Joe Rogan Experience #1175 - Chris Kresser & Dr. Joel Kahn

Joe Rogan 0:02 Five, four, three, two, one. (claps) Gentlemen, thank you very much for being here. I really appreciate it. Dr. Kahn, uh, before we get started, why don't you tell everybody what your background is. Uh, you will be representing the vegan portion of this discussion. Uh, tell people about yourself a little bit.

Dr. Joel Kahn 0:22 Thank you. I feel like the head broccoli in the United States today. But I am from Motown, Motor City, badass. Uh, born and raised University of Michigan School of Medicine, summa cum laude, internal medicine training, cardiology training in Dallas, Texas. Very hard to be vegan in Dallas, but I did it in the '80s, because I've been doing this 42-year vegan.

Joe Rogan 0:41 42 years?

Dr. Joel Kahn 0:42 42-year vegan, thank you.

Joe Rogan 0:43 That's impressive.

Dr. Joel Kahn 0:44 Age 18. And then, uh, Kansas City, Missouri, another tough town to eat plants in, only the steakhouse, KC Masterpiece. Did, uh, training in stenting. I was blasting open heart attacks from 1990 on. Came back to Michigan, very active cath lab, heart attack, you're dead, I bring you back practice, 24 hours a day with great partners. And about three to four years ago, I used all these decades of plant-based medicine I've been basically bringing my family up with and teaching patients, but opened a completely preventive cardiology practice. And along the way with my wife and son, we now own three plant-based restaurants, two in Detroit, one in Austin, Texas. Write books, do TV, write blogs, teach, teach, teach. Not gonna stop till I'm 150.

Joe Rogan 1:29 And-

Dr. Joel Kahn 1:29 Because there's a lot of erectile dysfunction to stamp out. That's my passion.

Joe Rogan 1:33 That?

Dr. Joel Kahn 1:34 Oh my God, what else? What better purpose in life?

Joe Rogan 1:37 Um, well, okay, we can get to that later.

Dr. Joel Kahn 1:40 Heart, heart, heart, heart dise-

Joe Rogan 1:41 (laughs)

Dr. Joel Kahn 1:41 Heart disease is somewhere in that mix too.

Joe Rogan 1:43 Okay, and, uh, if people want to read more about you, website is?

Dr. Joel Kahn 1:48 Yeah, uh, D-R-J-O-E-L K-A-H-N, drjoelkahn.com.

Joe Rogan 1:53 And you've written a ton of books, right? How many books?

Dr. Joel Kahn 1:55 Five books.

Joe Rogan 1:55 Five books.

Dr. Joel Kahn 1:56 And a bunch of medical papers.

Joe Rogan 1:57 Okay.

Dr. Joel Kahn 1:57 And a whole lot of blogs.

Joe Rogan 1:58 Awesome. And Chris?

Chris Kresser 2:01 Yeah, Chris Kresser. Um, I did my undergrad at UC Berkeley, and, um, then got a Master's of Science and, um, Co-Director of the California Center for Functional Medicine, which is a functional medicine clinic in, in here in California, up in Berkeley. And, uh, I came to this from my own experience with chronic illness. I- as, as you know, Joe, got really sick, uh, back in my early 20s when I was traveling around the world, and, uh, you know, conventional medicine didn't have much to offer for me. And so, that led me on a path of trying to figure out the best approach from a diet and behavior and lifestyle perspective to heal from my own chronic illness, and then that evolved into, um, me starting to write, you know, I started a blog and a website. And then, um, wrote a couple of books and now have, uh, an organization that trains practitioners in functional medicine and also trains health coaches.

Joe Rogan 3:00 And you, at one point in time, were vegan?

Chris Kresser 3:03 I was a macrobiotic vegan. I was apprenticing with a macrobiotic, uh, chef. So, uh ...

Joe Rogan 3:09 What's the difference between a macrobiotic vegan, for folks, and a regular vegan?

Chris Kresser 3:13 Uh, it, macrobiotic is a particular philosophy, it's a particular approach that came from Japan, and, um, it's vegan, but it's, it's, you know, it's, it's heavily influenced by Japanese, uh, tradition and cuisine, and it has some kind of different beliefs than a, a typical vegan approach. So I was, uh, when I was originally studying Chinese medicine, I was working and, and apprenticing with a macrobiotic vegan chef, and we were going around cooking for people who were really ill, often people with cancer who were following a macrobiotic diet. And before that, I had been a vegetarian for quite a while as well. Wh- when I was traveling around the world and got sick, actually, I was, I was a vegetarian at that point too.

Joe Rogan 3:55 And you discovered through your own personal ... What are you doing over there, buddy? (laughs)

Dr. Joel Kahn 4:01 (laughs)

Chris Kresser 4:01 Sorry.

Joe Rogan 4:01 And you discovered over there, through your own, uh, personal practice, that you- your body worked better and your illnesses, uh, went away when you changed your diet away from macrobiotic vegan.

Chris Kresser 4:15 Yeah, for me personally, um, vegetarian diet and particularly vegan diet was a disaster. Um, but I'm just one person. I don't put a lot of stock into, you know, a single-

Joe Rogan 4:26 Right.

Chris Kresser 4:26 ... person's experience one way or the other. Um, but certainly that did lead me down the path of questioning some of my earlier beliefs that I had about vegetarianism and veganism, and it, um, led me to make some different choices.

Joe Rogan 4:39 And that is important to discuss here, that everybody's body really is different.

Chris Kresser 4:43 Yes.

Joe Rogan 4:43 And different people's bodies and lifestyles, th- they're gonna have different requirements.

Chris Kresser 4:49 Absolutely. I mean, I, I would say, just to start off this whole discussion, if we're trying to answer the question, what's the optimal diet for everyone, I think that's a terrible question.

Joe Rogan 4:59 Yeah.

Dr. Joel Kahn 4:59 Yeah.

Chris Kresser 4:59 And it's an unanswerable question. Uh, w- we share a lot in common as human beings, but we have a lot of important differences too. And from the beginning, I've always argued that there's no one-size-fits-all approach when it comes to diet. Um, but I think there are some common themes, and we can- I'm sure we'll get to those later.

Joe Rogan 5:17 Yeah.

Dr. Joel Kahn 5:17 Yeah.

Chris Kresser 5:17 Yeah.

Joe Rogan 5:17 I think that's really important, right?

Chris Kresser 5:18 Yeah.

Dr. Joel Kahn 5:18 Yeah.

Joe Rogan 5:18 It's re- it's really important to discuss-

Chris Kresser 5:20 So important.

Joe Rogan 5:20 ... that p- people really do have different requirements.

Dr. Joel Kahn 5:23 Yeah, and I mean, we'll get in the mud a little bit as we need to, but we also, Chris and I share a lot in common. I mean, one, if we ate together, it would probably be 90% the same. We both are really respectful of what we call functional medicine, root cause medicine. I don't write scripts without thinking about the patient. He certainly doesn't do that without thinking about the entire patient. It's pretty unusual, and we're gonna represent a very small section. I, I honor what he's doing with his new book, Unconventional Medicine, the rest. You know, that is what is happening throughout medicine, um, and it's necessary 'cause it just, we're- we're just running out of dollars and, and health when we're just pushing pills and not even asking a person what they eat, how they sleep, you know.

Joe Rogan 6:00 Yeah.

Dr. Joel Kahn 6:00 The whole thing.

Joe Rogan 6:01 I think we all-

Dr. Joel Kahn 6:01 You know, we're real people.

Joe Rogan 6:02 Yeah.

Dr. Joel Kahn 6:02 We know that. We gotta-

Chris Kresser 6:03 We all agree on this.

Dr. Joel Kahn 6:04 Yeah.

Joe Rogan 6:04 What I, what I do want to say-

Dr. Joel Kahn 6:05 But, but it's still rare, Joe. I mean, this is, to have, you know, this is pretty rare segment. I don't know that 2% of the people in America will have a patient leave the office and actually ask what they ate today, you know?

Joe Rogan 6:14 Mm-hmm.

Chris Kresser 6:15 Yeah.

Dr. Joel Kahn 6:15 I mean, it's-

Joe Rogan 6:15 It's true.

Dr. Joel Kahn 6:16 It doesn't happen.

Joe Rogan 6:16 Yeah.

Chris Kresser 6:16 Let me say one more thing about this though 'cause I think you hit on a really important point, and I'm glad you did- did it right off the bat. The biggest problem with nutritional research epidemiology is that it starts with the assumption that there is one diet for everybody.... that's, that's something that's rarely discussed.

Dr. Joel Kahn 6:34 Right.

Chris Kresser 6:35 But it's, it's this idea that, you know, should everyone be on a low-carb diet? Should everyone be on a high-carb, you know, low fat... or, or, uh, low fat diet, you know? Should everyone do this, should everyone do that? And the whole, um... You know, there's a, a, a guy in Australia, a professor, who calls, calls this approach nutritionism, this idea that we can reduce foods down into these individual components just like macronutrients, you know, protein, fat, carbohydrates, and we can figure out, um, what works best for everyone just by looking at these isolated components without considering the, uh, the whole context of the diet. So I think, you know, Joel would agree that if, if you talk about a diet that's 50% calories and fat, and one diet is they're getting all of those fat calories from pizza and chips and candy bars and things like that, and then another diet, they're getting 50% of fat from avocados and olive oil-

Dr. Joel Kahn 7:31 Right.

Chris Kresser 7:31 ... and, uh, even, you know, eggs and animal foods, those are two totally different-

Dr. Joel Kahn 7:36 Yeah. Right.

Chris Kresser 7:36 ... diets.

Dr. Joel Kahn 7:37 Yeah.

Chris Kresser 7:37 And yet, in the scientific literature, those are equated as the same because they're-

Dr. Joel Kahn 7:41 Yeah.

Chris Kresser 7:41 ... all they're looking at is the calories from fat. They're not-

Dr. Joel Kahn 7:43 Yeah.

Chris Kresser 7:44 ... considering the quality of the diet.

Dr. Joel Kahn 7:46 And, and I'll just add in, uh... And again, we can go anywhere with this conversation, but a lot of the problem has been imprecision of language. So even the words low-carb diet, I eat a low-carb diet if we talk low refined carbs. I don't eat white flour. I don't eat sugar. I'm very careful about all those components. I eat a very high complex carbohydrate diet. So, we'll get there.

Chris Kresser 8:05 Vegetables.

Dr. Joel Kahn 8:06 A, a giant study that's been released this year, it was the PURE study, talks about carbs in the diet. They didn't differentiate complex and refined. Very hard to know what to do with data that doesn't spread that apart in, in your own life. I mean, low fat, high fat, I mean, we need to talk about, is it soybean oil that's, you know, processed and rancid, or are we talking about avocados and, uh, you know, healthy whole foods? So the precision of language... Even protein, protein, the big divide is animal versus plant. So anytime the word comes up, we need to differentiate what do w-... you know, w-... be precise, and then we'll help more people if we're precise.

