Why do we love food? Food has shaped the way we’ve evolved over the last million years. When we started to cook our food, our digestive tracts suddenly became shorter as a result of more easily absorbed cooked foods.
Our brains became larger, thanks to this increased nutrient intake — with a major part dedicated to our sensors, in particular those neuronal areas related to food.
As omnivores, we needed a good system to distinguish edible from non-edible foods, and those that were higher risk were those that gave a bigger reward.
This is why from a young age, we're hard-wired to be wary of bitter or sour foods that may be dangerous, and we're programmed to love sweet foods — with energy-dense fatty or savory foods lying somewhere in between.
The smell, texture, color, or shape of food or plant gives us clues as to what chemicals it contains and what it might taste like.
Taste is an imprecise term often used interchangeably with flavor, which is a combined food experience. Today, these signals are most clearly seen in infants, even before they’re exposed to many foods, but we’ve learned to overcome many of these inherited traits as we age.
We all know young children can be fussy eaters. But before the age of 2, they're still highly receptive to many novel foods, textures, and colors presented to them by their parents. This enables them to overcome their initial taste of bitter vegetables, such as broccoli.
In this episode, Jonathan speaks to Tim Spector about his new book that’s been 6 years in the making — Food for Life: The New Science of Eating Well — which has led him to uncover an abundance of new information that’s changed his outlook on the foods we eat.
Tim Spector is a co-founder at ZOE and one of the world's top 100 most cited scientists.
If you want to uncover the right foods for your body, head to joinZOE.com/podcast and get 10% off your personalized nutrition program.
Episode transcripts are available here.
Check the trial mentioned in today’s episode here.
Follow ZOE on Instagram.
This podcast was produced by Fascinate Productions.
[00:00:00] Jonathan Wolf: Welcome to ZOE Science and Nutrition, where world-leading scientists explain how their research can improve your health.
[00:00:10] Tim Spector: Why do we love food?
Food has shaped the way we've evolved over the last million years. When we started to cook our food, our digestive tracks slowly became shorter, as a result of more easily absorbed cooked foods. Our brains became larger thanks to this increased nutrient intake with a major part dedicated to our sensors, in particular, those neuronal areas related to food.
As omnivores, we needed a good system to distinguish edible from non-edible foods. And those who were at high risk were those that gave a bigger reward. This is why from a young age we are hardwired to be wary of bitter or sour foods that may be dangerous and programmed to love sweet foods with energy-dense, fatty, or savory foods, lying somewhere in between.
The smell, texture, color, or shape of food or plant gives us clues as to what chemicals it contains and what it might taste like. Taste is an imprecise term, often used interchangeably with flavor, which is a combined food experience. Today, these signals are most clearly seen in infants, even before they're exposed to many foods.
But we learn to overcome many of these inherited traits as we age. We all know young children can be fussy eaters, but before the age of two, they are still highly receptive to many novel foods, textures, and colors presented to them by their parents, enabling them to overcome their initial taste of bitter vegetables, such as broccoli.
If you haven't guessed already, this isn't Jonathan. I'm Tim Spector, and you just heard a passage from Food for Life, the New Science of Eating Well. In today's episode, Jonathan and I discuss the surprising discoveries I made during the six years it took to write this book. Enjoy.
[00:02:36] Jonathan Wolf: Tim, thank you for joining me today.
[00:02:38] Tim Spector: It's a pleasure, Jonathan.
[00:02:40] Jonathan Wolf: Good. So I know I told you that I wouldn't ask any quickfire questions, but it turns out I've cheated Tim. I woke up this morning and I decided that everyone likes a quickfire round of questions from our listeners. So I have a few which you haven't had a chance to be briefed on.
So are you ready to go?
[00:02:59] Tim Spector: Uh, no. No, not at all.
[00:03:00] Jonathan Wolf: I'm gonna do it anyway. The normal rules. Yes, no. Or maybe a one-sentence answer at the most. So let's start at the beginning. Tim, You're a medical doctor. Is the food as important as medicine for our health?
[00:03:15] Tim Spector: Absolutely. Although I didn't use to believe that, and most doctors still don't believe it.
[00:03:20] Jonathan Wolf: Did you think you had nutrition all figured out when you wrote Diet Myth, five years ago?
[00:03:26] Tim Spector: I was cocky enough to believe that, yes, thought that I had most of the answers, although, in fact, I'd only scrape the surface I think of what's coming.
[00:03:36] Jonathan Wolf: So are there things you got wrong?
[00:03:38] Tim Spector: A few things that people have pointed out in Dartmouth were wrong, but for the most part, I'm actually fairly happy that my speculations for what was gonna happen in the future, ended up being correct. So actually I didn't do too badly, although I was pushing the boat out a bit with that first book.
[00:03:55] Jonathan Wolf: And have you changed your own diet while writing your new book, Food for Life?
