ZOE Science & Nutrition - The shocking damage ultra-processed foods cause to your brain

Episode Date: September 14, 2023

There’s been a surge in our consumption of ultra-processed foods, especially in the United Kingdom and the United States, where these foods contribute about two-thirds of people’s caloric intake. Also a cause for concern is emerging evidence of ultra-processed foods’ detrimental effect on our brain health and overall well-being. When most of our calories come from ultra-processed foods, the risk of chronic physical and mental health conditions escalates. Scientists are now uncovering the intricate mechanisms behind this relationship, particularly concerning the effects of these foods on our brains. In today’s episode, we welcome back Prof. Felice Jacka, OAM. Felice is an Alfred Deakin professor of nutritional psychiatry and the director of the Food & Mood Centre at Deakin University, in Australia. She’s also the founder of the International Society for Nutritional Psychiatry Research and the world’s leading researcher on food’s impact on our brain and mental health. Now, she’s back on the show to delve deeper into the effects of ultra-processed foods on mental health and the brain, specifically the hippocampus, an area responsible for learning and memory. Download our FREE guide — Top 10 Tips to Live Healthier: https://zoe.com/freeguide Timecodes: 00:00 Intro 01:19 Quick fire questions 04:17 What is ultra processed food? 05:37 What is the NOVA classification? 08:18 How does food impact the brain? 10:33 What does the hippocampus do to influence our brain function? 12:58 Is there a link between the size of the hippocampus and quality of diet? 13:45 Is there a link between the quality of diet and depression? 20:37 What are the effects of long term dietary habits? 21:33 Is there a link between poor diet and dementia 23:18 Is there a link between autism and diet? 24:00 How real is the link between diet and dementia? 24:57 What is the oral microbiome? 28:16 New trial between whole foods and vitamin enriched nutritional foods 29:28 How does processing foods impact the makeup of foods on a molecular level? 32:10 How does the biodiversity around us affect our body? 33:08 How does the industrialized food environment impact us? 35:50 How strong is the evidence for this? is it comparable to smoking? 39:12 Practical tips to help with our diet 40:07 How does reducing consumption of UPF affect us? 41:25 How to cut down on UPF 44:04 Is it too late to change your diet? 45:39 Does exercise impact our brain? 47:41 Summary 52:57 Goodbyes/Outro Mentioned in today’s episode:  The SMILES trial published in BMC Medicine  Ultra-Processed Food Consumption and Mental Health published in Nutrients Western diet is associated with a smaller hippocampus also in BMC Medicine  Learn more about Felice on the Food & Mood Centre’s website. Follow Felice on Instagram. Episode transcripts are available here. Is there a nutrition topic you’d like us to explore? Email us at [e-mail], and we’ll do our best to cover it.

Welcome to ZOE, Science and Nutrition, where world-leading scientists explain how their research can improve your health. I'm your host, Jonathan Wolff, founder and CEO of ZOE. Today, we learn the shocking damage of ultra-processed food on your brain. In the US and the UK, a staggering two-thirds of our food intake comes from ultra-processed food on your brain. In the US and the UK, a staggering two thirds of our food intake comes from ultra-processed food. And this is rising fast. Scientists are only just now starting to understand just how bad this food is for our health

and particularly for our brains. In this episode, we'll take you through the latest scientific evidence and find out how to minimize the damage of ultra-processed food on our brain. Today, Professor Felice Jacquer is back on the show. Felice is the Alfred Deacon Professor of Nutritional Psychiatry, the Director of the Food and Mood Center at Deacon University in Australia, and also the founder of the International Society for Nutritional Psychiatry Research.

Above all, she's the world's leading researcher on the founder of the International Society for Nutritional Psychiatry Research. Above all, she's the world's leading researcher on the impact of food on the brain and on mental health. Felice, thank you for joining me today. It's great to be here. Wonderful. Well, look, you're an expert here now. So why don't we jump straight into our quickfire round of questions? And we got a lot of questions from our listeners this time. And just remind you about the rules. We want a yes, a no, or a maybe if you have to. You ready for it? Yeah. Brilliant. Can eating ultra-processed food rewire your brain? Maybe. Are the parts of our brain responsible for memory and learning affected by ultra-processed foods? Apparently, yes. Ten years ago, did anyone other than you believe that food affected our brains and our mental health?

Not to any great degree. Should we be worried about the impact of ultra-processed food on the brains of our children? Oh, definitely. So that's a lot of scary things. I'm hoping you're going to give us a little bit of positivity. If you stop eating ultra-processed foods, can your brain heal? It looks like it. Brilliant.

And last question, and you're allowed a sentence now. What's the most surprising thing that you've learned from your research looking at the link between diet and our brains? Just how big an effect size it is. So how large an impact it seems to be. So you're saying like the food really has a big impact on our brain? Apparently, based on the data we have so far. Felice, that's a lot of stuff and we're going to dig into that over the rest of the podcast. I'm really excited we're getting to do this in person because we did our first podcast about a year ago. It was over Zoom. You were in Australia, which is where you're based. And we had this like fascinating conversation about the links between diet and particularly mood and sort of mental

health conditions like depression and anxiety. And I recommend to any of our listeners who haven't heard that if they find this podcast interesting, which they will, to really go back. And we said at the end that it would be really fun to do some more research together. So I'm incredibly excited that you're actually here in London because you spent the last two weeks in our London office here at Zoe, sort of planning out a whole series of new studies that we can do together to really try and look at the impact of food and mental health and the brain on large populations. So thank you for coming here. Thank you for agreeing to sort of help push forward this area of research together and how much fun to actually be able to do it in person. It's great. And I love being here and, you know, the weather's wonderful and it's great fun

to work with the Zoe team. So I'm having a ball. No one is going to believe you're in London now. You said the weather was good. It's been great. You've brought the Australian weather with you. So I think today what we'd like to do is really dig into how ultra processed food affects our brains. And I think that this is one of the top topics that I think a lot of scientists are talking about now, but I think many listeners are going to be really, really shocked to be honest, because even the idea of ultra processed food is something that's very new. We did a recent episode of this podcast with Tim Spector and Dr. Chris Van Tulleken talking about ultra processed food. But I'd love to start actually just with a bit of a recap, because this is a new concept.

