The good and the bad of the new US dietary guidelines | Dr David Katz

Welcome to the proof. In early 2025 the United States released its newest dietary guidelines for Americans and almost immediately alarm bells started ringing. These guidelines are updated every five years, they influence school lunch programs, food policy and even what your doctor recommends. They're supposed to represent our best science on nutrition today. But something unusual happened this time. The guidelines followed a multi-year review by expert scientists including researchers like Dr Christopher Gardner from Stanford University. Yet when the final recommendations were published, many of their evidence-based suggestions were either ignored or contradicted. Meet and full fat dairy now sit at the top of the food pyramid and legumes, well, they barely get a mention. And the words sustainable climate and planet don't appear once in the entire document. Meanwhile, the Secretary of Health and Human Services is celebrating his birthday with a plate of steak, saying he eats only meat and fermented foods. So what's going on here? Has the science legitimately changed or are these new guidelines based on something other than evidence? Today I'm speaking with Dr David Katz, a preventive medicine physician and one of the most trusted voices in nutrition science today. He's been watching these guidelines evolve and change for decades. And today he's not holding back. This is the proof. Let's get into it. This episode is going to be entirely on the new US dietary guidelines. So to kick things off and sort of canvas this conversation at the highest level, what would you say was your immediate reaction when you first read the newly published 2025 US dietary guidelines? Subordination of evidence, science and epidemiology to ideology and politics. And if you were to narrow that down to one feeling, one overarching feeling that you were left with, what would that be? Honestly, hypocrisy because this administration in particular uses a term which is naive and silly. I mean most of us who actually do science rarely talk about gold standard science. We recognize that target in science is always moving. We do the best we can. We learn as much of what we need to know as possible, knowing there will always be another study and another question and another answer and evolving understanding. So the notion that there's this administration has access to some gold standard size. The rest of us have yet to find the silly. But invoking that and then blatantly not just ignoring the science collated by the dietary guidelines advisory committee group. We should talk about the work they did, which was outstanding by the way. But diametrically opposing it in key instances. So invoking science while ignoring and repudiating science is overtly hypocritical. Before we get into the committee and we will step through some of the specifics of that hypocrisy and some of the problems that that you and others say in the new guidelines. Were there any positives? Was there anything in the new guidelines that you were impressed with that were not just recommendations that had been in previous guidelines, but in fact were building on previous recommendations or strengthening recommendations or even novel recommendations that for the first time were added and and did in fact represent the best science on those particular topics. Yes and no. So I've seen some and other the number of colleagues being quite generous with these guidelines emphasizing the positive and in particular noting that these guidelines invade against alternatives to real food. So that they emphasize we should eat real food and they specifically reference hyper processed food. They ought to use the term ultra processed because if we're looking these days for an operational definition of what is an extremely processed food, we should avoid. We have it courtesy of Carlos Monterey and colleagues in the Nova classification and that's the prevailing measure. So they use different terminology, but they're clearly saying eat real food not franken food. And yeah that's good and frankly it's interesting because that is sort of a step beyond what the dietary guidelines advisory committee was able to say because that group of scientists had very strict marching orders about the scientific standard for making a recommendation and they had limited studies directly comparing ultra processed to non ultra processed and it was hard on the basis of just the available science to reach a strong conclusion. But most of us know intuitively franken food is not as good as real food and the dietary guidelines explicitly say stay away from hyper processed food in favor of real food. So a number of my colleagues I've read written commentaries in various places peer reviewed literature and otherwise have been pretty generous in assessing that and I agree it's good but I'm not impressed because you could make the case that that every set of dietary guidelines since the first in 1980 said the same. What's different? Well what's different is in 1980 we didn't have very much franken food. It's been invented in response to the dietary guidelines. So it's basically the vast proliferation of what we now call ultra processed food is industry exploitation of nutrient specific fixations. So if we say cut fat they invent low fat franken food. If we say limit carbs they invent low carb franken food and not enough goes. So that process really just got started in 1980. So the guidelines have always emphasized real food. They haven't always explicitly said stay away from the alternative to real food but by the process of exclusion they've always said what you should be eating is fruits and vegetables and whole grains and beans and lentils and lean meats and seafood and so forth. So I'm not terribly impressed with that. So but it is a good thing and of course the guidelines still recommend we eat fruits and vegetables. They're a bit begrudging frankly about whole grains but they're included and they're a bit begrudging about legumes particularly if you look at their infographic this inverted pyramid they develop but they're theoretically still in there. So they got some things right. Did anything impress me was your question and honestly I have to say no. And even on that that recommendation to reduce limit these hyper processed foods what would you say at least your feel from reading the guidelines because I don't think it's explicit. What would you say the kind of underlying message is around what foods will replace those hyper processed foods in the diet? Well honestly it's protein from the most concentrated sources because one of the most salient recommendations in these guidelines is everybody should be eating more protein which by the way is scientifically overtly wrong most Americans get more protein than they need excess protein does not turn you into an Olympic athlete. Excess protein is converted to body fat you don't just automatically grow muscle from eating more protein and there is explicit emphasis on getting protein from the most concentrated sources namely meat which people should eat every day multiple times a day. The guidelines explicitly say that and full fat dairy and we'll come back to the issue of saturated fat and the combination of beef and full fat dairy and the implications there but essentially there's only room for so much eating in any person's day before you max out on calories and so if we're supposed to eat meat multiple times a day and we're supposed to eat full fat dairy several servings a day it's going to make it very difficult to increase fruits and vegetables or make room for legumes so again they're there but if you just sort of look at the big picture they're de-emphasized expressly because beef and dairy are emphasized that they're they're the most actively encouraged elements along with increasing our total intake of protein. I've been using a loop for over six years and I can confidently say it keeps me on track when it comes to my sleep and exercise routines. 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And has therefore kind of been led to believe that well, he's he's aware that industry has influenced his recommendations. So he's gone out and built a team that's going to look at the science through a more objective lens. And and therefore, therefore what we're seeing publishes the new guidelines is in fact that, you know, previous guidelines five years ago that were recommending for human health and planetary health to eat more whole or minimally processed plant foods were in fact based off reviews and recommendations from scientists that had ties with industry. And in fact, what we're seeing here now is a much clearer, less conflicted set of guidelines. How would you how would you kind of help someone make sense of this that is confused by that? Well, you can guess what I want to say in response to that characterization size, but I'll be polite. So it's another example just glaring hypocrisy. So first let's talk about the dietary guidelines advisory committee. So this this was a carefully selected highly credentialed multi disciplinary group. Now folks just think about it, right? I mean, if you are involved in the food industry in any way, you're developing a new product, you're studying the health effects of walnuts or you want to know what the health effects of plant based meats are, who are you going to turn to if not somebody who's actually an expert in doing nutrition studies. So, you know, if people with actual expertise in nutrition and in research all said no, then these questions would never be answered. Our almonds good for us. Is plant based meat better or not better for cardiometabolic health than the beef that it's replacing? We would just never get answers. So fortunately, genuine experts routinely say yes. And by the way, I count myself among them. I did industry funded research in my lab when it align with questions I actually wanted to answer. So frankly, we have a prevailing problem with the definition of a conflict of interest. That's