Why unhealthy carbs are making you sick, and what to do about it

Do you realize how closely your diet affects your general health and well-being?

Have you ever wondered how advertising affects what you eat? How much do you think your childhood diet is affecting your health in the long run?

In today’s episode, Jonathan is joined by Prof. Walter Willet to discuss the importance of carefully considering what you eat and making decisions that support your health.

If you want to uncover the right foods for your body, head to zoe.com/podcast, and get 10% off your personalized nutrition program.

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Episode transcripts are available here.

Transcript

[00:00:00] Jonathan Wolf: Welcome to ZOE Science & Nutrition, where world-leading scientists explain how their research can improve your health. 


I'm your host, Jonathan Wolf, founder and CEO of ZOE. Today, we learn about how the food we eat has a powerful impact on our risk of serious diseases like type 2 diabetes, heart disease, and cancer. By the time we reach 65, a staggering 80% of us will have at least one chronic health condition and 68% of us will have two or more. 


Today's guest has been researching the links between food and health in a study of hundreds of thousands of people for over 40 years. In this episode, he explains which foods are responsible for the huge rise in those chronic diseases that prevent us from enjoying a long and healthy life and also, which are the foods that could extend our life.

Joining us today is Professor Walter Willett from the Harvard T. H. Chan School of Public Health. Walter is the world's most cited nutritional scientist, with over 2,000 publications and several books to his name. It's an absolute pleasure to have Walter on the show today to help us understand how to eat to protect our health. 


Walter, thank you for joining me today.

[00:01:22] Walter Willett: Very good to be with you, Jonathan.  


[00:01:24] Jonathan Wolf:  Brilliant. So we have a tradition here, which is always really hard for professors, which is that we start with a quick fire round of questions from our listeners. And we have some very simple rules. You can say yes, or no, or if you absolutely have to, you can give us a one sentence answer. 
Are you willing to give it a go?  


[00:01:44] Walter Willett: That is a challenge for a professor.  


[00:01:46] Jonathan Wolf: I recognize it. Will you try?

[00:01:48] Walter Willett: I'm game.

[00:01:49] Jonathan Wolf: Brilliant. Okay. Is our average diet making us sick?  
 

[00:01:56] Walter Willett: Yes.  


[00:01:58] Jonathan Wolf: See, that wasn't so bad. Despite all the public health campaigns, is the average diet in Western countries still getting worse?  


[00:02:06] Walter Willett: Probably about the same. But some people are getting much better. Some people are doing much worse.  


[00:02:15] Jonathan Wolf: If the average American improved their diet quality, could they potentially add as much as 10 extra quality years to their life?  


[00:02:23] Walter Willett: Probably not by diet alone, but with some other health behaviors.

[00:02:29] Jonathan Wolf: I can see you just don't want to give me a yes there. Okay, I'll accept that.  


[00:02:36] Jonathan Wolf: Is it ever too late to change my diet and reduce my risk of ill health? 


[00:02:41] Walter Willett: No.

[00:02:42] Jonathan Wolf: Does the food that our children eat impact their health for the rest of their lives? 

[00:02:47] Walter Willett: Yes. 

[00:02:49] Jonathan Wolf: Are there specific foods that might decrease my risk of cancer and heart disease? 

[00:02:53] Walter Willett: Yes. 

[00:02:54] Jonathan Wolf: And finally, and you don't need to just restrict this to yes or no, what's the biggest myth about nutrition that you still hear today? 


[00:03:04] Walter Willett: It has been that fat is the cause of all problems. We're starting to get over that now, but that's still lingering.  


[00:03:13] Jonathan Wolf: Hi, I have a favor to ask. I hope you're enjoying today's episode with Walter and rethinking your relationship with potatoes. Now, making this show takes a lot of time. We think it's well worth it in the name of improving your health. 
All we ask in return is that you hit the subscribe button and then turn notifications on. All right, back to the episode. 

Walter, it's an absolute pleasure to have you on the show today. You know this, but not all of our listeners necessarily know, you're the number one most cited nutrition science researcher in the world, which is a pretty big deal because there are an awful lot of those researchers now. 


And I think, really instrumental in discovering how important the food we eat is on our long term health and starting to actually be able to understand it, not in just some very generic way, but really starting to try and understand specifically what it is about our diet. 

I also remember that we met in Boston with Tim very early in my journey with ZOE and I remember how friendly you were with me, despite the fact that at the time I knew absolutely nothing about nutrition. So I'm very appreciative of that. I would love to start right at the very beginning, maybe, by saying, like, could you describe a picture of what the average diet in the West is like today? Sort of based on your research, what is it that people are actually eating? 

[00:04:26] Walter Willett: Yeah,
I think at this point in time, most countries, most populations are getting roughly half of their calories from carbohydrate. But about 80 percent of that carbohydrate is unhealthy, refined starch, sugar, and potatoes, and I think now that we've cleaned up the fat in our food systems quite a bit, that problem of unhealthy carbohydrates is really a major issue. And of course, we're not getting enough of the health promoting factors such as fruits, vegetables, and nuts.  


[00:04:59] Jonathan Wolf: That's slightly terrifying that 80 percent of the carbohydrates we're eating is unhealthy. And I definitely want to sort of dig into that more, but before you start to help us to understand it better, I'd actually love to like, actually understand a bit the research that you're doing. 


So you run these huge studies with hundreds of thousands of people and I think as regular listeners to this show know, that's very rare. Most of nutrition research is done on maybe 20, you know, maybe 50 people over short periods of time. Could you explain how you and your colleagues are actually studying the relationship between diet and health and how, therefore, it's allowing you to start to make statements like, you know, 80 percent of carbohydrates that people are eating are unhealthy? 


[00:05:40] Walter Willett: Yes. By the way, that number comes from our national food survey, not from our own research. The way we study nutrition is to gather and collect information from large numbers of people, as you say, several hundred thousand people. Where we started collecting data in 1980, using standardized questionnaires, and yes, we've done many studies comparing responses to very detailed weighing and measuring of diet and levels of nutrients in blood and in urine. 


And nothing's perfect, but this captures most of the information for most of the questions that we want to answer. And so we also collect data on smoking, physical activity, other risk factors for diseases, heart disease and cancer that could be what we call confounders that could be related to diet, but if we don't control for them, could be distorting the results. 


[00:06:38] Jonathan Wolf: So meaning you might think that somebody's diet is causing their real health, but actually it's because they're smoking or not doing any exercise or things like this.  


[00:06:46] Walter Willett: Exactly, and so we can statistically control for that. But what's really unique about our study is that we didn't just collect data at baseline, at the first time they participated in our study, but every 4 years we update diet now. 


And after, you know, 20, 30, 40 years, that's really important because most people I think actually do change their diet along the way, and not just their personal preferences. The food system is changing, different foods are available and even invisibly the production of a lot of foods has changed in very important ways. 


So we did an analysis recently looking at what we see when we update the diet, as people go along and we see some very strong relationships with the type of fat in the diet. But if we only use the baseline information from 30 or 40 years ago, we would miss virtually everything that we've seen.

[00:07:42] Jonathan Wolf:  And is that part of why it's so hard to really answer these questions about links from food to health, because I think almost everyone listening will feel like they're used to this idea that every few years, it feels like there's like a new big thing in like all the newspapers and TV about some particular foods being good or bad. And then a few years later, you feel like there's something like else. 


Why does it seem so hard to just get a really straight answer? And why haven't we had a straight answer 30 years ago on this?  


[00:08:14] Walter Willett: Right, part of that, there are multiple reasons that, some studies just have weak designs, not enough people just one measure of diet, they can miss a lot. But this is also related to the nature of disease, basically, that for example, heart attacks, what we call coronary heart disease, you need to be on a bad diet for decades before you actually get a heart attack. 