I didn't understand what this was until a couple of years ago when people started to explain. What do we mean by ultra-processed food and how is that different to just sort of regular processed food? Well, the definition of ultra-processed food means food that has basically been, if you call it food, deconstructed from its original ingredients and put back together again and it usually has a list of other ingredients that are not found in whole foods. So things like artificial sugars, for example, food colourings, preservatives, emulsifiers,

these types of things. So those foods make up a very large proportion of Western diets these days and often people think that it's only really obvious things like crisps or ice cream, these sorts of things. But it's actually often pre-prepared, ready-made meals that you might find in the freezer, a lot of things in the supermarket. Some commercial breads are very heavily processed. I think this is one of the terrifying ones that I'd never thought about, right? You sort of think like you know that McDonald's or a packet of Oreos, obviously that's not good for you and you

know that it's very artificial. But the idea that something like bread, which just looks like bread, might be ultra processed is something quite scary about how this is hidden and it doesn't look. Yeah, I think we have to be a bit cautious because there's many breads that would fall into that category. And this is the problem with the NOVA classification system is that... And will you explain for a minute what the NOVA classification is for us? So there's four categories in NOVA.

So NOVA was developed by Carlos Monteiro and his group in Brazil. And it really speaks to everything from category one, which is the completely unprocessed things like an apple, right through to category four, which is the ultra-processed food. The definitions are there to help guide discussion, help guide policy, but I think it's not totally strict. There's a lot of things that accidentally get swept up into that fourth category. So we always need to have a bit of nuance.

And I know that Carlos and his team have talked about this a lot, that it's really not just about individual things and maybe choose that bread over that bread. It's much more about food systems and food politics and how industry has really captured our global food system and displaced Indigenous food cultures, and certainly in Western countries like the USA, UK, Australia, but increasingly in countries that have had a far more traditional, really strong food culture. So we need to change the settings in industrialized systems in the West and also prevent this takeover of the systems.

With these foods that have got all of these ingredients you can never find in your kitchen, which is like a simple rule that some people have said to me that I find quite helpful as a way to try and navigate this myself. So I guess you wouldn't be wanting people to absolutely panic. And there'll be a lot of foods that might accidentally fall into that fourth category, like say wholemeal breads, that will still have healthful properties. But as a general rule, we understand what those ultra-processed foods are. They are the things where you pick them up and you see this long list of ingredients on the back that you don't recognize.

And it's things like preservatives and emulsifiers and all of those sorts of things. And we spend a lot of time at Zoe actually trying to do better classifications of this because this is early science. And so what's useful, I think, for scientists isn't the same as just if you're a listener and you want to understand when you go to the grocery store what to buy. You want to know for certain is this ultra-processed or not. And so this is clearly one of the challenges.

I think it's interesting to know too. I saw a statistic the other day that the very large proportion of ultra-processed food intake in the UK is coming from these processed breads that you get in the supermarket, whereas in Australia only 4% of the intake comes from bread. So I think that's probably differences in either what's available or the way they're produced in different countries as well. So it's difficult to talk about this without really thinking about the setting. I'd love to talk a bit about what it does and then maybe we can come back at the end to like what can people do as well as maybe what can we all do together

to sort of change the sort of food that's available. And so I think that the starting question to go back to your rather scary quickfire answers is why does the food I eat have anything to do with my brain at all? I think lots of people will start with like, you know, I eat the food, it goes into my gut. I can sort of understand how maybe that might make me put on weight or, but like, is my brain all sort of fixed and done by the time I'm 20? So like, isn't this all a bit crazy? Well, a lot of people will have heard of serotonin because it's called the happy neurotransmitter,

but it's a bit more complex than that, of course. A lot of the serotonin that is produced in the gut just stays in the gut. It's just used as a local messenger type of molecule. But your gut microbiota produce a lot of different neurotransmitters, including serotonin. And what is a neurotransmitter? Well, a neurotransmitter is a molecule that helps a neuron's brain cells speak to each other. But it also-

So are gut bacteria producing chemicals that actually change the way that our brain neurons communicate with each other? It's important to say that we don't have that level of knowledge yet. So it's still very sketchy because, of course, you're talking about something that is the most complex thing we know of in the whole universe, actually, the brain. But certainly the neurotransmitters that are produced by gut bacteria, and they actually do produce neurotransmitters. So even if you have kombucha or something, you could be drinking actual neurotransmitters that have been produced by these bugs, which is very cool. But we don't think they themselves cross the blood-brain barrier. They do lots of different things within the body.