[00:04:00] Tim Spector: I have, yes. So my diet has definitely evolved and for people who know me, it had already changed a bit, but it continues to change. And each time I discover some new interesting fact about food, it continues to be modified. And now perhaps I'll never stop changing.
[00:04:17] Jonathan Wolf: I think that's a wonderful way to think about it and I can think of one change we'll discuss later, which I think will really surprise people. Tim, is there anything you completely changed your mind about while writing Food for Life?
[00:04:29] Tim Spector: Yes, definitely. I've changed my mind on quite a few things. I don't know if you want me to list them all, but they're in the book, something we're going to maybe just get around to discussing. But my views, for example, on salt, have reversed really 180 degrees and my position is definitely gone from very strong to very weak or weak to very strong on many other points of food.
And I think this is the fun bit about nutrition science is that it doesn't stay still for long.
[00:04:59] Jonathan Wolf: Brilliant. Well, we look forward to talking about all of that. Now look, firstly, I'm just so pleased to be able to have this conversation with you, Tim, and mainly because it means you finally finished writing Food for Life, which I know has been a massive labor of love.
And for those of you looking at the video, I have got the book. So it is real. It's here and there is some weight to it. So this was a lot of work, wasn't it, Tim?
[00:05:22] Tim Spector: Yeah. Six years of my life, which I'll never get back but at the same time have been very rewarding. So it's like anyone who's written a book will know this balance between pain and pleasure that books give you.
But certainly, you know, you can't do something of that without learning masses about the subject. But I also realized why no one else before me had attempted such a massive feat of trying to cover the whole of the subject in one book. And, I realized that after I was about a year into it.
[00:05:55] Jonathan Wolf: And I really enjoyed reading it and I know that a lot of people will enjoy reading it.
There are so many things we could talk about because it covers so many different topics. But I think what would be most interesting, actually to talk about where you've changed your mind and where your view now is not the same as it was five or six years ago. And I think one of the reasons I think that's so interesting is it feels like there's so much focus on the idea that people mustn't ever admit that they were wrong or that they changed their mind. And one of the things that I love about you, Tim, is you're happy to admit this. And I think that's so important because the whole idea of science is, it's a process of getting a better and better understanding of the world. By challenging our assumptions, right?
Change in our mind when the data proves we were wrong. And so I think, you know, this book is your own doing science around nutrition and saying, Okay, this is what the latest data says. And so if you're alright, I'd love to talk about the top five foods where Tim has changed his mind and how this has actually changed what you eat.
And I particularly want to do that because when I first met you six years ago, I assumed you already had the perfect diet. So I think that if even Tim can get better, it tells us that, you know, all of us can continue to improve.
[00:07:15] Tim Spector: Absolutely. Yes. And I think just, it's worth pointing out that this book is different from the previous two, Diet Myth and Spoon-Fed in that it's more, of a practical guide. Yes, it covers the science, but it then goes into much more detail about how you can practically tell the difference between foods and what you should actually do.
And I think by forcing myself to write this more focused practical book. It did actually raise many of these questions that we don't always know the answer to, or I'd avoided when I was talking more in more general terms in the previous book. So it does put the writer on the spot to actually sort of say, Well, okay, how much broccoli should I eat today?
Or, you know, what is the best plant to choose, which is the best bread, for example? And these really bring it into tight focus as you then have to explain why you made those choices.
[00:08:06] Jonathan Wolf: And I think you just mentioned that the first topic I wanted to talk about, which was bread. And I think, you know, that is probably, you know, the number one thing that people ask us about in terms of food. So bread. How have you changed your mind about it, Tim?
[00:08:23] Tim Spector: Six years ago I thought that most bread if they looked brown and had some sort of healthy label on it, would be generally fairly good for me. And I knew to avoid very white bread or cheap supermarket white bread, but I thought that if it looked like decent, healthy bread, it was quite likely to be for me.
And I could have, yeah, not masses of it, but certainly, I could still keep it as part of my diet. And I think that was probably the first real shock that hit me was when I would take one of these brown, healthy-looking loaves that have whole grain, whole wheat made of, you know, all kinds of nice stuff with occasional bits of seed sprinkled on it, and it was when I started testing my blood sugar responses to these that I realized that, you know, all that glitters is not gold. And that actually underneath it, they're pretty much the same. And there was very little difference between the brown bread and the white bread that was made in very similar ways, except the brown bread was often dyed, or they had just a few things added to make them look healthier.
So I suddenly realized that there was this huge range within this one category of bread that I was calling the same. Suddenly I had to reevaluate and had to sort of go back to basics to say, Well, what makes bread different? What are the key fundamentals about some bread that are much less healthy than others?