And that's the reason why we don't see people dropping dead in fast fast food places. We don't see adolescents dropping dead. We know that plaques are starting to form in their arteries from autopsies, but the heart attack doesn't occur until, again, usually 40, 50 years and onwards. 

And for cancer, it's a little different. It's not just necessarily an accumulation of damage, but events that may damage our DNA back when we were adolescents. So we know, for example, that breast tissue is particularly sensitive during that period of life and factors that damage our DNA or that protect us from damage of DNA while we were growing up can actually be related to breast cancer and other cancers decades later.

But some things act fairly quickly also. 
So we need these studies that really go on for decades before we can get the full picture. 

And then of course diets are extraordinarily complicated, that it's not just one variable like an environmental pollutant, for example, it's literally hundreds or thousands of different chemicals in the foods that we eat that act together, interacting, that ultimately relate to higher or lower risk of disease. 


So we're studying things very complicated, but what's usually missed in most studies is the issue of time. 


[00:10:07] Jonathan Wolf: Because these things take a long time. And also because you're saying that people's diets themselves change. So what I'm eating when I'm 30, may be quite different to when I'm 45 and again, may change at 60. 
And so somehow you have to adjust for all of this in your analysis. 

[00:10:22] Walter Willett: Exactly. 

[00:10:23] Jonathan Wolf: So what have you found? You know, we're sitting here towards the end of 2023. What's our latest understanding about the links between what we eat and our risk of diseases?  


[00:10:35] Walter Willett: Now, we've learned a lot that when we started back in 1980, the general belief was that fat in the diet is the villain and it's responsible for most of heart disease and cancer in Western populations. 


And as the data emerged, that's not what we saw. That fat per se didn't seem to be related very much to any major disease, for that matter. In other words, the percentage of calories from fat in the diet wasn't important. 

But what did emerge was that the type of fat was very important and it turned out the worst type of fat was trans fat. And most people had not even heard of it. And nutritionists weren't paying attention at all to that in the diet. But we saw fairly quickly that high trans fat intake was related to higher risk of heart disease, and as time emerged, diabetes, infertility, and other conditions as well. 

And I would like to point out that conclusions in general, because of the complexity, should not be made just on the basis of one study or even necessarily one type of study. Because at the same time, we were seeing this picture of trans fat and heart disease emerge. Other colleagues were doing some of the short term studies that you described where you take a few dozen people and you randomize them to say high trans fat or low trans fat in their diet and they were seeing highly unusual unique adverse changes with trans fat and that kind of short term study. 


Now, neither study on itself would be definitive but when you put that kind of evidence together, you have, in short term, randomized studies. So there's presumably very little compounding in those kinds of studies, and you see adverse effects on risk factors, like LDL cholesterol, the bad form of cholesterol, and bad effects on the good form of cholesterol, and triglycerides in our blood going up. 


And then you look, that makes you pretty worrisome, and it would predict probably that trans fat would increase heart disease risk.  


[00:12:46] Jonathan Wolf: So you're sort of seeing this combination between you're able to see over the long picture across somebody's life, actually these people are having heart attacks and strokes and dying, but you're only observing, you're not changing their diet, you're just observing what they do. 


And then you're seeing these like small scale nutritional studies where people are really intervening like with a drug test and saying, Oh, actually, you know what, you give these people the trans fat and you see this like short term impact that looks very, very negative.


[00:13:11] Walter Willett: Yes, so that combination of evidence really can take us to a quite high level of certainty that trans fats are not good for us. And of course it's important to reproduce studies, not just one study, but other investigators look at this and see similar results, there's confirmatory evidence. And when you put all that together, it can lead us again to a high level of certainty in situations where we'll probably never do the theoretically ideal study where we take tens of thousands of people and put them on high trans fat diets and randomly other people to low trans fat diets and we follow them for decades. Those kinds of studies are just not going to happen. 

[00:13:52] Jonathan Wolf: Because it's just impossibly expensive and it's incredibly difficult to get people to comply, I assume.

[00:13:56] Walter Willett: And stay on a diet like that for years.  


[00:13:59] Jonathan Wolf: And so we actually did a podcast on trans fats with my colleague, Dr. Sarah Berry a little while ago. And my understanding was, out of research like this, basically trans fats have been removed from the food that we eat in sort of all Western countries. So this was a really big issue, but it's no longer an issue. Is that right, Walter?  


[00:14:20] Walter Willett: Yeah, that's, that's correct. And that's an area where we made some great progress. 
And the nice thing about this was we didn't have to educate everybody. We could actually fix the problem at the source. I wish all problems could be solved that way. 

[00:14:36] Jonathan Wolf: I was going to say, so that's solved, but the last time I checked, things like, you know, type 2 diabetes and rates of obesity and all these cancers are all still going through the roof. 
So I'm guessing that trans fat alone is not the issue.  


[00:14:51] Walter Willett: No, unfortunately, there's some other very bad trends that have been happening, just as you described that looks like they can counterbalance a lot of the benefits of eliminating trans fat.

[00:15:03] Jonathan Wolf: So what has been going on and what is this link between food and what's been going on with what we eat, that we're seeing this like ever rising burden of these diseases. 


[00:15:14] Walter Willett: Yeah. Well, it's multiple factors and what we do see is huge amount of again, unhealthy carbohydrates, refined starch and sugar in our diet and at the same time while the fat is actually for the most part, pretty healthy fats in our diet now. So that leads me to the conclusion that at this point in time, there's a huge amount of unhealthy carbohydrates is a serious problem. 


And the particular problem when the carbohydrate is sugar in the form of beverages, sugar sweetened beverages, basically that includes the sodas that we drink. But if you go to stores, grocery stores in our country, you see huge shelves loaded with these so-called fruit drinks that are really 90/95 percent sugar water, maybe with a little touch of actual fruit juice in there. 


And these have the same amount of sugar mostly as a Coke would have.


[00:16:14] Jonathan Wolf: Something like an orange juice or a strawberry juice or whatever they might put on the front. Is that what you're saying? 


[00:16:21] Walter Willett: Right. Yes. And it's usually a little, a few tablespoons of orange juice and a cup full of sugar that would be in those products and refined starch and sugar in so many different forms. 


But one of the things that's changing is not just the food but also aggressive advertising and subtle advertising. The food industry does massive amounts of research on how to penetrate our vulnerabilities. And you know, cokes are advertised as something that there's friends all around that athletes drink this and nothing could be farther from the truth. 


And this is undermining the health. They're basically using advanced psychological methods to basically exploit our vulnerabilities. And especially worrisome is that a lot of this is directed at children who are vulnerable, who can't be expected to make informed decisions about the long term consequences of what they're drinking or or eating.
So you've got this imbalance.

[00:17:25] Jonathan Wolf: in your opinion, like the industrialization of the food, and then the advertising in against these is an important part of the, the story of what you're seeing in your data?.

[00:17:33] Walter Willett: Exactly. That this production, vast production of unhealthy foods which are extremely cheap to produce because sugar and starch are very, very cheap. 


And so putting those together and thousands of different combinations of colorings, flavorings, marketing is a huge problem.

[00:17:52] Jonathan Wolf:  I think a lot of people listening to this will be like really clear about sugar and sugar in drinks because that's sort of quite easy to understand. It looks like something you, you know, we all understand at home how you can take a spoonful of sugar and you get terrified by how many spoonfuls of sugar they put in. 


But you've talked about unhealthy carbs and starch. Could you unpack that a little bit? What are the sorts of foods that people might sort of see on their grocery shelves that you're saying actually, these are really unhealthy and the things it's interesting that are at the top of your list is  you're saying this is what I'm seeing. 