But one of the things the gut bacteria do is help to metabolize something called tryptophan, which is part of what you eat. It's an amino acid. And in doing that, they influence the amount of serotonin that is produced in the brain. So they don't produce the neurotransmitters directly that make their way to the brain, but they do play a part in that. But the other thing that the gut microbes do, and also that food does, it seems, is influence the hippocampus. Now, the hippocampus is a very cool area of the brain. When I was younger, I think neuroscientists and everyone believed that you were born with

your full complement of brain cells. And as you grew older, they only got less. You lost brain cells. And I have to say, Felice, I'm 48 48 now and I do feel that in the last 15 years, I definitely haven't grown any brain cells and it feels like they're just sort of slowly decaying a little bit. So you sort of try and compensate with wisdom, but it definitely feels to me that way as though, you know, I'm not maybe quite as sharp and I'm certainly don't feel like I'm, it feels a bit like the rest of your body. Like at this point you try really hard to keep it stationary, but it's completely the opposite of like my 15-year-old where he wakes up every morning and he seems to have put on another half a kilo and you can see his brain getting smarter and more complex. Yeah, yeah. And the brain at that age is undergoing a pruning process and a refinement process, if you like. I'll tell him that. But what neuroscientists discovered probably the end of the 1990s is that we have this region of the brain called the hippocampus. Now, it's only tiny.

They're two little bits that sit together in the middle of the brain. And Felice is holding her, for those of you just on audio, she's holding her hands like very small. So you're saying there's like a lot smaller than that. Like really small. So you're saying there's like a- Probably a lot smaller than that. Like really small. But this hippocampal area of the brain seems to be very important in learning and memory. Okay. It also seems to be really important in mental health.

So there are particular proteins that grow new neurons in the hippocampus. So the hippocampus can actually grow and shrink over the life course. And is that unusual? Is that- It's the only bit of the brain that we know of that does this, where you can actually grow new neurons and it can get larger. So the rest of my brain, I am right. Basically, it's not growing anymore. All that's happening is it's sort of, I'm losing capacity. It does look like that. And people, as they get older, their hippocampus shrinks. And

that's when you start losing your car keys and forgetting your kids. So this is linked to dementia. Very strongly linked to dementia. But of course, it's linked to learning and memory right across the life course. So it's relevant for children as well, their ability to learn and remember. It's relevant to people in middle age in their jobs and their ability to function in the world. Now, what we see over and over again is that the quality of people's diets is linked to the size of their hippocampus. Now, we'd seen for many years. I just want to stop you for a minute because you just said

something really radical and I just want to make sure of that because you just said the hippocampus is sort of central in our learning and memory. It's the only part of our brain that keeps growing, that can grow as we get older. And then I think you just said very casually, but I just want to pick up. Oh, and by the way, the size of it is like directly related

to the diet that we have. That's exactly right. So when the hippocampus was identified as this region of the brain that grows and shrinks, part of that was because they could see that people with major depression, for example, had a smaller hippocampus. And when they were successfully treated, their hippocampus got larger. But there was actually a whole lot of really cool research in animals in the early 2000s. And it's one of the reasons I got really interested in this idea of nutritional psychiatry,

where they could manipulate the size of the hippocampus and also the animal's sort of learning and memory by manipulating exercise, which affects the hippocampus, and diet, and showed really quite profound effects. So in 2000, I think it was about 2013, I did the first study in humans to look at this. So we'd been working with this large epidemiological study. So that's when you're just observing people, you're not intervening, you're not doing an experiment. And it was a large cohort of people in Australia. And we'd already seen that the quality of their diets was linked to the risk of them developing depression

for the first time as they got older, independent of a really wide range of really important socioeconomic factors, income, education, these sorts of things. And then recognizing that there were brain scans done on a small cohort of the older people, about 250, I thought, oh, this is a great opportunity. So we actually looked at the hippocampal size of people as a function of their diet quality. And of course, we took into account depression, we took into account all of those other factors. And what we saw was a very clear link between the size of people's hippocampi and their diet quality. And it wasn't just a teensy little effect size. It was equivalent to about 60% of the shrinkage that you see in the hippocampus as people get older.

That's amazing. So you're saying 60% of the amount that this critical part of your brain shrinks is down to whether or not you were having a good diet or a bad diet? Well, this is observational, so we can't say definitely it's causal, but it was a very clear dose response. Since then, there's been two other studies, one done in the UK with the Whitehall 2 cohort that showed the same thing, diet quality very clearly linked to people's hippocampal volume, particularly alcohol.

So if you drink, it looks like you'll have a small hippocampus, even a small amount, which is a bit depressing. That'll depress Tim, who's always looking for reasons to say you can have one glass of red wine a day. And then in the Netherlands, they did an even larger study, more than 4,000 people, and showed that the quality of people's diets was linked to not only the hippocampus, but other regions of the brain and total size, gray and white matter volume, taking into account all these other factors. So it looks like diet is really clearly linked to your hippocampus. Now, this is incredibly important when you're thinking about your brain power. Now,

it's not just learning and memory. The hippocampus seems to be a key part of our emotional regulation systems. What we see in animal studies is if the animals are manipulated so that they can't produce the protein that makes the new neurons in the hippocampus, antidepressants don't work. So there's some thinking that actually the hippocampus, antidepressants don't work. So, there's some thinking that actually the hippocampus is a key way in which antidepressants can improve mental health. But the other thing the hippocampus does is it helps to regulate your appetite. Now, what- It sounds like it does everything.