Joe Rogan 8:40 Yeah, and if you can, just to illuminate this for people, what is the problem with e- epidemiology studies?

Dr. Joel Kahn 8:46 (sighs)

Chris Kresser 8:46 Oh boy.

Dr. Joel Kahn 8:47 Sure. You know, I'll, I'll, I'll go there real quick.

Joe Rogan 8:49 Okay.

Dr. Joel Kahn 8:49 I mean, I don't think there's a problem, but they're a part of the solution. They're not the whole solution. A lot of scientists... I'll give a shout-out to Los Angeles's brightest nutrition mind and somebody that I know Chris honors too, Valter Longo. No label, not vegan, not paleo, not nothing. He's at USC, been honored by the Royal Academy of Swedish Medicine, which is a Nobel Prize committee and this and that. Um, he says, you know, you do basic science and then you do an epidemiology study to test the hypothesis. You see something in a petri dish, you see something in a mouse, you see something in a cell, you ask the question, is animal protein pro-longevity, pro-early aging because of pathways-

Joe Rogan 9:26 Do you mind explaining epidemiology studies to people?

Dr. Joel Kahn 9:29 Sure. So you would take that concept, I'll just run with that, that, you know, you, um, you look at, uh, uh, an amino acid found in animal protein, throw out methionine and leucine. In a petri dish, looks like it might cause accelerated aging in a single cell. That's biochemistry. That is something you honor, but it's a long jump from there to human. Then you look at a database. Sometimes it's a crappy old database. Sometimes it's Harvard has these gigantic ongoing database. Uh, Loma Linda, an hour from here, has a gigantic database. And there's others, e- EPIC study, this PURE study I mentioned. You can test a hypothesis of what happens if our data may be crappy, but it's still data, and it allows you to go further with 100,000 people, 50,000 people, 500,000 people. Can w-... Do we have the data to ask the question, does protein correlate with survival, protein correlate with early death, animal protein, plant protein? These studies have been coming out a lot lately, and they let you parse it out. Now, it's what, you know, Chris talks about. Do you know everything about the person in the database? Do you know smoke or do you know diabetes, do they go to the gym, do they lift weights, they smoke dope, do they smoke crack? You don't, you don't know everything. Nowadays, most of these things are gonna ask all your blood pressure, cholesterol, all the basics to try and take those factors away and isolate the question you're asking. It'll be imperfect. And then you go to the best study, but it won't, it won't happen often, the randomized clinical trial. I mean, there's never been a randomized clinical trial of smoking, 'cause that'd be unethical. You're never gonna do it. It was epidemiology that proved an association strong enough to r- recommend to the public, "Don't smoke." There'll never be a randomized trial. And not everything... Parachutes don't need a randomized trial. You know, um, you know, taking folic acid in a pregnant woman to not have spina bifida doesn't need a randomized trial. I mean, there's some things that are so pressing, the public health can't allow that. And there's even more than that. The last little section is, um, you can study old people. Chris enjoys studying ancient societies. I enjoy studying the elderly in current, you know, modern, uh, environment, which is called the Blue Zones, and there's others. But, you know, what do old people do? The old, healthy people, what we would like to be. Would you like to be 90 and have your brains and have your joints and everything working? Well, we have that database. So the- that little four, uh, pod, uh, pedestal to sit on, basic epidemiology randomized studies and centenarian studies allows you to make reasonable conclusions. You know, we'll be wrong sometimes.

Joe Rogan 11:50 Mm-hmm.

Dr. Joel Kahn 11:50 We're not gonna be very wrong.

Joe Rogan 11:51 Chris?

Chris Kresser 11:51 I, I think there's huge problems with epidemiology. So obser-... E- epidemiology observational studies are studies that look at a certain group of people and then try to draw inferences from their behavior about associations with disease. So let's say we, we take a group and we look and see, you know, how much saturated fat are they eating, and we separate them into, you know, low consumption, medium consumption, high consumption. And in a prospective study where we're watching them over time, we might then look 20 years later and see how many people had heart attacks and died. Okay, and then we try to, you know, correlate that with their amount of saturated fat intake. Now, uh, I actually j- uh, just published two articles with, um-... going in detail, uh, on the problems with observational nutritional research and, um, you can find them at Cresser.co/Rogan. There's a whole bunch of information that we're gonna be talking about today there, so people can go and get the details themselves. But I'll just give you three of the, I think the mo- the worst problems with nutritional epidemiology. The first is data collection. So there's a saying in science, which is that, um, data are, are only as good as the to- as the tool used to collect them. All right? And in nutritional observational studies, the tool used to collect data is a questionnaire. Okay? (laughs) And so that relies completely on memory, and we know that memory is not a precise, accurate, or literal representation of events. It's more like a highly edited anecdote of what happened in the past. And back-

Dr. Joel Kahn 13:27 It's a little bit like the Kavanaugh thing going on right now. (laughs)

Chris Kresser 13:29 Yeah. (laughs) Back in the, back in the 13th century you had Francis Bacon who said, "For something to be scientific, it has to be independently observable, measurable, and falsifiable, and then accurate and vali-valid." And so let's use an analogy. If you're sitting there eating an apple, and I'm watching you do that, I can observe that you're eating the apple. I can measure how much of the apple you eat, and I can confirm or refute that you're eating the apple. If you tell me that you were eating an apple 15 years ago or 10 years ago, I obviously can't observe that. I obviously can't measure it, and I obviously can't confirm or refute it. And yet our entire foundation of nutritional epidemiology is based on that, basically people reporting on what they ate at some time in the past. So, you know, how much of a problem is this? Uh, there's a guy named Edward Archer who's done some really interesting, uh, studies, and he looked at the NHANES data, the Nurses' Health data, which is one of the longest running nutrition studies, 39 years, and he found that the, the self-reported calorie intake in those studies was either physiologically implausible or incompatible with life.

Dr. Joel Kahn 14:42 (laughs)

Chris Kresser 14:42 So the average person in those studies reported a calorie intake that would not support an elderly, bedridden, frail woman.

Joe Rogan 14:51 (laughs) So they just-

Chris Kresser 14:54 So-

Joe Rogan 14:54 ... it's just inaccurate.

Chris Kresser 14:55 It's completely inaccurate. And the, the people who are most likely to under-report are people who are overweight and obese. So if you... If calories are that much under-reported, all nutrition comes through calories. Everything we get, fat, protein, carbohydrates, micronutrients, they all come through calories. So if, if calories are that under-reported, that completely invalidates the data set.

Joe Rogan 15:18 So this is an obesity study, so they're, they're under-reported because of shame?

Chris Kresser 15:21 It's not an obesity study.

Joe Rogan 15:22 Oh.

Chris Kresser 15:22 It's just every... Americans are overweight and obese.

Joe Rogan 15:26 Right. Yeah.

Chris Kresser 15:26 The majority of Americans are overweight and obese, so in any data set of Americans, you're gonna have the majority of them overweight or over obese, so, or, or, or obese. So that's the first problem. The second problem is a healthy user bias, which I know we talked about before. But it's basically the idea that because, you know, when someone engages in an unhealthy and a behavior that's perceived as unhealthy, they are more likely to engage in other behaviors that are perceived as unhealthy and vice versa. So let's say you do a study of people who ate, eat more red meat. Well, red meat has been perceived as unhealthy for a long time. And so what we know is that in those observational studies, the people who eat more red meat are also smoking more, they have higher body mass index, they're eating less, fewer fruits and vegetables, they have a lower level of education, they're less physically active. So how do you know that it's the red meat that's causing the problem and not those other things? You don't, because they cannot control for all of those potential confounding factors. The third problem with observational research, and maybe the biggest, is that the, the, the relative risks in nutrition are so low that they're indistinguishable from chance. So in fields outside of nutrition and epidemiology, nobody would consider a relative risk, an increase in risk less than 100%, a doubling, to be really worth paying attention to. So to put this in perspective, the observational studies that Joel was referring to that confirm that y- s- that cigarette smoking led to lung cancer, that showed an, uh, a one- between a 1000% and 3000% increase in s- uh, lung cancer in smokers. Okay? And the studies that have shown that eating aflatoxin, which is a mycotoxin, increase liver cancer risk, that's 600% increase. Okay? The IAR- the IARC, the WHO report that suggested that processed red meat was a carcinogen, that was 18% increase. Most epidemiologists-

Dr. Joel Kahn 17:31 Hmm.

Chris Kresser 17:31 ... you talk to will say, "That is so low that it's really indisting- uh, indistinguishable from chance, especially given the healthy user bias and the problems with the data collection that I mentioned before."

Joe Rogan 17:42 So the studies that are cited, so when people are talking about red meat causes cancer, they're literally talking about something that showed an 18% increase.

Chris Kresser 17:51 Yeah. Right.

Joe Rogan 17:52 And-

Chris Kresser 17:52 Yeah.

Joe Rogan 17:52 ... this is over-

Chris Kresser 17:53 Which-

Joe Rogan 17:53 ... people that are also-

Chris Kresser 17:54 That-

Joe Rogan 17:54 ... consuming sugar, other-

Chris Kresser 17:55 So that, so that, that translates into four and a half, there were four and a half cases of cancer out of 100 in people with no, lowest intake of processed meat, and that went up to 5.3 cases out of 100 in people with the highest intake of processed meat. So, you know, there are quotes like y- if you, if you look even 20 years ago, like, there's an article in Science, um, the journal Science, and Marcia Angell, who was the former editor of New England Journal of Medicine, was quoted as saying, "We wouldn't even accept a paper for publication if it didn't have at least a 200% increase, especially if it was a new association or the, the, the biological mechanism wasn't known." And here we are today.

Dr. Joel Kahn 18:40 ... saying that, you know, this increase that by 7% or by 10%, and when you consider that the data is usually questionnaires of what people ate, and all of these confounding factors like exercise and, and fruit and vegetable consumption and things like that are not accounted for, then we're really just playing games with numbers. Is part of the problem as well that there's this clickbait culture now in terms of journalism- Well, sure. ... where they just want to publish something that says- Of course. ... a study shows, you know, 18% of people eat red meat get cancer?

Chris Kresser 19:14 Yeah.

Dr. Joel Kahn 19:14 That's a huge problem, and there is a study that was done that showed that 43% of findings that came from observational studies were portrayed in the media as being causal. Mm. Which, which any epidemiologist would tell you that that's-

Chris Kresser 19:30 Yeah.

Dr. Joel Kahn 19:30 ... a faux pas, you can't do that. But nobody is gonna click on a headline that says, you know, "Small association between these two variables seen. We don't know what it means." Right. (laughs)

Chris Kresser 19:43 Yeah.

Dr. Joel Kahn 19:43 "But please read th- this story, it's really interesting." Right. So, so let me just grab a couple. (clears throat) And again- Sure. ... a lot of respect and agreement, but if we throw epidemiology away, we've thrown away about 80% of nutrition knowledge, 'cause that is the most common kind of study. And that still leaves us with basic science, which is rocking. It leaves us with, um, randomized clinical trials, which are very hard in nutrition, and they're very expensive, and there's less than we need. And it finally leaves us with studying old, healthy people, centenarian studies. We'll just go to Loma Linda. 10 times more people in Loma Linda are over 100 than there are in Los Angeles. 10 times more.