not a conflict of interest. It's a confluence of interest. You're asking a question that falls within my area of interest and expertise and no matter the results of our study, I'm not going to change what I say based on the weight of evidence, but I am genuinely curious to help answer this question and I'm going to lend my expertise to do it. That's not a conflict. So, those are not conflicts of interest or conflances and the dietary guidelines advisory committee group was assembled so that there was a balance among the affiliation. So sure, some people did studies of plant based meat and some had ties to studies related to nuts and seeds, but others had ties to dairy and beef and seafood and so forth. Different dietary preferences, personally, different associations and importantly, all completely transparent and exposed. So there were no hidden conflicts. Everybody was obligated to say here's the consulting I've done, here are the books I've written, all completely exposed. And then they worked together to produce a consensus statement about the weight of evidence. So I think that process was beautiful and I think everybody can trust the dietary guidelines advisory committee. I think they did a terrific job with only one caveat there, Simon, and that is they were only allowed to answer certain questions in the first place. So the politicians at the start gave the marching orders that said, you guys cannot look at sustainability, for instance, out of bounds, not allowed to ask about it, not allowed to look at the science, don't bother opining, we won't pay any attention. Now that's unreasonable. So they took flight with their wings clicked right at the start, but other than that, they did outstanding work. Let's contrast that with RFK's writing group, which was nine handpicked people, seven of whom had direct and significant ties to beef and dairy industries and what guidelines did we get? Everybody should eat beef, everybody should eat dairy multiple times a day. So we need to differentiate first, between conflict and confluence. We need to allow for the importance of transparency, the dietary guidelines advisory committee group, work without compensation for two years in a fishbowl, inviting public commentary every step of the way, exposing their conclusions at multiple time points with all of their potential conflicts or in my view often confluence of interest exposed. It's a totally different standard. And then finally, I know you want to ask me your next question, so I'm sorry, but just to go back to your first key question, what can people trust? Honestly, folks, nutrition is both endlessly complex and profoundly simple. We all know Michael Collins' famous aphorism, EFOOD, not too much, most of the offense. It's just spun on right. And nothing's going to change that because yes, we'll learn all sorts of details about this fatty acid versus that fatty acid. But the profound implications of a fundamental dietary pattern aligned with our basic requirements is the type of animal that we are that's never going to change. So eat real food, mostly plants, and by the way, if you do that, then not too much tends to take care of itself. So mostly eat vegetables, fruits, whole grains, beans, lentils, nuts, and seeds, mostly drink plain water when thirsty. If you do that, you will never go too far wrong. And if you don't do that, no matter what else you do, you'll never get it right. And that's not going to change. So I think one of the ways for people to reach a fundamental understanding, Simon, is to accept that we already know the fundamentals of good nutrition. I'm interested in, is there more? Are there details? Is there something that's maybe personally relevant to me? Can we tweak it? But I'm not looking to replace the fundamental knowledge. That would be like, you know, looking to decide, is walking really good for me? I'm not sure. The science is unclear. We haven't seen studies that have told us whether the active ingredient and going for a walk is step 4,723 or 4,724. Until I have that answer, I'm just going to be confused and pretend that I don't know that walking is good for me. We tend to do that with nutrition. We don't do it with physical activity. Honestly, I don't understand why. Okay, so that's really the before we go further. That's the takeaway from this episode. If you're left confused by the new guidelines, what I'm hearing is that, firstly, these new guidelines are not built on new kind of better science that somehow the committee overlooked. It's just that they applied a different process, which you're saying is not as objective, and in order to come to their recommendations, they have to overlook and discard a lot of credible science, would that be inaccurate? Let's be clear, Simon, we have a particular problem with this set of dietary guidelines, because this was more blatantly ideological than ever before. This more directly opposed the dietary guidelines advisory committee than ever before. And this is the first time the dietary guidelines have been internally inconsistent and factually wrong, you know, as if they were written by people who have no particular nutrition knowledge. And we ought to talk about some of the facial mistakes. But to be clear, I've always ranted against the dietary guidelines in comparison to the work of the dietary guidelines advisory committee, because the dietary guidelines advisory committee is always a group of multi-disciplinary scientists genuinely qualified to assess the literature and reach a consensus conclusion. That's their job. They're not invited to say what you think aligns best with your personal interests, or tell people to eat what you prefer they eat. They're obligated to work with colleagues who likely disagree with them much at the time and reach a consensus about what the weight of evidence says. That is then turned over to politicians at USDA and DHHS, who get to decide which of these science-based conclusions do we like, and which maybe don't we like because they don't align with our particular political interests or where our pockets are being lined or all the usual stuff. That's always been a problem. Many of us have argued for years that the dietary guidelines should not be housed at USDA and DHHS because it does put politicians in charge. It should be at the National Academies and Medicine, for example, which is independent of the federal government, affiliated and influential, but independent, doesn't have political ties, not subject to lobbying and so forth. I always tell people the report of the Dietary Guidelines Advisory Committee, 2025, 2020, 2015, 2010, every five years is in the public domain. It's posted online along with the dietary guidelines. Look right past the dietary guidelines, which is what politicians tell you they want you to do based on what the science actually says. Go right to the source material where there's an executive summary that says, "Here's what the scientists actually think is in your best interest." Politicians have no qualms about mortgaging public health to fatten their coffers. On factual error, as we will definitely get to the olive oil essential fatty acids. It's not the only one. Yeah, they're three really important ones. What would you Would you say the clearest departure if you were to summarize them, the biggest departure from the committee's evidence-based recommendations? The most glaring one is the emphasis on eating meat every day. The committee expressly said we should be reducing our intake, red meat, along with processed meat. I'm sure they wanted to talk about impacts on planetary health and frankly, Simon to be clear. In my position, my career has been devoted to adding years to lives and life to years, but it's just too fundamentally important and true to ignore the ineluctable ties between public health and planetary health, human health and planetary health. We have some hope of being healthy vital people on a healthy vital planet, or we have no hope of being healthy vital people. And so, to talk about a healthy diet that doesn't take into account the long view, the sustainability. Well, then we're eating at the expense of our children. It really makes no sense. So, I'm sure they wanted to talk about that, but even without talking about that, they reached the conclusion that Americans over-consume meat. And this invites a quick digression, Simon. And I worry, people list me out, cats is vegan and he's just advocating for, he believes it's true. No, it's the other way around. My diet has become ever more plant- predominant over the years because I'm following the evidence for leads and I'm paying attention. And it's not ideological in the sense that I don't think foods are good and evil. I don't think there's anything evil about eating meat. I don't think there's anything evil about saturated fat. I don't think there's anything evil about sugar or salt either. What I care about is balance. It's just that simple. And this is true for everything related to metabolism and physiology, moving toward balance is good, moving away from balance is bad. You can, that's just too fundamentally true to argue with. So, the issue with meat and saturated fat is if prevailing diets tend to provide more than we need, tipping our diets out of balance, then continuing in that pattern or getting even more compounds the imbalance. And eating less moves us toward balance. If there's something we get too little of getting more of it moves us toward balance. So if I had to pick the one word that most reliably characterizes good versus bad with regard to diet, it's balance. Balance is good and imbalance is bad. So that the dietary guidelines per se directly, overtly and hypocritically refute the recommendation of the Dietrich Guidelines Advisory Committee, which was Americans should be eating less beef and it tells us to eat more. The second is that the Dietrich Guidelines Advisory Committee reached the conclusion there was absolutely no evidence to increase protein intake. Most Americans get more than they need. And the Dietrich Guidelines Group, again handpicked