious but meets their budget and is accessible, that would be criminal, to be perfectly honest, and that's, that's why the health community is trying to figure out how to react to this. So part of this is... I'll just take an example, several examples of things that fall into the line of these ultra-processed foods. There's actually quite a few whole wheat breads, yogurts, salad dressings, and things like tomato sauces. So picture a very inexpensive quick meal for a family where the, the parents have three jobs. They're trying to make ends meet. Sure, it'd be great if they could be home growing their garden and scratch cooking all day, but they can't, so they come home. They cook some pasta. They heat up some red tomato sauce, and they pour it on top. More nutritious than, let's say, a fast food something or other. So if you take that tomato sauce away, and they whip together a little salad, and the kids don't want to eat the raw vegetables that are just plain, they want some salad dressing on it. You picked up some salad dressing, and for breakfast, they're gonna have, um, some yogurt or whole wheat bread. So, they're gonna make some toast and put some avocado on it and have some avocado toast, and it was s- said whole wheat bread. All four of those things could have met the criteria for ultra-processed food. So you take those off. They can't have the salad. They can't have the pasta. They can't have the yogurt, and they can't have the avocado toast 'cause you took those all away, unless we had seen that and said, "Yes, we know these should be replaced with more nutritious food that don't have the cosmetic additives," and until we get to that place, you can't get rid of them all. That's just cruel.

Andrew Huberman 35:45 Yeah. No, it's a, it's a wonderful, uh, well, sad but, um, uh, important, excuse me, example of the challenges that people face, um, in terms of how to feed a family. Um, and at the same time, we could wage the argument that people in Europe, um, you know, have families. Um, they work very hard. Um, and their grocery stores include a lot of ultra-processed foods and processed foods but also a lot of fruits and vegetables and, as we talked about before, maybe m- more variety of grains, et cetera. So we don't want to, um, paint a picture of, like, the French countryside, uh, where everything is grown and harvested and, um, you know, searching for truffles during the morning. I spent some time in the South of France, and they actually do this. People there, uh, spend an immense amount of time and energy thinking about what they're going to eat, preparing that food, eating it, and talking about other great meals they've had while they eat it. And even people with- without large budgets, at least at that time, um, ate exceptionally high-quality food, um, in reasonable amounts, and it was incredibly delicious. So there are areas of the world where people do this, but Northern Europe, there's a lot of processed food, and at the same time, we don't see the same sorts of issues with obesity, at least not to the same degree that we do in the United States, the same chronic health and metabolic issues that we see here. So what... I- if we were to compare and contrast, just because they're closest, um, a Northern European grocery store and family and the North American...... grocery store and family, which you just described, you illustrated for us, I think a, a fairly representative example. What's different? What are they eating for dinner that's different? Is it that the tomato sauce doesn't contain these dyes, that it doesn't contain sugar? Um, and what are they replacing, uh, those foods with, if they're replacing them at all?

Christopher Gardner 37:37 So probably at least two answers, and, and one of them is going to be I can't tell you how many Europeans or other folks from other countries have said, "I bought the same product that I buy in my home country here, and it has twice as many ingredients." It's the same company. It's the same food. It could be, um, what's the hazelnut spread?

Andrew Huberman 37:55 Nutella.

Christopher Gardner 37:56 Nutella. Like, here's the Nutella you sell here, and here's the Nutella I buy there. I've had multiple people bring those up to me and show me the different ingredients. And so it can be made-

Andrew Huberman 38:08 Mm-hmm.

Christopher Gardner 38:08 ... the other country way, but in the US it's made another way for Americans. So if we could even just make that move, if we could say, "Okay, you already make this in another country another way. Can you just make it the same way in the US?" That would be a start right there.

Andrew Huberman 38:25 Why is it that there's this discrepancy in ingredients? This, um, became, uh, very much, uh, uh, in the media recently with Froot Loops. It was argued, I don't know if this is true, but it was argued that Froot Loops in Canada are, um, colored with carrot juice and beet juice, and Froot Loops in the United States use artificial dyes. And I- I- I- I can't verify that. Um, I don't know that to be true, but I think a number of examples pointed to that possibly being true. Why would you, uh, have a system like ours if other people can do it presumably for same or lesser cost?

Christopher Gardner 38:57 I agree. I can't back up that one statement either, but I think that is true for reasons that I can't explain, and that's why it would be helpful to talk more to the food industry. I think there are some challenges with this reaction against ultra-processed foods. I think there are some problems with NOVA that I brought up ear- earlier. You'd have to make those foods accessible, but some of them you could fairly quickly if you took advantage of some of the other ways that people are making it and the, the rules are just too loose in the US. So I, I think that's important. And the level at which this could be impactful is not educating the public to look at the back and find the ultra-processed cosmetic additive and removing it. It's to say that we're gonna do this, and the food industry will say, "I'm gonna have to reformulate. If somebody's gonna buy my product, if they're gonna call me out on this, not only am I gonna have to reformulate, it won't be hard because I do it in another country and I could reformulate and so that ingredient will be gone."