Chris Kresser 20:16 Really?

Dr. Joel Kahn 20:16 That's by definition, yeah. It's called the Blue Zone, and we'll talk about Blue Zone. But that doesn't- Well, it was discovered in the 1950s. If you lived in Loma Linda, you were living 12- Where is Loma Linda? Loma Linda's an hour east of here. What, what's going on over there? Well, it's a center of the Seventh-Day Adventist Church- Oh. ... which teaches people eat your veggies, don't drink, don't smoke, and exercise. Oh. So it's an amazing lifestyle-oriented, uh, a- aspect of the Christian church. And they, in 1958, got huge funding from the government to explore why the heck are they living 12 years, eight years, 10 years longer, and they've parsed that out in probably 1,000 publications. They're, uh, you know, it's not a randomized study, you know, it wasn't LA versus Loma Linda, we'll feed you different diets and follow up. Won't ever happen. But it is, you know, a reliable, longterm peer review. This stuff's published in, uh, the finest of journals, and it at least lets you ask questions. I mean, why is there a 104-year-old cardiac surgeon, Elliott Warsham, walking around doing his gardening and he just finished operating on heart patients? I mean, it's insane. At 104? 104, Elliott Warsham, love you buddy. Oof. Rolling dice. So but let me go back for a minute. If we throw epidemiology out, we are left with basically biochemical energy- Uh, I'm not suggesting that, by the way. (laughs) No, I know, I know, I know. But so food f- this is all technical stuff and, but you've got a sophisticated audience. Food frequency questionnaires, what Chris said, is the source of a lot of these epidemiology studies. You fill out a four page, a 40 page at, in Loma Linda, it's a 58 page survey. But it, you do it once, that's called the pure study. The headlines, you've seen them. Cheese, eggs, meat are good for your heart. It's been in the news the last two weeks. That comes from a giant international study. They did one food frequency questionnaire at the beginning, 12 years later they're reporting the data, it's all clickbait headlines. It's like you say, people love to see this stuff. So if we throw out some studies, we have to throw out the largest nutritional study that's been reported and the most recent one that's getting all the headlines. It's gotta be played fair. Now, you go to Loma Linda, it's every four years they're asking. You got to Harvard School of Pub Health, every four y- they update the data. So if you change your diet, that's the weakness. You fill out the survey and then you get healthy or you get sick, and you make changes and then they're counting if you're dead or alive. Well, it might be what you did year six, not what you filled out year one. So there are- So- ... there are better and worse forms. The second I'd say healthy user bias is the idea that people pick a certain diet and might have other lifestyles that might be as or more important. Well, it's gonna be true of the paleo group. I mean, these guys are, you know, look at Chris, he looks wonderful. He's healthy, he's thin, he's not the obese American, the 75% that are overweight and obese. I mean, that's true in the, uh, plant community to some extent. We have chubby vegans, oh my God. But, but there's no observational studies with significant numbers of paleo dieters, Joe. Oh, I know, I know that.

Chris Kresser 22:50 So, so the-

Dr. Joel Kahn 22:50 So we-

Chris Kresser 22:50 ... healthy user bias is not an issue for-

Dr. Joel Kahn 22:53 Well-

Chris Kresser 22:53 ... paleo people in studies.

Dr. Joel Kahn 22:53 ... but if you don't have data, it doesn't mean ... I mean, you don't have data 'cause it's a new movement that hasn't had the data, but it's not to cast stones that plant-based eaters go to the gym more. It's probably true, we don't know, but ... But- And that's the third thing, yeah. ... to stop you for a second- Yeah. ... m- meat eaters do get lumped in with the paleo group. They, they consider paleo group part of the meat eater group. Sure. Like when people talk about these epidemiolo-

Chris Kresser 23:15 Yeah.

Dr. Joel Kahn 23:15 ... epidemiology studies where they show that people- It's- ... they consume red meat- That's right. ... are more likely to get sick or more likely- Well- ... to get cancer. They're not talking about- They're not referring to paleo dieters. ... people that are eating avocado and grass-fed beef and things along those lines. Well, you gotta remember, I mean, most of the paleo movement is the last dozen, 15 years. You know, we can talk about that. 1985- Mm-hmm. ... 2002. Loren Cordain published his book in 2002, the book didn't sell. Republished 2010, it took off. This is a relatively new movement. So if you filled out the study in Loma Linda in 1958, you don't have to worry, there weren't too many people following a classic paleo diet. That's also true at Harvard. These are just ... The last is just the relative risk, that's what we call it. These are pure statistics. I'm a, I'm a heart doc, not a statistician. But there are some exceptions. I mean, anybody ... And I'll just say it, I've got a red button on my website that says Rogan references 'cause I thought it would be good to have people a place to go just like Chris mentioned. And I'm not massaging the data, it's scientific peer-reviewed data. Um, there was a study October 2016, October 1, 2016, SONGS from Harvard. 6,000 people, observational data, animal protein, plant protein. Actually, let me go to 2014, Morgan Levine. This is an amazing Harvard researcher, beautiful woman, Morgan Levine. She looked at 6,000 people prospectively. Observation, fill out all this data. If you were an animal protein eater, that's called meat, you had a three to 400% increase in cancer risk. Three to 400%, that's three to four times. It isn't 1.1, 1.08, 18%. The data's there, this is peer-reviewed data. If you ate plant-based proteins, uh, risk of cancer goes down. This is in the highest possible- Let's pause for a second.

Chris Kresser 24:51 No, no, no.

Dr. Joel Kahn 24:51 Let's pause on that.

Chris Kresser 24:51 No this is-

Dr. Joel Kahn 24:51 This is a- Pause on that stat.

Chris Kresser 24:51 That's not-

Dr. Joel Kahn 24:52 I just wanna say, there are nutritional data that are powerful risks. Okay, but this is an e- but this is also an epidemiology study? That's where 80 ... You know, nobody's gonna do a randomized study of 6,000 people. Right. You eat beans and you eat p-

Chris Kresser 25:04 Listen, I, I think-

Dr. Joel Kahn 25:05 Okay.

Chris Kresser 25:05 ... I have a, a good example that can clear some of this up.

Dr. Joel Kahn 25:08 Okay.

Chris Kresser 25:08 So ...... um, you mentioned the Loma Linda and the Seventh Day Adventist-

Dr. Joel Kahn 25:12 Right.

Chris Kresser 25:13 ... studies. So, um, first of all, the ... let me just make a comment about observational nutritional research. It can ... there are good observational studies and there are bad ones. You can design an observational study-

Dr. Joel Kahn 25:25 Sure.

Chris Kresser 25:25 ... in a way that controls for some of these potentially confounding factors, like the healthy user bias, et cetera. So ... but this is a story that will, I think, clear some of this up. So there are about eight studies, major studies, that have compared lifespan in, in, uh, vegetarians and vegans and omnivores. So the, the earlier s- uh, studies, there are three studies that were Seventh Day Adventist studies. So they were done in the Seventh Day Adventist community, which Joel mentioned is a religious group that has, as part of its credo, you know, a healthy lifestyle, diet and lifestyle, um,-

Dr. Joel Kahn 26:00 Yeah, about 20 million.

Chris Kresser 26:01 ... ideology.

Dr. Joel Kahn 26:01 20 million people.

Joe Rogan 26:02 So, let's not talk over each other. Let's just make sure we give each other enough chance to breathe.

Chris Kresser 26:05 Veget- veg- vege- you know, vegetarian diet, but also, you know, uh, e- uh, live healthy, eat fruits and vegetables, don't smoke, don't drink excessively, et cetera. So, uh- you know, a health-conscious group of people. And the, the s- the f- the first one that ... the Seventh Day Adventist study in the Netherlands compared them ag- with the general population, which is just garbage because of the healthy user bias. So we can- we can just cross that one off the list. The two Seventh Day Adventist studies that were done in Loma Linda in the US, they did a better job because they compared people who do eat meat amongst the Seventh Day Adventist population with people who don't, and there was a slight, uh, advantage in lifespan in, in the vegetarians versus the meat eaters. But one of those studies didn't control for smoking and body mass index, so that data is highly suspect. And the other study did and there was a slight advantage. Since then, there have been four studies that I think did a much better job. So this is kind of an interesting design. So they said, "Let's try to find a group of more health-conscious omnivores to compare these vegetarians against." So they ... the first one was called the Health Food Shoppers Study. So they looked at people who shop at health food stores, when the idea is people who shop at health food stores are gonna be generally more health-conscious. And they found-

Joe Rogan 27:21 And by health food store, you mean like a Whole Foods or Erewhon?

Chris Kresser 27:23 I mean, there was no Whole Foods at this point, but that-

Joe Rogan 27:25 Okay.

Chris Kresser 27:26 ... that was the idea.

Joe Rogan 27:27 Okay.

Chris Kresser 27:27 Right? And so that study found that both groups, vegetarians and omnivores who shop at health food stores, had a hugely reduced risk of death compared to the general population, but there was no difference between vegetarians and omnivores. Second study, Oxford Vegetarian Study in the UK, they recruited people by ... first they recruited vegetarians and then they asked the vegetarians to ask their friends who also ate meat. So that the idea was the people that the vegetarians were hanging out with might be more health-conscious than the general population. Same result. Big difference in the ... in, in lifespan between those two groups and the general population, but no difference between vegetarians and omnivores. EPIC-Oxford cohort, same thing, same way of recruiting people, same result. Big difference, uh, between the two groups and the omnivores, but no difference between vegetarians and omnivores. And then the Heidelberg Study was in the U- in Germany and exa- similar way. They ... I think they recruited people who read vegetarian magazines and then they asked them to bring their friends or family members who ate meat. Big difference in lifespan between the two groups and general population. No difference between vegetarians and omnivores. And then you had the 45 and Up study that was recently done in Australia. This was a little different because they didn't set out to find, you know, more health-conscious people. Instead, they looked at 250,000 people, big sample size, and they did a much better job of controlling for all of the various factors that might affect, you know, the results. So exercise, physical activity, fruit and vegetable consumption, cigarette smoking, alcohol, education level, because we know that has a big impact on lifespan. And they found that there was no difference in lifespan between omnivores ve- and vegetarians, uh, in that study as well. And then there have been two meta-analyses of all of the studies that have looked at this. Both meta-analyses found no difference between vegetarians and omnivores in, in total i- in lifespan. So I think this is a really good example of what we're talking about here. That's all observational data, so we're not throwing it out or saying we should throw it out. But all of those studies did a better job at dealing with the potential pitfalls of observational studies. And when they did that, they found no difference. So ... and I wanna point out that it ... the- th- those ways of picking more health-conscious omnivores were ... they're- w- they still weren't comparing like someone on a paleo type of diet with a vegetarian. They were just guessing that someone who shopped at a health food store was at least a little more conscious about health than the general population. So-

Dr. Joel Kahn 30:00 Can I quick little thing now?