[00:18:25] Walter Willett: Right. The sugar-sweetened beverages are clearly the single, if you have to look at one problem, that's the single most important, in part because many people have three or more servings per day. 

But we've just published a paper a couple of weeks ago looking at different forms of carbohydrate and weight change. 
And what we see is that yes, sugar is a real problem, but actually a bigger problem is the amount of refined starch that we consume. And this would be basically white bread. I think other things made with white flour, white rice, potatoes, small amounts are okay, but that's a form of carbohydrates. It's very rapidly turned into blood sugar.  


[00:19:08] Jonathan Wolf: And I think that's really interesting because I think I was brought up, and I think a lot of people listening to this will have the same thing that like, well, rice is really healthy, you know, white rice is this really healthy food. 

And I was also, I think about my grandmother. 
She'd be absolutely shocked at the idea that you shouldn't eat a limitless number of potatoes and that would be good for, you know, growing up in, you know, she grew up in Scotland. 

That's like part of, you know, that that's healthy. Obviously the sugar drinks, they'd understand. So can you help people who are listening to this to understand, I guess, why you're as worried about these sort of what you call refined starches, these things from white flour and white rice and potatoes as you were about, you know, Coca-Cola where everybody like no one thinks that giving Coca Cola to their children is a good idea. But I think lots of people will be thinking, Oh, well, if I get them to eat rice, I’m doing great. 

[00:19:57] Walter Willett: Yes. And in fact, again, when we started our work back in 1980, the American Heart Association and health promoting organizations were pushing people to consume more white rice and pasta and things like that, because they didn't contain much fat. 

But basically in the processing of say a rice or wheat, the first step, the refining, removes the bran from the outside. That's where most of the fiber is. That's where most of the minerals are. That's where most of the vitamins are.  


[00:20:31] Jonathan Wolf: And so this is when I think about it as being actually like a little grain. 


This is like the outside bit that you see that looks, makes it look more like a sort of like, it's all the bits that make it look like a seed rather than the sort of the white bits stuck in the middle.  


[00:20:43] Walter Willett: Right. Yes, exactly. And that's, again, that's where the nutrients are hanging out. It's not just fiber there. It's the fiber plus all these minerals and vitamins. And that, and then the germ is also removed. And the germ is a little part of the seed where the embryonic plant resides. And it's amazing that that can, that embryonic plant, can be there for years and then you provide the right moisture and temperature and it sprouts, it's alive during that time. 


And the reason that it's alive is that, and it can persist, is it's packed in fat, because that fat can be damaged with time and bad conditions, it's got lots of antioxidants there, so it's a little sealed off package that seals out oxygen and then has lots of antioxidants in there. 

And so the food industry rips off the bran, rips out the germ, and that takes away roughly two thirds of most of the minerals and vitamins that are originally there in that grain, that intact grain. 

Now, what does it do with those, that bran and that germ? The food industry knows that that's very valuable in terms of nutrients. So we feed that to animals and they grow big and strong. 

[00:22:07] Jonathan Wolf: So hang on, I just want to make sure I've got this. They take the grain that they're growing, they strip out all the really good bits, including things that you say that give us all the nutrients, they give us sort of the leftovers and they feed the good bits to the animals. 

[00:22:22] Walter Willett: Exactly. Yeah. 

[00:22:23] Jonathan Wolf: That doesn't sound like it's a great idea.


[00:22:26] Walter Willett: It is not a great idea. But that's a big chunk of that 80% of carbohydrates that are unhealthy, much more than sugar. 

But then it gets worse, then it takes that, what's left, that, what we call the endosperm, and it's mostly, almost all starch that's depleted in minerals and vitamins, and then it grinds that into fine particles, if you're making flour, and those fine particles create much more surface area. So when we eat that, say, bread or something made with those dozens and dozens of other products made out of white flour, that starch hits our stomach and our digestive enzymes can very readily break that starch into glucose. 

What is starch? It's basically a chain of glucose molecules, and glucose is the form of sugar that we absorb, and that's blood sugar that we measure. So you get this very rapid increase in blood sugar after consuming white bread and potatoes, cooked potatoes. If you ate raw potatoes, just fine. But they're disgusting, actually, if you want to try it.

[00:23:41] Jonathan Wolf: But just to make sure I've got this, basically, they take this thing that's a bit more like a seed, the whole grain, they rip out like almost all the bits that have all of the goodness. And then they end up with this thing that you're calling mainly is starch and the way to understand it. Then they smash it up into pieces so that when we eat a starch, basically our body turns that into blood sugar almost immediately. 


[00:24:06] Walter Willett: Exactly. And that's not good for us because we get a big spike in blood glucose that demands a big surge of insulin that our pancreas pumps out, and that insulin does drop the blood sugar down quickly, but then, in fact, it overshoots much of the time, and so we're often hungry after an hour or two after that. 

In contrast, if we eat the whole grain, it takes a while. It's like a little time release capsule of starch that bran protects the starch from immediate digestion, and we digest it with diet. 

Digestion essentially means breaking that starch down into glucose, and we get a much slower increase and lower increase in blood glucose levels and we don't get hungry right away. 
It's satisfying for a longer period of time and it's not surprising.

The paper we just published, there was quite a substantial difference in weight gain over time between people who ate the refined starches and people who ate them as whole grains.

[00:25:17] Jonathan Wolf: It's really interesting talking about this. And you know, ZOE sort of looking at your own blood sugar responses is one of the things that is sort of quite eye opening. 

So I definitely remember the first time that I ever saw what happened when I ate white rice. And just as you're describing, it's sort of amazing. It was actually having a bigger spike than when I tested having Coca Cola, which was not at all, I think what I was expecting. And, you know, I grew up, as always, you sort of grow up with your parents' generation of nutritional advice. 


And my father had high cholesterol when he was young. And the doctors at that time were giving the best advice, which was basically, you know, eat as low a fat diet as possible. And therefore you should eat all this healthy stuff, like lots of white rice. 

And I guess my question is, if we had been having this conversation, you know, even maybe 15 years ago, would you have led as strongly talking about unhealthy carbs as the sort of number one thing that you're concerned about? Or is this something that has been sort of shifting over the last 15 or so years?  


[00:26:26] Walter Willett: I think by 15 years ago, we had seen this picture emerging. So we were seeing that. But when we started our study in 1980, no, I was, as a physician, I was advising like you were describing, that following American Heart Association guidelines that reduce all types of fat, load up on these carbohydrates. 

In fact, it was pretty hard to find very many whole grain carbohydrates back then. And that's one of the… not everything has been bad over time we've eliminated trans fat. And there are many more whole grain carbohydrate, whole grain foods available than there were back in 1980. It was actually pretty hard to find much of anything.  


[00:27:12] Jonathan Wolf: So it's like easier to eat more healthily if you want, is that what you're saying, in one direction, and yet like the sort of the standardized, you know, I see this a lot with my son who's nearly 16, that it's really easy to also eat a truly terrible diet if you just go with whatever is sort of being offered to you as standard and you're not choosing to make sort of these, these healthier choices, you know, actively.  


[00:27:38] Walter Willett: Yes. And that's basically what we see happening in the US at least. And I think it's probably happening in other countries. We are, as you know, we're not one country. Some people have sort of defined our country into seven different groups, but even more crudely into two groups. 


So that one group has more education, more resources, and they're taking advantage of this new knowledge. And like the participants in our study who are all health professionals, we've seen a huge increase in whole grain consumption over time. And that part of our population is getting much healthier.

But there's another huge part of our population that has either less education or the lack of resources to act upon a good new knowledge, and they're going in a very bad direction. 