Andrew Huberman 39:59 I should ask directly, uh, for your research, do you take funding from, uh, companies in the food industry?

Christopher Gardner 40:05 So several times. So I've got avocado money, I took soy money. Most recently, I took Beyond Meat money. Let me talk about the Beyond Meat, which was the most recent one. I pitted, uh, Beyond Meat versus red meat for cardio-metabolic outcomes, and the Beyond Meat won in several categories over the red meat, and I got a lot of grief for that.

Andrew Huberman 40:25 People love their red meat, including me.

Christopher Gardner 40:27 Yep.

Andrew Huberman 40:28 Yeah. I'll go easy, but I'm not gonna go completely easy. (laughs)

Christopher Gardner 40:30 Oh my god, Gardner is an industry shill. All he does is take... Uh, no, most of my money does not come from there, but I actually couldn't get NIH funding to do that 'cause they would say, "Wait a sec, Beyond Meat makes a crap ton of money. They just sold their IPO. Why would we fund that research? Let the food industry fund that." That actually happens all the time, and we could get into how problematic that is or isn't. It's certainly at least somewhat problematic that the company is funding the research that will test their product. But more interesting to me was that this was sort of Beyond Meat 1.0., and Beyond Meat actually did better than the red meat, and they actually, after that, took out the coconut oil, took out some other ingredients, added some more benign ingredients, and they've actually reformulated multiple times. And so by reformulating, even though the study we did show they had a benefit, I totally respect that. They're like, they are listening, they're looking at the health concerns, they're trying to be responsive, and I think if the food industry as a whole did this and we could work more closely with them, that would be the way to im- improve the US food supply as opposed to we have a new thing, it's NOVA, get rid of them all. That won't really work.

Andrew Huberman 41:45 So I'm hearing two things. One, we need to pressure the food industry to reformulate, get rid of these additives, dyes, what you call cosmetic additives that may or may not be deadly, um, certainly not in the short term, but that in the long term could very well be problematic. We just, we need to do something to make sure that that stuff's removed. It just doesn't make sense to, to hedge on that one. And we can look to Europe and other places that don't... Clearly, that, if nothing else, they've proved that you don't need these things in the foods for them to have a stable shelf life, et cetera. Okay, so that's one. Uh, the other is this issue of, of food industry funding of, of studies because-

Christopher Gardner 42:27 Uh-huh.

Andrew Huberman 42:28 ... um, you know, I'm not an expert in nutrition, but I pay a lot of attention to the way that nutri- nutrition and, and health is discussed online, and that's, I mean, that's my business more or less. And every time somebody hears that a researcher took money from a company to run a study, uh, they assume that there's bias, um, in fairness to you and to the process, I'll just ask, are they able to influence the question? Certainly not the collection of data. There's, I mean, you know, the data are the data. Um, your graduate students and postdocs who, are the ones who actually run these experiments, um, presumably know... have a hypothesis at the beginning, they ask a question, and they try and disprove that hypothesis. Um, but does the company say, "We want you to test a given hypothesis," or is it funding for you to test a hypothesis that you select? In other words, is there good separation-

Christopher Gardner 43:22 Yeah.

Andrew Huberman 43:22 ... of concept? Um, clearly the money issue gets people inflamed, but...It's a very different thing when a company says, "Hey, can you test whether or not our product outperforms in terms of cardiometabolic markers compared to red meat?" Versus, "Hey, listen. You know, you wanna study, you wanna study cardiometabolic markers in people that consume Beyond Meat versus cow meat? Um, okay, we'll fund that." There's, it, there's, it, it seems subtle but it's not so subtle, because in one case, they have a, an endpoint that they're interested in. In another, in the other case, you have an end- endpoint that you're interested in. Yeah.

Christopher Gardner 43:55 It's not a simple answer to that, 'cause it's not a yes/no question, it's a total continuum. So, they could say, "We'll give you this money if you'll do that." They could say, "We'll give you this money to do anything you want, but tell us about it as you go." Uh, you could write up the results. I'll give you the most interesting ex- personal experience that I had in this. So everything was pretty benign all the way up till when we got the study done, and this had to do with cognitive impairment. And so I'm not gonna even talk about the product, I'll just set this up, 'cause I think you'll find it interesting. So, turns out the people we recruited had pretty high cognitive ability. There's a cogni- there's a survey you can take and I think 50 was the top, and everybody who signed up was a 45. And we were kind of looking to see if this supplement could increase cognitive ability, but we should've realized in the beginning that there wasn't much room to increase. They were 45 out of 50 to begin with. And it failed to show that the product increased cognitive ability. So we shared it with the company and they said, "Well, I can see you're saying there's a null finding here, but could you also say, uh, there was no deleterious effect?" And I said, "We weren't looking for a deleterious effect. We were looking for an improvement." And they said, "Yeah, but isn't it also true that it didn't make it worse?" I thought, "That's actually true. It didn't make it worse. Could I, to make these guys happy and to maybe get more money later, should we say it didn't make it worse?" So that would be a really subtle influence that they could have-

Andrew Huberman 45:25 Mm-hmm.