Chris Kresser 30:02 Please.

Joe Rogan 30:02 Mm-hmm.

Dr. Joel Kahn 30:02 Quick, quick little thing. I just wanna go back for a minute to meat and cancer. World Health Organization is not a vegan group, it's not a nothing group. You know, it's a fairly well-respected international organization that puts out health, uh, claims. So although I ... absolutely, Chris had the data right. 18% increase in cancer risk with processed red meat. I wanna make that clear. I hope you don't eat too many hot dogs, salami, baloney, pepperoni. That's the, uh-

Joe Rogan 30:26 Nitrates.

Dr. Joel Kahn 30:27 Yeah. Uh, well, it may be more than nitrates, but it's just a whole-

Joe Rogan 30:30 Preservatives.

Dr. Joel Kahn 30:30 ... it's the salt, it's the preservatives, it's junky pieces of the animal that they're putting into a hot dog. That was a group. That's an 18% increase. You can go 4.5% to 5.5%. That's still 50 to 60,000 people a year that get colon cancer if that data's right. They wouldn't get colon cancer if they just would stop eating hot dogs. At a minimum, and I know Chris will agree, frigging hospitals are serving hot dogs and the data's out there that it promotes cancer to people getting chemotherapy with the IV pole. It's insanity. So, 50,000 people avoid colorectal cancer with small differences that the World Health Organization suggests. It was 800 papers and 22 world experts. There's no perfect study, but when they announced that October 25th, 2015, the world was shocked. You just said that processed red meat causes cancer. They didn't say related. They were strong enough data to say cause. They've been beat up. They published more data. They haven't backed down. I just wanna put that out. The healthy user bias will exist in the paleo community when the study's done 'cause they ... I mean, look at Paleo FX. They're ... it's everything, and I honor that. I mean, we should promote healthy lifestyle. Food's only one part of this. I mean, we will all at this table live longer than the average American. We're not smoking two pack a day. We don't have 38-inch waistlines, the whole deal. We're doing the whole thing. Hopefully you guys are enjoying a little cabernet now and then, or ... uh, that's always on the list. Just don't overdo it. But the healthy user bias, that particular ... that health food study paper, it's 1996, it's a pretty old paper. In the paper in the limitations, they beat themselves up. "We were missing this or that." Anybody just read the paper. It's not that it doesn't bring up an interesting point, but to say that we, again, throw away all these papers 'cause they are biased. Lastly, and I'm done. Multivariate analysis. Chris was just talking about better studies that factor all this stuff. Let's not bore your audience with statistics, statistics. But there's certainly the ability now to say, does animal protein associate with an increased risk of cancer? And put in smoking and weight and diabetes and blood pressure and vegetable intake and alcohol intake and family history, and then you just isolate the one thing.... is there foibles, are there downsides? Of course. But all modern epidemiology does multivariate analysis to try and isolate it. You know, you can cast stones everywhere, but, you know, there are, you know, the World Health Organization, I mean, there's 21 organizations say, "Limit your saturated fat in your diet," and none that are international societies say, "Increase it." So you put, uh ... Nutrition science needs to incorporate as much as you can with as much reliability, and at the end of the day, you can see we'll still have questions.

Chris Kresser 32:54 Well-

Dr. Joel Kahn 32:54 But I can't throw-

Chris Kresser 32:56 ... the organi- the US used to say, "Don't eat much cholesterol." Now they don't. They used to say, "Limit your total fat," and now they don't.

Dr. Joel Kahn 33:02 That's wrong.

Chris Kresser 33:02 Because they've gone out ... It's not wrong, actually.

Joe Rogan 33:05 Well, it is wrong.

Dr. Joel Kahn 33:05 Well, the USDA says in the guideline-

Chris Kresser 33:07 But, b- but-

Dr. Joel Kahn 33:07 ... "Eat as little cholesterol as possible."

Chris Kresser 33:08 ... it says, "Cholesterol is not a nutrient of concern" in that sentence.

Dr. Joel Kahn 33:10 Because they couldn't identify the exact milligram to recommend. It used to be 300. They said-

Chris Kresser 33:14 Because the science doesn't support-

Dr. Joel Kahn 33:16 No, it's 'cause inter-

Chris Kresser 33:17 ... limiting dietary cholesterol anymore. Let me go back and, and to the ... this question of-

Dr. Joel Kahn 33:22 That's wrong. They say, "Limit cholesterol."

Chris Kresser 33:23 Hold on. You-

Dr. Joel Kahn 33:23 They say, "Limit cholesterol to as little as possible." I mean-

Joe Rogan 33:25 But who, what, what's this th- they? Who is they and-

Dr. Joel Kahn 33:28 USDA. USDA.

Joe Rogan 33:29 ... the USDA?

Dr. Joel Kahn 33:29 The guidelines come out every five years, and they are im- uh, used for school menus and hospital menus. It was a big buzz in 2016 when it was announced. They no longer were giving a so many milligrams of cholesterol a day you'd never exceed.

Joe Rogan 33:42 Okay.

Dr. Joel Kahn 33:42 They said, "We can't pick the number."

Joe Rogan 33:44 But isn't USDA behind the curve in, in terms of science?

Chris Kresser 33:47 Yeah, so, so let's, let's, but they're influ- they're influential.

Dr. Joel Kahn 33:48 Let's step back a little bit. So total mortality is the most important end point we should be talking about here. That means deaths from any cause, right?

Joe Rogan 33:55 Okay.

Chris Kresser 33:55 Mm-hmm. So if, because that's what we care about most, right? If you-

Dr. Joel Kahn 33:59 Right.

Chris Kresser 33:59 If I die of, uh, you know, if, if I, if, if an intervention reduces the risk of a heart attack, but increases the risk of cancer, I'm not happy with that.

Joe Rogan 34:08 (laughs)

Dr. Joel Kahn 34:08 Right.

Chris Kresser 34:09 Right? In fact, I'd rather go out, have a heart attack in, in my sleep.

Joe Rogan 34:12 One shot, bam.

Chris Kresser 34:13 (laughs) Um, so you need to consider total mortality. And if something, you know, if meat increases the risk of cancer, uh, and cancer mortality, then why aren't we seeing that in the studies that compared lifespan with vegetarians and omnivores? We have, as I said, we have, uh, five studies that did a better job of controlling for that healthy user bias, and there was no difference in any of those studies. There's not a single study that sh- that, that compared relatively equivalent groups of people that shows that vegetarians or vegans have a lifespan advantage, period. There's not. And so if, you know, red meat isn't ... If we're saying red meat, processed meat increases the risk of cancer by 18%, uh, maybe, maybe not. Um, but that's not showing up in any of the tot- the total mortality data. The second thing, and this is a really good example of what we talked about the bi- very beginning of the show, context is everything. Quality is more important than quantity. So let's talk, let's think about processed meat. So there's several proposed mechanisms for how processed meat causes cancer. One is that it increases N-nitroso compounds or NOcs, which damage, damage the gut lining. Another is that, uh, they ... When you cook meat at high temperatures, it forms heterocyclic amines, or HCAs, which damage the gut. Another is that the heme iron content, uh, in meat, uh, causes oxidative stress and, and increases the risk of cancer that way. And then there's TMAO and Neu5Gc. But let me just give you a few examples of why context is important. So there's evidence that chlorophyll-rich green vegetables prevent myoglobin from being turned into N-nitroso compounds. So if you're eating processed meat, but you're also eating kale and broccoli, then it's not gonna have the same effect on the body as if you're just eating a hot dog. Um, cruciferous vegetables and spices and marinades have been shown to reduce the formation of heterocyclic amines, or HCAs. So same thing, if you're, you know, if you're marinating meat or if you're eating broccoli and cruciferous vegetables with meat, it's not gonna have the same impact. There are several studies that have shown that eating fruits and vegetables attenuates the oxidative capacity of heme iron and even reduces the absorption of heme iron in the gut. And, uh, you know, dietary antioxidants have been shown to reduce the risk of gastric cancer. So heme iron intake, really you can think of it as a proxy for a crappy diet in these observational studies. There's a quote from a study that d- did find a relationship with heme iron and, um, cardiovascular disease, and they ... But the stu- the study author himself said, "With respect to heme iron intake, we found a significant association only in the studies that were based on American cohorts." They didn't find an association in the Netherlands, Canada, France, Italy, Japan, and Sweden, which suggests that it's because of the standard crappy American diet. You know, most people who are eating processed meat in, in the US are eating it in the form of hot dogs and oth- all kinds of other unhealthy food.

Joe Rogan 37:17 Buns, sugar, ketchup.

Chris Kresser 37:17 And it's another example of healthy user bias. I'm not saying ... I, I'm open to the possibility that too much processed meat can be problematic.

Dr. Joel Kahn 37:24 Yeah.

Chris Kresser 37:24 But you have to consider the context. It's not gonna have the same effect if someone's eating a ton of fruits and vegetables versus the- someone who's on a standard American diet. And we have no studies that separate that out.

Dr. Joel Kahn 37:36 Okay. I think we have a gong moment, 'cause I'm, I really want you listeners to come away with a few tips from Chris and I that make a difference. 'Cause I know your listeners aren't gonna stop eating meat at the end of this show.

Joe Rogan 37:46 They might.

Dr. Joel Kahn 37:47 Chris just said-Meat with vegetables is safer than meat without vegetables. Meat with chlorophyll is safer than meat without. I can give you cardiac studies that agree. I t- I teach-

Joe Rogan 37:57 Well, he-

Dr. Joel Kahn 37:57 I teach-

Joe Rogan 37:57 ... he said processed meat.

Dr. Joel Kahn 37:59 Well, it's all meat. I teach that if you-

Joe Rogan 38:00 Oh, is it all meat?

Dr. Joel Kahn 38:01 Yeah. If you-

Joe Rogan 38:01 Is it the same?

Dr. Joel Kahn 38:02 No. Listen, we agree here. I want people to hear this.

Joe Rogan 38:04 But do we?

Dr. Joel Kahn 38:05 When- when you grill-

Joe Rogan 38:06 Oh, whatever. Yes. (laughs)

Dr. Joel Kahn 38:06 How many people in the audience grill, barbecue? Everybody. If you grill meat, another chemical group that's formed are called advanced glycation end products, AGEs, that go along with the list. But if you grill meat that's marinated, and we want ... This is the tip, in dark beer. This is science, randomized science. You put a piece of beef in dark beer and you grill it, you don't create as many of these toxic chemicals as a dried piece of beef. So let's, uh, let's, like, right now, everybody listening, next time you eat meat, get a salad. Next time you eat meat, order broccoli. Next time you have bacon, get a, get a, you know, sliced tomatoes. You will actually improve your health. There's this classic, and now I'm shifting to cardiology, that they took, uh, healthy volunteers and they took them down to the hospital cafeteria and they fed them a hospital burger, and they were measuring on their arm how their ar- arteries function. Cardiology topic. Artery function goes down in three hours when you eat a hospital burger. It acts like you just had a toxin in your body. You did. They took the same group a week later. They had them eat the same burger with a big salad. They didn't see that finding. I mean, I want this to be an important point. You know, everybody should be jamming fruits and vegetables, or at least vegetables with some fruits. You can go low-glycemic berries. I'm fine with papayas, cantaloupe, and apples. But, you know, up your veggies, listeners, and you'll counteract a lot of the crap that's out there in the world. I- it's an important message.