And that's really where I came across this idea of looking at to fiber in the bread versus the number of sugars that are easily absorbed and the processes by which bread is made. Whether it's the highly chemical process that you can make bread in a couple of hours and a factory with a trolley or wood method, or it's made over 24 hours with a sourdough method that is the old, traditional way of making bread. And what actually those differences were. And I also discovered bread that I thought was fantastic ancient bread from Italy that had been used for centuries like ciabatta, which we see a lot. it turned out it was just a marketing invention in the 1980s, which I -
[00:10:37] Jonathan Wolf: - that is rather disappointing, isn't? -
[00:10:39] Tim Spector: I did feel very let down by that, but realized, well, what else? You know, we've been fooled about into thinking is healthy is not healthy.
[00:10:47] Jonathan Wolf: And I think you mentioned actually some of the labels that we often see on bread being in the UK or the US are also similarly sort of empty marketing. Can you give some examples?
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[00:10:57] Tim Spector: Yeah, there are also all kinds of terms like that, that really fairly meaningless, like whole grain and full of fiber, high-end fiber. And actually, the bar for having high-end fiber is so low that it's pretty irrelevant. And if you match that fiber with masses of starchy carbs, the overall balance means that that fiber is trivial compared to the damage it might be doing to you if, like me, you've got a susceptibility to carbohydrates.
[00:11:28] Jonathan Wolf: And so what have you changed, Tim? What were you eating before and you know, what are you doing today?
[00:11:33] Tim Spector: Well now I pretty much only regularly eat dark rye bread. In terms of purchase-bought foods and I try and get rye sourdough, but it's not always available.
But actually, those rye bread you can get, do have a long shelf life, I think are quite reasonable because they really are packed with fiber and they don't give me the sugar spikes. And I also make my own sourdough bread now. I sort of alternate with my wife, we compete a bit and mine are all packed with various grains. I try to do multi-grain ones, so not just rye, but I put spelt and other ones that I have around, and there are even some flowers where you can get 10 or 20 different grains combined.
Always add nuts and seeds. And I find that. A very small amount of that really fills you up much more and doesn't give me at all the same sugar spikes or energy levels. Unfortunately, you know, my love of croissants and baguettes and bagels has had to take the second choice. So, you know, I no longer see them as stable.
[00:12:39] Jonathan Wolf: Which is tough because everybody loves a croissant and a bagel.
[00:12:42] Tim Spector: So I now have them as a special treat rather than saying, well, I can have these regularly. So even if I'm in France, you know, there's no way I'm gonna have these every day. But if there's a particular famous boulangerie where you can pick up your croissant or just taste a, you know, a superb crusty baguette, yes, you'd be stupid not to, but I think changing that idea, Or treat, there's in fact equivalent of a sugary treat from a staple I think is really something important. But in general, I'm eating much less bread because I'm much fussier about it. And so I reject a lot of bread that I'm offered because most people, you know, in our cultures eat bread two or three times a day.
And I think it's definitely the wrong thing to do and it's much more harmful I think than people realize.
[00:13:33] Jonathan Wolf: Really interesting and I think it's a great transition actually to number two of the things that you have changed, which is actually not a food, the topic is actually personalization. Tell us about personalization and how your views have changed.
[00:13:46] Tim Spector: Up to six years ago, obviously I was very keen on the gut microbiome. I started studying that about 12 years ago, so, and my book, The Diet Myth was all about reintroducing the gut microbiome to people and its interaction with foods. I thought that if you just act for your gut, then generally most things would follow, and I think that's still broadly true.
That all of us can get to a certain level of healthy food by listening to our gut microbes. What do they like to eat? And in general, what they like to eat is good for their health and generally good for the planet. But within that, I think there are some quite important rules. And it was only when I did the early studies for the ZOE Predict study. We were doing pilots. I think you did this around the same time as me, Jonathan.
[00:14:36] Jonathan Wolf: I did. I remember being in the hospital, having needles stuck in me like 10 times. For you, you were more used to it, Tim. I mean, you know, you're a famous scientist, a medical doctor. For me, it was like a huge shock. So I definitely remember that time.
[00:14:51] Tim Spector: No, I did it. Because actually, I do all the experiments that we put our twins through. That's one of my rules is that I wouldn't, you know, ask subjects to do things that I haven't already done. And so I've had bone biopsies. I've had fat biopsies. I've had all kinds of - even had a colonoscopy and other things, you know, more invasive things.
So it was routine.
[00:15:13] Jonathan Wolf: I love that. It's like testing your own material before you give it to the public is
[00:15:16] Tim Spector: Yeah, but I think it builds trust to say, well, you know, he's not in some ivory tower not doing this stuff. He's seen what it's like and he's survived. So if Tim can do it, then we can. And so I went into not knowing really how I would respond to foods and we had those very early primitive muffins and, you know, this is the first time I'd seen this really big spike in my blood sugar when I had that first muffin and followed up by milkshake and, it was in a range that, you know, I really hadn't thought I'd be at, at my age and thinking I was relatively healthy. So, you know, I'm not overweight. I exercise, I look after my diet, but I couldn't change those figures, which for me show me this really big sugar peak and below the average fat peak. So it wasn't like I could eat any amount of fat, so it suddenly said I had to be really much more careful about what I was eating.