So there's, what we see is the average means almost nothing anymore. It's the average can stay the same, but you've got two groups going in opposite directions.  


[00:28:45] Jonathan Wolf:  Which is obviously incredibly depressing because we don't, we think about other public health things, it's not like we say, here's healthy water and like deadly water. 


And you just have to be educated enough to understand what to drink, right? 

We make sure that the water we get, you know, hopefully the air we breathe, all these things are safe. And in a sense, you know, I always listen to this and I feel like, it's one thing when we don't understand, but if the science has reached the point that it's really clear, something's going wrong, isn't it? 


When we are just delivering. food that we just know isn't really safe, at least without being really clear. It doesn't mean that nobody can have something that's a treat by any means, but that as a standard diet, that you're just gonna be like, you are just gonna eat all of this. It feels like it's really a public health issue.

[00:29:36] Walter Willett: It is, and unfortunately, it's also become politicized. You can see mortality rates by red states and blue states in this country diverging over the last decade. This sort of rejection of science and information about diet, about vaccines, you can see that showing up in mortality rates now. 

So as you say, the ideal public health advances are where we don't have to educate. In fact, it's invisible and people only learn about it when something goes wrong. That clean water, clean air, the fact that control of bacterial contamination of food is pretty good. Not perfect, but enormously better than it was 50 or 100 years ago. People can assume for the most part that you're usually not going to get sick. 


[00:30:33] Jonathan Wolf: And Walter, you were just talking about like, that you've changed your view very dramatically since the 1980s. I'm curious, is there anything where your view has changed more recently? If you were going to look back over, say a decade ago, is there anything that you're now thinking a bit differently than you were then?

[00:30:50] Walter Willett: Mostly the more recent data has reinforced what we've what we saw a decade ago. We're fine tuning this information with more quantitatively reliable data. 

Like looking at red meat consumption, for example, which is an area that is… high consumption of red meat is characteristic of most of the Northern European, North American diets. The benefits of replacing red meat, not with refined starch, but replacing it with nuts. Actually, nuts have really emerged as sort of the, if you don't want to look at a single food, one of the healthiest foods. Replacing red meat with nuts, with legumes, some soy products. 

And I guess that the maybe one thing where we have refined our information somewhat is around the soy products. We did have concerns that high amounts of the phytoestrogens, the plant estrogens that are contained in soy might be adverse for breast cancer and some other hormone related cancers, but it was also possible that they could be blocking high levels of natural estrogens. And it turns out that the latter is actually what's emerging mostly from studies in Asia actually, where soy consumption has been high. That does look like a higher soy consumption, especially during adolescents and young adult life as related to lower risk of breast cancers.  


[00:32:24] Jonathan Wolf: So, just to make sure I understood that a decade ago you were like, maybe soy is actually
negative, bad, has like cancerous… And now you're sort of reversing that view. And you're actually thinking that it is definitely not harmful, but actually positive, probably positive benefits.


[00:32:40] Walter Willett: Yes. Although a decade ago, I would say it was ambiguous. We just didn't have adequate data, but there were reasons to be concerned. 


Interestingly there still is a lingering concern about very high soy consumption and cognitive function. There are several studies from Asia and populations consuming really high soy consumption and within those populations, the ones having the highest soy consumption, which would be a lot, some studies suggest adverse effects on cognitive function. 


[00:33:14] Jonathan Wolf: Now, I'm guessing that having had this conversation, one of the cases, the amount of soy that you're talking about that people might be consuming in Asia is off the charts, versus anyone who's listening to this in the states or you know, the UK or something, Is that right? So in general, they could probably be feeling they should be eating more rather than less if I'm making this practical. Is that right?  


[00:33:36] Walter Willett: Yes. And you know, there's a general principle in nutrition that is sort of extremely simple, but I think still valuable to consider. Especially we don't have all the data we would really like to have, which is usually the case. And that's variety. 

So that I think is part of our alternatives to red meat, not just only replacing that with soy or only replacing it with walnuts, is not the best thing, but to have a variety of alternatives. Some soy products, some walnuts, some other peanuts, some beans. A variety is good because you're unlikely to get too much of something really bad. And you're also less likely to have a gap, to be in your diet to be missing something that's important.

[00:34:28] Jonathan Wolf: I just want to talk a bit more about the red meat before you switch to the alternatives because I think this is still a live debate for some people. And I think you here you're saying you haven't really changed your view from 10 years ago. 

Well, could you help our listeners understand how much should they be concerned about eating red meat? There will be plenty of people eating this who were brought up feeling you should be eating, you know, some red meat every day and it has all this great protein and after all didn't our ancestors hunt meat So, how can it possibly? Be bad for us. 



[00:35:02] Walter Willett: Yeah. Not just what every day, every meal, that's how I grew up in the Midwest. 

There have been concerns about red meat for quite a while because of the high amount of saturated fat and cholesterol in red meat. And it's been suspect for a long time. 

I think one of the things we've come to appreciate, it's not just a high amount of saturated fat, but also the fact that there's almost no polyunsaturated fats in red meat, and those really have, they're essential, and they have positive health benefits beyond just being essential. They do, polyunsaturates, lower LDL cholesterol. Now we also see they improve insulin sensitivity as well, which would help reduce diabetes risk. 

So, it's that, proportions of polyunsaturates, desaturates and beef in particular, especially that contribute to being adverse. So we published a paper just last week, in fact, an update in our cohort studies. Now, after more than 30 years of follow up, about 22,000 participants have developed type 2 diabetes.

[00:36:09] Jonathan Wolf: That's an  enormous number of people, isn't it? to be studying. 


[00:36:13] Walter Willett: Sadly, I mean, to think of the health burden of it, you know, all the individual cases, people who have health burden and then collectively 22,000 participants developing type 2 diabetes just during the time we've been watching. 

The studies are really only possible because of the incredible contribution of the participants of the studies. It would not be possible without that and their willingness to share their experiences that together we learn a lot. But when we have so many participants, we can see even consumption of red meat about twice a week, we could see a statistically significant increase in risk of type 2 diabetes. 

And again, part of the confusion comes because most studies have only compared red meat to the rest of the diet. Sometimes you see not much increase in risk or a weak increase in risk, but if the rest of the diet's not very healthy, you're basically saying red meat is about as bad as the rest of the diet. 


And so the comparison in nutrition is always an issue that we have. We physiologically, unconsciously control our total caloric intake pretty tightly over a day, over a month, over a year, within about 1 percent intake versus what we burn off by physical activity. 

Basically, the whole plate is the same size, so if we remove something, we're going to replace it with something else. And that replacement, of course, makes a huge difference. So if we replace that red meat with refined starches, that would not be a good replacement. But if we replace it with some mix of plant protein sources, like nuts, legumes, soy products, that turns out to be a good replacement.

[00:37:59] Jonathan Wolf: Is this important? I guess Walter is a question because you could say like it's better, but it makes almost no difference in fact, your likelihood of getting type 2 diabetes or having heart disease or any of these other sorts of things. Like how bad is the red meat and how much better is it if you suddenly, cause you know, you're, I think talking about reducing it to you know, below twice a week and you were said you got brought up eating it 3 times a day.

This is a pretty dramatic change. So how bad is the meat? How bad is the red meat?  


[00:38:30] Walter Willett: Yeah. It's not like smoking and lung cancer where there's sort of one thing that is the overwhelmingly dominant cause and that's true of most things we look at. There's no one factor that describes it, and the increase in risk is, and I would say sort of in the moderate category. 

But when you put a whole lot of moderate risk together, then you get a big risk and we can see if we put the diet and lifestyle factors together, we could prevent over 90 percent of type 2 diabetes. 