Joe Rogan 39:22 I don't disagree with that.

Dr. Joel Kahn 39:23 No, you know you wouldn't. You have to.

Joe Rogan 39:25 We glossed over this very quickly in the beginning of this, but there was a dispute about cholesterol and a dispute about saturated fat. Um-

Dr. Joel Kahn 39:31 Nah. Serious?

Joe Rogan 39:33 You were saying that saturated fat ... that there's recommendations to reduce saturated fat.

Dr. Joel Kahn 39:39 Yeah, there's-

Joe Rogan 39:39 And reduce cholesterol.

Dr. Joel Kahn 39:40 So let- let me go ... Real quick overview, and I'm gonna talk fast. So just-

Joe Rogan 39:44 Just talk normal.

Dr. Joel Kahn 39:45 It was felt.

Joe Rogan 39:46 You, we got plenty of time. (laughs)

Dr. Joel Kahn 39:46 It was felt. So until the '40s, it was not common to have a heart attack. Heart attacks were described in 1916. Not to say they didn't happen, but the first medical article that used the word myocardium infarction, 1916. 1940, there were not many heart attacks seen in a modern American city. After World War II, we ... our economy went up. In the city of minne- Minneapolis, executives started suffering heart attacks. It was also Franklin Delano Roosevelt died of high blood pressure a few years later. Eisenhower had a massive heart attack. That's when our government, National Institutes of Health, started funneling major money into studies like the Framingham Study. You're from Newton.

Joe Rogan 40:23 Mm-hmm.

Dr. Joel Kahn 40:23 Framingham's a city outside of Boston, and they basically invaded this town in 1958 till today, said, "We're spending money. We're gonna figure this crap out." The idea had come up, heart disease wasn't just aging. Heart disease could be explained by what's called risk factors. Smoking might not. You can smoke and live to 100, but it's gonna increase your risk. And then they got into blood pressure and cholesterol and, uh, uh, family history. They identified what we call risk factors. So until that point, diet was not considered a factor in the development, the number one killer of men and women. I wanna point out, and Chris puts this on his website. I do too. During this interview, every 39 seconds, an American dies of heart disease. Every 39 seconds, most frequent cause of death. So there will be about 200 people, perhaps, that will die during this podcast of the number one killer. And 80% of it's preventable. Chris is gonna prevent some. I'm gonna prevent some, 'cause the biggest enemy out there is smoking and crap diet, calorie-rich and processed foods, crap SAD diet, standard American diet. It became apparent in the early 1950s, diet might play a role. And a notorious scientist and many others, his name, Dr. Ancel Keys, PhD, PhD, had two of them, suggested dietary fat might be a factor. It was a hypothesis. It's this early stage. Epidemiology doesn't prove anything. He went out and did studies. Other people went out and did studies. And the idea transitioned. Actually, he was criticized for saying dietary fat. The dis- ... The, uh, the conversation transitioned. There's some good fats, like, uh, omega-3 fatty acids are essential. You have to have them. And then maybe polyunsaturated fats from plants are more healthful. But the focus went on saturated fat in food, which is basically chicken, red meat, pizza. Those are the highest sources. And, um, subsequently, enough data accumulated that guidelines started to suggest, we've got this huge problem with heart disease. We should limit saturated fat in the diet. It was never limit all fat. Eh, 35% of calories. That's not in anybody's, word, a, uh, low fat diet. Um, and that has now promulgated in 21 international statements. There is no opposite. Whether it's the World Health Organization, American Heart Association, American College of Cardiology, whether it's the institute of ... Institute of Medicine says, "Eat as little saturated fat as possible." They couldn't be more clear. And these are highbrow. These are not, uh, associated with vegan movements or paleo movements or whatever. These are medical authorities. If there was half and half, you'd say controversy. 21 of 21 say the same thing. They might pick a different cutoff point, but we will enhance the health and cut down the number one killer. Whether it's in Asia, whether it's Europe, whether it's Australia, whether it's, uh, in the United States, there's unanimity that-

Joe Rogan 42:59 Okay, but why did they- So- ... come to the conclusion it's saturated fat?

Dr. Joel Kahn 43:01 Well-

Joe Rogan 43:02 So-

Dr. Joel Kahn 43:02 We- well, the basic science, 'cause there is basic science, and let me tell you, when you eat foods rich in saturated fat, which is called meat, cheese, eggs, and such, receptors on your liver for cholesterol ... I've got cholesterol in my blood. I'd like to get some of it out into the liver to be metabolized. I need a receptor. You eat saturated fats, receptors go down. Cholesterol has no place to go. Cholesterol stays in the blood, bumps into your artery wall. I'm putting a stent in your artery. That's the basic biochemistry. Then they had epidemiology studies. Flawed, perfect, it doesn't matter. There was so-

Joe Rogan 43:31 It does matter.

Dr. Joel Kahn 43:32 Whoa, whoa, whoa. Whoa, Chris, Chris, thank you very much.

Joe Rogan 43:35 (laughs)

Dr. Joel Kahn 43:35 Then they did controlled trials. Three ... I- uh, everybody just go read Clark 1997, 395 ... It's called Metabolic Studies. Change the diet, see what happens. You add saturated fat, cholesterol skyrockets on average, not in a single person. If I gave you a steak, Chris a steak, and me a steak, our cholesterol would rise differently. It would rise. It would rise differently. It's our microbiome. It's our genetics. It would rise. So i- i- that's a problem in the studies when you average everything together. So they had that and then finally, finally, they looked at populations that live over 100. These are called the pillars of longevity. They don't eat foods rich in saturated fat. They have a little, they don't have a lot. They eat a lot of olive oil in Italy and Greece. They eat almost no dietary fat in Okinawa, Japan, and they live, they have the greatest longevity in the world in 1970. They eat almost no dietary fat, about 6, 7%.

Joe Rogan 44:23 All right, let's, let's- Okay. We're getting-

Dr. Joel Kahn 44:23 So you put all that together-

Joe Rogan 44:25 We're getting into the weeds here.

Dr. Joel Kahn 44:25 Well, no. It's actually ... That is the basis for a major push to say cut back on animal products, 'cause that's largely, with exception of coconut and, um, palm, uh, you know, where saturated fat comes from. So the-... to, to negate that is to throw out every major health agency in the world. And I don't believe Chris Kresser can do that. No disrespect, I don't think Chris can throw out 100 years of cholesterol research. Let's- let's back up a little bit here.

Chris Kresser 44:52 Okay, let's back up. Yeah. So, um, first of all, every food that we consume has all of the fats in it: polyunsaturated, monounsaturated, and saturated fat. And in fact, two tablespoons of olive oil has more saturated fat than a seven-ounce pork chop. That's a little-known fact. Um, the, the oily fish, mackerel, you know, which all of these health agencies that Joel is talking about advises us to eat, has twice the total fat and one-and-a-half times the saturated fat that we're, of the meat that we're told to avoid. Um, does it make sense that nature, you know, would include, th- that you could eat, uh, uh, you know, mackerel and the polyunsaturated fats in it are good for you, but the saturated fat in it is bad for you? That's kind of nonsensical. But, you know, t- let's talk a little bit more about the research. So, um, there never really was good evidence to suggest that dietary cholesterol and saturated fat are connected to heart disease. And, uh, Zoe Harcombe, who's a, has a PhD, a nutritional researcher, she wrote her thesis, her PhD thesis, on the evidence back in the '70s that led to the restrictions on, uh, saturated fat and cholesterol. And then she also reviewed the evidence year, y- uh, all the way up until 2016. And, and if, uh, I have th- um, this information on my website, if you go kresser.co/rogan, you can find it. And what you'll find is, there never was en- really good, uh, evidence to support the limitations on di- on saturated fat and cholesterol. And people have started to look at this more recently and, uh, for example, you have a meta-analysis of observational studies, including about 350,000 participants recently that found no relationship between saturated fat intake and cardiovascular disease. You have an exhaustive review of studies, something like 25 randomized controlled trials, gold standard of clinical evidence, and s- almost 40 observational studies involving 650,000 participants. And I'll read you a quote from the conclusion. "Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of saturated fatty acids." Now, look, one of my favorite quotes is the ph- the philosopher Anatole France: "Even if 50 million people say a foolish thing, it's still a foolish thing." And the other thing to consider is that the history of science is really the history of most scientists being wrong about most things most of the time. And, uh, you know, sci- i- in science, we have to continually challenge our, our hypotheses and try to falsify them, and that's how the scientific process moves forward. And that's why in 2010, the US, uh, federal government removed restrictions on total fat, whereas before there was a restriction on total fat, because they, they acknowledged that the research was showing that not all fat is the same and that, y- you know, we don't need to be restricting fat from avocados and things like that. And then in 2015, they removed the restriction on dietary cholesterol. Now, they did that fairly quietly, because how do you think it looks when people have been told to, you know, limit their fat and limit their cholesterol, and then the, the federal agency goes back on that lim- th- that recommendation after so many years of telling people to do that? People lose faith in the agencies that are, that are issuing these guidelines, you k- I ... And don't take it from me. You know, I'm, I'm, I'm not expecting anyone to believe me, and that's why I've put all of the, the studies and the research supporting this at kresser.co/rogan. But how about John Ioannidis, who's one of the most renowned epidemiologists in the world? He's a professor of medicine at Stanford, and he has wrote some, written some scathing critiques of nutritional research recently that have been published in JAMA and British Medical Journal. So here's a quote from one of them: "Some nutrition scientists and much of the public often consider epidemiological associations of nutritional factors to represent causal effects that can inform public health policy and guidelines. However, the emerging picture of nutritional epidemiology is difficult to reconcile with good scientific principles. The field needs radical reform." (laughs) And he goes on to point out that meta-analyses of observational studies have found that almost all foods are associated with a higher risk of death if you crunch the data in certain ways. So, uh, it's not enough to say that d- you know, governments are recommending this or that. We have to look at the science and what the science is saying. And as I said, you, two recent meta-analyses covering over a million people are not showing a relationship between saturated fat and heart disease, and they're not showing any benefit from replacing saturated fat with polyunsaturated fats.

Joe Rogan 49:44 So these organizations, Joel, that-

Chris Kresser 49:46 Yeah.

Joe Rogan 49:46 ... you were describing, why do you think that they recommend ... Based on what Chris has just said, why do you think that they recommend reducing your saturated fat, reducing your cholesterol?