by RFK to represent his personal ideology, expressly recommended we get more protein. So those would be the two instances where the Dietrich Guidelines per se most directly repudiated the science and opposed the clear recommendations of the Dietrich Guidelines Advisory Committee. Now, the Dietrich Guidelines Advisory Committee did not recommend full fat dairy, but I would argue if you're going to have dairy in your diet, which by the way is not necessary and we should talk about that. But if you're going to, there's some legitimate debate and a lot of lack of clarity in the relevant science about which is better and reasons why one versus the other might be better. That's a good conversation for us to have. It's a subtle topic, but we can get into that. But I wouldn't go so far as to say the recommendation that full fat dairy is preferred directly opposes the Dietrich Guidelines Advisory Committee. I would say the emphasis on everybody should have three servings of dairy. The Dietrich Guidelines just made that up. That wasn't in the Dietrich Guidelines Advisory Committee report either. They obviously, you know, that represents the interest of the dairy industry and maybe RFK's personal ideology. It doesn't represent science. But the question of whether or not if you're going to have dairy, should it be full fat or not? It's an interesting question. There's a lot of nuance there. Okay. So let's step through some of these specific recommendations in the Guidelines. And then you can kind of add your thoughts and provide some clarity on these along the way. Starting with protein. So you mentioned there that the new Guidelines have an inverted pyramid and protein is now featured sort of top left and prominently there is meat and dairy foods and eggs and less emphasized our foods like legumes and peas, you know, plant-based sources of protein. And you know you're being kind when you say it that way, Simon, because actually you look at the infographic. So yes, legumes show up in the narrative recommendations. But you can see how begrudging that is because in the infographic that upper left corner is all meats and dairy and eggs and cheese. I don't see any legumes up there. So it's like, you know, eat the good protein stuff and you know if you're a real American, it'll be meat and if you're somebody else, it can maybe be a lentil. So they're in there, but they're clearly deemphasized. And unlike the Canadian dietary Guidelines, which I remember when they came out, they explicitly said they were trying to minimize industry influence on this set of guidelines that was going to inform their public how to eat for human and planetary health. And within those guidelines, they have a clear recommendation to choose plant protein over animal protein. As do food-based dietary guidelines around the world, there are a number of them that are very, very good. I like Brazil, I like Spain, I like Norway, I like Japan, a number of other goods. But invariably, those that are getting it right, paying attention to epidemiology because all developed countries have fairly common epidemiology and planetary health, they're all saying preferentially source your protein from plants and ours did too until this iteration. So what's the exact problem with recommending people to sort of focus or emphasize protein-rich foods while putting animal-based foods at the front of that list as the best options, at least that's the insinuation? What does that do to the average Americans' current diet and diet quality? Well, it may not do anything because let's be honest, Simon, most Americans have never been eating in a court with the dietary guidelines anyway. And that's an interesting aside, by the way. Now obviously, I keep thinking, you'll have me back and I'll tell you what I really think as I try to hold my horses here. But the simple reality is, is ideological. And by the way, there's always political conflict with the dietary guidelines. This may be more about one person and a personality called than ever before. RFK just has very strong feelings, often uninformed, ignorant feelings about matters of public health. So this may be less about political affiliations and pork barrel politics and getting your pockets lined and more about RFK's personal ideology. It's hard to know for sure. But as bad as these dietary guidelines are, and I think they're really bad. I think there's baby in here and a whole lot of selling bathwater and that's how I've written about it. They're still better than the typical American eats. And by the way, although they say stop eating hyper-processed food eat real food, I think they could be much more explicit on that topic. I think they should have lists. So here are commonly consumed things in America. Dunkin' donuts and Doritos and pop tarts and hot pockets. I mean, they should, don't eat this stuff. And here's stuff you shouldn't drink. Don't drink Coca-Cola and don't drink Pepsi and they don't do that. They're not quite brave enough to say we're actually going to give you an inventory of branded products that make up the bulk of the American diet that are glow in the dark, franken foods and drinks you should avoid. They don't do that. So are they really being bold, saying stay away from hyper-processed food? I don't think so. But as bad as they are, they are better than the typical American diet, which is, in the case of kids, 70% ultra-processed junk food and in the case of adults, 50 to 60% is terrible. So when you ask me, what would happen to public health if people actually ate this way? I'd hate to see people eat this quantity of beef and dairy except for the most part they already are. The only difference may be the dairy tends to be low fat, but people are already eating lots of bacon and sausage and so a lot of processed meat. So if they move from processed meat to unprocessed meat, it would be incrementally better. And if they move from a diet made up of too much meat and too much dairy and hyper-processed food to a diet just made up of too much meat and dairy, but not quite so much hyper-processed food, ultra-processed food, honestly, it would be better. So the dietary guidelines are terrible relative to what we actually know represents the optimum. As bad as they are, this is sad, they're nonetheless better than the typical American diet. So believe it or not, you know, with all the concerns I have about these dietary guidelines, the one that I don't have is what would happen to public health if people followed them closely, because the prevailing diet quality in the US is so poor would actually be an incremental improvement. I certainly am concerned with people who are eating badly. already. This is what I really worry about. So people who are eating badly look right past the the guidance to avoid hyper-processure because they're not going to give up their pop tarts and donuts and Doritos and they're not going to stop drinking soda but they are going to see the license to eat more meat and to eat full fat dairy. And so diet quality could actually go down further if people retained all the bad elements of the prevailing diet and said less emphasis on fruits and vegetables. I was really trying with fruits and vegetables. I was really trying to eat more soybeans and beans and lentils and I'm not going to bother with that anymore because I'm not supposed to. Now I can eat all the hamburgers I want. And I'm not being glive when I say hamburgers. The infographic doesn't just show steak and chicken and it actually shows chop meat. So you have steak and chop meat in that same upper left region where the high quality protein choices are some. So it wasn't enough to show red meat once it's shown twice. 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I'm glad you said that, because I feel like earlier you mentioned that you've seen some people who have been a little bit generous with their review of the new dietary guidelines. And I think some of that is coming from the position that you've just stated, David, that the American diet is so crappy that anything is an improvement. So let's not be nitpicky. But what I'm hearing from you is that, yes, that can be true, whilst these guidelines also do not necessarily recommend the most optimal way to eat for human and planetary health at the same time. But, well, again, so first, I think the generous assessments are partly people accentuating the positive. Partly the recognition that these guidelines are bad, but nonetheless better than the prevailing American diet. I also think it's probably a bit of cautious opportunism. I mean, after all, this is the administration. This is the maha movement. And if you want to get anything done in public health or science, alienating the powers that be tends to create impediments. And so, you know, if I've got colleagues who are running on NIH-funded grants, they've got to care. Whether or not they wind up in RFK's personal crosshairs, because we've seen how vindictive this administration can be. We don't like what you're talking about. We'll terminate your grant funding, and they'll go to war with Harvard University, for instance. So it's rather fraught. And I'm perhaps being brave and foolish to speak my mind so candidly, but that's how I roll, and not about to change now. And again, I do think it's critical to recognize that while the current American diet is even worse than it would be if people followed these guidelines, we have 45 years of watching that people don't follow the dietary guidelines. Their greatest influence is on federal food programs, right? So kids in schools and WIC and SNAP and so forth. So federally subsidized feeding programs, they must conform to the dietary guidelines. And we're already seeing a shift there where school menus are getting full fat dairy to replace fat reduced dairy and presumably going to be elevations in protein and more meat represented when the trend up until now had been in the other direction more plant-based opportunities for kids. So if people don't follow the guidelines, but they do follow the zeitgeist and just the prevailing sentiment