Christopher Gardner 45:25 ... later on.

Andrew Huberman 45:26 In theory, they could market with, "This supplement maintains high levels of cognitive performance."

Christopher Gardner 45:31 Something like that.

Andrew Huberman 45:31 And be truthful but not giving the whole picture.

Christopher Gardner 45:34 And at the end of the day, really, the important thing is to look at the study design.

Andrew Huberman 45:38 Mm-hmm.

Christopher Gardner 45:39 So let me, I think I can flip this to something that's way more practical than that. It's not even industry influence, it's the investigator influence. So in my world of nutrition, and this is gonna go back to the parking lot of not doing one thing at one time but doing multiple things at one time.

Andrew Huberman 45:54 Mm-hmm.

Christopher Gardner 45:54 Let's say I wanna study vegan or paleo or keto or something like that. I can have diet A versus diet B and make a kickass diet A and a crappy diet B, so it's really unlikely that B will win.

Andrew Huberman 46:07 Mm-hmm.

Christopher Gardner 46:08 And then I publish that and there's a headline on it, and then there's someone else who actually favors a competing diet. They start a study, they make a kickass diet B and a crappy diet A, and the diet B wins because they set it up that way. No industry influence at all here. This is investigator influence. And then the public comes and says, "What the hell? Wha- it said diet A is better one day and it said diet B is better the ne- my god, you nutrition scientists never agree on anything. I'm just gonna go have a burger." It's like, ugh. If you had looked at the design, so one of my favorite new words in nutrition is equipoise. I've been trying to set up studies where it's the best diet A that you could be and the best diet B. So if I can just riff off a couple things, one of my most famous studies is DIET-FITS. It had to do with a low carb, low fat diet, 600 people for, uh, a year. This was an $8 million study.

Andrew Huberman 47:04 This is the 2018 study?

Christopher Gardner 47:05 Yeah. Uh-huh.

Andrew Huberman 47:07 Mm-hmm.

Christopher Gardner 47:07 And we tri- and I told the dieticians, I said, "I don't really care which one wins. Uh, we actually think there's some genetic predisposition or metabolic predisposition. It'd be great if everybody won. But just to test this fairly, I want all the dieticians to be advising the 600 people in the study, you have to teach both low fat and low carb. You get assigned to different groups and teach the best low carb you can and the best low fat you can so that if one wins at the end, we can say we gave both of them a fair shot." Um, when we did SWAPMEAT, uh, this is our, our study, the study with appetizing plant food, meat-eating alternative trial, SWAPMEAT trial with Beyond Meat. What should we pick for the red meat? Should we pick fast food? Should we pick-

Andrew Huberman 47:50 Where do I buy?

Christopher Gardner 47:51 We went to, uh, San Francisco and got Good Eggs, which prides itself on getting organic, regeneratively farmed, pasture raised, so we wanted to get a good quality red meat. Uh, we did a study with a vegan diet versus an omnivorous diet, and so for the omnivorous diet, we went to a company that makes really good food and we have it delivered versus vegan. We did ketogenic versus Mediterranean and we made a good Mediterranean diet, and we did Jeff Volek and Steve Phinney's well-formulated ketogenic diet as the comparison. So in all these, our group was ha- been having fun trying to address your comment separate from industry influence just to, to try to make the two arms as fairly-

Andrew Huberman 48:39 Mm-hmm.

Christopher Gardner 48:39 ... competing against one another as you can. Going back to the industry one, there's no way to pull it off 100% clean. There's just no way. There's so many subtle things that could happen. So the thing that does help these days is you have to regiter- register your trial on clinicaltrials.gov to start with. You have to name the primary outcome ahead of time and the whole study design for the world to see, so that if it gets to the end of the study and you switched it, somebody'll say, "Calling you out on BS. That wasn't your primary outcome." You can have a third party analyze your data. You can lock down the data at the end. You can make the data publicly available. There's m-

Andrew Huberman 49:19 Yeah.

Christopher Gardner 49:19 ... a couple more of these steps that you could, this is as transparent as I can be so you can make the chance of industry influence lower...But you can never eliminate it. So if I find a positive result, maybe they'll fund me again later for something else. Um, even though they didn't, some of the st- uh, industry folks, like I often get gifts. If it's a gift, they can't demand to see anything, but I can offer to show them what happened. And if I, if I show them and they say, "Hey, would you consider doing this?" I'd be pretty stupid to say, "No, you gave me a gift and I'm not gonna consider the thing you said." I, I would say, "Yeah, I'll consider it. I will look at it and I want to present objective data." But it's, I don't think it's the industry as much as the investigator and how they handle it.

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Andrew Huberman 53:12 When it comes to... Well, let's just, um, close the hatch on the industry funding part because I, I know that's gonna get, um, some people, uh, hair standing up a little bit. Is there a world where you don't have to rely on industry funding to do these studies? I mean, my first response is, is like, um, why go there? Why not just, I mean, we have a National Institutes of Health. Um, they fund studies on everything from, uh, developing novel molecules for the treatment of Parkinson's to studying the effects of breath work on cancer outcomes.

