ZOE Science & Nutrition - Nutrition Scientist: This is why you're confused about ultra processed food | Prof. Sarah Berry

Episode Date: August 7, 2025

Scientists agree that processed foods are contributing to poor health — but when it comes to ultra-processed foods (UPFs), there’s growing confusion. The term is now used so broadly that it includes everything from crisps and sweets to wholemeal bread and plant-based milks. So what do we really know about the health effects of UPFs? And is the label actually making it harder for us to eat well? In this episode, Jonathan is joined by Dr. Sarah Berry, ZOE’s Chief Scientist. Sarah is a professor of nutrition at King’s College London who has run some of the world’s largest human nutrition studies. Her work explores how different foods — and how they’re processed — impact metabolism, fat storage, and long-term health. Sarah shares insights from her recent global conference talks, breaking down the good, the bad, and the misunderstood sides of ultra-processed food. By the end, you’ll have a clearer, more nuanced view of how to eat for your health — without falling for the hype. Unwrap the truth about your food 👉 ⁠Get the ZOE app  🌱 Try our new plant based wholefood supplement - Daily 30+ *Naturally high in copper which contributes to normal energy yielding metabolism and the normal function of the immune system Follow ZOE on Instagram. Timecodes 00:00 Introduction 02:50 The scary headlines about your food are wrong 07:40 The food classification system scientists call 'useless' 09:25 Why not all peanut butters are created equal 11:05 What really makes a processed food unhealthy? 12:20 The difference between 'safe' and 'healthy' food additives 15:50 What food companies remove from your food 17:30 The invisible 'food matrix' that processing destroys 19:05 Why you don't absorb all the calories you eat 22:25 An apple vs apple juice: the shocking results of a 1977 study 25:05 The ingredient label lie you're falling for 26:25 Why soft food makes you gain more weight 28:40 Even a nutrition scientist with 25 years of experience is confused 32:45 How we're building a new system to score processed food 35:52 The science of 'hyper-palatable' foods 39:00 How food is engineered to make you overeat 42:10 It's not 65% of food, it's this much you should worry about 45:30 The financial reality of eating healthy 51:47 Using processing for good: the 'wonder bread' of the future 55:17 If I switch to low-risk food, will my health improve? 56:45 Is processed food damaging our brains' hunger signals? 📚Books by our ZOE Scientists The Food For Life Cookbook Every Body Should Know This by Dr Federica Amati Food For Life by Prof. Tim SpectorFree resources from ZOE Live Healthier: Top 10 Tips From ZOE Science & Nutrition Gut Guide - For a Healthier Microbiome in Weeks  Have feedback or a topic you'd like us to cover? Let us know here. Episode transcripts are available here.

Welcome to Zoe, Science and Nutrition, where world-leading scientists explain how their research can improve your health. Today's supermarkets are full of processed foods. We know beyond doubt now that they play a major part in the epidemic of poor health and obesity across the world. But while science now shows us the risks of food processing, In many cases, simply labelling all processed food as bad can be misleading or even wrong. In fact, processing can in some cases make things healthier, reducing blood sugar spikes,

or improving micronutrient absorption, just as examples. And let's not forget, making things more affordable and longer lasting too. The truth is, there's a deeper, often unseen science behind food processing that significantly impacts our bodies. Today we welcome back Professor Sarah Berry, a world leader in large-scale human nutritional studies, a professor in nutrition at King's College London and chief scientist at Zoe. Sarah has dedicated decades studying the intricate ways that food processing affects on metabolism and our overall well-being.

By the end of this episode, you'll understand how processing makes some foods unhealthy so you can make better choices for your long-term health. So, Sarah, I thought we'd try and do something different for this podcast episode, because I know that you have been doing this talk about processed food to lots of different nutrition science conferences around the world. And I actually just thought it would be really amazing to let our listeners actually hear that. And hopefully we can talk a bit about it and I will ask some questions when I don't understand it and really bring, you know, literally the cutting. the edge of science around processed food to anyone who's listening today. Love that. I love doing something different and I also love doubling up on things. I've done all of this work that I've been presenting to the scientific community