is meat is good again, full fat dairy is good again. I think people will latch onto the parts of this that are easy and preferred, right? I mean, you know, being told what you can eat, you should stay away from hyper-processed food. Well, I'm not going to give up what I like, but I love the part about, you know, eating more beef and eating more ice cream and cheese. So I'm going to do that. I do worry that's a probable outcome here. And it will be detrimental to public health. It will be detrimental to coronary arteries. It will be detrimental to years in life and life and years. And it will be another devastating blow to the critical issue of planetary health. Speaking of coronary hot disease, haven't we been here before? And I saw this quote from Mary Nessel and she said, and I'm quoting here, that these guidelines take us back to the diets of the 1950s when everyone was eating well to meat and dairy, not worrying much about vegetables and hot disease was rampant. So even if people were to eat less hyper-processed foods, but we're in exchange doubling down on on red meat and full fat dairy and cream and butter and all of these foods, is that not similar to the diet that many Americans followed in the mid 1900s when hot disease was quite prevalent? Or would you say that that is that's an unfair kind of statement and that the diet quality patent back in the 1950s was in fact different? Well, first of all, some of that I don't think dietary improvements is zero some game. It's not as if you have to increase your intake of sugar and refined carbohydrate if you're reducing your intake of beef or full fat dairy or saturated fat. So we can improve our diet in multiple ways at once. And again, just less to anybody get lost in the sauce here. Eat food mostly plants. Mostly eat vegetables, fruits, whole grains, beans, lentils, nuts and seeds, really honestly folks. That is the news, that is the only news that is always going to be the news. Ariane agrees with me. And frankly, everybody who isn't trying to sell you something and knows anything about nutrition agrees, it's fundamentally clear. So yeah, if you go back to the middle of the 20th century, our diets were very excessive in meat and dairy, but not much more so than now. Meat intake has actually gone up over time because in addition to everything we had back then we have a greater variety of processed meats now than we ever had before. Our intake of dairy fat has sort of popped around a little bit. It went down because we started consuming low fat and nonfat dairy in the place of full fat dairy. But all too often those fat reduced dairy products had added sugar. Well, that's a sideways move. That's a lateral move. We were not improving health. Whether you over consume sugar or over consume saturated fat, two ways. to harm your metabolism and your health. And indirectly, excess sugar consumption contributes to coronary disease. It's not quite the direct effect on atherosclerosis that saturated fat tends to have, but excess sugar in the diet drives up insulin requirements, increases inflammatory responses in the diet, and inflammation harms the arteries, and inflammation propagates atherosclerosis. So it's a key contributor to major chronic diseases. So you could argue that diets in the middle of the 20th century were far from optimal, but had fewer liabilities than modern diets. Because again, we didn't really start inventing ultra-processed, frankenfood until about the middle of the 20th century and after, really ramping up after the initiation of dietary guidelines in 1980, but maybe beginning in the 1970s. Before the first dietary guidelines, Simon, we had healthy people objectives, and they offered guidance about diet, and the food industry was watching. So while people are focused on fat, we know how to deal with that. And what the guidelines really mean is people should shift from naturally high fat foods like beef to naturally low fat foods like beans. That's what they really mean. But we know the public won't understand that subtlety. They're just being told to eat less fat, so we'll invent snack-well cookies and tell them it's good for them, and they'll eat it. Because that's what people do. And then they've done that every step of the way. So again, you could argue that die quality after the 1950s went down because of the advent of these ultra-processed alternatives. And with regard to dietary fat, by the way, it's interesting if you really scrutinize the trends, what you find is total dietary fat and take in the US after we were talking so much about the potential ills of saturated fat, courtesy of the work of Ansel Keys, the seven-country study, which by the way was brilliant and important and is now subject to all kinds of revisionist history. It's totally unfair topic for another day, probably. But the average American actually never reduced total dietary fat and take. What we did was we had license to eat low fat foods, so we just added them. So total calorie intake went up largely represented by nutrient empty foods filled with sugar and refined carbohydrate. And so we diluted fat as a percent of total calories not because we shrugged the numerator but because we grew the denominator. All of this speaks to an earlier point that you made that you wished there was some images of swaps. If you're going to eat less hyper-processed foods, for example, this one ate more of this. And when I think back to the 1980s and you mentioned Ansel Keys, there are all links. I think you wrote a white paper with some other folks on Ansel Keys. I remember reading that a few years ago, which was really thorough. But his work very much supports downshifting on saturated fats and consuming more polyunsaturated fats. And that replacement being particularly important. But through the 1980s, as you say, the food industry propagated this message that all fats should be avoided and just consume their ultra-processed low fat foods instead. So the replacement wasn't actually what science reflected as a beneficial shift. And so it would seem that fundamentally in terms of making this easier for the population, guidelines really should place much more emphasis on that replacement factor. Couldn't agree more. And I mean, that would be brave. And that would say we don't care what industry has to say about this. Here's what the science says. This is about public health. Eat more of these. Eat less of these. And we should be specific. Yeah, we should name names. I've never seen that done. So again, the generous assessment of the current dietary guidelines that I've seen from so many quarters is they're being explicit for the first time ever about eating less hyper-processed food. But they let it go with that. We leave you the American citizen to figure out what we mean by hyper-processed food, knowing that you'll choose to define hyper-processed food as stuff you don't routinely eat. As opposed to telling you, hey, no, Doritos count. And don't stop. America should not run on Dunkin' and cut it out. But they're not going to say that. They're not going to go to war with corporate America and say, here are all the products, branded products, that should not be part of a healthy diet. But they should. I couldn't agree more. I think substitutions. And you could even say there's room for some of these for the sake of pleasure. So if you occasionally want to eat red meat, you occasionally want to eat poultry. But the optimal choices are the following. So we could even have optimal, optional, and avoid. You could do three columns. But I completely agree. And it should be food-based. And when they're nutrient-based, we get into all kinds of trouble like internal conflicts. So we're going to need to talk about those. But these guidelines did very begrudgingly, I think, maintain the recommendation to restrict total saturated fat intake. But then with their food level recommendations, they made that threshold impossible to achieve. OK, let's get to that. But let's tie a little bow and protein. So maybe you can summarize it for us if we were using that optional optimal and avoid kind of framework. What would that look like for protein? Yeah. We did a paper a couple years ago. One of my co-authors was Christopher Gardner, friend, colleague at Stanford, and a member of this latest dietary guidelines advisory committee. And Christopher does some of the best nutrition research out there. So he was a co-author. We called-- as was David Jenkins at the University of Toronto who invented the glycemic index. And we called for a modernization of the definition of protein quality. What is quality, Simon? What was the average person think I was quality? I would say Gertrude Stein famously said a difference to be a difference must make a difference, like that. And I think similarly, quality is this quality does. If you tell me something's high quality, but it invariably hurts me, say, that doesn't seem like quality to me. I mean, you give me sign that's high quality. I wanted to do me good. Stuff that does me good is high quality. Something that improves my quality of life is high quality. Well, the definition of protein quality and there are these elaborate acronyms, PDCAS, and so forth related to the digestibility of specific amino acids and their absorption from different food sources. It's all predicated on biochemistry. And believe it or not, studies related to the rate of growth of wienling rats. That's where these definitions come from. How fast can you get baby rats to grow? Now, the problem is things that make baby rats grow the fastest also make tumors grow the fastest and also fuel obesity to the greatest extent. It's just a lousy definition of protein quality. I think the definition of protein quality should be, gives you everything you need from a source that actually tends to make your health better. So yes, you care about how much protein and yes, you care about the distribution of essential amino acids can ignore those components. We need what we need is construction material for the body. But eating this food will tend to improve your