Once I sort of knew this, I started thinking more carefully about what I should have for my meals and breakfast and how I actually felt after them.
[00:16:26] Jonathan Wolf: And what were you eating at that point, for breakfast and lunch? And how have you changed that, sort of, personalized to you?
[00:16:32] Tim Spector: I don't remember the exact sequence of events, but as moving off the super healthy mueslis, I was still having it occasionally. You know, these expensive mueslis you think are better for you with nuts. And I was starting to experiment with things like oat porridge, which apparently, you know, according to some of the data had been shown to be better for some of your blood fat levels.
[00:16:56] Jonathan Wolf: Yeah, I think we've all read lots of things about how that's supposed to be a really slow-release, healthy breakfast, right? Oatmeal for our US listeners.
[00:17:05] Tim Spector: Yeah, so I'd already given up orange juice because I knew that was bad and I had actually taken my blood sugars using different methods and, and seen that my orange juice was just as bad as coca-cola for me. So I'd just given up coca-cola. But it's still in this transition period saying, well there must be some healthy carbohydrates I can have in the morning that would work for me. And oat porridge was one, you know, a lot, the muesli with nuts and seeds, I thought, that would compensate. It turns out that those two were still terrible for me, so I ended up with really big glucose spikes with my breakfast and that really told me I had to change it.
[00:17:44] Jonathan Wolf: And for people listening who maybe haven't heard about this, why is that bad, Tim, in your opinion?
[00:17:50] Tim Spector: Everyone gets some sugar spike after eating food. It's a normal response to the body. Carbohydrates get broken down and the body gets rid of the sugar by releasing insulin, so you need a little bit of the blood sugar to go up in order to trigger the insulin to bring it down again, and for most people, this is a little hump and it goes down again.
But in some people, there's an exaggerated response that lasts a bit too long. And this causes stress on the body over time, it can lead to stress on the insulin system. So you might end up with type two diabetes, but short term it leads to inflammation. Which means that the body is under much more stress than it should be.
And this can stress the blood vessels, it can stress the brain, and many parts of the body just slightly in a state of tension that over time leads to all kinds of diseases, accelerated aging, metabolic problems, et cetera. So...
[00:18:44] Jonathan Wolf: So not something you want.
[00:18:46] Tim Spector: It's not something you want if you can avoid it.
I mean, sometimes there are some things in life you can't avoid, but it seemed to me once you start doing these experiments, that suddenly you're empowered to change the way your body is responding and so you can actually make a real conscious decision to do things about it. So, you know, eating a healthy oat porridge and seeing you had this big spike when all the experts were telling you, oh, it should be absolutely fine for you, and particularly in the US oatmeal is seen as the holy grail of foods. It was rather strange that this happened, so I knew that really I had to get rid of, particularly in the morning, this whole idea of this carb load and I switched to a healthier fat protein predominant breakfast, and this was really important to me.
And so as soon as I started getting this full-fat yogurt with nuts and seeds, I felt much better. I didn't feel as hungry.
[00:19:48] Jonathan Wolf: And that's breakfast of choice now, is it, Tim?
[00:19:51] Tim Spector: It's breakfast of choice when I have breakfast and we may come on to that, but I've since discovered that you know, another way to avoid the sugar spike is actually to not have breakfast at all. Which I know I find easier to do than you do.
[00:20:06] Jonathan Wolf: Yeah. It's a catastrophe for me. But again, this is the joy of personalization, isn't it?
[00:20:10] Tim Spector: Exactly. And you have to experiment and it's something I slowly started to do more of. It's not something I just jump to on day one, but I also try and vary my breakfast.
Some days I will still have my rye bread, but I will cover it with cheese or avocado to improve it. And this is what the personalization also adds is that as you layer on these other foods, you get an idea of their score for you, and you try and balance this out so that you can have fun, interesting, diverse food that's good for your microbiome, also protecting yourself from excess stresses on the body.
[00:20:49] Jonathan Wolf: And I remember one of the things that were really striking when we were all in the hospital, right, that very early day, is we also were joined by our other co-founder, George. And you know, you and I both actually had very high blood sugar responses, it turns out. And George's were way lower.
And so that I remember as being just like a real eye, eye opener because you know, there's nothing on the outside that would've made you guess. And so for me, you know, I remember just being sort of really stunned and I think, you know, similarly, this has obviously had a big impact on what I eat afterward.