Well, it's a really, you know, your brain is amazing, right? And it does all sorts of things. And a lot of what we know is coming from animal studies because, you know, it's very difficult to chop humans' heads off and have a good look at their brains. Which is good to hear. We do have two very cool studies, though, that have actually manipulated diet, just for the short term, in young, healthy people. So tell us about them. So these two studies were done in young, healthy, lean people.

So they're not overweight, obese. In the first study, they gave them just over four days a breakfast of toasties and a chocolate milkshake. And toasties is? Just like a toasted sandwich probably with cheese or something in it. But in one group, their version of that was very high fat, high sugar, and the other version of that wasn't, and they were randomly assigned to both. And what they saw was that within four days, they could see an impact on this hippocampal

related learning and memory tasks in these young people. Wow. So they changed the breakfast and in four days. In four days. And then the second study, and this is in over 100 young healthy people, they gave one group, you know, this same breakfast and then they sent them off with some vouchers for well-known food chains, told them to have Belgian waffles or something similar for breakfast and to have the rest of their meals from these food chains. The other group were given the

healthier version of the same breakfast and then told to continue their diets. Now, it should be said these people all had reasonable diets to start with. They weren't eating a whole lot of junk food. Similarly, after a week, they saw the same impact on hippocampal dependent learning and memory tasks. And it seemed to be particularly pronounced in those who had a very strong glucose response to the diets. So like not good control of their blood sugar, is that what that means? That's right. Yeah. So what also happened in those, in both of these studies is that people consuming these unhealthful foods also had lower appetite regulation. So we know that people, when they're eating ultra-processed foods, they seem to eat more, even when they say, oh, the food is just as tasty.

And we know this from randomized control trials in the States, very famous trial done by Kevin Hall. But we don't really know why. Well, in these studies, it looks like it affects the hippocampus, and it seems to do so through glucose regulation. And that seemed to affect appetite. So people were more likely to want some more of these types of food. So it's saying that what you eat has a really important influence on your hippocampal volume

and your hippocampal function, which could affect your learning, your memory, your mental health, your appetite regulation. In the second study, they tested people again three weeks later when they'd reverted back to their normal healthy diet. All of those deficits were gone. So it suggested once they stopped eating those foods, they actually, their brain kind of went back. Maybe the hippocampus is very plastic, so it probably grew some more neurons. And so what would this mean over time, Felice? So imagine that I eat a diet of ultra-processed food for the next decade and you don't. What does this mean in the long run? Because you talked about these sort of short-term effects on maybe something you can measure in your hippocampus.

But what would it actually mean to somebody in terms of their health and capabilities? Well, we know from, again, the epidemiological literature, so this is when you don't intervene, but you're just looking at people, large groups of people that you are assuming are representative of the population. And we see right across the world, this clear link between the quality of their diet and their risk for these common mental disorders. So that's depression and anxiety. These are very common. They're very, very burdensome. So at the population level, it looks like right across the life course, if people are eating a less healthy diet, it has an influence on mental health. And what about other brain? Because you were

touching a bit on things that go towards dementia. Do you see that as well, or is that? We certainly see that diet and also the things that are linked to diet, like blood glucose and body weight and blood pressure, they're all very clearly linked to dementia risk. And we know globally that poor diet is pretty much the leading cause of illness and early death. And I think a lot of people listening know that. That seems quite clear. But I think they'll be surprised by the link to dementia. Just in the same way, I think that they will be surprised about the link to depression and anxiety

if they didn't listen to the podcast in the past. I feel like that is not well known. No, it's not. And it's interesting because when these huge studies like the Global Burden of Disease Study estimate the burden that comes from poor diet, they are not necessarily including brain disorders like neurodegenerative disorders. They're certainly not including mental disorders, but they're also not including things like ADHD and autism. And now it looks like there's a pretty clear link there as well.

So tell us a bit more about all of this, because I think that you're right. Almost nobody talks about this, and even the scientists that we have on our shows. In general, there is still this thing in science, I think, about this huge divide between people talking about anything to do with the brain and people talking about any other part of the body. And I've had explained to me by doctors that this also follows the way that like the medical profession still has this like really big divide between sort of psychiatry on one side and everything else. Yes. And so it's great to have you here. How serious are these risks, I guess? I think many people, you know, my grandmother had Alzheimer's and it was sort of a fast onset, you know, as for everybody, like devastating impact on the family and, you know, devastating impact on my father.

It's still like his number one fear in life is that he's going to have the same thing. And I think for many people, it feels as though this is something you have no control over. I think that's a story that I have understood. I think my father understands. Whereas I think many people feel, I think rightly, given all the evidence that diet and exercise can have a lot of impact on your risk of strokes and diabetes. So, I mean, is there actually, how real is this linkage?

Well, it's very consistent. And the difficulty is, of course, doing an intervention like a trial over a long period of time. You can't really give someone junk food diet for 40 years and follow them for 40 years and look at how likely they are to develop dementia. I mean, some people might say that's exactly what we've done across the world as an experiment on all of us. Yeah, yeah.