Christopher Gardner 53:48 Yeah.

Andrew Huberman 53:48 I mean, I mean, it's a, nowadays, it's a very wide range of topics that the NIH embraces, but I think most people don't realize this, but there's an everything in between. So why not just go to NIH for the money?

Christopher Gardner 54:02 Historically, the proportion of the NIH budget gone to nutri- that goes to nutrition studies is infinitesimally small.

Andrew Huberman 54:09 I see.

Christopher Gardner 54:09 There, there's been many requests to create an Institute of Nutrition. I, personally, that'd be pretty selfish, I'm all in. I wish they would have more resources for me to do those kinds of studies with objective money. So-

Andrew Huberman 54:23 My guess is Robert Kennedy would be a fan of that sort of thing.

Christopher Gardner 54:26 Right.

Andrew Huberman 54:26 I'm not speaking about this with any p- um, political affiliation, but he seems to care a lot about getting dyes and additives out of food and cares a lot about the food supply. At least he stated that.

Christopher Gardner 54:37 Yeah.

Andrew Huberman 54:37 Um, and NIH is currently in a state of massive revision right now, pause/revision. (laughs) Um, and I would imagine they would allocate more funding for studies of nutrition, um, given who's in charge now.

Christopher Gardner 54:54 The, the bigger challenge is how many nutrition questions there are. So I just served for two years on the Dietary Guidelines Advisory Committee. We had two years to consider 60 different questions. Each one of the questions generated sub-questions. The vast majority of questions resulted in a conclusion that was either not enough data available or only enough data available to generate a limited strength response. To get a moderate or a strong, more data are needed. This was almost mind-numbingly repetitive through the whole two-year process. More data needed, more data needed, more data. And this had to do with-... snacks, skipping meals, heart disease, diabetes, cancer, pregnancy, infancy, processed foods, seed oils, meat and protein. The questions are pretty endless. So if, even if you opened up the NIH and said, "Yeah, we're gonna, we're gonna move 25% of our budget to studying nutrition," you wouldn't even come close to answering all the questions that the public has right now.

Andrew Huberman 56:04 Yeah, that's an important point, and I would say that the, the public is also doing these experiments. You know, the health and wellness, uh, community gets, um, catches a lot of flak from the standard scientific community. They'll say, "You know, supplements aren't regulated." They are regulated. There is a variety of qualities across brands, and even, probably even supplements within brand. But, um, the experiments are ongoing. You have people who are carnivore, you have people who are vegan, you have people finding what works for them. They eliminate this or they add that, and they're becoming scientists for themselves. And we've really decentralized nutrition science, uh, in my opinion. That's just my little editorializing.

Andrew Huberman 56:41 Um, you mentioned this 2018 study, and I'm so glad that you mentioned, um, your efforts to remove investigator bias by making the vegan diet not like crap vegan food, and not making the meat diet all processed meats because that's happened-

Christopher Gardner 56:56 Yeah.

Andrew Huberman 56:56 ... in a lot of studies.

Christopher Gardner 56:57 Yes.

Andrew Huberman 56:57 And then that's why the headlines are so confusing over the years, or even within a year. So, um, could you just share with us the major results of that study, uh, what the, what the key takeaway was so that people who have heard, "Oh, I heard paleo, vegan, vegetarian, um, uh, you know, Mediterranean and omnivore," which diet was best, if any, and for what purpose?

Christopher Gardner 57:18 Yeah, at the end of the day, my take, if you put all of my studies together, it's a whole food, plant-based diet, which does not mean vegan and doesn't mean vegetarian, but could.

Andrew Huberman 57:28 Wait, plant-based but includes meat?

Christopher Gardner 57:31 Yeah, so I don't like this new thing about plant-based being vegan. Sorry. So, we're not-

Andrew Huberman 57:35 It's a terrible name.

Christopher Gardner 57:36 So let's just do this for 60 seconds. (laughs) So, uh, pescatarian, lacto-ovo-vegetarian, lacto-vegetarian, ovo-vegetarian, uh, vegan, flexitarian, reducetarian-

Andrew Huberman 57:51 Flexitarian? Oh my goodness.

Christopher Gardner 57:52 There's all kinds of words out there, and clearly one of the ones that doesn't go over well is vegan. Vegan is very polarizing, and a lot of that is because the vegan community, uh, an important reason many of them are vegan is animal rights and welfare. And it becomes sort of a condescending thing, "Oh my God, you're so unethical and immoral. You slaughter animals and eat them. Uh, I am holier than thou. I don't." So-

Andrew Huberman 58:15 Well, and then it gets into issues whether or not a vegan is wearing leather shoes or not wearing leather shoes.

Christopher Gardner 58:19 Uh-huh.

Andrew Huberman 58:20 And the vegan community an- historically was very t- closely tied to the animal rights community-

Christopher Gardner 58:24 Yes.

Andrew Huberman 58:24 ... some of which were radical animal rights activists-

Christopher Gardner 58:26 Yeah.