and the fact that I can present it here to you is really exciting. So what was the talk called? So it was called Process Food, the good, the bad and the ugly. Tell me about it. It was very much bringing together all of the science that I'd been involved in around looking at the health effects of how food processing impacts our health. But taking a new perspective and moving away from this kind of demonisation that we've been using around ultra-processed food and actually understanding how different processes involved in processing food can impact our

health differently. They're not all ultra-processed food is bad for us. Now, if you look in the newspapers, you see on social media on the TV, every day there's a new headline saying, ultra-processed food, it's going to kill us, it's giving us Alzheimer's, it's giving us cancer, it's giving us every disease going. You see a headline every day, don't you? It's all down to ultra-process food. It's going to end mankind. And these are really scary headlines. Yes, we have a problem. Yes, our food landscape is broken. Yes, we're eating so many heavily processed foods are so bad for us. But demonising all ultra-processed food is just wrong. And as I always tell you, Jonathan, on the podcast, it's just not as simple as that. It's a lot.

lot more complicated. So now I'm intrigued. Tell me about it. So I actually started working in the area of how food processing impacts our health back in 1999. And it was interesting when I was developing these talks, it actually made me stop and think, well, you know, this isn't anything new yet we're only hearing about it now. And I started back in 1999 looking at how processing fat to change the texture of fat, the mouth filler of fat, the melt profile of fat impacts our health. And so this is something a scientist we've been doing for many, many years. We've been looking at how processing food and therefore processed food can impact our

health. When you say processing food, could you help to understand what that means? Because I think when I hear the word processed food, I immediately jump to like Frankenstein food that's really bad for me. But I think you're using this in some different way? When we think about processing food, you know, even cooking rice is processing it, even cooking your carrots is processing it in some way because you're changing it from how it came out of the ground. But I think when we think about how processing food impacts our health, we need to think about it taking it a little bit of a step further, thinking about how not necessarily we process it in the home, but how we process it using industrial techniques, how we process it commercially. And there's a wide variety of techniques that the food industry use.

There's really simple techniques, just like grinding. So you're just grinding something down into her powder. There's techniques called extrusion that sound a bit scary and it's pushing these things through at high heat, at high pressure. So think of what sits, for example, or cheesy puffs. They use various processes, including excruion. So it doesn't even look like the food that it came from. Then you've got processing that's changing the structure, adding chemicals, ripping things out,

putting things back in. But again, it's not meaning that they're all unhealthy for you. So I think the first thing you need to think about is what is it about food processing that makes it unhealthy? And how can we therefore recognize the really ugly ones? How can we recognize the bad ones? And how can we not worry about the good ones? It's really interesting what you say because, you know, I think I do naturally think about food processing as being bad. But as you said, it suddenly made me think about like making cakes.

I am not a big baker. But like I've done a little bit of this, like with my little girl. because it's really fun. And one of the things that is really interesting if you've ever done it for the first time only as an adult, which was me, is you realize, like, you do all this weird stuff with eggs, right? And you, like, separate out the yolks and the white,

and then you realize, you can, like, sort of beat them and put them together and suddenly magical things happen that don't just happen if you smash the egg up and throw it into the cake. And I'm sure lots of listeners are like, what an idiot, obviously know that. But to me, I was like, wow, that's really amazing. Brought out, like, my inner physicist. With that counters processing, what you're just, you know, like, separating out the whites,

and the yolks and using that to make a cake? Is that also a sort of processing because it's not just sort of completely raw and natural? Yeah, in really simple terms, anything that you do with the food that changes it from when you kind of pull it out of the ground, so to say, is a form of processing. But I think what we should be focusing on here today and what listeners should be thinking about is how processed food is processed in such a way that can negatively impact our health. And I think there's some really scary statistics out there that we need to really put into context. So you see these scary headlines saying, you know, 65% of our food intake is from ultra-processed food, which is why it's, you know, going to kill us, going to cause

all of these awful things. And not all old-processed food is created equally. There's lots of research in these big population studies that show that people who have more ultra-processed food have higher rates of many, many different diseases. Yes, there's evidence out there. The problem is, is that once you break down into food groups, you see that they're not all the same. So, for example, sugar, sweet and beverages, so fizzy drinks, processed red meats, salamis, hams, those kind of things. They're driving a lot of the association. And so some ultra-processed foods for us are a lot worse than other ultra-processed foods. But there's a classification system that's typically used in order to classify if a food is ultra-processed. And this is called a NOVA classification.