[00:21:20] Tim Spector: Yeah. My wife can eat croissants, which is really annoying. , you know.
[00:21:24] Jonathan Wolf: Is that the best special Belgian genes, is it? Is that, that you're sort of adapted to a croissant for breakfast?
[00:21:30] Tim Spector: It must be. Yes. So, it just shows you that this personalization is definitely gonna change the family breakfast, and the idea that one size fits all is obviously complete nonsense.
And the idea that there is this idea of healthy food for everybody, I think it largely goes out the window. But yeah, so this increasing personalization layered on top of my microbiome knowledge has really sort of helped me shape where things are going, but taking bread out of the equation apart from, you know, occasionally and when I do try to make sure that I'm compensating for those extra spikes I get from the carbs and the bread.
Not only with the fiber in the bread, but also layering on other things that will delay how quickly that sugar gets into my bloodstream, I think is also important. And the nice thing is it's actually quite fun to think of other bits to put on your food to add to it. It's suddenly like a chemistry set.
[00:22:33] Jonathan Wolf: I agree. I loved the spices podcast we did a little while ago. You know, I'm still playing at trying to figure out the spices to put on my breakfast, half of which are a disaster. I have to admit someone who doesn't really know anything about spice, I think many people I think must be like us at home, who feel like they've sort of ended up in a bit of a rut eating the same food over and over again.
And I think one of the things that I've really enjoyed over the last couple of years is this push to very different food. And my wife has actually just finished doing ZOE quite recently and it's interesting, it's had a huge change now suddenly on what we're eating, she, it's really changed what she feels is right for her and suddenly we're just eating all these foods that I've been trying to convince her for years we should try, but now she's got the results for herself.
She's interested. So anyway, we were talking about breakfast and I think that might be quite a good segueway onto your third thing where you told me you'd really changed your mind and which I really enjoyed reading about here, which is milk.
[00:23:27] Tim Spector: Yeah, so I've had an on-off relationship with milk pretty much all my life.
I had terrible sinusitis as a kid, and I was told that I should give up all dairy products by my mom's acupuncturist because milk was associated with mucus production. And so I did as I was told, and gave it up for about 10 years. Amazingly made absolutely no difference at all to my sinusitis or mucus production.
[00:23:55] Jonathan Wolf: I'm shocked! You're saying that your acupuncturist medical analysis wasn't completely accurate?
[00:24:02] Tim Spector: Yes, but I'm sure I could have gone to any number of other doctors as well. I'm not picking on acupuncturists, but you know, people have had very strong views on milk and a lot of people do have milk allergies and are seen as foreign by some people and as life-giving by others. So, quite polarized, people's views, and I've sort of oscillated between the two and certainly I was one of the first to probably move to low-fat milk. I never liked totally skimmed milk. I thought it tasted revolting, but I would go for a semi skim milk.
So is that one 1%? I can't remember, in America, the semi-skimmed.
[00:24:40] Jonathan Wolf: Yes, think so.
[00:24:41] Tim Spector: And six years ago, I thought, oh, you know what? I'm going to try some of these alternative milk because I didn't think milk was particularly good for you. And, you know, I knew for the planet it was probably better to have dawn dairy, so I tried a lot of these other milk, soy milk, almond and milk and more lately oat milk.
And I was using that instead of my dairy milk. But as I read more and more in my book, I changed my mind basically. And I will either go back to the occasional bit of full-fat milk in very small quantities. So, you know, nothing like the amounts we used to have because I don't believe that switching was a better alternative.
So as I read more and more realized that actually milk tends to come out pretty neutral. In epidemiology studies. I don't think it provides a huge benefit for most people in terms of bone health or menopause or anything else like that, but it's not negative either. So it obviously got some components in it that are good for you. And there are lots of nutrients, particularly in the fatty bits of the milk.
[00:25:56] Jonathan Wolf: Can we talk about that just for a second? Because you know, I think your chapter on milk is really interesting and it's, you know, it's something we've also talked a bit about. I was certainly brought up to believe that skim milk was much healthier than full-fat milk.
And of course, that's, as usual, a product of my generation being told that you know, low fat was always gonna be better. Do you still believe that skin milk is healthier than full-fat milk?
[00:26:20] Tim Spector: No the latest evidence shows there's no clear daylight between them in terms of any health benefits. And if anything, there are fewer nutrients in it. And therefore, I think full fat is probably, you know, slightly better for you if you had to choose one or the other. Certainly tastes better and has a better mouth feel to it. Seems more substantial, but that's sort of where we are. So that's sort of been evolving, this milk story.
And I think we've largely, you know, certainly in the nutrition research community largely dispelled the myth that the fat in milk is, is particularly bad for you. I don't think anyone's shown that to any degree. So there isn't really now a health reason to switch to alternative plant milk.