Andrew Huberman 58:26 ... that blew up buildings and, you know-

Christopher Gardner 58:28 Yeah.

Andrew Huberman 58:28 ... and worse.

Christopher Gardner 58:29 Totally agree.

Andrew Huberman 58:29 I know people who have been targeted by those explosions.

Christopher Gardner 58:32 I have been plant-based vegan for many, many years, and I haven't blown up any buildings and I haven't thrown any rai- red paint-

Andrew Huberman 58:39 I believe you.

Christopher Gardner 58:39 ... on anybody wearing a fur. But because that was so polarizing, recently, and I think this is gonna have, uh, this is gonna have a backlash and it's gonna be failed, people have u- been using plant-based as a different word for vegan. Just like, "Oh, we're not the polarizing group, we're the plant-based, which is not polarizing." So, I've been doing this for 30 years. When I said plant-based for the last 20 years, I meant most of it's plants, and some of it's dairy, and some of it's meat. So I actually use it differently than what it has just morphed into recently. So, when I say whole food plant-based diet, that could be 25% animal products, it could be 30% animal products, could be 10%, it could be zero animal products, but it'd be mostly plants. This is sort of Michael Pollan's old-

Andrew Huberman 59:27 Right.

Christopher Gardner 59:28 ... eat food, not too much, mostly plants. So, that's what my research would suggest. Um, the vegans did better than the omnivores in our twin study that was featured on Netflix. The Mediterranean versus the keto diet, it's a little more subtle, we might have to get into that. The low carb versus low fat was very specifically for weight loss. So another issue here is, you know, what's the goal? Is it a weight loss thing? Is it a cardio amount? You have to think about the exposure and the population. So the DIETFITS study, my most famous study with the 600 people, was really fun to work. We had sort of unlimited funds, mostly from NIH, but from, some from the Nutrition Science Initiative that Peter Attia and Gary Taubes led. If it's okay if I go here just for a minute, I had done another study before that called the A to Z study, and A was Atkins and T was a traditional health professional's approach, and O was Ornish and Z was Zone, and these were f- three of those were popular books that were bestsellers, and they were wildly different in carbs and fats. Atkins was super low carb, Ornish was super high carb, Zone was kind of in the middle, and the traditional health professional's approach was sort of the control. We had 311 women who did it for a year, and it was a weight loss study. And at the end of the day when we published the paper in JAMA, there were a few pounds different. The only statistically significant difference was between Atkins and Zone, which was weird 'cause those were the two low carb diets. You would have thought maybe it's Atkins versus Ornish, the two extreme diets, but those weren't different. When I looked at that study published in 2007, what really struck me was not the small differences between groups but the within group differences, which were massive in every one of the groups, 75 women in a group. Somebody had lost 30, 40, and 50 pounds, and somebody had gained five or 10.

Andrew Huberman 1:01:20 Hmm.

Christopher Gardner 1:01:21 And I thought, "Oh my God, like the, the difference within the diets is way cooler than the difference, the average difference between the diets." I'm starting to lear- learn about insulin resistance. I'm starting to learn about genetic predisposition, which is sort of where our conversation started today.... "Ah, you know, maybe I should be looking at these personal factors, these predisposing factors, so I could help see if somebody was better on one versus another." And as we looked through our data and the rest of the literature, the two things that arose were insulin resistance, maybe better on low carb, 'cause folks who are insulin resistant have a hard time putting away carbs. So the low fat is problematic if it's high carb. And genetic predisposition, there was a group called Interleukin Genetics that came and looked at some of our data and said, "Oh, my God, we actually have a three SNP, single nucleotide polymorphism, a three SNP multi-locus genotype pattern that we hypothesize predicts who's low fat and low carb." And we said, "NIH, would you fund this?" And they did, and we got this extra money from the Nutrition Science Initiative. We got 600 people. We randomized 'em for a year. Everybody was into it. It was just, like, the best, highest rigor, highest generalized ability study I've ever done. And importantly, there was no average difference at the end of the year in the two groups, which is actually exactly what we wanted. If we had a high quality of low carb and low fat, we assumed that the average difference would be negligible based on our past work, but we would get this range, and we did. This time, somebody had lost 60 pounds and somebody had gained 20 in both groups, and it was a continuum. It's like, "Oh, this is perfect." We are gonna have a chance to explain this variability with a glucose, uh, oral glucose tolerance test, which is sort of state-of-the-art, other than the steady state plasma glucose thing Gerry Reaven does, which is too intense and too expensive. Oral glucose tolerance test, much better than a fasting glucose. Um, and we'll genotype them, and... (fingers drumming) Neither of them predicted the variability-

Andrew Huberman 1:03:31 That just means it was the wrong-

Christopher Gardner 1:03:32 ... in the two diets.

Andrew Huberman 1:03:32 ... the wrong probe. You were, you were using the wrong test to, to try and address this correlation.