health. You will be less subject to obesity, diabetes, heart disease, not more. And when you look at protein quality that way, so we argued the days of a biochemical definition of protein quality should be over, we need a public health definition of protein quality. What sources of protein predominant in the diet produce the best possible outcomes for the population? And then the answer clearly becomes and compellingly becomes beans, lentils, chickpeas. They're highly concentrated protein sources. The distribution of amino acids is nearly perfect and perfectly complemented by other foods that make up any balanced diet. And the foods themselves are mainstays in the world's healthiest populations. So for example, when you ask Dan butner, the founder of the Bluzons, what's the single most salient dietary commonality among these very diverse populations that routinely live to be 100? It's legumes. That's number one. And I completely agree with him. The other thing is, again, balance is the operative word about getting diet, right? Well, we get too much saturated fat. We get too much sugar. We get too much salt. We get way too little fiber with very important health implications. And legumes are not just a great protein source. They're a great fiber source. So they're feeding the microbiome optimally. Whereas every time you add beef or full fat dairy to your diet and bump something out, chances are you're reducing the already quite pitiful intake of fiber that prevails in the United States and denying your microbiome, the essential nutrition it needs and harming your metabolism. And that's an important consideration, too. The trade-off, right? I mean, when you eat more of X, you're probably going to eat less of Y, or you're just going to eat more total, which means we're going to make the obesity epidemic even worse than it already is with dire public health implications of that. But otherwise, the food that we're most emphasized in you eat more of is going to push something else out of your diet. Everything about the recommended pattern in these dietary guidelines favors taking the excess of saturated fat and protein and making them worse and taking the deficiency of fiber and making that worse. So getting the definition of protein quality right and saying it's the quality not just of the protein, but of the impacts on your health of the food delivering the protein. That's how we should be talking about it. Chickpeas win, lentils win, a variety of beans win, whole grains, certain whole grains in particular. seed grains like quinoa, excellent source of protein, they would be up at the top, beef would be well below that. 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But if you change the focus of protein to a similar kind of wording to health Canada's dietary guidelines and it was choose source of plant protein over animal protein while not having to exclude animal protein. But having this bias towards plant protein as you say that really seems to straighten up the diet and it fixes some of the problems with the existing American diet being a little high in saturated fat, low in fiber and depending on the switch there you could also improve the unsaturated fat intake in the diet at the same time. So if there was one main takeaway from this episode as to what's the single biggest change to these dietary guidelines if someone was following them that would improve their diet quality would it be that choosing plant protein over animal protein? Everywhere they say beef, cross it out and write beans. Yeah, probably. That would probably be number one. Again, legumes are an incredibly valuable food source rich in a wide variety of micronutrients, vitamins, antioxidants, minerals, highly concentrated in fiber, outstanding sources of protein and by the way they tend to be nitrogen fixing plants which means they restore nitrogen to the soil. So using them as part of crop rotation actually improves soil health. You know, as all this talk about regenerative agriculture is if the only way to do it is to have cows in the pasture and that's an interesting topic in its own right probably not when we have time for. But using nitrogen fixing plants is a form of regenerative agriculture. Crop rotation is a form of regenerative agriculture and so legumes have that property as well. So beneficial to the soil, beneficial to sustainability, beneficial to the microbiome at the root of it all, microbiome of the soil. And unbelievably nutritious and you know, if you're interested in outcomes, again, I think the best evidence for health outcomes and I say this as somebody who has conducted and published randomized control trials conducted and published systematic reviews and meta analyses. What we're striving to do with all of our statistical ledger domain and research methodology is to approximate an understanding of what would happen if everybody in the real world actually did this. So we really want to know what happens to entire populations of real people in the real world over meaningful stretches of time like lifetimes in generations. What we have, that information, that's the beauty of the blue zones. They tell us, you know, here's what happens to whole populations living a particular way for lifetimes in generations. And again, legumes are very salient and the blue zone diets are quite diverse. We have two in the Mediterranean region of the world, one in Okinawa, Japan, one in Loma into California, one in Nucleus and Costa Rica, they're not all the same. But they have a high intake of legumes in common. I think that's important. And we have all sorts of mechanistic studies showing what intake of these foods does directly to metabolic markers, directly to the health and diversity of the microbiome. So I think the case could be made, Simon, if you and I were put in charge and we were authorized to, you can make just one change. Yeah, I think wherever we see the recommendation to eat meat, we'd probably try to strike that and say legumes instead. That would do a lot of good. Let's slide on over to fat. And maybe before we get into the specifics in the guidelines, you can give us a kind of high level understanding based on the best science we have today. What are the important takeaways when it comes to fat, the different types of fat in our diet and how that affects our long-term health? Yeah, sure. Well, first of all, I'm fairly agnostic about the total amount of fat in the diet. Again, in bokeh and the blue zones, the Okinawan diet is extremely low in fat. Well below 25% of calories, potentially down as low as 15% or 10% of calories in fat. But eachery agrees since Sardinia, Italy, it's up around 45% well above the typical America diet. So we've got high, we've got low who cares. Which is why that message, eat real food mostly plants is so important. If you get the distribution of foods right, all the rest is just noise. There is no specific macronutrient threshold that's exactly right. So I think we can all be fairly agnostic about the total quantity of fat in the diet as long as we get the quality of foods right. Always focus on the quality of foods. The one caveat there is fat is highly energy dense. So if you take a gram of carbohydrate, it's about four kilocalories. If you take a gram of protein, it's three to four kilocalories. If you take a gram of fat, it's nine kilocalories. So more than twice as energy dense as the other two macronutrients, which means at the same volume of food, if you are consuming a high intake of fat, it's easier to over consume calories. And that's a potential concern. There have been studies over time that suggest that has implications for weight management. So we could think about that. And that might be an argument for eating lower fat. But frankly, if you mostly eat plant foods, vegetables, fruits, whole grains, beans, lentils, nuts and seeds, only very few of those are naturally high in fat. Nuts and seeds are. For the most part, the other foods are not. So your diet won't tend to be very high in fat anyway. So I'm agnostic on total fat. Then the issue is, what is the distribution of fat that's optimal? And it's quite clear that we thrive when the bulk of the fat and our diet is unsaturated. In particular, polyunsaturated. And perhaps to a slightly less extent, monounsaturated. So there are three main categories of fats. Polyunsaturated, monounsaturated and saturated. What is that even all referred to? Well, fats are made up of strings of carbon atoms lined up next to one another. And a saturated carbon, carbon theoretically has four arms. And if each of the four arms is holding something, that carbon is saturated. If some of those arms are not holding anything, then they hold their neighbor. And you have a double bond between two neighboring carbons, right? So there's available hand and they just hold hands. When carbons are holding more than one hand with their neighbor, they're unsaturated. So those double bonds represent the places where a fat molecule is unsaturated. And you've got polyunsaturated, which means multiple places where neighboring carbons are. are holding two hands and mono unsaturated where there's just one pair of neighboring carbons holding two hands and then saturated fat everybody's arms are full and these have very different biochemical properties they have different culinary properties and what really matters again is balance adaptation. So you know in the native homo sapient diet there wasn't a lot of saturated fat to be had because wild at the flesh of wild animals is quite low and saturated fat tends to be high in unsaturated fat the nuts and seeds that are ancestors ate were high in unsaturated fat so we're just not adapted to a very high intake of saturated fat and it's associated with inflammation, arthroscalrosis, chronic disease we too we very readily get too much of it. So the exact distribution of polyunsaturated mono unsaturated satris probably beyond the scope of this discussion but suffice to say more unsaturated fat tends to improve modern health outcomes more saturated fat tends to exacerbate already bad health