It was created about 20 years ago. And it was created in order to assess the degree of processing and the purpose of processing and where the food was processed. It was never developed to tell us how processing impacts the helpfulness of that food. And so it's actually quite a useless tool because it's telling you, yes, how much it's processed, but it's not telling you whether it's healthy for us or not healthy for us. And this has been a real limitation around the use of the term ultra-processed food and something that's been really contentious for us as scientists. I once gave a talk a couple of years ago around ultra-process food, and ultra-process food was in the title of the talk. It was at a nutrition conference and the speaker before me at the end of

his talk said, well, the next talk, which is on ultra-process food, should. shouldn't even be allowed at a nutrition conference because we all know the term UPF is nonsense. Wow. So that was a bit hard getting up and giving that talk. But I got up and I gave that talk with confidence knowing that yes, the term UPF, old processed food, which is generally using this NOVA classification, yes, I don't think it's fit for purpose to tell us which food someone should select in order to know if it's healthy or unhealthy.

Yes, it's been great in giving us an overall idea that hold on, there's a lot of food processing that may negatively impact our health, but we know that it's a lot more complicated than that. And what's really important as well is that we need to be thinking about processing right down to the brand level when we think about how it impacts our health. So what I mean by this, and I use this as an example in a lot of my teaching, is imagine peanut butter. Now, you might be told, okay, Jonathan, peanut butter, it's healthy, go have some peanut butter. Well, actually, you can have a huge diversity of peanut butter. They're all processed because you've taken the butter, you've ground it.

So they're all processed. But you could have something like Reese's peanut butter that has about 20 different additives, emulsifiers, colorants, sugar, all sorts added to it. It's really, really unhealthy. It's my kid's favorite, unfortunately. You could have something like a sun pat peanut butter that I know is very common in the US and the UK that's got a few extra bits added in it. And then you can have these kind of more homemade style of peanut butter.

like pipa nut and, you know, the very kind of whole food style peanut butters that are literally the peanuts that have just been ground and might have a pinch of salt. Now, processing has impacted that entirely differently. And so you've got two foods, but they're going to have entirely different impacts on your health. But generally, we would classify them all probably under one category. And so this is why we need to think about food processing or rather processed food in an entirely different way. And we need to think about it by first taking a step back and thinking, okay, what is it about processed food that makes it unhealthy? And therefore, how can we assess the healthfulness of that food? But more importantly, how can we guide consumers

in order to choose they're good rather than the bad and the ugly? Well, I feel you've just set me up now because I want to ask the question, what is it about processed food that can make it unhealthy? So processing food can impact the healthfulness of food through lots of different ways. the first thing is by what is added in. Typically, it tends to be higher in sugar. It tends to be higher in salt. It tends to be higher in saturated fat. Also, it tends to have lots of added ingredients that we don't fully yet understand how healthy they are. So by this, I mean additives, I mean emulsifiers, I mean colorants, for example, and non-color ingredients. So ingredients you wouldn't typically find at home. Now, many of these have been passed as being safe by very tight

regulatory bodies, but we're really starting to understand now that actually, although they might be safe, they might actually, over the long term, negatively impact our health, because we're starting to see studies emerge to show they might negatively impact our microbiome, and we know it's very how central our microbiome is to all of our health. Can you just help me to understand what it means when you say they are safe and that they negatively impact my health? Because I think about those as, well, you can't say both those things at the same time? So there's regulatory bodies that look at the safety of different additives, different kind of commercially or industrially created ingredients. And they do all of these

kind of toxicology studies where they feed them at certain doses, typically quite high doses to mice. They look, does it affect cancer? Does it affect cardiovascular disease, etc., etc.? And so those studies have to show that they are safe, that they're not causing cancer, that they're not causing these diseases. But what hasn't been looked at typically is in humans is seeing, okay, does it affect kind of novel parameters or novel features that we haven't typically thought about, such as the microbiome, which is a new area of research. So you're saying there is this like way of checking whether something's sort of toxic, right? So you're saying you're feeling it to mice at very high levels, you would realize that it was poisonous or that

it was like going to cause your liver to fail or something you could really measure. So is this sort of thing that would catch, hopefully, whether something is causing cancer. Yes. But then you're saying what it doesn't do is catch maybe subtler effects, which is, for example, it's disrupting your microbiome, it's changing the microbes inside it, and that might affect your health over time, but not in such a dramatic way that a mouse is going to get cancer. Yeah, absolutely.