Christopher Gardner 1:03:38 So, you know, postdoc looked at me afterward and said, "There are, like, 50 single nucleotide polymorphisms that have been linked to obesity, and you tested one set of three of them. So that does mean there's 999,999 other genetic probes or tests that you could use, and you've disproved one of them." And I said, "Yeah." But the insulin resistance one was very popular. There were a bunch of studies that had done this, and I have to share a really funny comment that Gary Taubes made while we were doing this 'cause Ga- Gary Taubes was involved in

Andrew Huberman 1:04:08 What's he best known for? Could you just-

Christopher Gardner 1:04:10 Low carb.

Andrew Huberman 1:04:10 Low carb.

Christopher Gardner 1:04:11 So Gary Taubes is a low, low carb fanatic. Um, and he, he gives excellent talks. He can riff on and on about data and data and data. But I have to tell you a funny comment that he made as we got to the end of the study. He said, "I realized now that you're at the end and you're about to publish it that you screwed up the study." I said, "How did I screw up the study?" And he said, "Well, for the low fat group, you told them not to have added sugar or refined grain, even though those are low fat." And I said, "Well, yeah, actually we told both groups to have a really healthy diet, and added sugar and refined grains aren't healthy." And he said, "Well, that's gonna diminish the chance to see a difference 'cause most people who are eating low carb versus the traditional low fat do better 'cause the low fatters eating high carb are eating added sugar and refined grain." I thought, "That's not screwing the study up. That's doing the equipoise thing." I saw a lot of literature showing that insulin resistance did suggest that there was a subset of the population that would do better on low carb than low fat. And we've actually now followed up on that study with a ketogenic versus a Mediterranean diet study. And in that particular study, the way we set it up is both groups would get a lot of above ground vegetables, which keto says is okay. A- avoid added sugar and refined grain, and keto would have no beans, no fruits, no whole grains, and Mediterranean would embrace beans and whole grains and fruits. And so they didn't have a glycosylated hemoglobin difference. That was the primary outcome listed on clinicaltrials.gov. The keto diet raised LDL. The keto diet did actually a better job lowering triglycerides than Mediterranean.

Andrew Huberman 1:05:51 The keto diet did better at lowering triglycerides-

Christopher Gardner 1:05:54 Yes.

Andrew Huberman 1:05:54 ... than Mediterranean.

Christopher Gardner 1:05:55 Yes.

Andrew Huberman 1:05:56 That surprises me.

Christopher Gardner 1:05:57 No, because they did better at wiping out carbs. When they wipe... When you wipe out all your carbs, then those extra carbs don't go into your liver to make triglycerides. Not surprised. And the keto diet was higher in saturated fat.

Andrew Huberman 1:06:10 Okay.

Christopher Gardner 1:06:10 So it raised the LDL.

Andrew Huberman 1:06:12 But the Mediterranean diet carbs generally are pretty he- quote, unquote, "healthy carbs."

Christopher Gardner 1:06:15 Yes, and that's the point. So can we go back there for a minute? So to me, that is the point of sort of looking at this equipoise. So when we made the low carb and the low fat both healthy, our primary, um, predictive outcomes, the genotype thing and the insulin resistance didn't work. And, and what we took home from that message is you could do either one. If you do them in a healthy way, it would be okay. And when we took it to ketogenic and Mediterranean, they both lowered glycosylated hemoglobin. One had... The keto had a worse effect on LDL, but a better effect on triglycerides. But we, as we tracked the adherence, people couldn't adhere to the keto. They couldn't maintain that really low level of carb and the really low level of fat. And so as you're working through these questions, those are the subtle nuances in nutrition that y- y- you just said the poor public, and I agree, looks at so many of these and says, "Oh my God, you guys can't agree." Can I go back to the fact that I've actually helped American Diabetes with their guidelines? I work a lot with the American Heart Association. I just rotated off the Dietary Guidelines Advisory Committee, and when there are scientists looking at nutrition data, we almost always agree. Nutrition scientists don't really disagree. We're almost boringly more in agreement than most people think. And what's fun for me personally, what, why I get up in the morning and stay up late at night is the, the way you do science around food is fascinating.... and complicated, and the reason I'm on your show today is 'cause I, I think if we had more of an opportunity to explain some of these subtle nuances, people would understand that the extremes probably aren't gonna help you. There's really some middle of the road stuff, like a whole food, plant-based diet, where you could be vegan, you could be vegetarian. If you were vegan, you could be a crappy vegan. You could have Coke, french fries, and Oreos. Those are all vegan. If you were keto, you could be eating a whole bunch of meat, which is super low carb, but a keto diet is all fat. It's really not a lot of protein and meat. So, it's fun to come on your show and have the chance to dive a little deeper and talk to the listeners about some of the important facts that get a little obscured when the social influencers or the headline is just capturing an overall message about seeing some of the rest of this. How do we communicate this in a fun way? And my... the personal way I've been doing this, actually, my career has shifted now. I now work a lot with the CIA. I am on the scientific- scientific advisor board of the CIA, not the Pentagon one, the Culinary Institute of America.