outcomes. What's the evidence? Well all sorts of evidence the usual things mechanistic studies randomized control trials meta analysis studies of lipid panels studies of inflammatory markers but the example that I particularly like in this instance Simon is the North Carrieria project so in North Carrieria Finland which had the highest rates of premature death from coronary artery disease of any population in the world in the middle of the 20th century. Men were routinely dying in their 40s of advanced coronary disease. They launched the North Carrieria project following on the learnings from the seven countries study in the work of antself keys and keys was directly involved in counseling, peca pushka the Finn who initially led this project and then over a span of decades they did all sorts of things to try and improve health and one particular focus was trying to get saturated fat from animal sources out of the diet and replace it expressly with unsaturated vegetable oil and as fate would have it particularly conno oil. So a seed oil which which maha has vilified although they didn't expressly do that in the dietary guidelines and the result over span of decades was an 82% reduction in the rate of prevalent coronary disease and cardiovascular mortality stunning. And again it's not because unsaturated fat is good and saturated fat is evil it's because eating in accord with our native physiologic adaptations and requirements is good balance is good imbalances fat. We could go further and talk about essential fat so they're essential fatty acids there are two varieties of those omega-3 and omega-6 why are they essential? Because we need them for specific biochemical pathways they are critical rate limiting construction materials for stuff the body has to make and the body can't make them and the two key essential fatty acids are alpha linoleic acid often called ALA that's an omega-3 and linoleic acid that's an omega-6 we need both you're a bit of a year in a year they actually omega-3 and omega-6 are used in many of the same biochemical pathways they're often involved many important roles and we can't get into all of that obviously but they're often involved in the production of a broad class of chemical compounds called icosenoids a subclass of which is prostaglandins that may be a term most people have heard and many of our hormones are prostaglandins and as fate would have it omega-3s tend to produce anti-inflammatory compounds in the prostaglandin class and omega-6s tend to produce pro-inflammatory compounds in the prostaglandin class and so getting a balanced right among the different subclasses of unsaturated fat is probably also important but that's a that's a bit of a nuance most people tend not to think about but the simple takeaway here Simon is we over consume saturated fat probably over consume omega-6 fat we under consume polyunsaturates in general and public health outcomes improve when going from the current levels of saturated fat to less saturated fat more unsaturated fat and monoinsaturated fat which is sort of the case apart from the other two well we know that that tends to be a good thing too because monoinsaturated fat predominates in olive oil so extra virgin olive oil and everything we've heard about the wonders of that and the good of the Mediterranean diet predominant fatty acid in olive oil is oleic acid that's a mono unsaturate again just by way a reminder that means that those carbon neighbors only one pair of them doesn't have a full set of hands and and they're hanging onto one another so one unsaturated carbon carbon bond that's a monoinsaturated fat oleic acid is of that variety and it has somewhat differential effects than the polyunsaturates but clearly beneficial so where should we be getting our fat that's really the question right the end of the day it's about food honestly who cares nobody eats unsaturated fat right I mean we use certain oils but seeds nuts olives avocado all rich sources of unsaturated fats meat and dairy highly concentrated sources of saturated fats fish and seafood when they're fatty concentrated sources of unsaturated fat so if you want to eat animal foods is fish and seafood better generally then terrestrial animals absolutely yes and we could talk about the specifics of fish oil and so forth but nuts seeds olives avocados the oils they produce fish and seafood unsaturated fat consistently and strongly associated with better health outcomes and back to your point earlier when you look at those diets around the world of people that are living long healthy lives the way that they eat that naturally takes care of itself the naturally eating a diet that's lower in saturated fat and tends to have more mono and polyunsaturated fats to varying degrees like you said in terms of what the total overall fat content of the diet looks like but generally speaking they're ticking those boxes of having lower saturated fat and more of these unsaturated fats you know it's interesting Simon because you know we do want to keep bringing the conversation back to simple actionable understanding and I that's easily achieved eat food mostly plants it really really is and and in a balanced assembly so wholesome foods real foods mostly plants in a balanced sensible assembly and then the nutrients all take care of themselves so sure as an expert is somebody who's devoted decades to the study of this and writing books about it we can get into the details and by the way not all saturated fat is created equal there's palmitic and meristic acid which predominate in beef and dairy there is stearic acid which is present in beef but predominates in for instance dark chocolate there is loric acid which predominates in coconut and you know he didn't we could parse all of that and it's interesting and not irrelevant and you know once you're at that level of detail it's good to understand all those different things too but for the average person who just know cares about when a what should I eat for better help all that's unimportant that's just noise I mean really simply if you mostly eat a variety of wholesome minimally processed plant foods and less of everything else you will without trying shift your intake of total dietary fat in a salutary direction your health will be the better for right but back to these these guidelines and I'm looking at the incorporate healthy fat section there there is some stuff in here that is good stuff but then there are a lot of internal contradictions so for example they've they've maintained the the idea of not exceeding 10% of calories from saturated fat but in the same same breath they say things like healthy fats are plentiful in many whole foods such as and then they lead with meat's poultry and eggs so they're labeling those foods as containing healthy fats which seems contradictory to what you've just walked us through and then on top of that they say when consuming dairy include full fat dairy so what do we make of that internal contradiction and whether you know someone follows these guidelines as they're put forward whether they would actually meet that saturated fat consumption recommendation of less than 10% of daily calories so the answer to that last part is absolutely not so these it's interesting Simon so the nutrition community has seen this coming for a while for all I know you've been on some of these exchanges where there's been fussing about you know are they going to abandon the recommendation to limit saturated fat and there was also a concern that they might and I think the reason they didn't at the end of the day is the evidence is so overwhelming that saturated fat should be limited that it was just a hill they didn't want to risk dying on in the court of public opinion that they abandoned you know don't restrict your intake of saturated fat there just would have been an overwhelming response from all of the nutrition organizations and nutrition experts and dietitians and it would have been overwhelming so I think to avoid that direct conflagration they preserve the recommendation to limit total saturated fat and then said but eat these foods have three servings of full fat day to day include beef as your preferred source of protein and the simple fact is in the typical American diet. Doing that and you're already at or above the recommended threshold for saturated fat. And if you then get saturated fat from anything else, you have baking with your breakfast or you have deli meats at lunch or any other. So by the way, there's some saturated fat in a wide variety of foods that are mostly not saturated fat. There's some saturated fat in olive oil. There's some saturated fat in nuts and seeds. There's some saturated fat in whole grains. So no, there's pretty much no way to follow the food-based guidelines and honor the saturated fat restriction. And I honestly, I think that was not an accident. That was hypocrisy. We're going to keep the saturated fat recommendation so we don't get into too much trouble, but then we're going to make food recommendations that basically blow it to smithereens. I think they did that on purpose. Here's what they didn't do on purpose. They started talking about essential fatty acids and recommended olive oil. That's gibberish, rubbish. Olive oil is not, it's a healthy fat. Again, rich in oleic acid, negligible to trivial source of any essential fatty acid. As you said, they recommend eating healthy fats, which they had talked about being unsaturated fats, and then include a list of foods that have very little unsaturated fat and are rich in the saturated fat. We already get too much of. And again, just by way of reminder, that's why it's bad. It's not bad because it's bad. It's not bad because it's evil. It's bad because imbalance is bad for us. And getting more of what you already get too much of is coals to new castle. It's just not helpful. It tends to be harmful for that reason. So but they lump them together. They talk about olive oil, beef, tallow, and butter as essentially co-equal sources of healthy fat. They are as different as night and day. They