And does that help to explain why, particularly in Europe, right, where those regulations are quite tight, like we've also seen this explosion in diseases that are. lifestyle diseases over the last, you know, 40, 50 years and the changing food, but all of that food, like it did sort of pass this test, but obviously something has happened because we're all feeling less healthy. Yeah, so I don't think it's just to do with the additives, and I can come on to some of the other mechanisms, but I think we need to be more mindful of do we really need these additives? Do they really have no long-term impact on our health? And we're starting to see certain additives. So, for example, certain sweeteners, we now see, yes, some do seem

to be neutral, but actually there's now some good emerging evidence to show some sweetness, for example, negatively impact the microbiome, and that how they impact the microbiome may, in the long term, cause insulin resistance and change how you process glucose, etc. So I think it's something that we're going to start to see more and more evidence appear. One of the things that I understand is that the restrictions in the US have not been as high as the restrictions in Europe in terms of these additives. Is that right? And is it a meaningful difference?

So from what I understand that's right, it's at this point, as always, Jonathan I caveat, with what's not my area of expertise. And I don't fully understand all of the legislation around the additives that are allowed in the US versus the UK. But generally speaking, in the UK, we've been stricter around what we allow compared to the US. But there have been, in the recent months,

a lot of discussion around now really clamping down in the US on some of the additives and some of the added chemicals that are put in food. So I think things are starting to change now in the US. I think you were saying it isn't just a story about additives, however. Yeah. So at the moment, I think lots of people think, ultra-processed foods, it's all of these scary additives that are put in and these colorants, etc. But in addition to that, and in addition to the fact that ultra-processed foods or tend to have a lot more of these unhealthy ingredients like the salt, saturated fat, they also tend to be really low in really healthy nutrients. They tend to be really low in fibre, really low in bioactive. So bioactives, I mean chemicals like polyphenols,

which are found naturally in plant-based foods that have these wonderful effects throughout our body. So they tend to be low in healthy nutrients. What we also know is they tend to be quite energy dense. So what we mean by that is, you know, per gram of food, they tend to have more energy than an unprocessed equivalent, which means that it's very easy to overeat them. To translate that from your nutrition science, that means that like in a small amount of this food, there's a lot of calories compared to a normal food that I, like our ancestors would have been able to eat? Absolutely. So it means therefore you can get a lot more food in, a lot more calories in, a lot more quickly. And one of the reasons for this is because the food

matrix. So the food structure has changed. And so the way I often think about how processing impacts our health, I think about it in two broad buckets. One is the nutrients and the chemicals, which we've just talked about, and the other is the structure of the food. And the structure of the food, we call the food matrix. And the food matrix is typically destroyed when a food is processed. So this could be really simple just by grinding the food down. It changes the structure of the food. It changes, therefore, how much of the food we absorb, so how much of the calorie we digest. It changes the rate at which we digest it. It changes where we digest it in our gastrointestinal tract. Could you just explain for a minute what this food matrix was that you've now destroyed by grinding? So food matrix

really simply put is the structure of a food. When we talk in nutrition science about the food matrix, we talk about the structural integrity or the structure of the food and also how the nutrients within the food kind of interact with the other nutrients and the structure of the food. So I can give you a really simple example from one of my own studies. So if you take whole almonds, for example, nuts, and you grind them down, you change the matrix, you change the structure. By grinding them really finely, you break the cell walls and it's the cell walls. And it's the cell walls that have quite rigid structure that encapsulate the nutrients of the nuts. So this means like the protein and the carbohydrate and the fats and the nuts. So what that means is

if I was to give you a whole almond, so the matrix, the structure is intact and you were to eat that, what would happen is, is that actually a lot of it is resistant to digestion because you're eating it, you're chewing it, you're breaking some of the cells, but actually not many. The point at which you swallow is about one millimeter particle, and we know this because we do these unglamorous chew and spit studies where we actually get people to spit them out and we measure it with, well, actually not with a ruler. We use a fancier piece of equipment, but anyway. You get to do all the most glamorous studies, Sarah. The chew and spit ones are the worst. And then you swallow, and you swallow these big particles.