[00:27:09] Jonathan Wolf: They're not better for you then from your perspective, Tim?
[00:27:12] Tim Spector: Not in my reading and my research on this. No. And it's been interesting because obviously in my previous life I did a well of work in osteoporosis and there was a huge belief that calcium and milk were crucial for bone health.
And that evidence has really disappeared in the last 10 years so all those early studies have been disputed and now whether you take milk or you take calcium supplements, it doesn't seem to help prevent fractures in any way. So clearly we've lost that bit of the puzzle to think that was one really important reason to drink milk and promote milk.
So I think it's gone from being on both sides, either really bad for you, really good for you to somewhere pretty neutral, that if you like it, have a bit of it. But really for the planet, we should be drinking less of it and probably look for higher quality stuff rather than using it as a mass drink that's gonna be good for our health.
And that's why I moved in a way, to the plant foods, these plant milk, because I thought at the time there'll be healthy for me. But it turns out that's not true. They have large amounts of other ingredients compared to milk. They're much more highly processed. Generally, they're not just the almond squeezed in a bit of water. They've got all kinds of other stuff to make it look like milk. It has a sort of vague color that resembles milk and a mouthfeel that is pleasant. And similarly with soy milk. And then you've got oat milk, which for me, I discovered a while ago, gives me a very big sugar peak as well. So in a way that's relating back to the personalization that some people will react actually quite badly, so it's a bit like having, a sugary drink.
[00:28:59] Jonathan Wolf: As a result of this, what's sitting in the Spector refrigerator, in the milk department, if anything?
[00:29:05] Tim Spector: Well, I'm sort of fighting with my wife on that, about what's actually there. But, um.
[00:29:09] Jonathan Wolf: Alright, so tell us the real story. You know.
[00:29:15] Tim Spector: Generally, I more or less cut it out, and if there happens to be some milk in there, and I need to add it to something, I will do. But I'd be probably equally happy if there was some oat milk to add because if it's only in very small quantities, I know it's not gonna be particularly harmful to me, but I know that actually, that is better for the planet and because of its apparent benefits for climate change. But I've really gone off the need to have milk at all. I think you can have your tea and your coffee black, and I think that lots of reasons we should be weaning ourselves off these products, which are more habits than anything else. And if we do just use very small amounts of them. . So that's the way that I changed.
But it's interesting how, you know, plant milk has come from being the savior to suddenly realizing just by understanding more about how these foods are made, which is part of my research by the book, Food for Life, you come to a slightly different conclusion and in a way, what it illustrates, the dilemma that we are now in with food, that we're thinking about food in three ways now, you know, effects on yourself and your health, which may be personalized.
You're thinking about the ethics of how it's made. You know, are those cows really happy in that environment? Are they inside? Do they ever get to see the grass? And thirdly, the effect of that food on our planet, on climate change. And I think that's why I wrote the book. It is so people can actually see some of the facts and make their own minds up about which of these three is important and it's gonna differ at different times in life.
I think that's also important.
[00:30:54] Jonathan Wolf: Can we talk about number four on where Tim has changed what he eats and that is mushrooms, which I personally thought was my favorite chapter in the whole book? Tell us about mushrooms.
[00:31:07] Tim Spector: Yeah, I discovered lots about mushrooms, which I didn't know. I had no clue about them. I used to, you know, enjoy the odd mushroom in a risotto or with a Sunday fry maybe.
But I didn't realize quite how many thousands and thousands of species there are and the fact that they're closer to animals than they are to plants as well. So they're not actually. members of the plant kingdom.
[00:31:31] Jonathan Wolf: That's crazy.
[00:31:32] Tim Spector: And about a third of our, you know, the Earth we're standing on is made up of fungi and their, their mycelium, their network and it's incredible how they can produce these mushrooms that suddenly appear after a bit of rain and grow massively and then disappear again for another year.
It is incredible and it turns out they are potentially a real lifesaver for the planet if we can harness them right because they have an amazing amount of nutrients in them and very high-end protein levels as well. So it doesn't regard which species there are. And they have this meat-like quality to them that humans can recognize the so-called umami flavor.
So they're often used to disguise dishes, particularly Italian sources that, you know, they couldn't quite afford the meat, so they just put in mushrooms. And it's well known for centuries how you can do that. And it turns out, not only are they high in all these nutrients, but if you leave them in the sun, they actually, like humans produce vitamin D.
So rather than taking highly controversial supplements...
[00:32:45] Jonathan Wolf: This is after you've cut them and put them in a basket while they're still connected to the rest of the fungus?
[00:32:52] Tim Spector: Well, I've seen data show both so they can actually still produce it because many plants do actually stay alive once you cut them from the rest of the family if you like.