[00:39:01] Jonathan Wolf: So if you changed all of the diet and lifestyle factors from sort of like the worst to the best, you could reduce the amount of type 2 diabetes by tenfold, to just 10 percent of what it is. 

[00:39:12] Walter Willett: Yeah, instead of 
22,000 cases, we could have 2,000 cases. 

[00:39:17] Jonathan Wolf: That is absolutely extraordinary. And it doesn't obviously mean that people are responsible for this, right? 
Because this is the environment they're living in, and people don't always have either the understanding or the ability to do all this. I think when, you're not being judgmental about it, but just sort of talking about the difference between maybe the food that we're eating now and and the environment we're in compared to what we might have had a you know a few hundred years ago. 


[00:39:39] Walter Willett: Yeah, you're absolutely right. I’m not blaming or pointing a finger at the people who developed it because many of them, that unfortunate thing is many of them have been doing what they were told to do by the by the health community.  


[00:39:52] Jonathan Wolf: I mean, this is one of the most frustrating things, isn't it? Is that people feel like they're constantly trying to do what they're told. 
And then we go back and say, well, actually, maybe what we told you was worse. 

So just to wrap up on the red meat, because I'm going to make my son listen to this bit afterwards. Despite all the stories that like, you know, actually it's really important. Again, I think of my grandmother who's like, make sure you eat your meat, you know, you're going to never grow up to be big and strong unless you eat this. This is more like a treat because you like it. If you like it. Then it is like an essential healthy thing that you should be an important part of your diet.  


[00:40:26] Walter Willett: Yes, exactly. Say one serving a week is very, some people would consider this radical. 
If I had said this when I was growing up, it would have been. But it's actually very consistent with a traditional Mediterranean diet and the diets that many people around the world consume. 

And if you really like a big, half a kilogram steak or even a kilogram steak, you could have that once a month. 
In many cultures, they do have red meat. You could have red meat almost every day, but it would be just a small amount, maybe 25 grams. But a little bit of a mixed dish, for example. So there's many different ways of putting together this quite modest amount of red meat, but it's not essential at all. 


[00:41:13] Jonathan Wolf: Last question on that one, Walter, because there'll be a lot of people saying, well, we know that you know, the red meat that you would eat in the States, that the sort of things that those animals are allowed to be fed are like a long way away from what maybe a wild animal would eat, or even maybe what might be the case if you were in France or something that was more restricted. 


Is this just a statement about antibiotics and weird food that's going into the cows. Or is this actually broader than this? And you see it outside. It's not just a product of the particular sort of red meat that maybe somebody might be getting in a grocery store in the States. 

Hi, I want to take a quick break from this incredible conversation with Walter. 
Now, back in March last year, we created this podcast to uncover how the latest science can help us all live longer and healthier lives. And over hundreds of hours of conversations with world leading scientists like Walter, we've uncovered key insights that have the potential to help you improve your health. 


Now, if you don't have hundreds of hours to spare, not to worry. At the request of many of you, our team has created an amazing guide summarizing the top 10 most impactful discoveries that you could apply to your life and you can get it for free, simply go to zoe.com/freeguide, or click the link in the show notes. 


And please let me know what you think of it. Okay, back to the show.  


[00:42:46] Walter Willett: We actually can't study that very well in our population because 95 percent of the beef is not grass fed for the life of the animal. But this is mostly something that's more related to red, to beef, no matter where it's produced or how it's produced. 


There's been a lot said, oh, the grass fed beef has much more omega 3 fatty acid in it, a healthy unsaturated, polyunsaturated fat. But it is higher in grass fed beef, but in grain fed beef, it's very, very little. So even doubling very, very little is still very little. That, just for example, a walnut, the same amount of walnuts, has about 100 times more omega 3 fatty acid in it than does grass fed beef. 



[00:43:34] Jonathan Wolf: Okay. So it's hugely different. And I have to say, I've yet to meet a nutritional scientist from anywhere around the world who's argued about the positive benefits of the red meat from where they come. So I wasn't expecting you to say anything different. 

Walter, one thing you haven't touched on is dairy. 
And that also seems to be one of those things where there has been a lot of change in view over the last 10 or, or 20 years. Where are you on that today?  


[00:44:05] Walter Willett: Right, well dairy is, I think perhaps the most complicated and interesting part of the plate because there are definitely nutritional value in dairy. 


And milk is, of course, incredibly interesting because an infant can live on human milk for 6 months and grow and develop with nothing else but milk. So it's actually designed to be fully supportive of young mammals, but is that necessarily something we should be consuming all our life? 


And also, milk from cattle is very different than human milk. There's about four times the amount of calcium, about four times the amount of protein in cow milk compared to human milk. So if we think of human milk as the ideal, but still not necessarily ideal for a lifetime, cow milk is really quite different. 


And it does have a good amount of calcium, a sort of uniquely high amount of calcium in milk. That's often what's pointed to as being really valuable and necessary for growing children. But it does come with a lot of saturated fat, again, and almost no polyunsaturated fat. So that ratio is really a very bad ratio. 


And we do see very clearly that dairy fat does increase the bad cholesterol in our blood and when we look in our large populations, high dairy consumption is related to higher risk of cardiovascular disease and overall mortality, and especially if you compare it to plant source, plant types of fat. 


And again, like I was talking earlier with trans fat, there have been good randomized control feeding studies, short term, looking at what part one of the questions was whether dairy is cheese or is fresh milk, whether cheese is better. Slight difference, but that this study also included then fat from olive oil or other plant sources of fat and those plant sources of fat had dramatically better effects on blood cholesterol levels. 


So we put our long term studies together with our short term studies, which are very consistent, and it would say, favoring the unsaturated plant oils is better. And this is really going back to studies of 50 or 60 years ago, comparing, say, Finland with the Mediterranean countries, where there was a huge difference, about an 8 or 10 fold difference in heart attack rates. 


The difference was not in the type of the amount of total fat. It was in the type of fat. That's not the only difference of course, differences in fruit and vegetable consumption, but virtually for sure that the type of fat was a major contributor to those huge differences.  

[00:47:05] Jonathan Wolf: You touched on this early, so I'd really like to come back to it, which was to what extent I should be worrying about what my children eat. 


And I think you said that there's some really new evidence linking what a, a better understanding of what maybe we might be eating as children to our risk later on. So, how much do I need to worry? And what, you know, what does the latest science tell us? 

[00:47:26] Walter Willett: I think
we do need to be more concerned than we have been about what we're feeding our children. 


And we've actually known for a long time that the process of atherogenesis, of building up a plaques in the arteries that ultimately results in a heart attack, that's been going, that goes on starting from probably year one. And we know from autopsies of soldiers killed in wars that the, you can see the plaques developing early stage plaques developing even at 18 or 19. 


[00:47:57] Jonathan Wolf: And that means like starting the very first part of our, our blood vessels getting blocked even when you're already 18 from, from the food we're eating.


[00:48:06] Walter Willett: Exactly. Yeah. That's not new. We've known that for decades. And so,  basically the best thing to do is to not begin that process, when you're a child. 

More recently, we've been looking at cancer and just starting to get data now on what people were consuming as adolescents and cancer risk later. 
And we've seen that high soda, high consumption of soda during adolescence is related to higher risk of colorectal cancer later in life.

And for breast cancer, we had lots of indications that that's a critical period of adolescence and early adult life. That mainly comes from the American atomic bombing of Nagasaki and Hiroshima in World War II that women who were exposed to radiation while they were children or young adults, a few decades later had a substantial increase of breast cancer. But if they were exposed after age 40, there was not much increase in risk of breast cancer. So there's a critical window there

And we're seeing that low intake of fruits and vegetables, low intake of whole grains, for example, during that adolescent period is related to breast cancer risk later in life as well.