have the distribution of fatty acids in those different foods. It's utterly incomparable. So it's actually complete and utter gibberish. And in the case of recommending you get your essential fatty acids from olive oil and these other sources of healthy fats meet and dairy, it's factually wrong. It's just completely ignorant nonsense. When I read that, when it says to prioritize oils with essential fatty acids, I kind of laughed to myself because this is coming from a group that a diabolically opposed to seed oils and vegetable oils. But when you recommend prioritization of oils with essential fatty acids, the oils that are most rich in essential fatty acids are vegetable oils. Yes, for sure. And canola oil, top list. There's high omega-3 canola oil readily available. Organic, expeller pressed, high omega-3. It's definitely one of the best choices you can make. Now, it's interesting, Simon. These dietary guidelines didn't indulge every ideological inclination of RFK and his acolytes because I was expecting to see stay away from seed oils. Consume healthy oils, but don't get them from these sources of healthy oils, but they didn't do that. So I suppose back to your very first question, what am I impressed with? They stifled their ideological impulses with regard to seed oils. Yeah, I mean, in fact, they've kind of encouraged them without actually stating vegetable and seed oils based on the way that that sentence is written anyway. The other thing that I wanted to get your thoughts on here was that in that incorporate healthy fat section, where they mentioned the less than 10% of calories from saturated fat. At least the way that I read it is that it seems they want people to think that you will achieve that less than 10% of calories coming from saturated fat. If you just steer clear of the packaged, you know, hyper processed foods, in fact, it says significantly limiting highly processed foods will help meet this goal without educating and informing people that there are a lot of saturated fats in the protein rich foods that they're recommending. Again, I think it's hypocrisy. I think that was a case of being cagey. So there are examples of just pure ignorance. They talk about sources of essential fatty acids that are absolutely not sources of essential fatty acids. They talk about substituting olive oil, beef, tallow, and butter for one another as if they have anything vaguely resembling the same distribution of fatty acids they don't. That's ignorance. They list non-nutritive sweeteners at one point and include xylitol. On the list, xylitol is a sugar alcohol. It's a naturally occurring substance in many fruits, relatively low levels, but it's not a non-nutritive sweetener, just pure ignorance. But in the case of saturated fat, this is not ignorance, this is ideology. They know, because it's incredible how ignorant you would have to be not to know this, that most of the saturated fat in the American diet comes from meat and dairy. In fact, even when it comes from highly processed food, it mostly comes from processed meats and processed dairy. For example, ice cream with added colorings would be a processed food. But saturated fat comes from the dairy and it not from the colorings. So you could oppose the colorings, but the saturated fat is there as well. If you steer clear of highly processed food, mostly what you will be reducing. Again, I very much doubt Americans are going to pay much attention to that part, because most of the food supply, let's face it, is ultra processed foods, unfortunately. If you did that, it would likely help considerably in reducing intake of refined carbohydrate, which is a good thing, and added chiver, which is a good thing. But frankly, it would tend to have a relatively negligible impact on total intake of saturated fat. For a whole host of reasons, including the fact that ultra processed foods have long ago switched over to vegetable oils. So the, it's not as if they don't include fats, these concoctions, and again, hoes and twinkies and Doritos and pop tarts. I don't eat that stuff. So I often do a poor job of enumerating the list of commonly eaten ultra processed foods, but you know what they are. Anyway, those foods, when they have added oils, it's often vegetable oils. It's rarely concentrated sources of saturated fat. So I disagree emphatically. Steering clear of ultra processed food, absolutely a good thing. In general, there are exceptions, by the way. With ultra processed food, there's also baby and bath water, and we could talk about that. But by and large, less ultra processed food, more real food would be a very good thing. But mostly good in reducing our intake of sodium, added sugar, and refined carbohydrate, negligible impact on saturated fat. And I suspect they knew that, and they were talking at both sides of their mouths. Speaking of added sugars, perhaps now we can slide across to dairy, specifically as a food group. And I'm thinking here even for the listener who enjoys a plant-rich high fiber diet, and let's say they consume dairy or they're wondering if they should. The guidelines date when consuming dairy include full fat dairy with no added sugars. Is that the recommendation that you would have in the guidelines if you were in charge of writing them? And if not, what would you kind of want to modify that to? So it's a really challenging topic. When I've tried my best to sum up the evidence regarding dairy, and by the way, the debating epistemology, because some people argue it's just wrong for adult mammals to consume dairy. It's unnatural. And other people argue that it's the most natural thing of all, it's start out, obviously on breast milk, and it's highly nutritious food. It's a really fraught topic. So let's go back, and I'll do this as succinctly as I possibly can, but if we go back to bedrock here, it is true that in the natural scheme of things, mammals start out on maternal breast milk and then stop consuming dairy. So if we're looking at adaptation and evolution and the paleolithic era, there was no dairy in the diet. Nobody consumed dairy. We didn't have the opportunity to, and the gene that clones for lactase, which is the enzyme that breaks down lactose, that gene in all mammals turns off in early childhood. So all adult mammals, normally, are lactose intolerant. That is the normal natural state. And it was true of humans too, until some groups of humans found themselves under extreme survival stress, in particular, Scandinavians who were colonizing Iceland and Greenland with much in the news of late, and the survival advantage of being able to digest dairy effectively resulted in the propagation of a mutated gene that kept lactase activity active throughout life. So lactose tolerance in adults is the abnormal or mutated state. Lactose intolerance is normal. So many people argue that human beings have no business consuming dairy. It was not a part of our native diet, and that's true. But you can also look at what happened to Scandinavians and say that's natural selection too. And so some humans now are adapted to consumed dairy. So the big question, should we consume dairy or not? It depends. There's an argument for, there's an argument against, and it really depends sort of instead of what, the context of what overall diet, you could make a case either way. I tend to lean against to get, because I'm thinking about public health and planetary health and how we treat our fellow creatures and all that, but too much to get into. Then the question about dairy fat is interesting because two things. First, when fat was stripped out of dairy, a lot of mischief came along for the ride. Meaning sugar was added, we got strawberry flavored milk. vanilla flavored milk and chocolate milk and that at best, at best is a lateral move. You're taking out saturated fat you're putting in sugar. All of the relevant evidence is you know well Simon indicates you know there's more than one way to eat badly and Americans seem committed to exploring them all. So you know you can harm yourself with excess saturated fat. You could take out the saturated fat replace it all with sugar. You're not doing yourself a favor. You just found a new way to eat badly and cause many of the same hills. We did that. So there's absolutely a case to make against fat reduced dairy products that have other ills along for the ride. And then there's the issue of satiety. So if you're eating a highly processed diet, one of the many problems with it is those foods tend to increase the total amount of calories you need to eat before you feel full. And you could argue that fat reduced dairy in that context contributes to that. So these are now foods that don't tend to fill you up. They're less energy dense than they would be with the fat content. Your whole diet has a lot of low fat fat reduced foods in it. You're never filling up so you're eating the whole box of snack wells kind of thing. In that context full fat dairy as opposed to fat reduced dairy could offer a satiety benefit. Meaning that when you have that glass of whole milk, a kid actually feels full for a while and eats less of other things. Which is why I said earlier in the conversation Simon it's a very subtle topic. It depends on the overall dietary context. Let's look for just a second though at the optimum. Let's say you're eating the way humans really ought to for ideal health outcomes. So you actually are eating real food mostly plants. Well among the many virtues of wholesome minimally processed foods mostly plants is that they fill us up on many fewer calories. So it's it's satiety is taken care of. It's taken care of by the high volume of fruits and vegetables and by the high complement of fiber which fills us up without providing calories. If you're eating like that, I see no advantage in the addition of full fat dairy because you're adding saturated fat you don't need and you're probably not deriving a satiety benefit. So when we talk about specific foods or food groups, here's what you always need to think about. Instead of what along with what and in the context of