They will continue to still be alive. So we don't totally understand this, but they're now done commercially, so you can buy, especially vitamin D enhanced ones, but many mushrooms contain natural amounts of vitamin D and I think we're gonna see more and more of that if, you know, our other sources might be drawing up if we're having too much ultra-processed food.
So that's interesting. They like to, you know, absorb the sun like we do, and convert in their skins in a way, precursors into this vitamin D, which they obviously use themselves and vitamin D is very good for our immune system, but we know that my particular views are that, you know, see vitamin D supplementation has not really succeeded in preventing any disease at all.
So natural forms of vitamin D are really important.
[00:33:48] Jonathan Wolf: The last topic where I think you said you really changed your mind and that is ultra-processed food, and maybe Tim, you just start by explaining what ultra-processed food is and then explain how you've really changed your views about it
[00:34:02] Tim Spector: So the language around processed foods is complicated because most food we eat is processed to some extent.
So even something like butter or milk can be considered processed because it's not just eating the raw plant or just cutting that bit of meat from the animal and eating it. But what we mean by ultra-processed is when the food itself no longer resembles the original ingredients. So that. You are using extracts of plants or meats that no longer are the same as those original members, and you're putting them together in a factory in a way that you lose all the structure of those original foods and you're just taking bits of them from a sort of chemistry set, and they tend to have at least 10 ingredients and to make them stick together, they've often got these glues or gums or thickeners to make them seem like real foods again. So they're like reconstituting these foods. And this is unfortunately what constitutes 50% of our diet in the UK and 60% of our diet in the US.
[00:35:14] Jonathan Wolf: Which is an enormous number, right? So you're saying, you know, half too, well over half of everything you eat is this sort of rebuilt food instead of something which bears any real resemblance to the diet that we clearly ate until a hundred years ago.
[00:35:29] Tim Spector: Absolutely right, and not every country does. So there are countries in Europe and in the Mediterranean, like Portugal, that only have 10% of their food in that way.
So it's definitely something that affects particular countries that maybe lack food culture, but also had very strong business links and lobbying links of the food industry to point us in this direction. And the fact that we went for new modern scientific foods that may be easier to cook with and cut out a lot of those old time-wasting methods.
But at what cost? And I think when I first started writing this book six years ago, the emphasis was all about, oh, they have high-end sugar, they have high-end fats, they're high-end salt. And basically, if you reduce those three things, you can make them healthier. And that's still the main establishment government approach to ultra-processed food. And one that the food industry is quite happy with because they can keep substituting different chemicals to reduce sugar by adding artificial sweeteners, they can reduce fat levels by increasing carbohydrates and other sugars and sugar alcohols, et cetera. And they can reduce the salt by again, tampering with the structure of the food and using different preservatives.
So all of it you can get around, but I think what I found was that there was some new research showing that ultra-processed food works not through the bad effects of those chemicals, those three macronutrients if you like but actually it's the whole process. It's these extra chemicals that act in two ways to really harm us.
First is our gut microbes through the chemicals like emulsifiers and thickeners that add artificial sweeteners that in most people, and this might be personalized as well, our gut microbes to and produce chemicals that make us sicker than if we weren't eating them and might make us more hungry. Might send signals to the brain to overeat and put on weight and, generally mess up our gut microbiome.
[00:37:38] Jonathan Wolf: So basically there are chemicals and this is just to make sure that, that we're all following. You're saying now you feel these chemicals in this ultra-processed food, which are sort of directly triggering actions in these trillions of bacteria, which are then creating their own chemicals that really affect our health and our brain and things like that. Is that what you're saying, Tim?
[00:37:58] Tim Spector: Yes. So it's not a direct effect, as you said, it's through our gut microbes, which I think we need to think of as like these pharmacies where they're producing chemicals for us, instead of our body. And sometimes they produce the same chemicals that our body produces but through an alternate pathway and something that we are just learning more and more about all the things they produce.
So this is a very new science, but it's showing us how things that we thought were completely inert, like artificial sweeteners like carrageenans, which add thickness, or other lesser thin emulsifiers sucralose. They can't harm you because we've done the studies to show that. Doesn't cause cancer or anything, but it does mess with your body and it does that we think through the gut microbes, but the other convincing bit of evidence for me was this study from the NIH, Kevin Hall's Group, where compared in a very strict environment in a lab, they gave for a couple of weeks, people two different diets, one matched for calories completely. One is a whole-food diet made from real food and the other is a copy of it made from ultra-processed food.
And they were both equally satisfying for the participants. But the group that had the ultra-processed equivalent kept saying they were hungrier and they went back to eating more and more every day. So they were overeating by about 200 calories a day. So there's something else in that food that's nothing to do with the calories, nothing to do with the salt, the sugar, everything else because they were matched, that is telling the brain to eat more. And we don't know if that's direct or through the gut microbes, but once you really absorb that information, you think, gosh, if I'm having this every day of my life in some form, this is perhaps why we're in such a mess in countries that have high, ultra-processed food percentages in their diet, like the US, like the UK, like Canada, Australia, and Germany in Europe.