Well, that's very true. The other interesting thing about dementia is it's not just excess body weight or high blood pressure, high blood glucose that seems to be involved in the risk for dementia. And again, these are just associations and so many things are involved in the risk for any illness in humans that it's often very difficult to narrow right down and say, okay, this specific thing. But certainly that is a very clear and very consistent finding in the literature that these factors are linked to the risk for

dementia. What I'm really interested in more recently is the oral microbiome and how that might be linked to dementia risk. So these are the bacteria in your mouth? That's right. It looks like there are particular microbes that may set up shop in the neurons of your brain because they can get there pretty easily. And your brain lays down these plaques. You know how in dementia people have these plaques on their brain, and that's one of the hallmarks of dementia. And there's thinking that these plaques are actually antimicrobial, and it's your brain's

attempt to get rid of the infection sitting in the neuron. Now, this is very new research. It's very speculative, but I think it's super interesting because the oral microbiome we already know is very clearly linked to cardiovascular health. We've done research to show that it's linked in a dose response manner. The number of oral health conditions are linked in a dose response manner to depression risk. Could you explain dose response? It means that if you had two oral health conditions, your risk or your likelihood of having depression was down here.

But if you have eight, it's up here and it goes up like this in a stepwise manner. So it gets higher and steadily as you get more of these oral issues, then your risk of depression is just steadily going up and up and up like like a graph that's sort of like a straight line going up. So the oral microbiome is, of course, directly has access to the brain, but it also makes, there's many pathogens that make their way to the gut, particularly if you're on those PPIs, those proton pump inhibitors, those things that people take for gastric reflux, because that reduces the barrier that stops these microbes making their way to the gut. So all of our microbes- We actually had a podcast talking about this and some of the downsides of taking these pills. That's correct.

And we know that the oral microbes, like everything else, they seem to be influenced by the food that we eat. So this is another link to diet and another way- So again, you're saying it's not that this has always happened with these plaques in your brain. You're saying that the microbes in your mouth are themselves affected by what we eat and then your inflammation is different. It's highly speculative at this point. But basically, diet seems to be able to affect your risk or your mental and brain health

via a lot of different pathways. A lot of this is based on animal evidence at this point, so we really need to do it in humans. We're doing a lot of research at the moment. We've just finished a really, really cool trial where we've looked at the possible impact on the brain of fermented dairy, like kefir, yogurt. We've also just finished a trial, which is sort of a proxy investigation of ultra-processing. So, you know, when people are living with obesity or sometimes they have to have surgery and they need to lose some weight and they get put on these very low calorie diets, so 800 calories a day, really low. And usually they're put on these shakes and bars, you know, these highly processed foods

that say they're nutritionally balanced. They've got vitamins and minerals added and they've got protein and all the right, they've even got fiber added to them. We worked with a couple of dieticians who've developed a range of pre-cooked and frozen products that are the same very low calorie, but they're based on vegetables and legumes and things like this. So that people, because they were concerned that people going on these very low calorie diets really weren't doing their health any good. So we randomly assigned 40 women to receive either the shakes and the bars or the whole foods over a period

of time. And the primary endpoint was the gut microbes. So seeing what happened to their bacteria. Now, I can't give too many results away because this is, we're only just analyzing the results now. But basically, we do see pretty much what we would expect to see. And this, to my mind, reinforces that just because foods have vitamins and minerals added to them, just because they have this nutritional profile that doesn't look like it's too bad, these ultra-processed foods, and here it could be everything from protein shakes and bars

to whatever, I don't think that the body and the brain recognize them in the same way that they do whole foods. If you think about whole foods like plant foods, it's estimated that there's possibly as many as 150,000 different phytochemicals in them. Now, we know about only maybe 20,000 if we're lucky, but that includes things like the polyphenols, the flavonols. 150,000 of these phytochemicals that interact with each other in highly complex ways, interact with every bit of your hugely complex body brain in highly complex ways that we can't even begin to map, not to mention the food matrix, you know, the way a whole food is put together by nature.

All of that is lost when you process foods. It's sort of crazy, isn't it? Now it drives me because I've heard Tim and others talk about this and now it drives me slightly crazy because you see, you know, on some packaged food something says, you know, high in potassium or whatever and I'm now thinking, well, that's fine. But apparently there's 150,000 other things that I need to get. So this sort of focus on these individual things sort of shows you how we've ended up in this world where you have this food that's stripped back

and then has, you know, 15 things in. And then you wonder, I guess, how much we're missing as well as there's been a lot of focus on the bad things in the ultra-processed food. But clearly, there's also this thing about this huge absence of all the things that our bodies are used to having. And even just think about fiber. Fiber isn't just one thing. There's multiple, multiple multiple multiple different types of fibers everything from non-fermentable to highly fermentable everything in between they're all

treated by your gut microbes differently they all have different effects you can't put that into a processed food and just say well it's got fiber and it's okay well what sort of fiber you know like where's the complexity of the fiber that your microbes are expecting to come in? And this is a major issue. And it gets back again to the food system. When you think about the way the food industry... So, our global food system costs the world around $20 trillion a year. $20 trillion? Trillion American dollars.

I don't even know how much that is, but it's a big number. Well, an equivalent would be the whole GDP of China is about $16 trillion a year, right? So this is huge. This is coming from the UN Food Summit. Now, about $11 trillion of that is the impact on health, but about $7 trillion is the impact on the environment. And these two things can't be torn apart because biodiversity in the environment influences the biodiversity in us, our microbes in our gut, in probably every part of our body, in our lungs, the microbes we breathe in. Now, the soil, ideally healthy living soil, the way those phytochemicals get into the

plants is via this very complex, tight relationship between microbes in the soil and fungi in the soil. So nutrients, phytochemicals make their way into the plants from healthy living soil. The way our industrialized food is produced now, soil is dead. There's an estimation that over the next 100 years, we'll actually lose about 30% of the food producing capacity of the soil across the world

because of what we're doing to it with herbicides, pesticides, artificial fertilisers, and also that intense cropping where we just take everything out of the soil, leave it barren, and then go put the same thing back in again. So we've completely got away from how soil used to help our food to grow. Now, that food is eaten by us. It's also eaten by livestock that we then go on and eat.