But the particle size, actually, of an almond nut is only a few microns. It's smaller than a grain of sand. So you've got all these intact cells passing through your intestinal tract. a lot actually comes out in the poo. About 30% of the calories in nuts just comes out the other end. So what's on the backpack labelling is a total overestimation because it's coming out in the poo. What's also happening is then you're giving loads and loads of great food for your microbiome who are having a party down there. You're delaying the post-prangeal, so these post-meal responses that you see in circulating fat that also happen after milk.

So you're having loads of things going on, which I think are good for you. Now, if I then go and grind it, so I'm breaking that food matrix, I'm using industrial processes to really finely grind it. That's different from an at-home grinding? Yes, it would be quite difficult to grind nut particles down below the size of a cell of an almond. So this would be using industrial processes, for example, are used to make marsupan, for example, into a flower. Now, you're breaking all the cell walls, so you've destroyed that matrix, you've destroyed, you've destroyed that structure, it passes through your gastrointestinal tract really quickly. You have a big peak in circulating blood fat from the fat in the nuts, and you absorb it all.

You're not getting that 30% difference. And so you could have two foods. They have identical back-upac labelling, but they have entirely different effects on your body. And we see this with carbohydrate-rich foods again. So we see this with large porridge versus finely ground porridge. You see differences in terms of if you're having large porridge. Open me off for some of us. Yes.

If you're having that, then what happens is you have a very slow release from your stomach. You have a very slow, more gentle change in circulating blood sugar. You don't seem to get the dip in blood sugar that you would get from most carbohydrates. So you stay full for longer. It's also absorbed lower down your gut, your gastrointestinal tract, where you're packed full of these fullness receptors. So it's saying you're full. yet if I was to feed you, and we've done this experiment at Kings, if I was then to feed you exactly the same porridge but finally grind it.

So again, all you're changing is the structure. It's totally different. You get a 50% higher increase in circulating blood glucose. You get this big dip. You feel more hungry. You get less of a release of your fullness hormones. So things like GLP1, which we know tell you how full you are. All we've done is change the structure.

And this is really important when we're thinking about how processed food impacts our health, beyond just the nutrients, the additives, for example. So if I understand rightly what you're saying is it's not just about the additives in this process food. You're saying that this process of like grinding things up or some of those other extrusions or whatever else fundamentally changes the properties of this food so that then when I eat it, it might still be called a nut in this example. But actually what's going to go on inside me is completely different. Absolutely. It's changing how much you digest, it's changing how quickly you digest it, and it's changing where you digest it. And I think another way that's

really easy for listeners to visualize is to think about it in relation to smoothies. So this is a really great example of where just changing the structure of food can change how full you feel, how you metabolize it, and how much energy you go on or calories you go on to consume. And actually, there was a study that was done in 1977 by a guy called Haber was published in the Lancet. It was probably one of the first studies ever published in the Lancet because nutrition science historically was the poor man science. It's only now that people are actually talking about it. And this was a study where he fed people whole apples. He fed people exactly the same amount of carbohydrate from apple puree. So he literally took the apples and just pured it like in a liquidizer or blender.

and then he fed people the apple juice where he strained out all the kind of pulp. But each one had 50 grams of available carbohydrate. What he found first was that the apple was eaten a lot more slowly. The apple puree was eaten about 10 times more quickly. And the apple juice was eaten about 20 times more quickly. Wow. That's a huge difference. Now, I've actually repeated this experiment at my kid's school on one of those 10%.

your mum to school day and got all the kids to do it. And they replicated these results almost identically. Anyway, so what he did was he then said to everyone, okay, can you come back and can you all eat these exactly the same time? So first, you're eating them very quickly, which is before your fullness signals will hit in for the ones where the texture has been changed. Come back and have the apple, the apple puree and the apple juice and eat them within the same time. So you're going to have to really consciously slow down the apple juice and the apple puree. And even though they ate them at the same rate, there was still a big difference in the blood glucose response, so the blood sugar response.