Andrew Huberman 1:08:58 (laughs)

Christopher Gardner 1:08:58 And what's really been fun about them is how much they appreciate taste, energy, taste, like, the, the things that people really care about, not some of my P values and my statistics and my equipoise. They want the aesthetic, they wanna look good personally, they want the food to look good, taste good, be accessible, so I've been doing some new fun studies where chefs are sort of leading the way, so I'm pretty much against this whole protein craze thing that's going on. And the Culinary Institute of America has introduced this concept called the protein flip, where instead of having a massive piece of flesh in the middle of the plate, with maybe some vegetables and starch on the side, it's vegetables and grains and beans in the middle of the plate with an African, Asian, Mediterranean, Latin American, um, emphasis, and the meat is two ounces or it's a condiment or it's a side dish. And it's like making the aesthetics look good, making it taste great. So the phrase I use is from Gregg Drescher, from the CIA, unapologetically delicious. So I'm hoping to have the science in my back pocket, I'm a card-carrying PhD nutrition scientist. I got the science, we'll probably go there later, I got the environment in my back pocket too, but don't people o- don't beat people over the head with that. Beat people over the head with, "Oh, this is gonna blow your friggin' taste buds away. This is so good."

Andrew Huberman 1:10:23 Well, that's a

Andrew Huberman 1:10:24 good incentive.

Christopher Gardner 1:10:24 Working with chefs has been very fun.

Andrew Huberman 1:10:27 Yeah, that's a good incentive. Um, I would like to kind of just offer the opportunity, you don't have to take it, but offer the opportunity to finally at least start to do away with this ridiculous naming, which is plant-based. I mean, I have to say that, again, I've spent a good, good amount of time in the, uh, public health sphere and public education sphere. How things are named means everything.

Christopher Gardner 1:10:50 Yeah.

Andrew Huberman 1:10:50 If there's ever a hope to get people eating more, let's just say, fiber from vegetables and maybe fruit also, that sooner or later, this plant-based naming, I'm gonna say, has got to go. It just is never gonna work because people hear that and they hear vegan. It's just been too long. It's been too long. It's, um, it, it's just, it, it sort of go- defies, uh, any kind of logic to think that the public will eventually think that plant-based includes meat. I think there just needs to be a new name, so I don't expect you to come up with one on the fly, but could we call it plant biased perhaps? (laughs) Um, or-

Christopher Gardner 1:11:26 So if, um-

Andrew Huberman 1:11:26 ... or just omnivore. What's wrong with healthy omnivore?

Christopher Gardner 1:11:29 Omnivore is fine. Plant-forward people have used. Plant-centric people have used.

Andrew Huberman 1:11:32 I think as long as it's just... Plant-forward just sounds like no meat.

Christopher Gardner 1:11:35 So let me tell you a funny story. So I participate in something called the Google Food Lab, which is a whole bunch of people that come together for Googly casual collisions twice a year. And at one of these twice a year events, probably a decade ago, uh, it's, it's usually a two-day event and they have all kinds of different talks and sometimes breakout groups. They had... For a whole hour and a half, two hours, we separated into 10 tables, and the challenge was, with 100 really bright people all from the food industry, to come up with options for plant-based, and they failed.

Andrew Huberman 1:12:11 New names.

Christopher Gardner 1:12:11 Two hours. Two hours, 100 people couldn't come up with a name that everybody agreed on. So, it's a problem. It's gonna-

Andrew Huberman 1:12:22 That sounds like a psychological problem.

Christopher Gardner 1:12:24 We need more marketers-

Andrew Huberman 1:12:25 Mm-hmm.

Christopher Gardner 1:12:25 ... and we need more infographic people-

Andrew Huberman 1:12:27 Mm-hmm.

Christopher Gardner 1:12:27 ... to help with this thing, and but these were all really bright people, so I agree the naming is problematic. Instead of naming it something, let's just point out that Americans eat more meat than anyone else in the world. It is a m- if you see these WHO, World Health Organization, graphics of who eats how much meat, it is the US and Canada and some European countries that eat the most. And there are countries who eat the least and they have limited access to foods, and some of those countries would benefit from more meat per person because the... really, they're eating cereal. They're eating dry cereal-based foods that honestly just don't have the full nutrition. They're just trying to get enough calories for the day, and it's not just about calories. And part of that isn't just access to food. A lot of those are countries where there's political issues, where somebody's actually withholding food or making the distribution of food problematic. So there's something called the Lancet report that came out in 2019 published in Lancet, the EAT-Lancet commission, and came up with a, a healthy transformative diet for the planet that was the intersection of human and planetary health, and it was very little meat. It wasn't vegan. It was very little meat, open to the idea that some of these countries that ate the least meat should probably eat more. But what was obscene-... was how much meat is eaten in America compared to the rest of the world. And to eat that much meat and be affordable has led to the concentrated animal feeding operations, which if they had glass walls, probably most of the country would go vegan. Um, if you saw what was happening, not just to the animals, the way that they're raised and the speed, the line speed, part of this is the way the humans are treated who are in the meatpacking industry. So it's a very repetitive, uh, job. There's a lot of injury- injuries in that, uh, situation, and it's part of the reason we have very inexpensive meat that's very inaccessible. There's a guy named Timothy Pachirat, who, uh, for his doctoral thesis went and worked in a slaughterhouse for a year undercover and published a whole book on this. And the title of the book is Every 12 Seconds. And the reason it's titled that is 'cause a new cow came through the slaughter line every 12 seconds, every day, all day, every year. And that the ability to protect some animal rights and welfare, the a- the ability to protect the rights of humans to have some dignity. They have, like, people peeing in bottles 'cause they can't leave the line. Uh, they can't even take a bathroom break. It's a messed up food system. So I, I had an interesting debate with Mark Hyman the other day, who's all into regenerative meat.