And don't even get started on the industrialized production of chicken and pork and these things that have huge amounts of antibiotics in them, often to make them fatter. And of course, they make their way into us as well. Now, everything in our industrialized food environment, including the environment we live in, the advertising, the food that's available to us, the subsidies that make these ultra processed foods just so much cheaper than whole foods and so much easier to get. This is what needs to be changed. So, you know, I talk to people and I say, well, we know from the evidence that, for example, the diets that women consume when they're pregnant is linked to their children's emotional health and things like ADHD. We have to change our food environment so that the population is eating in a way that

supports the health of the population. You know, there was a really interesting paper just published. It wasn't a scientific study. It's like a report in Norway. Norway has exceptional data because they have these registries that you can actually go and look at and do scientific testing on. And they basically looked at the introduction of fast food restaurants into the population, which happened in about sort of the 80s in Norway, and then cohorts of children that grew up exposed to fast food restaurants.

So it wasn't directly linking consumption of fast food and children. Just the change in the environment. In the environment. So what happened? And you see an increase in body size, of course, but also a decrease in IQ. Wow. And Felice, you're incredibly passionate hearing this. And I think what's striking is, you know, you're a very serious scientist. You're really on the cutting edge of all this research around the brain and food. And, you know, I heard your answers to the question at the beginning, you know, like many scientists, you're a little cautious about not wanting to say yes or no, but you sound pretty convinced here. I mean, I think you sound pretty convinced this ultra processed food really is having an impact. This isn't just a hypothesis without a lot of data. You sound like you say, no, like the evidence is quite strong enough

in the same way as it might've been with smoking. Maybe that's a good example. How would you compare this? Like we said, wow, that smoking turns out really does have all of this bad impact. We really need to change things. We need to try and convince ourselves to stop. My grandmother smoked for years. My mother smoked in her frozen for years. And then people realize, no, this is really bad. And so people try and shift. And then of course, we try to change the overall environment. I mean, how serious, how strong is the evidence, I guess? Is this just like, oh, I think this might be the case, but really, you know, who really knows?

It's a very interesting analogy because if you look at the global burden of disease study, so the largest health study in the world, it brings together everything we know from health studies across the world, involves more than 2000 scientists. You know, we're doing some work for the global burden of disease study now. Tobacco smoking is up there in the top five risks for illness and early death, but it's up there with the other four factors which are all diet related. So at the global level, poor diet and smoking are roughly equivalent. And the main causes of people dying earlier than they would otherwise.

But at an individual level, people vary enormously in terms of their risk. What you have to do is look at converging evidence. So converging evidence from all the epidemiology where you look at large populations and see these links over and over again. We did a systematic review and meta-analysis that looked at the link between ultra-processed food intake and a whole host of outcomes. Now, obviously, body weight and size was one of them. All-cause mortality was increased by about 30%.

So that's just dying, right? That's just dying, yeah, for anything. But also the risk for depression. It was associated with an increased risk of depression of about 24%, I think. Which is a huge increase in the risk of depression. It is, yeah. And then, you know, we've just finished a study in Australia that's looked at this again in a very large sample of, I think, about 20,000 people and shown about the same increased

risk of a measure of depression over time for people with a higher intake of ultra-processed foods. What's interesting in that study is that the people with the higher intake of ultra-processed foods. What's interesting in that study is that the people with the highest intake of ultra-processed foods were also the most advantaged. So they weren't the poorest or having the lowest income or the lowest education. It was actually those at the other end of the spectrum. But what was also interesting is that those people were actually having less energy intake, less saturated fat intake.

So it looked like these were like diet foods. These were the ultra-processed foods with the artificial sweetness and things like that. Yeah, this is one thing that makes me really angry, which is how many people have been trying to do the right thing, basically, and follow what they think is good and eat based upon the labels they see in the grocery stores they go into of like, oh, this is good for me and based upon the labels they see in the grocery stores they go into of like oh this is good for me and it's got this added thing um one of our previous guests said

this brilliant thing which is said basically any food that has a label on it saying that it's good for you isn't and i thought that i'd never heard that before and then you realize it's basically it's all of these ultra processed it's these breakfast cereals for the kids that say, you know, hi in these vitamins and whatever and those are exactly the foods that. Look, I have had a bit to do with some of these industry players and the nutrition people who work for those big food corporations. They're generally traditionally trained dieticians. They may have been trained however long ago and they genuinely

think that because food has added vitamins minerals whatever that it is a healthful product because that's based on what we knew back then what practically i'd love to switch maybe now it's like to practical practical advice maybe let's start with children and let's think about maybe for our listeners and also maybe also thinking about people as we get really quite old. Any practical tips for us about what we should do? How do we identify this UPF? What should we be worried about and what could we do about it? The thing with these sorts of foods like ultra-processed foods

and these foods that have got a lot of added sugar and salts and fats, they're all designed to interact with the reward system of the brain. Well, they're probably not explicitly designed for that, but they do. They interact with the reward system of the brain. Well, they're probably not explicitly designed for that, but they do. They interact with the reward systems of the brain. And for children and adolescents, those reward systems are particularly sensitive, if you like. And there is some evidence, I believe, that suggests that it is programming the immune system and inflammation and the reward systems of the brain when they're young,