Dr. Joel Kahn 49:55 Okay. Um, and thank you. And, you know, the, the importance here, we're s- we are, you know, technical in the weeds, but I wanna bring it back. This discussion is, do you have a stroke, heart attack, erectile dysfunction, lose a leg, or do you not, because at least one factor in development of these horrible medical problems that are 80% preventable, at least one of it is your nutrition and the content of your nutrition? I mean, there's no doubt. It's the single most important factor. It's never been the only factor.

Joe Rogan 50:19 Okay, but why do you think these organizations-

Dr. Joel Kahn 50:21 So the stuff matters. Right.

Joe Rogan 50:22 ... are saying this if he's saying-

Dr. Joel Kahn 50:23 Okay. So-

Joe Rogan 50:23 ... that the studies don't support that?

Dr. Joel Kahn 50:25 Well, uh, I disagree that the science ... And I wanna be s- very specific. Let's talk about cholesterol and let's talk about saturated fat.

Joe Rogan 50:31 Okay.

Dr. Joel Kahn 50:31 So stay with saturated fat, 'cause there is differences there. They're-

Joe Rogan 50:34 Okay.

Dr. Joel Kahn 50:35 ... both, uh, you know, c- contents of food, fatty contents of food, but they're chemically different and the volume weight is very, very different. Um, cholesterol only comes from animals. Saturated fat is in animals and plants, uh, depending on the food source. So when this rise in heart attacks developed, research began, 1948, 1950, 1958. There were observations made that carefully done dietary logs suggested, these were hypotheses, there might be a connection between what you eat and heart attacks, and then it's centered on, um, you know, is it foods high in protein, foods high in sugar, foods high in fatty sources? Ultimately, they got sophisticated. Foods high in-... plant fat sources, foods high in animal fat sources. So by the late 1950s, there was a very strong consensus already that foods high in animal products with saturated fat, they go together, we're talking meat, egg, and cheese, may be a role. Why? L- let me give you a great example. In 1959, you grew up in Japan, you have a cholesterol of 120, you almost never see a heart attack. You move to Hawaii because there's migration. Your cholesterol rises to 180. Welcome to America. Your heart attack risk triples. You move to this great city, Los Angeles, this was published in 1959, your cholesterol's now 210. You have 10 times the heart attack risk that you had when you lived in Japan. Genetics don't change that quick. This was within one generation. They're called Nisei, people that leave Japan to move to California, the Nisei, and there's the Nisei-Han study that tracked these people. Now, is it the air? Is it that they adopted other bad habits? Sure, it could be, but within a very short time, they had 10 times the risk of heart attack. So public research and dollars, this stuff matters.

Joe Rogan 52:13 But why is this correlated with animal fats and proteins-

Dr. Joel Kahn 52:16 'Cause they're, yeah.

Joe Rogan 52:16 ... and why isn't it correlated with sugar-

Dr. Joel Kahn 52:18 Right.

Joe Rogan 52:18 ... and refined carbohydrates?

Dr. Joel Kahn 52:19 So, carefully done studies say, and I think we all agree, more so now 'cause we're overweight and now we're more insulin resistant and added sugars in the diet are more important in 2018 than they were when the country was thin in 1960. They weren't good then, they aren't good now. But when you parse it out, multivariate analysis, there's a stronger relationship between the number one food in studies like this is usually butter, more than red meat, it's actually butter. That's just an R value. It's called statistic. I don't wanna go so deep into statistics. It is. Somewhere there is sugar. I'll give you a classic study. If you could hold sugar the same and increase dietary saturated fat, heart disease rockets. If you could hold saturated fat the same and increase sugar in these manipulations, coronary heart disease doesn't increase. Let's point something out. I've been inside of hearts 15,000 times, I've never scooped sugar out of a blocked artery. I scooped cholesterol out of blocked arteries. 20% of every blockage in a heart is cholesterol. It's a fact that was discovered in 1910. It's never varied. Then we fed animal, uh-

Joe Rogan 53:18 Let's pause for a second.

Dr. Joel Kahn 53:19 Yeah.

Joe Rogan 53:19 Chris, do you have something to say about that?

Chris Kresser 53:20 Yeah. So that doesn't mean that the cholesterol is there because people were eating it, Joel. You know that.

Dr. Joel Kahn 53:25 It could be though.

Joe Rogan 53:26 But hold on.

Chris Kresser 53:27 And, and let me... Let's say, let's look at the, what the research says again here. So they've done controlled feeding studies where they fed people two to four eggs a day, and those show that in 75% of cases has zero impact on blood cholesterol levels. For the other 25% of people, they're termed hyper-responders. And in that group, dietary cholesterol r- r- does modestly increase LDL cholesterol, but it also increases HDL cholesterol and it does not increase the risk of heart disease. This is why the, the guidelines were changed on dietary cholesterol, is there is no evidence that, that consuming dietary cholesterol increases the risk of blood cholesterol in most people. And even when it does, there's no evidence that it increases the risk of a heart attack, which is again, why the dietary guidelines changed. For saturated fat, again, it... Most of the studies that showed harm were short-term studies. These, uh, longer term studies have shown that on average, eating saturated fat does not increase the saturated fat levels in the blood. And of all of the long-term studies that looked at this, only one showed any association between saturated fat intake and, uh, cholesterol levels in the blood. Then we have a meta-analysis, lots of meta-analyses actually, but one of the, uh, best known meta-analyses was of 17 randomized controlled trials of low-carb diets that were high in saturated fats in... Published in the journal Obesity Reviews, and they found that low-carb diets neither increased nor decreased LDL cholesterol, but what they did find was that low-carb diets were associated with decrease in body weight, improvements in several cardiovascular risks, risk factors, including triglycerides, fasting glucose, blood pressure, body mass index, abdominal circumference, plasma insulin, C-reactive protein, as well as an increase in HDL cholesterol. Now, there have now been 10 meta-analyses of randomized controlled trials looking at low-carb diets for weight loss. All 10 showed that, uh, the low-carb diet either outperformed in most cases or was, was on the s- at the same level as low-fat diets. There have been several meta-analyses now, you can see them all at kresser.co/rogen, that have looked at, um, low-carb diets for diabetes and even cardiovascular risk markers, and all of these meta-analyses have found that low-carb diets are superior for glycemic control, for reducing insulin, for reducing triglycerides, and have beneficial effects across the board without increasing cardiovascular risk markers. So we're now... We're t- we're talking about (laughs) randomized controlled trials, which is the best form of evidence that we have, and we're not seeing any harm from incr- you know, increased consumption of saturated fat. So-

Joe Rogan 56:14 So is the problem that you're citing epidemiology studies from the 1940s and the 1950s?

Dr. Joel Kahn 56:19 Well...

Joe Rogan 56:19 Is that... Because this is what-

Dr. Joel Kahn 56:20 I would, I would definitely, uh-

Joe Rogan 56:21 ... you keep going back to.

Dr. Joel Kahn 56:22 ... I think we need to, to pur- to prefer randomized controlled trials over that kind of evidence, for sure.

Joe Rogan 56:27 Why are you... Why do you c- continue to go back to these studies from the 1940s and 1950s? What do you think they're relevant?

Dr. Joel Kahn 56:31 Well, they're just the beginning. Well, they're, uh, th- the beginning, but, uh, Chris just, like, took 14 topics and put them into one, from meta-analysis to randomized controls to low-carb to low-fat. I mean, they're all different topics and I don't know how he, you put that all together. It... You, you need clarity and laser focus. So we were talking saturated fat. I mean, so hypothesis is generated. Saturated fat in the diet, butter, eggs, and cheese may be bad for heart disease. Something killing Americans left to right in 1940, 1950s. Let's go into countries with wildly different diets, let's see what they're eating, let's actually take their friggin' diet back to Minneapolis, let's analyze it so it's not guessing, not food frequency questionnaires. We're taking their meals back to the United States to analyze them. Ba-boom, there's a relationship between dietary saturated fat and your risk 50-year follow-up. There's no short-term follow-up. The study I'm referring to has 50-year follow-up. 1958 to now and, um...... that strongly suggested that dietary saturated fat and heart disease, that doesn't, that's not what's called the ultimate randomized clinical study, but it's one high quality. Second study done in China the same time with, you know, years of follow-up. So these are right up-to-date. There's publications right now from studies starting at then, but the publications are now. But then you get the best kinda study. Okay, I'm still on saturated fat, I'm not talking any other topic. You put people in a metabolic ward at the National Institute of Health, 395 of these studies published in 1979. You change their diet. This is the ultimate careful experiment. It might be for four weeks or six weeks. You up their saturated fat, their cholesterol rises sure as can be. We're all different. The change in cholesterol's consistent. You're gonna go up 20%, 20%, 20%. We start at different points, you have to track the change in cholesterol. Chris referred to... A- a- act- can I go off on a tangent? R- it's really interesting. This will fascinate your listeners, but it's right on the topic. 2008, this is published data, I don't bullshit on this. 2008, Mexico City, the National, the International Dairy Council meet and they publish their notes, which is why we know this, and they said, "We are losing the battle. People are eating less dairy around the world and we are losing sales. What we can do is influence researchers, influence academeticians, influence speakers-"

Joe Rogan 58:40 This was in Mexico though.

Dr. Joel Kahn 58:41 The, well, it's every, every dairy council in the world just happens to meet in Mexico City that year. Then they go meet in Portugal, then they go meet in New York, whatever. 2008, "We're gonna put dollars into changing research and influencing people." Doesn't mean it's all bad. They published those notes that our global initiative for the next year, they looked for sympathetic researchers that would change public opinion, and that was right before the milk mustache campaign. They find a guy I actually respect now, but I'm gonna beat him up a little, Dr. Ronald Kraus, MD in Berkeley, California, right by him, runs at a lipid center. He's had beef funding for 10 years, he's had dairy funding. All of a sudden he's speaking to dairy industries all over. In 2010, two years later, he publishes, we call it a meta-analysis. That's not new research. That's statistical playing with previous studies that can be fair or can be unfair, whatever. Whatever it is, their conclusion is they could not find and verify that saturated fat in the diet, butter, eggs, and cheese raises the risk of heart disease. They never said, "Eat butter, eggs, and cheese." They just couldn't verify it. What's amazing, it's in the American Journal of Clinical Nutrition, that same journal is a, is a editorial that destroys the study. This is 15 reasons this is horrible epidemiology by a guy named Jeremiah Stamler. I've never seen a medical journal destroy a piece that they accepted for publication. Okay, so everything's, like, stirred up and 2014, a guy named Chowdhury publishes a similar analysis that is the reason that Time magazine put on the cover, "Butter Is Back" because it was not new research. It's a meta-analysis. It's all following this Mexico City, uh, effort to, uh, fund dairy positive publications, a, a study so bad that both the journal required them to adjust and republish the data 'cause of mistakes. The Harvard School of Public Health said, "Take this thing away. Statistically, this is nonsense." Since those two times, and that's just the bottom line, we have had confusion in the public. We've got experts like Chris, experts like me, experts like Dr. Mark Hyman, experts like Dr. Walter Willett, on and on. There is a quote from the tobacco industry that our product is confusion. They didn't care about, you know, winning the battle when the public's confused, they're just gonna keep on doing habits they have. And that is-

Joe Rogan 1:00:54 Okay, I gotta stop you- ... 'cause now we're in the weeds with conspiracy theories.