There was a really big difference in the dip. And I think this is what's really interesting. There was no dip in circulating blood sugar after having had the apple, two to three hours after. When they had the apple puree or the apple juice, there was a big dip. And we know from our own Zori research that if you have a dip in circulating blood sugar, you go on to eat 100 calories more at your next meal, 300 calories more over the day. you feel more hungry, you have less energy, etc. So we know that's not a good thing. But also,

there was huge differences in hunger and fullness. So the apple kept them full for ages. The puree and the juice, they felt ravenous really, really quickly. All we've done is change the structure. All we've done is change the texture. And I think this whole area of texture research is fascinating. And this is something that when we're thinking about how healthy a processed food is, we can't just think of those additives, we have to think about the texture. We have to think about how it impacts things like energy intake rates, so how quickly we're eating those calories. We have to think about how it's impacting how much and where and, you know, these calories are absorbed as well. And am I right that if I was to look at an apple juice or an apple puree or an apple with a

label on? And I turned it over to look at the label. They would all just say ingredient apple. So they would all say ingredient apple. I mean, some apple juices do have preservatives added to them, but let's assume they'd all say apple. If you were to look at the apple and the apple puree and you looked at the breakdown of the nutrients, they'd be identical. Exactly the same fibre, fat, protein, carbohydrate, water. So there's no change in that example of what's in there. It's just the act of like breaking down these, I think about this like my, you know, school biology, like the cell wall. and all this stuff being broken down into sort of this mush has suddenly completely changed the way my body's responded.

And it sounds like in a very negative way. Like the way you're describing it sounds like eating this as apple rather than the apple puree is much better for me. Absolutely. Because you're eating it more slowly. You're absorbing it lower down your gastrointestinal tract where you've got more fullness receptors. So you're feeling more full. You're allowing the time for the fullness of receptors to say, hey, Jonathan, you've had enough. rather than this kind of like fast food, so to say.

And I think if we bring it back to where we started this conversation around this dreaded term ultra-processed food, there's some fascinating research that's just come out where they've looked at food texture, which is what we've been talking about, in relation to ultra-process food, and how that impacts our energy intake and our weight. And what they found was that if you feed people,

ultra-processed food, and this is according to that NOVA classification that we've talked about, that's soft, you eat loads of that, you eat excess calories from that, and you're more likely to put on weight. If you feed unprocessed but soft food, you still eat that quite quickly. Could you give me an example? Oh, now you're putting me on the spot. It could be yoghurt is a good example of an unprocessed soft food. So you're still eating it very quickly because of the texture.

If you then have an ultra-processed hard food, you eat that more slowly and have less over-consumption of calories even than the unprocessed soft food. So it's a bit complicated, but it's like this kind of, if you think this step down, where the worst in terms of the rapid rate of eating, the over-consumption is your soft ultra-processed, then the next step down is your soft unprocessed. then the next step down is your hard ultra-processed, then the next step down is your hard unprocessed. So it is a little bit complicated, but what I'm trying to say is it's not all about whether it fits in this terminology of ultra-processed food according to this NOVA classification.

Actually, the over-consumption, the calories, is more related to the texture, which goes back to the food matrix rather than, oh, is it NOVA-4, which means it's ultra-processed or not. I'm also struck that it took you a second to think about what was a soft, unprocessed food, which tells you that there's not that many of them in our natural environment, I guess. Yeah, I find this whole segregation of unprocessed and ultra-processed actually really hard. So I think, yes, it's partly that, partly because most foods in nature are quite hard. So I think you've picked up on a really important point. But I would say if people ask me, oh, is this old processed, isn't this old processed?

I actually don't know. I've had 25 years training as a nutrition scientist. And I don't know. I'm so confused. And, you know, I shouldn't be confused. I should be able to tell you, oh, that's old to process, that's bad for your, that's not. And it's because of the way that this classification system has been set up. And this is why we need to look at things differently.