if they're exposed to it, so that they will want to keep eating those sorts of foods. They'll make those choices. And is this all or nothing? Or can anyone listen to this say, you know, either for myself or for my family, maybe I can't cut out all of these ultra processed foods. You know, is there a certain amount? Is it better if you reduce it? Definitely and so what we've seen in our latest study so this big sample of Australians

is that it's only those in the very top quartile like that top 25 percent of consumers of ultra processed foods that had the increased risk for depression. Now you want to normalize healthful foods but we recognize that so many people have challenges with access, maybe storage, maybe food preparation, education. It's going to take time to overhaul our whole global food system. There's huge pushes on to do this. There's big players and things happening at the level of both industry but also government, that I'm hopeful will start to feed into changes in the way we produce foods,

changes in the way we market them, all the rest of it. But governments have to get real about food policy because we're talking about the whole health of the population. But in the meantime, if people are consuming these these foods even just small reductions are going to help and let's say someone's listening to this now and you know we've talked quite a bit about children but let's say i'm a 48 year old listening to this and i would like to cut down on upf but i don't even really i don't even know what upf i'm so sort of like oh my god i suddenly just discovered i've been smoking i didn't even realize I was what's the the way to start down this path if you're advising someone who's who's listening to this podcast and wants to go and do something yeah yeah I think I believe that there's

apps that can help you know like swap sort of apps where that you can go okay I was going to choose that but actually I'll get that instead reading the labels they're always designed to be very very difficult to understand. And what would be your simple- Simple would just be if you pick up and it's got a label with lots of different things in it that you don't recognize, then don't choose that. One of the important things that we did with our SMILES trial was we estimated the cost of the diet that we were advocating compared to the cost of the diet people were eating when they came into the trial.

So people coming into the trial had lots of UPFs, lots of discretionary foods, and we estimated the cost very carefully of their baseline diet. And then we looked at what we were advocating for, and our diet was actually cheaper. Because what we were saying was things like frozen vegetables, they're fantastic. They're nutritionally often even superior. You don't get the food wastage. You have them available the whole time. And they're really inexpensive, relatively speaking.

Tinned and dried legumes. These are your absolute gold in the food department because they're so cheap. And these are beans and chickpeas and things. Beans, chickpeas, even green peas, you know, mushy bees, go for it, because they have so much fibre, so many phytonutrients, and they are very cheap and easy to prepare. Tinned fish. I love the pre-cut salads that you get at the supermarket.

I live on those during the week. I literally get the pre-cut during the week. I literally get the pre-cut salads, especially if I can get the ones that have got like, I don't know, kale and beetroot and all sorts of different, like that rainbow, because then I know I'm getting lots of phytochemicals. I stick them in a bowl. I have a tin of chickpeas or something like that on top. Sometimes I'd put in like a small tin of fish or something, mix it all up, lots of extra virgin olive oil, which is a really important source of these phytochemicals, and some balsamic vinegar, and there's a meal.

And if you want to add in, make it a bit fancier, and herbs and things like that, that increases those phytochemicals too. But super easy. So it's good for your health and sounds really tasty as well. And really tasty and really quick so and I like quick. I think that is brilliant advice I mean maybe final question I think because we've talked about many stages of life but you haven't really talked about older age. Is it all too late if you're listening to this and you're already 80? I think it does matter a lot.

So there's been a couple of really important studies done where they've looked at the gut microbes. So we know that in general, a healthy diet means that you have a more diverse gut microbiota. And your gut microbiota diversity is in turn linked to things like frailty, which includes measures of cognitive decline. And they showed that when people moved into nursing homes, the diversity of their microbes really reduced because their food diversity really reduced. And that was associated with increased frailty and more cognitive decline. Now, we don't actually know over what sort of timescale, you know, what we eat. Just to make sure I understand, you're saying like, basically, again, like bad food leads to bad microbes. And when you're older, time scale, you know, what we eat. Just to make sure I understand, you're saying like basically again, like bad food leads

to bad microbes. And when you're older, you get, you know, your cognition, your brain function is getting worse than other people. So actually it's incredibly important as you're older to think about this. And when we think about- And it's not too late therefore to do something positive to support you with the right food. And so what we see is, you know, when we think about those junk food diets that affected the hippocampus and learning and memory in just such a short timeframe, within a week, within four days, we also see that you get improvements in that within a very short timeframe. And if we look at the literature from the dietary interventions for depression, we can see in as little as three weeks, these really major changes in depressive symptoms.

So within three weeks, potentially, if you really change your diet, you could really feel better mentally. Your hippocampus is super plastic. And one of the interesting things I think is that your skeletal muscles, so the muscles that you build if you're going to the gym, lifting weights, whatever, they actually produce the proteins that help to grow your hippocampus. So when you're going and

you're lifting your weights you're directly increasing the size of your brain so that's really cool that's amazing so i don't think most of us don't think when we're going to the gym that we're in fact we have this bias right that you know you're people go to the gym all the time this is only when i was a kid i think it was like well that's not you know it's like people not really think about their brain and now you're saying actually they're working out their brain as well as their body it looks like like it, yeah, based on the information we have so far. But it does look like you can affect change in your hippocampus and your ability to learn and remember and potentially your mental health really quickly. And that makes

sense. If you think about, you know, you put in food, if it's high in sugar, it gets absorbed by your short bowel, doesn't even make its way to the large bowel, gets straight into your bloodstream and your blood glucose increases. And that seems to create inflammation. It seems to influence your hippocampus really quickly. If you eat good things, fiber and the polyphenols and the healthy fats that we know that the gut microbes need, once it gets down to the large bowel, all those bacteria get to work and produce all these thousands of molecules really fast. And that influences all these systems in the body, our immune system in particular, our metabolism and our body weight, the way genes are turned on and off, the mitochondria, the

way neurotransmitters are produced in our brain. It all happens really quickly. So that's really exciting because it means you can make changes today and have an impact really fast. And that's a brilliant place maybe to wrap up because I think quite a lot of this is slightly depressing. And so I think to finish with this idea that actually you could make a change right now if you listen to this and within three weeks, you could really feel an impact on your brain is rather magical. Even less than three weeks potentially.