Dr. Joel Kahn 1:00:57 Yeah.

Joe Rogan 1:00:57 I'd like to go back-

Chris Kresser 1:00:58 Oh, it's uh, so no, I mean, so I, I, I-

Dr. Joel Kahn 1:00:59 Well, that's when the pendulum of 1950, 1960, 1997, 395 of the best done studies in the world say, "You eat more saturated fat, your cholesterol goes up."

Chris Kresser 1:01:09 No, it's, it's actually-

Dr. Joel Kahn 1:01:10 "You eat more saturated fat, coronary heart disease goes up." It was crystal clear and the guidelines said it. The guidelines still say it, the guidelines still say limit saturated fat.

Joe Rogan 1:01:18 Are you, are you suggesting that the same science from the 1950s and the 1940s is-

Dr. Joel Kahn 1:01:23 Who, who-

Joe Rogan 1:01:23 ... is applicable today?

Dr. Joel Kahn 1:01:24 If it's, in retrospect, valid. Here, let's point out one that's not.

Joe Rogan 1:01:28 But is it?

Dr. Joel Kahn 1:01:29 Yeah, absolutely.

Joe Rogan 1:01:30 Do you think it is?

Chris Kresser 1:01:30 No.

Dr. Joel Kahn 1:01:31 Absolutely. I abs-

Joe Rogan 1:01:32 Why, why do you think it's not?

Chris Kresser 1:01:33 What, what's changed?

Joe Rogan 1:01:33 Because we keep bringing this up. Why do you think it's not?

Chris Kresser 1:01:35 So we're, we're, we're going back to observational studies done 50, 60 years ago that suffer from all of the problems that I mentioned to begin with, and several more that we didn't have time to go into. Um, we have randomized controlled trials now, and you know, observational studies were never meant to prove a hypothesis. They're meant to generate a hypothesis. And it's true that in some cases it's not possible to do a randomized controlled trial, like with cigarette smoking. You'd have to, you know, do, have the trial last for so long and you'd have to isolate people in a ward so they weren't exposed to air pollution and other factors that could affect the result. You can't do that. But in that case, the risk was 1000 to 3000% higher. So there are criteria called the Bradford Hill criteria, which you can use and apply to observational studies to assess the chance that there's a causal relationship. And in the case of smoking, which actually was when the Bradford, Bradford Hill criteria were created, that relate, that meets many of those criteria. In the case of nutrition research, very seldom did they meet more than a couple of the Bradford Hill criteria. Now observational research, in order to be valuable, needs to be confirmed. You know, it, the, the results need to be replicated in a randomized control trial. That's how science is supposed to work. But there was one analysis that found that zero of 52 claims that were made in observational nutrition studies were replicated when they were tested later. And in fact, five were replicated in the opposite direction. In other words, they, when they did an experiment, they found the opposite result to what the observational study suggested. So good examples of this are...... observational studies originally suggested that beta carotene, an antioxidant, that s- people with the highest intake of beta carotene had something like a 30% reduced risk of death, which is not really plausible anyways. But then when they started doing trials where they were giving people beta carotene supplements, not only did it not improve their lifespan, they got more cancer. It increased the risk (laughs) of cancer. So, this is why it's so important not to rely just on observational data and to do these experiments. Now, going back to saturated fat, as I said, we've got a 2013 meta analysis of 20 randomized controlled trials that found that low carb/high protein diets led to greater improvements in glycemic control compared to low fat, American Heart Association, American Diabetic Association diets. We've got a 2014 meta analysis of 10 randomized controlled trials that showed that low carb diets are more effective than high carb diets for patients with type 2 diabetes. And we've got another meta analysis of 25 randomized controlled tri- uh, trials just published in 2018 that found the same thing. So, you know, science marches on. We, we, we learn more, we change, and now we've got randomized controlled trials that are replacing some of the observational evidence from the '50s and '60s and '70s, which b- which, by the way, in, in, in Dr. Harcombe's paper you'll see that that evidence was never strong to begin with. And this is what we should be looking at.

Joe Rogan 1:04:37 So, why are you consistently bringing up these studies from the '50s?

Dr. Joel Kahn 1:04:40 Well, 'cause Chris is mixing everything up. He's talking low carb data. "Let's talk low carb diet. That's keto diet, that's low carb diet, let's be like that."

Joe Rogan 1:04:47 B- but before we go to that-

Dr. Joel Kahn 1:04:47 But we, hey, yeah, I know, I know.

Joe Rogan 1:04:48 ... b- before we go to that-

Dr. Joel Kahn 1:04:48 Well, that's what he, right-

Joe Rogan 1:04:49 ... but I, but you, you consistently bring up these studies from the 1950s and the 1960s. These-

Chris Kresser 1:04:53 Low carb diets are high in saturated fat.

Joe Rogan 1:04:55 Okay, so that's-

Dr. Joel Kahn 1:04:55 Yeah, but 1950 to 1960s was the initiation. 1997, Clark, 395 randomized clinical trials, what Chris is looking for. In Metabolic Ward, say, you jack up the saturated fat in your diet, you jack up your cholesterol. We can talk about cholesterol in a minute, but cholesterol matters, LDL-

Joe Rogan 1:05:11 Wait.

Dr. Joel Kahn 1:05:11 ... cholesterol matters. The higher it is-

Chris Kresser 1:05:12 Can, can I just ask you a question?

Dr. Joel Kahn 1:05:13 Hold on, yeah.

Chris Kresser 1:05:13 Did you say 395 randomized controlled trials?

Dr. Joel Kahn 1:05:16 Yep. Clark, Clark (1997) . Clark (1997) , 395 metabolic-

Chris Kresser 1:05:19 Yeah, I'd love, I'd love to see that reference.

Dr. Joel Kahn 1:05:20 Oh, it's, yeah, Metabolic Ward study. I can show you here. It's, I mean, it's right here. I'll give you the ref- 395-

Chris Kresser 1:05:25 There's 395... He, are you saying he reviewed-

Dr. Joel Kahn 1:05:27 Three hundred and ninety-five-

Chris Kresser 1:05:28 ... 395, uh, randomized controlled trials in a meta analysis?

Dr. Joel Kahn 1:05:32 In Metabolic Ward, the tightest dietary exchange studies, the best science.

Chris Kresser 1:05:35 I understand what a metabolic ward is-

Dr. Joel Kahn 1:05:37 Yeah.

Chris Kresser 1:05:37 ... but I don't understand the 395.

Dr. Joel Kahn 1:05:39 That's how many were there that jack-

Chris Kresser 1:05:40 Three hundred and ninety-five people?

Dr. Joel Kahn 1:05:42 No, 395 individual studies that played with fat content in diet and looked at markers of cardiovascular risk.

Chris Kresser 1:05:47 There's 395 Metabolic Ward studies-

Dr. Joel Kahn 1:05:48 Three hundred and ninety-five Metabolic Ward studies.

Chris Kresser 1:05:51 ... that were randomize, randomized controlled trials?

Dr. Joel Kahn 1:05:54 In metabolic wards. Yeah, they're gonna be short-term, that's true. You gotta read the literature. It's there. It's there for you.

Chris Kresser 1:05:59 Oh, I've, I've read the literature.

Dr. Joel Kahn 1:06:01 Well, you missed that one.

Chris Kresser 1:06:01 Yeah.

Dr. Joel Kahn 1:06:02 Tha- that's a pretty important one.

Joe Rogan 1:06:03 Well, what are you gonna...

Dr. Joel Kahn 1:06:03 Okay, but let's go back, but, but-

Joe Rogan 1:06:04 Hold on a second. This is a dispute here, right?

Dr. Joel Kahn 1:06:06 Yeah.

Joe Rogan 1:06:06 So, what is your issue with this?

Dr. Joel Kahn 1:06:07 Okay, I mean, I'll just give you... Uh, it's no big deal. I'll give you the reference.

Joe Rogan 1:06:09 But Chris, what is your issue with this?

Chris Kresser 1:06:10 Uh, I'm not aware of 395 randomized controlled trials that have been done in a metabolic ward on this-

Dr. Joel Kahn 1:06:16 Yeah.

Chris Kresser 1:06:17 ... question.

Joe Rogan 1:06:17 Oh.

Chris Kresser 1:06:17 So, I'd love to learn more about that if that's true.

Dr. Joel Kahn 1:06:19 I'll give it to you in one second. It's for Clark. But, so, I mean, I'm not stuck in the 1950s, but, you know, if you don't-

Joe Rogan 1:06:25 But you would agree-

Dr. Joel Kahn 1:06:26 Right.

Joe Rogan 1:06:26 ... that science has moved far past that, and our understanding-

Dr. Joel Kahn 1:06:29 Well-

Joe Rogan 1:06:29 ... of nutrition and our understanding of the, the mechanisms of the effect of the food on the body, all that has changed radically?

Dr. Joel Kahn 1:06:37 Our, uh, we have not changed. Our food source has changed.

Joe Rogan 1:06:41 Well, our, hold on. But, but that's not what I asked you.

Dr. Joel Kahn 1:06:43 Has our understanding-

Joe Rogan 1:06:44 Yes, the science-

Dr. Joel Kahn 1:06:45 ... of food changed?

Joe Rogan 1:06:45 ... has advanced pretty radically.

Dr. Joel Kahn 1:06:45 I actually think, I actually think, uh, well actually, I, I would say that the observations made in the '50s and '60s have held up, which is why 21 international societies still say, you will, you will lower your r-

Joe Rogan 1:06:56 But what, what observations have held up?

Dr. Joel Kahn 1:06:58 That low, saturated fat in the diet, chicken, eggs, cheese, beef, is related to raising your cholesterol, is related to your increased risk of heart attacks-

Joe Rogan 1:07:05 Based on these-

Dr. Joel Kahn 1:07:06 ... and strokes.

Joe Rogan 1:07:06 ... 1950s epidemiology studies-

Dr. Joel Kahn 1:07:08 S- initial.

Joe Rogan 1:07:09 ... that you-

Dr. Joel Kahn 1:07:09 Initial.

Joe Rogan 1:07:10 Initial.

Dr. Joel Kahn 1:07:10 Then we got randomized clinical trials. Those are called Metabolic Ward studies and such. The first, the first chink in the, in the armor was, uh, 2010. I gave you the background to it, the Ciri-Tarino study, the Chowdhury study, but they have been resou- we've decided to throw out 50 years of science.

Chris Kresser 1:07:28 No, but I just mentioned several other meta analyses of, of-

Dr. Joel Kahn 1:07:31 I know.

Chris Kresser 1:07:32 ... probably, uh, 50 randomized controlled trials c- collectively.