what. So is there a context in which you could make the case that otherwise unprocessed full fat dairy has certain advantages to fat reduced dairy? Yeah potentially a satiety advantage. Are the saturated fatty acids in dairy interesting and not universally harmful? Yeah, there are actually some studies showing that some of the the medium medium chain fats may have favorable metabolic effects in particular and fermented dairy products. Yogurt, cheese is really very interesting. So I don't think the jury has fully reached a conclusion about all the different saturated fatty acids in specific dairy products. But in the context of an optimal diet, a. Dairy is not necessary. Homosapiens do not need. Homosapiens adults do not need to consume dairy at all. So it's it's a discretionary food group. So a dietary guideline that says you should eat dairy, full fat dairy or any other type multiple times a day. That's just made up nonsense. Nobody needs to eat dairy. It's a give or take. You do need to eat vegetables. Dairy is your choice. Included or excluded. And then is there an advantage to full fat versus fat reduced? It depends. It really depends on the context of your overall diet. But the one thing I do agree with him fatically is fat reduced dairy with added sugar is a bad bargain. Yeah, this gets me thinking of an image that I think was produced from Walter Willard and maybe Frank's sex or Frank who's sorry work at high-havard where they've produced this image that speaks to compared to what with regards to dairy and it sort of shows that like dairy fats, unprocessed dairy fats. So I'm not talking about butter here. Better than the saturated fats in in red meat when it comes to cardiovascular disease. But not as good as a steppe again. The unsaturated fats in olive oil or plant, nuts and seeds or fatty fish even. It's a great reference. And Simon, I'm in touch with Walter Willard and Christopher Gardner and other friends all the time. I can't tell you the number of times Walter Christopher and I in particular have had exchanges where we're kind of ranting at one another about the instead of what question. And it would really be helpful to provide you suggested this earlier in the conversation to provide people guidance that way. So here's the optimal. Here's some of the optional. If this is an important source of pleasure for you or including this in your diet is going to make your life better, here's where you have options. And here's the stuff you really ought to avoid. And then yes, it would be perfectly clear that you could include dairy in your diet, but you wouldn't specifically choose dairy as the optimal source of fat in your diet. So it's not by any means the healthiest fat. There's some questions about the specific fatty acids as I say, especially in fermented dairy, but it's not by no means the top choice. And we should be clear when the jury's out, it often means we don't know whether it's overtly harmful, but we don't have evidence that it's beneficial as opposed to extroversion all of them. Clearly beneficial and unsaturated fats from sources like canola oil or the long chain omega-3 is in fish and seafood, clearly beneficial. That would be the ideal, is consuming foods that actually are known to promote human health, not where we have doubt about, is it overtly harmful? So we know that saturated fat because we over consume it is harmful. There are certain sources of saturated fat that may not be quite as harmful. That's a pretty low bar. You think this is also an area where personalization could become important and this does get a little bit technical, but I'm thinking right now, I get asked this question a lot by people. They eat a very plant-rich diet. Should they have any dairy in their diet? Is that dairy fat going to be harmful for cardiovascular disease risk? One of the things that I often ask them is if they have tested their blood lipids and what does their cholesterol look like? I ask that question because at least the research I've seen, clinical trials, show that even though dairy fats, the saturated fat and dairy does not have the same effect on cholesterol as the saturated fats in other foods like red meat, it does seem to increase cholesterol relative to those foods that we just mentioned, like the vegetable oils or probably even olive oil. I'm not thinking of a trial. That's looked exactly that, but that would be my hypothesis. By looking at your own lab results, you can then get some idea as to whether you want to make further changes to your own diet. It's a really interesting point, so first of all, to personalization at large, definitely yes. Let's be clear though, we are cousins, not just you and I, but you and I and everybody listening. We're all the same kind of animal. We're all part of the extended human family. We're all more like the different, all around the world, of the same basic biological requirements. We have the same basic anatomy, the same basic physiology. The fundamentals of the diet that's good for homo sapiens are the fundamentals good for all of us. That shouldn't shock anybody. It's also true of giraffes and koala bears and dolphins and zebras and zebrafish and every other species under the sun. We're kind of animal and what we're adapted to is what's good for us. Beyond biological adaptation, human beings have culture and we have a wide array of cultures and cuisines and we are adapted to those as well. In some cases, we are just dispositionally adapted, meaning we like what we like, we know what we know and that matters too, right? I mean the Mexican diet and the South Asian diet and the Cuban diet, they're all different and they can all be optimized. But I also mean in some cases biological adaptations. This fascinating work by Tom Brenna, who's a lipid researcher at the University of Texas formerly at Cornell, he compared gene frequencies between Americans in the US and Indians in South Asia and found that the Indians who were part of a population that had been vegetarian for many generations had a particular version of something called the FADS2 gene that made them much more efficient at producing long chain omega-3 fats, so think fish oils from plant based omega-3 fats than Americans were. So if you're always getting your omega-3 from plants, it's actually an advantage for survival and health. If you can turn those plant based omega-3s into the long chain omega-3s that are metabolism needs in a variety of ways and again, a lot of subtlety here, but we're talking about ALA, plant based, DHA and EPA, the long chain ones, and the body makes those from ALA, but it doesn't do it very efficiently. But the Indians, South Asians, do it far more efficiently more of the time than Americans. So there are examples of biological adaptation to a particular type of diet and absolutely, that then translates into biomarkers. So two groups of people eat the same. One is very subject to harm, say, from the saturated fat in the area and another is less subject to it. But the other critical issue you're raising is in the context of what. So, including cheese or yogurt or other full fat dairy in the context of a diet that formerly had been a lot of ultra-process junk and high intake of processed meat and could actually be a good one. step up, you could improve your biomarkers. But if you're talking about a diet that would otherwise be vegetables, fruits, whole grains, beans, lentils, nuts, and seeds, and then what happens if I go out of my way to add full fat dairy to that, as a very good chance you're going to see deterioration in your blood lipids and your inflammatory markers. So in the context of what refers both to the context of what you're eating and in the context of your specific biological adaptation, which because we're both human is going to be more alike than different, but still none the less different. Simon, you know that what I do these days, you know, is related to refining the assessment of dietary intake, founded a company called diet, I.D., where we do that. And the relevant part of that is we stratify all the different types of diets we look at into 10 tiers of objectively measured quality using the healthy eating index 2020. And what I want to point out is we have those same 10 tiers for South Asian diets and Mexican diets and Cuban diets and Vietnamese diets and Chinese diets and Japanese diets. So that's where personalization I think is really important. There are two key questions I think. One is what is it you want a better diet to do for you? What specific health objectives do you have? Are you trying to improve your lipids? Are you trying to manage your diabetes? Are you trying to lower your blood pressure? Are you trying to enhance cognition, reduce inflammation, optimize athletic performance? That's up to you. So you tick all the boxes that pertain and in those can be and in our case have been turned into algorithmic filters that say here are all the diets that pass that test. And then the second question is of these dietary patterns that line up against your health objectives, which one looks like something you'd actually like to eat? That kind of personalization I think is critically important because I think food should be a source of pleasure as well as health. I don't think we should have to trade one off against the other. So that cultural overlay, that overlay of how you prepare the food and how you put foods together and what spices you use, really, really important, familiarity is important, upbringing is important, culture is important. But the fundamentals of what's good for homo sapiens are the fundamentals of what's good for all of us because again, we're all part of the great big extended human family more alive than different. There you have it friends. I hope you enjoyed this episode. If you did and want to stay up to date with future episodes, be sure to hit that subscribe button on YouTube and follow on Apple or Spotify. Finally, thank you for showing up and the effort that you're making to take control of your health. I look forward to hanging out with you again in the next episode.