Wonderful. I'm going to try and do a little summing up. It was a bit complicated today, so correct me if I get anything wrong. I think we started by just saying that we're now starting to understand that ultra processed food is not just something that might be affecting our weight and some of those sort of cardiovascular risks like heart disease and things like this. It's actually directly affecting our brain and therefore affecting not just our mood, but even our cognition that you think a lot of that is influenced sort of directly through the microbiome and all of these bacteria who apparently make these magic neurotransmitters, which I don't really understand, but they sound like they're

very important as one of the ways that sort of links from what we eat through to things that are going on inside our brain, that there's a particular part of our brain called the hippocampus, which although it's very small, and Felice, I remember you had your hand like, it's very small, but apparently it controls almost everything, like learning and memory and appetite control. And amazingly, it's the only part of our brain that can actually grow, you know, once we're an adult and which is sort of constantly changing. And that the quality of the diet we have is directly linked to the size of this hippocampus. And so you can see that basically people with a bad diet and lots of ultra processed food that you can see see in real time the sort of hippocampus shrinking, and that's linked to a lot of bad things as well, like dementia.

And on the other hand, there is this possibility to improve your diet. It's not too late. You can actually grow your hippocampus. I love that. It's a bit like going to the gym, but for your brain. That overall, the impact of this ultra-processed food, it looks like on a global scale, is as bad as smoking and that that is the only other thing that's sort of as bad as this. And then I think we talked a bit about sort of different life stages that you said to me,

I was right to be worried about my little girl because with children, it's incredibly important. There's sort of this huge amount of their diet that is ultra processed food today that once again, it's like a tough story for pregnant women because you're saying, well, actually like what you eat does affect your children's mental health. And there's already, I think always so much pressure on pregnant women having seen my wife go through this, but also what, but obviously critically what they're eating afterwards is so important. And above all, try and get them to eat as much an adult diet rather than thinking that we should

have all of these like highly processed special foods for um for children and at the other end with older people actually again like the positive story is you could potentially really improve your cognition and frailty by eating the right food. And on the reverse, like the sort of food that you might be given on a hospital or a care home could actually be leading to really fast decline. And then I think the final thing that you said I thought was brilliant I had heard of is potentially you could exercise to improve your brain and that there is actually this direct link. So, you know, if you could cut down the ultra processed food and improve the exercise, you're actually working out on your brain in the same way as you're working out in

your body. Yes, I would agree with a lot of that. I would say that a lot of what we know from association studies, which talks about averages across the population. So, we can't say about any individual the degree to which this is going to influence them. A lot of what we know comes from animal studies, so we still need a lot more work in humans. But if we bring all the evidence together, it looks like diet really does matter to mental and brain health right across the life course from the start right to the end. The degree to which it matters, we don't know yet. In regards to smoking, I think at an individual level, junk food is probably not as bad as smoking, although it might be.

At the global level, it's certainly diet and cigarette smoking are pretty much the leading causes of illness and early death. So there's a lot that we still don't know. But if we bring together all the evidence from human and laboratory studies, we see that it's all converging on this idea that what we eat is just as important for our mental and brain health as it is our physical health right across the life course. And that makes sense because mental and physical health are really just one and the same thing. We are one highly integrated, highly complex system.

I love that story, Felice. And I think in terms of getting more evidence, I hope we're going to be able to announce to our whole ZOE community soon some new studies allowing us to do some of these interventions and understand more in sort of the large populations, which are normally so hard to do. So lots of people, how what we can affect our brain health, our mood, our cognition, because it seems like one of the reasons we don't understand this is just there's been incredibly few studies until very recently. Yeah. What we need to do is push our politicians to help us, help the whole population to have access to better, healthier food through food policy. We need to have proper food policy. It shouldn't be up to the individual to have to make those really hard decisions every

day about what to eat because it's confusing and industry has had a vested interest in making it confusing. Please, that's a wonderful place to finish. Thank you so much. Really excited by the studies that we have planned together and excited to talk about some of these new studies that will be coming out in the next year. We've got a lot coming out in the next year.

So watch the Food and Mood Centre space. We will. And we'll have links on the show for all of this. Thanks, Jonathan. Bye-bye. That was great fun. Thank you, Felice, for joining me on Zoe, Science and Nutrition today. If you want to understand how to cut down on ultra-processed foods

and support your brain with the best foods for your health, then you may want to try Zoe's personalized nutrition program. You can get 10% off by going to joinzoe.com slash podcast. As always, I'm your host, Jonathan Wolfe. Zoe Science and Nutrition is produced by Yellow Humans Martin, Richard Willen, and Alexfe. Zoe Science and Nutrition is produced by Yellow Humans Martin, Richard Willan and Alex Jones. See you next time.