[00:49:21] Jonathan Wolf: Walter, can I just check I understood, because I'm really shocked by it. Slightly depressing, unfortunately, but I just want to make sure I understand you're saying that now there is this dated looking at what women who in fact at the time was still adolescents were eating, and the sort of how healthy that was, is having a real impact on the risk of breast cancer, I guess, sort of 30 years later.

And it's not just because they're on a, you know, maybe on a better diet throughout this period is better, you're saying that there's something about like, you know, the diet we're eating as we're actually going through puberty, is actually shaping this, this risk of breast cancer many decades later.  


[00:50:02] Walter Willett: Yes. Right. And that's exactly what we're seeing. And when we look at midlife, we do see some hints of those relationships, but it's not as, what we're seeing at midlife is not as strong as what we're seeing during adolescence in terms of the importance of healthy diets. 
 


[00:50:17] Jonathan Wolf: And is that only true for breast cancer or is this true for other things as well. You know, my, I should be just as worried about my son right now, who is, you know, growing inches every week, as far as I could see. And similarly, potentially, is there similar evidence that actually the diet now is really important for his long term health? 


[00:50:38] Walter Willett: Some, yes. I mentioned we have the example of sugar-sweetened beverages and colorectal cancer. We have more data for breast cancer than we do for other outcomes. So, this is an area of research that I think is really important. But there's, unfortunately, not very many studies. 

We've, with colleagues and Denmark, set up a lifetime study there, where we collected data from the largest population so far. But that group is only about 30 years old now. So they're just starting to enter the era when cancers are, will be emerging.  


[00:51:09] Jonathan Wolf: So I think you will have just made everybody who's a parent or a grandparent more paranoid about their children. Because we also know that this is an environment where, like levels of ultra processed food are much higher for children in fact than they are for adults and where I feel I take my daughter to, you know, a birthday party every week and it's nothing but like highly, highly refined white flour and sugar, which is fine as a treat. 


But if it's like, all the time, it becomes quite hard, I think, to convince her to eat anything else because after all, you know, this is designed to be so nice. I think what you're saying is that we do have to worry about it.  


[00:51:47] Walter Willett: We do. Yes, this, there's a lot of the problem is brewing, during that period of life. That's pretty clear  


[00:51:55] Jonathan Wolf: So could we swap to something more positive because almost everybody listening to this is not a child. So like what was going to happen to them during their childhood is done. Clearly true for you and me Is it ever too late to change what we eat in a way that can really improve our health? 


[00:52:09] Walter Willett: Before I go to that, I'm going to go back to childhood. It's so interesting. Even the fracture risk has been really interesting. The data there that, there's been this paradox for decades that the main justification for consuming a lot of milk has been the calcium and while you're growing up, you really need to drink a lot of milk to build up the bones that will be with you for the rest of your life. 
And it does relate to later in life too, the issues there.

But we've seen for a long time that the countries that consume a lot of milk, the northern European countries actually have the highest fracture rates by quite a bit.  


[00:52:49] Jonathan Wolf: And this is when later in life you fall over and you break your hip or break a leg or something like that. 


[00:52:54] Walter Willett: Right, what would normally would have been a bruise, is a hip fracture instead. 

One of the things that milk does, it promotes growth and it does make people taller and have longer bones. And we published a study some years ago showing that height is actually a strong risk factor for hip fractures. And it's probably because we fall from a higher distance, but also just a long stick is easier to break than a short stick. And there's a greater torque with a long stick. 

And so we looked at the childhood consumption of milk, and actually we saw that there wasn't a benefit of high milk for fracture risk later in life. In fact, it was in the opposite direction, especially in boys, at quite a higher risk of hip fracture decades later. Among the boys who consumed the most milk during childhood, they were taller too. And it looks like at least that greater bone length does explain part of the risk there.

[00:53:55] Jonathan Wolf: And there is no benefit for women, which is where I think we've heard all this thing about going through menopause that you need to make sure that you're, you know, you should be drinking milk because you should be getting calcium in order to avoid these fractures later. The data says this isn't true?

[00:54:11] Walter Willett: We just
don't see it, especially during childhood. Now we do, calcium is essential and we have to have enough, but what is enough? 

The interesting, the country in our, looking across countries, among the countries to have good data on fracture risk, the lowest fracture risk was in Indonesia and they don't consume any milk, basically after weaning. 
And the calcium intake was 250 milligrams a day in their national survey. So I think some of my colleagues for years have said, actually, we don't really need that much calcium as has been recommended. I think that's turning out to be true. 

It doesn't mean we shouldn't drink any dairy. But this three or five, I was told we had to have four glasses of milk growing up in the Midwest. 
We don't need that much milk. Some of it is fine to have, you know, I think about when serving a day is not a bad target to think about, and some indication that it would be maybe best to have it as yogurt or some fermented product, but anyway, it's a really, I think, important example of this connection across the lifespan.

And getting into your question about is it ever too late, it's clearly better to start on a healthy diet as soon as we can, but for something like diabetes, we know you can drop your risk in two days by a better lifestyle.


[00:55:38] Jonathan Wolf: That's pretty good. Two days, I'll take.

[00:55:41] Walter Willett: Okay. Yeah. As long as you do what you need to do, not like we're doing sitting here. 

Diabetes is not just an issue of too much glucose and refined starch and sugar in our diet. A large part of it is insulin resistance, the resistance to the action of insulin. And in our dietary studies, actually, it looks like factors that contribute to insulin resistance are actually more important or just as important as too much rapidly absorbed starch or glucose. 


There's studies going back a couple of decades that by just being physically active, using your muscles, which are, most of the insulin resistance is coming from muscles. And if you just exercise within about 2 hours, you drop your insulin resistance quite a bit. And that persists for about two days. 
And if you exercise your muscles every 2 days, you'll stay at a low level of insulin resistance.  


[00:56:43] Jonathan Wolf: So if someone was listening to this who's in their 60s or their 70s. And they're saying, wow, you know, a lot of your guide… this is really different to the guidance that I was told by my doctors and the government and all the rest of it 30 years ago.

Are you saying to them, it makes sense to change your diet today? Or are they saying, well, you know what? I'm 70, right? Like it's obviously too late and I'm just going to keep… it doesn't matter what I eat anymore.

[00:57:12] Walter Willett: Definitely what you eat today and tomorrow will make an important difference. 
Especially, you know, I'd like to maybe make the analogy of sort of walking toward a cliff, that we're going along and eating an unhealthy diet and we're getting very close to going over that cliff. If you just stop two steps before the cliff, you won't fall off. And that's sort of the way we are. 


Or another analogy may be with our coronary arteries, which in some ways are very simplistically like a pipe. If we're accumulating atherosclerosis over time and they're getting close to the point of blocking that artery, And we stop that progression, then we prevent the heart attack.  

[00:57:59] Jonathan Wolf: And your analogy here is if you were to change to a much healthier diet, you're effectively stopping walking towards that cliff. So it's not too late. It's not like you're just going to fall off the cliff. There's nothing you can do. Actually, you can change your diet even at that very late stage when you're very close to the cliff and you will no longer fall off it.  


[00:58:17] Walter Willett: Right, exactly. And what it means is the time relationship is quite asymmetrical. It takes years to get to that point of a precarious artery or falling off the cliff. But then if you stop getting worse, then you can stop that progression, stop crossing that line, or stop a heart attack. 

[00:58:37] Jonathan Wolf: I think that's incredibly positive. And I think it matches actually a lot to what we see with members who take part in, in ZOE actually, then in a sense that as you're obviously, you've probably gone, you're describing how we start to take this damage, even as children. 