Dr. Joel Kahn 1:07:36 Here we go, sorry.

Joe Rogan 1:07:37 And these are modern studies?

Chris Kresser 1:07:38 Yeah.

Joe Rogan 1:07:38 So, Joel, what is the difference? Like what, why, why do you think-

Chris Kresser 1:07:43 I just-

Joe Rogan 1:07:43 ... that these old studies are applicable and why are you dismissing this new evidence?

Dr. Joel Kahn 1:07:48 Okay. So, I just w- just so Chris and I can resolve this issue, British Medical Journal, 1997, dietary lipids and blood cholesterol, 395 individual dietary experience, uh, put together in a meta analysis. It's a classic study that people know. They actually estimated if we could lower the saturated fat content of the British population by 60%, we would save X number of heart attacks every year.

Joe Rogan 1:08:11 This is in what year?

Dr. Joel Kahn 1:08:12 1997, yeah. 1997.

Joe Rogan 1:08:15 (sighs)

Dr. Joel Kahn 1:08:15 So, to answer your question, why do I think old studies are relevant? You have to keep probing and questioning and probing and questioning. But until this date, every major medical society, not one, if there was one, you'd question it. 21 international societies say you will further the populous health if you lower saturated fat in the diet. Um, and we can't pinpoint the amount of cholesterol you should lower, which is only from animal sources, but you should lower it to as low as possible-

Joe Rogan 1:08:40 Okay.

Dr. Joel Kahn 1:08:40 ... according to the USDA.

Chris Kresser 1:08:41 Yeah.

Joe Rogan 1:08:41 But again, these are epidemiology studies, correct?

Dr. Joel Kahn 1:08:43 Well, they're, this is randomized data. It's, it's, it's-

Joe Rogan 1:08:46 It's randomized data based on-

Chris Kresser 1:08:47 And, and the guidelines have changed, uh, as we said.

Dr. Joel Kahn 1:08:50 Right.

Chris Kresser 1:08:50 In 2010, they, they changed the relationship with fat-

Joe Rogan 1:08:51 But would you, wouldn't you agree that the new evidence, the, the new evidence is the, the new science? Like, whatever they're studied today.

Dr. Joel Kahn 1:09:00 Right.

Joe Rogan 1:09:00 Like what, what n- they have better methods of detection.

Dr. Joel Kahn 1:09:03 Yeah.

Joe Rogan 1:09:04 M- more, more understanding, more data to go from. Wouldn't you agree that-

Chris Kresser 1:09:08 ... we should look at new studies-

Dr. Joel Kahn 1:09:10 Well, I... We should. Let me tell you one.

Chris Kresser 1:09:12 So what did he just say?

Dr. Joel Kahn 1:09:13 So, so let's... So, so wait. Let me tell you one.

Chris Kresser 1:09:14 Okay.

Dr. Joel Kahn 1:09:14 I published a study in 2012 that's been quoted 100,000 times from a major medical journal. It uses something called Mendelian randomization. We don't need to do randomized clinical trials all the time. There are these gigantic databases now about genetic abnormalities and certain other parameters. So there is a database with 300,000 people. We know what's called their SNPs. You've probably heard of SNPs. You know, Chris' biology and genes aren't the same as mine, and there's variability. If you're born with one of nine SNPs that keeps your cholesterol low your entire life, this is a genetic gift to you, the observation in this major study quoted all over the world... The first author's Brian Ference, but I'm their number five, LDL randomization, is new data that it is an advantage to your survival and an advantage to your risk of heart attack and stroke to have a low LDL your whole life. New data. Is it consistent with 60 years of science? Ba-boom, it sure was. We actually have learned stuff that has changed our mind. When you do that same cutting-edge science on HDL, the happy one, the high one, you cannot show the same association anymore. We're totally confused by the HDL particle. LDL is the focus of atherosclerosis, low LDL. And I'll just finish, Dr. Loren Cordain... I'd love to talk about the history of the paleo movement. Dr. Loren Cordain, who had the first popular book, a PhD in Colorado, um, has written an article in 2004. It says the ideal LDL cholesterol is 50 to 70. Well, man, he should be a cardiologist 'cause I'm gonna hug him for that, 'cause he thought that saturated fat raises your blood cholesterol r- increase your risk of heart attack and stroke. This is the founding father of the paleo-

Chris Kresser 1:10:47 This is what year was this?

Dr. Joel Kahn 1:10:47 2004, and a big m- It's in a medical journal.

Chris Kresser 1:10:49 Mm-hmm.

Dr. Joel Kahn 1:10:49 I mean, this is peer-reviewed-

Chris Kresser 1:10:51 Right.

Dr. Joel Kahn 1:10:51 It was an editorial, but it's peer-reviewed. 50 to 70 LDL. I'm really cool there with Loren Cordain and 50 to 70.

Chris Kresser 1:10:58 Right, but our understanding of nutrition is advanced pretty radically since 2004.

Dr. Joel Kahn 1:11:03 (sighs) Yeah.

Chris Kresser 1:11:03 And, and I'm not... Yeah.

1:11:04 Would you agree?

1:11:04 And I'm not here to represent paleo. I mean, I, I have never been a, a, a ideological about paleo. Even my... If you read my first book, it's like-

1:11:14 Right.

1:11:14 ... I'm recommending dairy products and grains and things.

1:11:16 But I, I don't wanna get lost in this-

Dr. Joel Kahn 1:11:17 Mm-hmm.

Chris Kresser 1:11:17 Yeah.

1:11:17 ... 'cause you, you... Pause for a second. So what is your response, though, to all these studies that he was citing? You, you're citing these old studies that seem to-

Dr. Joel Kahn 1:11:26 Well-

Chris Kresser 1:11:26 ... contradict what he's saying, but these new studies that he's showing, and you could... We can go over them again, but you didn't address why-

Dr. Joel Kahn 1:11:34 No, I did.

Chris Kresser 1:11:35 You didn't.

Dr. Joel Kahn 1:11:35 He didn't.

Chris Kresser 1:11:35 So what's the result of them?

Dr. Joel Kahn 1:11:35 Well, he didn't say them by name. I'm saying them by name. The big why-

Chris Kresser 1:11:38 Okay, but does it-

Dr. Joel Kahn 1:11:38 No, the big why is names.

Chris Kresser 1:11:39 I'll tell you the exact (overlapping dialogue)

1:11:40 But what did... What... Why are the results so different in the new studies?

Dr. Joel Kahn 1:11:44 Oh, well, people better at statistics than me would say manipulation of what's called meta-analysis. These aren't new studies. I mean, these are old studies lumped together with different analyses that led to a conclusion that was surprising.

Chris Kresser 1:11:57 Is that accurate?

1:11:58 No, these are... These are randomized controlled trials that are meta-

Dr. Joel Kahn 1:12:01 Name one. Name one. Name one.

Chris Kresser 1:12:01 Okay. Hold on. Here we go.

Dr. Joel Kahn 1:12:03 That's long term. That's 20 years, 30 years, 40 years. There's no such things.

Chris Kresser 1:12:06 Joe, of course they're not doing 20- or 30- or 40-year randomized controlled trials.

Dr. Joel Kahn 1:12:10 Well, we have 50-

Chris Kresser 1:12:11 So you're, you're n-

Dr. Joel Kahn 1:12:12 We have 50-year data on seven countries studied.

Chris Kresser 1:12:14 You have observational study of 50 years.

Dr. Joel Kahn 1:12:16 So the question is-

Chris Kresser 1:12:17 And that suffers from all the same problems.

1:12:17 We agree that there's a big difference. Again-

Dr. Joel Kahn 1:12:19 Yeah.

Chris Kresser 1:12:19 ... there's a big... We've already outlined, there's a big difference between epidemiology studies and randomized trials.

Dr. Joel Kahn 1:12:25 Absolutely.

Chris Kresser 1:12:25 You agree?

1:12:26 100%.

Dr. Joel Kahn 1:12:26 100%. Yeah.

Chris Kresser 1:12:26 These randomized controlled trials are not short term. Many of them are... Go up to two years in length. If we're gonna see changes in lipids, we're gonna see them within a few weeks, and certainly within a few months. So if we're not seeing them in a few months, we're not gonna see them later. And you know, the... If you look at Dr. Harcombe's paper, she reviews all of the, the meta-analyses and looking at saturated fat and the connection with h- heart disease. There were 39 meta-analyses of RCTs or prospective cohort studies that looked at saturated fat and health outcomes. 35 of 39 did not show significant correlations between saturated fat and any outcome. Okay? 35 of 39. Of the four that did, one, uh, was more related to trans fats, not saturated fats. One showed a benefit of replacing saturated fat with polyunsaturated fat, but it excluded two studies that would have totally changed the result. And as I mentioned, there's the meta-analysis of 25 RCTs and 40 observational studies that showed no benefit of replacing saturated fat with polyunsaturated fat. And then the last two were Cochrane reviews, and in those two, saturated fat and cardiovascular disease were correlated, but saturated fat was not correlated with total mortality, cardiovascular disease mortality, uh, fatal heart attack, nonfatal heart attack, stroke, or, uh, heart... Death from heart disease or death from any diagnoses of diabetes. So- Now Joel, I'm gonna let you get to this in a second, but-

1:13:54 You, you had... You know, out of those 39 trials, virtually none showed that eating saturated fat will in- increase your risk of heart disease and none showed that it will increase your risk of death from any cause. So that is pretty damning evidence.

1:14:08 Now, if I could summarize for you or get you to summarize-

1:14:11 Yeah.

1:14:11 ... your position is that his reciting of these older studies, that they are not relevant, that they are epidemiology study, that, that they are, they are not as, uh, as rigorous, and that this new evidence is based on new understanding and new science and that he's ignoring this?

1:14:29 Yeah, that early studies showed some relationship, but they were short, very short term between eating saturated fat and then, and then cholesterol. The other problem is they were using cholesterol as a proxy marker. They weren't looking at, did people eat saturated fat and die more? They looked at, did saturated fat increase cholesterol? Um, so when they... When they did longer term studies, there's no increase in cholesterol on average. That doesn't mean no one will experience an increase. That's not true. Some people will, but on average there was no increase in ch-... And then when they looked at... They just took cholesterol out of the equation. Let's just look at, is there an increase in heart attacks or death from eating saturated fat? When they did that, there's no increase. And, and, and these are, uh, that... Those are observational studies and we have all these randomized controlled trials that are showing no, no increase in cholesterol, no increase in insulin levels, and actually a decrease in all of those markers.

1:15:26 Joel?

Dr. Joel Kahn 1:15:27 ... um, important stuff and a lot of stuff was said. And I doubt, unless you're really high level, you understood. I just wanna pick out one thing Chris said. Does anybody know what the Cochrane Database, a word that flew out of his mouth ... Cochrane, C-O-C-H-R-A-N-E, is a group of scientists that try and be very objective, very independent, don't have any emotional, any books, any supplements, any food and nothing. And we all love supplements around this table, but let's get outta