And that's why we've got part of this problem because we've just seen it as a reductionist idea, oh, we only have got to change the salt for, saying potassium, we've only got to switch the fats for proteins and a bit of carb. We've only got to take the sweetness away and add other chemicals. That changes nothing. And so I've really become much more anti-ultra-processed food.
[00:40:31] Jonathan Wolf: And that's a big shift, isn't it? That you are saying, you know, I think, you know, I remember when we first talked, that you were particularly concerned there was no fiber in it, so it didn't sort of positively feed the bacteria and now you're talking about it almost as if we were taking a drug, right? It sounds almost like you're describing what would be happening if I was taking a medical drug that I don't need. And we all know that all these different, you know, many drugs have side effects, right? They say on the label, you know, may cause obesity or may cause nausea. If I played that back, Tim, you're really describing this as if these are sort of like medication, but we are not being prescribed by the doctor, right? We're just buying it at the corner store and eating it because it tastes delicious.
[00:41:12] Tim Spector: Yeah, and it's been designed by really brainy people, brilliant food scientists who have spent 30 years now trying to create this perfect mix of chemicals that satisfies your taste buds and makes you want to eat more of it.
And that's what they're paid to do, and they do it brilliantly, and they're doing it ever and ever cheaper. So using cheaper and cheaper products, more synthetic products to do that with really no restraints at all.
[00:41:40] Jonathan Wolf: Brilliant. I'm gonna try and do a quick summary of what has covered a lot of ground today and, correct me if I get wrong.
So, I think the first thing is that you know, Tim thought he really knew a lot about nutrition, and it just goes to show how complex it is because this book has really led you to change your mind about a lot of things. On bread: that you really changed your view that in fact a lot of bread you thought was healthy. You've really got to look beyond the label. The second thing is personalization and discovering that you know, your own results were very different from lots of other people's. The third is milk. So since your acupuncturist convinced you to give it up, you've been on a lifelong sort of in and out of milk, and today you sort of ended up on a sort of neutral view on this.
Then you talked about mushrooms and we heard it here. We'll all be eating many more mushrooms in the future. And then finally, I think you talked about ultra-processed foods. This is half of our diet or even more. And that you're not saying we can't have it ever, but we need to really think about this as having much more impact than just having, you know, some sugar in something that we made ourselves at home.
[00:42:53] Tim Spector: Absolutely. I think you summarized it beautifully.
[00:42:55] Jonathan Wolf: Brilliant. Well, what I would say - Go on Tim.
[00:42:57] Tim Spector: There's plenty more. Yeah, you've just scraped the surface of what's in the book, so...
[00:43:01] Jonathan Wolf: Oh, I was going, I was gonna say that! I was gonna say, I think we just scraped the surface. There are so many chapters we haven't touched on.
If you're interested in fish, you have to read the fish chapter. If like me, you really like fish, I definitely can't recommend the book enough. And again, in the show notes, we'll make sure that there are links there. Tim, thank you so much for coming in. Thank you so much for continuing to challenge yourself as well as everybody else in terms of what is the latest science on nutrition.
And I think the final question is, are you done? Every time you do a book, it seems like it takes a lot out of you. Are you done or is there another book in Professor Spector?
[00:43:37] Tim Spector: I think from what I heard, it's a bit like childbirth. You know, you need a little break, but then you, you forget all the pain and you come back and do it again.
So we'll see. This will certainly keep me going for a while, but there are bits that I left out of this book because it got too big. That will definitely be another book, but, I'll leave it a safe distance to recover. Until then.
[00:44:00] Jonathan Wolf: Brilliant. Tim, thank you so much for spending the time with us.
[00:44:03] Tim Spector: My pleasure.
[00:44:04] Jonathan Wolf: Thank you, Tim, for joining me on ZOE's Science and Nutrition today. I hope you're as excited as I am about Tim's new book. If based on today's conversation you'd like to understand what personalization means for you, then you may want to try ZOE's personalized nutrition program. Each member starts with an at-home test, which is very similar to the test that Tim was talking about today.
And those tests help you to understand your own biology and compare you with thousands of participants in our science studies. We then create a personalized program to improve your health. If you're interested in learning more about ZOE, you can head to joinZOE.com/podcast. And get 10% off your purchase.
If you enjoyed today's episode, please be sure to subscribe and do leave us a review as we do love reading your feedback. If this episode left you with any questions, please send them in on Instagram or Facebook and we will try to answer them in a future episode. As always, I'm your host, Jonathan Wolf. ZOE Science and Nutrition are produced by Fascinate Productions with support from Sharon Feder, Yella Hewings-Martin and Alex Jones here at ZOE.
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