So by the time you're in your fifties, your sixties and seventies, that's a lot. And interestingly, I think often we see particularly strong and rapid changes in how people feel. And I guess the point is at that point, there is this dramatic change. 

Now, Walter, we've talked a lot about changes in guidelines and thoughts. I'd love to ask you one final question around that. I'm curious about how you feel about current sort of American guidelines to the public on what to eat. So let's say sort of USDA and MyPlate here in 2023. And we know that these things, there's always a sort of lag between what the guidelines might be and where the latest science is. 


And that's, and you know, for people listening outside of the US you know, this is very similar to the guidance that is being given in the UK, for example, by the NHS.

Are there any areas where you've, where you feel that isn't fully aligned with your views today?  


[00:59:50] Walter Willett: Yes. There's some serious divergence. And the guidelines over time have gotten better. They, I think there's a lag between where the science is and the guidelines, but they were totally directed to fat avoidance. 

If we go back a few decades and they've shifted quite a bit to emphasize not reducing fat intake, but more focused on type of fat. They didn't mention trans fat for a long time. They finally did and then we got rid of it and they more emphasized the type of the carbohydrates. 

So those are important differences, but you can't touch animal sources of protein, basically meat and dairy and the guidelines. And in a sense, the guidelines are corrupted by powerful economic interests. 

And that's partly mediated through Congress, which, this is baked into our constitution that every state gets two senators and the electoral college or presidency is also very biased towards state suitable populations. 

And Congress even passed a law in 2015 that the guidelines could not even mention the effect of diet on environmental factors, climate change, for example. Which is an existential crisis that the whole globe is facing. 

And so even our Secretary of Agriculture said about a year or two ago that he's not even going to suggest that people reduce red meat. Despite all the evidence and despite the clear fact that red meat per serving has about 160 times more greenhouse gas emissions compared to a serving of beans or soy products.


[01:01:34] Jonathan Wolf: To say that you think the guidelines are corrupted and that you can't touch discussions around meat and dairy, for example. That sounds like pretty strong disagreement with what has been delivered as public health advice. 

[01:01:37] Walter Willett:Yeah, sadly it's so.

[01:01:40] Jonathan Wolf: And even outside of meat and dairy, I feel like what you've been describing around carbohydrates is a lot stronger than the standard advice that is given in these guidelines. 


[01:02:05] Walter Willett: Yes, they talk about added sugar. It wasn't until you got to page 64 in a footnote that added sugar meant sugar sweetened beverages. It's obfuscated in grams of added sugar.  


[01:02:23] Jonathan Wolf: And obfuscate is a very scientist word, but does this make you angry, Walter?  


[01:02:27] Walter Willett: It does, yes. Because it's causing premature death and suffering. 


You could say that the big soda companies have blood on their hands. They are making children sick and die sooner. It is a serious issue.  


[01:02:43] Jonathan Wolf: I think that's really powerful. And I also think your point about the way in which a lot of this is hidden. So I think for a lot of parents… and honestly, I was the same way six years ago, I think about the differences. I think about my young daughter versus my son. 

I was like, well, okay, Coca Cola is bad, but you know, orange juice or one of these other like apple juice, that's like a really good, healthy thing. And now I understand it's very close. It's basically water with lots and lots of sugar in it. 

So I feel also quite angry that we're asking people to understand things at a level that we would never ask elsewhere from some other, nobody asked us to understand how you know, powers, you know, how our car can be safe, right? We rely on the government to make sure the car is really safe when we get in and we drive and they are incredibly safe now. 

I do understand that. I feel that the more I've understood it, the more angry I am, because this isn't just about choice, right? It's about making sure that people are well informed. And particularly, I think if you're thinking about things like children, where you actually, you've slightly terrified me with the extent to which my children might eat, could be affecting their health in 30 or 40 years.

[01:04:00] Walter Willett: Yes, it's, it's worrisome. And I think that it's not just that we haven't provided the information, but we allow them to be exploited by aggressive advertising and just to make money on the part of the big soda industry and junk food industry. 

[01:04:17] Jonathan Wolf: Walter, I'd love to go from like the big picture of what's going on in government advice and the rest of it to sort of actionable advice for, for our listeners. 


And I think a lot of people have listened to this saying like, this is really fascinating. And also, you know, this isn't just the same advice maybe as I'd understood historically. 

So if someone was listening to this and they want to change their diet to make it healthier, would you be able to maybe suggest like three tips, like your top three things that you might suggest to them that might be changes that they could do, that could really have an impact on their long term health? 


[01:04:50] Walter Willett: Right. Now, of course, you're asking me to do something I try to avoid because it really is not just so simple as three things. It's putting the whole package together.

But realizing that not everybody's ready to do that all at once. But I think the biggest single sort of offender is sugar-sweetened beverages and really keeping those very low,  occasional treat.

And second at this point in time, the massive amounts of refined starch and sugar, in our diet in general. 

And then of course, I think where there'd be uniform agreement that more fruits and vegetables as part of our daily diets would be good. 

The industry likes to say that we should emphasize the positive. But that's, of course obfuscating that there's a lot of bad things that are in our diet too. But anyway, those would be three areas where just even those would make a huge difference. 


[01:05:48] Jonathan Wolf: And it sounds like one of the ways you're saying you're doing this is like, it's the things you're swapping out. So it's like reducing the red meat instead of replacing that with more potatoes, which you're saying is one of the things that's actually really bad. 


It's moving that towards these things that are more whole grain that you described where... like not all the good stuff has been removed. 

We had a lot of questions about vitamins because this is an enormous industry. And a lot of people were saying, asking us, well, you know, do people, if they are eating well, do they need to take vitamins in addition, what's your perspective on that?  


[01:06:29] Walter Willett: That's a good point. If you're really eating a sort of optimal diet you, we may not need extra vitamin supplements. 

One in particular we won't get is vitamin D. That even from a very healthy diet, the vitamin D would be quite low. Because mostly we get that from sun exposure. And in northern climates, we get much less sun exposure than we would in tropical climates. And if we try to get too much sun exposure, we'll likely get skin cancer, which is serious also. 

So, I think the best way to make sure we get enough vitamin D is by taking a vitamin D supplement. And, I do note in UK that's actually recommended now. 


There's also the reality that it's hard to have an ideal diet for most people. That I try to do that, but I'm traveling, I’m not always where I could have an ideal meal. 

And also an important recent study showing that taking a standard, low cost, RDA level, vitamin mineral supplement costs less than 10 cents a day. That actually reduced the rate of cognitive decline. Which is a pretty important issue for the, for anybody over 40. We do prefer not to end up demented in our later years. So I think you can take, you can get your vitamin D that way if you have a supplement that's say 100 or 1000 international units of vitamin D. It’s a low cost RDA level vitamin supplement does make sense for most people.

After age 45, some people don't absorb vitamin b12 as well and end up low in that. So it could, it’s a sort of a nutritional safety net, not to be a mega vitamin superpower kind of a thing, but just making sure that we don't have some holes in our diet, which  most people do actually. 


[01:08:28] Jonathan Wolf:  So it's a sort of safety net. If you aren't eating this sort of like really great, loads of whole food and fresh vegetables and the rest of it, then it's a way to make sure. 

And you're saying it's like, you just need to, recommended daily intake, this is like 10 cents a day. So this is just your standard one, one pill a day. 
And Walter, do you, do you do this yourself?  


[01:08:51] Walter Willett: Yeah, I do. And it's not, it definitely is not instead of a healthy diet because there's lots of things we'd get in a healthy diet that are not going to be part of that.

[01:09:01] Jonathan Wolf: Brilliant. I have one final question, Walter, and then I'd love to do a quick summing up. Which is what's the area of research that you're most excited about that you might be talking to us about in a few years time where you feel we don't have the answer right now. 