Andrew Huberman 1:15:11 You mean, like, regenerative farms, like, uh-

Christopher Gardner 1:15:13 Regenerative farming?

Andrew Huberman 1:15:14 Yeah.

Christopher Gardner 1:15:14 Yeah. On regenerative ranches, and said, you know, if we, I, he's all against the CAFOs, the concentrated animal feeding operations, if we could just move all those off to pasture. And he said, "Yeah, we, we could just do that." And I said, "Do you know how much pasture that would take? That would take, like, three planets of agricultural land to move the millions and billions of cattle out of the CAFOs into there." So I would like to move in your direction, where some meat would be fine if it was raised in a way that didn't require hormones, didn't require antibiotics, didn't require feeding cows corn and soy. They're supposed to graze on grasses, and the corn and soy give them health issues, and so they have to be treated prophylactically for the problems they'll have digestively with that. If we could go back to sort of the old animal husbandry of the day when the cattle and the pigs and the chickens were on pasture, we would eat a lot less meat, but we would eat meat that was raised appropriately and would be more healthy. And that would be that middle-of-the-road, where we were having multiple types of wheat, not just the one grain that grows right. We wouldn't be mono-cropping corn. We wouldn't be mono-cropping soy, which is mostly going to livestock feed or fuel. Very little corn or soy that we grow in the US is eaten directly by humans as corn or soy. I would be all for that. If we spread out that, the meats that way, it would be better, basically less meat, better meat.

Andrew Huberman 1:16:45 Mm-hmm.

Christopher Gardner 1:16:46 Would work fine. That would be part of a healthier diet for people on the planet. That meat would cost more. Raising it that way would certainly cost more, but if you ate less of it, it wouldn't be that big of a hit on your budget. So if you had less meat, better quality meat, you might be spending the same amount, but then you could also have more fiber for your microbiome, more other vitamins and minerals, less saturated fat, less hormone, less antibiotics.

Andrew Huberman 1:17:14 I love hearing that. I completely agree, by the way, and, um, I think that there is a, a theory, right, um, I forget the name of this theory, that one of the reasons why people in Europe, especially Southern Europe, can eat all these foods that we consider kind of bad for us, they'll have a dessert, they have bread, they have butter, they have olive oil, they eat meat. In fact, they have a fairly pork-rich diet in certain parts of Southern Europe, that, on average, the obesity rates are, are much lower. And the argument, I think, is that the, the nutrient density is so high in these well-raised, um, appropriately raised and farmed foods that people end up eating less of them. It's not just that portion sizes are small. It's that the food tastes really good, and it's satiating it at a level that's different from volume or caloric intake. I think so much of what people, um, think tastes good actually is just relative to the fact that they've never tasted, like, a real strawberry.

Christopher Gardner 1:18:07 Yeah.

Andrew Huberman 1:18:07 And I think, um, so what we're talking about here is revising the entire food supply. And I'm all for it. I, I really am. I, I'm all for it, um, because addressing this from the level of following this diet or that diet, at least according to your work, doesn't really seem to be, um, the best approach, assuming that what people really are after is the experience of food.

Christopher Gardner 1:18:30 Right. And that's why it's so fun now working with chefs. So really, our emphasis for right now, think about educating the population. That usually doesn't work. Like, this is a, this is a big shift, potentially, that we're talking about. If you tie this to the environment, we're kind of on a horrific path to not having enough air and land and wha- whatever, water, to do this. Um, but in the US at least, 50% of food is eaten outside of the home. And if you think of a group like the Culinary Institute of America that trains chefs, you might think chefs, I bet their goal is to be in a three-star Michelin restaurant. They've, apparently, they've trained 55,000 chefs to date, and very few of them run Michelin three-star restaurants. They're in hospitals. They're in the Marriott Hotel. They're in universities. Uh, they're in schools. More of them could be in schools. And, and really their gift, their superpower is taking different food sources and putting them together in flavorful ways that people enjoy. And so my current interest, uh, actually in working with the new Doerr School of Sustainability at Stanford is to bring the chefs in and to think of these institutional food settings where so many people are eating at the work site, at the school, while they're visiting the hospital, whatever, and their choices are different, and they taste good, and they look good.And in the back pocket, they're actually good for you nutritionally, and they're actually good for the environment. We don't have to teach any about this. We, like, work with the chefs, chefs and scientists and businesspeople. Uh, this group that I work with, uh, at the Culinary Institute of America, about 12 years ago, I was invited to something, uh, that's now called the Menus of