[01:09:17] Walter Willett: Well, I think at the ends of the life spectrum are the most interesting because most of our data comes from sort of middle life. And sort of diet during childhood and adolescence and how that does relate to later life risk. That is an area that we're just recently starting to have enough data to look at. 
And then at the older ages to neurodegenerative conditions, including dementia, Alzheimer's disease, Parkinson's disease. Those are areas that we're just building up a substantial body of evidence in those areas.

[01:09:50] Jonathan Wolf: That will be fascinating to understand. And I know a lot of listeners, obviously, these are the things that we're all scared of and we'd like to understand better what we can do ourselves, to try and reduce those risks. 


[01:10:03] Walter Willett: Actually, in the last 10 years, we have learned quite a bit about that, but it's clearly an area where more data, more evidence will be valuable. You could say we've just after 2000 years, rediscovered the Mediterranean diet.  


[01:10:13] Jonathan Wolf: I was going to say, could you wrap up by explaining when you say the Mediterranean diet that there's like the core diet that would help you know, prevent those diseases? 
What are those components? 


[01:10:23] Walter Willett: Well, I should, usually try to insert the adjective ‘traditional Mediterranean diet’, because it's not what people are eating today. That's what people were eating back in the 1960s. And it really was a primarily plant based diet, but not a vegan diet. It had a small amount of meat in it, more emphasizing in most places fish, but emphasizing large amounts of fruits and vegetables, whole grains, and the type of fat being in that tradition, olive oil. 


But we're seeing other non hydrogenated plant oil, soybean, canola oil are also pretty healthy and maybe fit with other dietary patterns as well. 

So it's basically healthy sources of fats, healthy sources of carbohydrate, healthy protein sources, lots of fruits and vegetables. And put that together, and you could put it together in thousands of different ways that will have very important health benefits, both by not getting too much of some less healthy parts of the diet, but getting an abundance of health promoting parts of the diet. 

[01:11:33] Jonathan Wolf: I love that. And it is interesting how much of nutrition seems to be about getting back to the advice that maybe my, you know, my grandpa, my grandparents were brought up with about what one was supposed to eat. 
And we seem to have gone on this very long detour to start to be heading back and saying that maybe they. knew more than we thought they did.  


[01:11:56] Walter Willett: It depends where your grandparents lived.

[01:11:59] Jonathan Wolf: Walter, I would love to try and summarize today. We were very wide ranging. So I'm going to do my best to pull that together and do please correct me anywhere I've got wrong, if that's okay. 

We started by saying, what do we think now when you look at all your data you got this amazing data spanning hundreds of thousands of people since 1980 and that through this period what you now understand is really unhealthy is actually shifted quite a lot.

So in the 1980’s you thought the fat was really the villain. And it turns out that hasn't really been true. 

And interestingly, the number one thing you talked about is the fact that probably 80 percent of the carbohydrates that we're now eating are unhealthy. And you talk very much about not just sugars, but interestingly, these starchy foods. And so you were talking about potatoes and white rice and white flour, which is then turning up in anything from white bread to, you know, almost anything. 


These beverages, so the sugary drinks are a big problem. But interestingly, that's shifted from being really obvious things like, you know, everybody listens, know that Coca Cola is bad to saying, actually, we just shifted to these other sugary drinks, you know, the orange juices and the apple juice and all the rest of it. 
And actually they're a huge problem. 

You also said really explicitly that advertising is a big issue and not a lot of people on the show are maybe as forthright. And I think that's wonderful to hear that, you know, there is a lot of advertising, a lot of it, you know, being directed at children as well as adults, taking advantage of pushing these foods which are very cheap for them and which you say are really a problem. 


That we understand basically the whole grain is good for us and what's happening is that two thirds of these grains are being removed. And we're just being left with this starch, which almost immediately turns into sugar when it goes into our body. And that is like, what's starting off this race towards type 2 diabetes and other diseases.


Then we shifted a bit and we talked about red meat, and you said, you know, looking through all the data, it's really clear this is not good for us. We don't need to be eating it all the time, you know, and if you do want to eat it, you should be thinking about it as a treat. Rather than I think you described growing up and having it three times a day, 

We talked a bit about, I think, some really interesting new research where, where you're saying we now see, I think really for the first time that what we eat as children and adolescence has a profound impact on our health later. 
And for example, this, I think, really scary idea that the food that, you know, a young girl might be eating is going to affect their breast cancer risk later. And therefore we do need to think hard about what our children and grandchildren are eating. And that's also true for heart disease, where you can see already at 18 that the food we're eating is starting to affect our arteries. 


But on the other hand, you said very positively, you could be listening to this right now in 75 and you had this analogy of like walking towards the edge of the cliff of the thing that's gonna make you really sick. You could change your diet right now and you could stop walking towards the cliff and therefore, even though you might only be, you know, a foot away, a few centimeters away from, from the edge, you can make that change, which I find incredibly positive. 


We talked about the way that there are real issues with government guidelines. You were really strong. You know, I think you actually said corrupted when you describe it and that therefore there is a real gap, particularly around things like meat and dairy, where you think they're nothing like as strong as the scientific evidence. But also even around sort of whole grains and things like this, that they're just not as strong as the, as the science really discusses, which I think is a fascinating topic I'd like to do a whole podcast on. 

And then finally you said, okay, what about some really actionable advice? And I think we picked up lots of different things during the talk. Bbut when you came down to like your three tips, you know, your number one, I think is if you're drinking any sugar sweetened beverages, then stop. 


Your second one is reduce refined starch and sugar in your diet. And this might be things like white rice and potatoes that you might not really been aware of as being quite negative. It's not only thinking about like, sugar in your diet. It's not only  white bread and replace that with a lot more, this is your third thing, a lot more fruits and vegetables. 


We talked about a couple of other interesting things, like that you do take a vitamin supplement daily, so you figured that that makes sense. 

You talked that you'd reversed your view on soy, so I definitely take away that I should be making sure that there's soy in my diet, which I think for most of us in the West tends to be very small. 


And then I think you summed it up by all saying, actually we just need to eat the way that our ancestors did 2000 years ago with this traditional Mediterranean diet. It's mainly plant based. You know, there might be a small amount of meat, it’s often fish. In fact, lots of fruit and vegetables, lots of whole grains, lots of olive oil. 
And if you could switch to that, you could actually profoundly reduce your risk of, you know, dementia and heart disease and all these things that we feel will rob us of the, you know, the end of life that we want to have.

[01:17:08] Walter Willett:  You're getting an A in my class.  


[01:17:11] Jonathan Wolf: Thank you. Well I thought that was a masterclass. I would love to follow up. Maybe we can do something next time I'm in Boston because I think there's so many areas that would be fascinating to dig into in more detail. 

Thank you so much for taking your time to really explain what is coming out of the research as you know, as you continue to learn more. 


[01:17:32] Walter Willett: Thank you, Jonathan. And I look forward to seeing you in Boston.  


[01:17:36] Jonathan Wolf: Thank you, Walter, for joining me on ZOE Science & Nutrition today. It's been incredible to have Walter on the show today, sharing his knowledge about how what we eat is linked with our long-term health and our risk of disease. 

Now, if after listening to this conversation, you'd like more science-backed tips from our podcast, you can actually download our free guide, with our top 10 most impactful podcast insights, by simply going to zoe.com/podcast. Here, you can also find out more about how a ZOE membership can help you improve your diet and get 10% off.

As always, I'm your host, Jonathan Wolf. ZOE Science & Nutrition is produced by Yella Hewings-Martin, Richard Willan, and Tilly Fulford. See you next time.