You've talked about added ingredients that can be bad and which means. maybe we weren't testing for in the right way up until now. So there's all these additives, some of which we just know are bad and maybe we've allowed into our food for any reasons, but also things that maybe like sweeteners and things like this that we didn't know as much. But Jonathan, I think it's sort of important to say, I wouldn't worry, no one should be worried that there are additives in there that are about to give them cancer. We just need to be more cautious that there's some that there's some evidence emerging

that we should be trying to avoid. and there's others that we know are less problematic and there's others that we know actually might even be beneficial. Okay. So we've got these additives. You're saying we shouldn't necessarily be like, oh, there's any additive that's immediately going to give me cancer. That's not the way to think about it.

Then I think you said there is sort of the absence of healthy things. So this is like stripping out all of the nutrients that you would get from like a whole food that might be feeding my microbiome and my body. in general because I sort of ripped that out and then sort of doubling down on sugar and saturated fat and things that are bad. So that's the second part I think you talked about. And then you said, but hang on a minute, there's this whole thing to do with the structure of the food, which historically no one's really focused on. But we haven't been talking about it enough. Okay, this whole thing about structure and the difference between the food being turned into something soft versus something

being hard, meaning that you're going to eat much more of it and you'll eat loads before you realize that you're full, but also that the grinding itself can destroy a lot of those nutrients. So it's not that in that case, they haven't necessarily been pulled out of the food, but actually just they've been smashed to pieces so you're no longer getting the benefit of them. Yeah, so spot on, apart from the last bit, it's not so much that the grinding destroys the nutrients, but it destroys kind of the properties of the nutrients. So most fibre, very simply put is plant cell warm material, so has a really important structural role. And so it has a structural role in essentially kind of slowing down the food.

So when it's intact, it slows down the rate it's absorbed. It changes where it's absorbed. Hence why fiber can also add this satiating, this fullness effect to food. If you grind the food, basically you're breaking the fiber up. So the fiber is still there, but it's not intact and it's not performing that magical role that it performs in that structural way. Got it. So it's still in there, but it's sort of like the, again, I'm thinking back to like my little school cell wall picture. It's like keeping everything safe inside and delivering it slowly. Almost like a little pill, I guess. Like when I take medicine, right? Like takes it, keeps it intact for longer. And you're saying I've broken all of those cells. So everything is just open and my body digests it sort of instantly. And then my blood sugar goes through the roof and all of these sorts of things. Totally. Like imagine a water balloon, for example. And so you've got the rubber, you know, keeping the water.

safe inside. So that's just like the fiber is like the rubber, keeping all the nutrients inside. And then you break that. And everything comes out. And this highly process feels like being hit by water balloons. I like this. So you took us up to this point. Is it also complex that was sort of doomed and it's impossible to sort of differentiate between any of this? So I think it is really complex. And I think it's a really, really difficult challenge to be able to to differentiate between a good processed food, a really bad processed food and an ugly processed food. But this is what we've been working on with the team at Zori over the last year and working on really hard, building on all of the science that we already know that's been going on over the last 20 years or so

and using the fantastic database as well that we have at Zori that kind of gives us that ability to be able to do science in a slightly different way than I would be able to do in my traditional academic setting. So we have this kind of gold mine of data that we can leverage in order for us to develop this kind of understanding and put it into something that's translatable for individuals. And so we've been working on trying to pull together the different features that you and I have just been talking about that we know processing impacts to negatively impact our health and trying to do that in such a way that we can then advise people on what foods are really bad and what foods aren't really bad. And these features include everything that we've just talked about. So it includes things like the additives, the emulsifiers, the colorants, but it grades them. A food could have 10 additives, but they could be all low risk. They could even have an additive like in your limb, for example, which is fiber, which is class as an additive.

But actually, it's healthy. Or you could have a food that just has one additive, but we know it's one that the evidence is starting to emerge that is negative for our health, negatively impacts our gut microphone. yes, won't give us cancer, but still we feel that it's not something that we should be having regularly. And so we wanted to create a system where firstly we looked at these additives, these emulsifies, these colourants, but graded them according to their predicted impact on health, where you've got some badies, you've got some in the middle, kind of medium risk, and then you've got some that are neutral. Then what we wanted to add in is something to be able to look at how that food matrix, that structure, the processing also impacts our health.

So we've added in a measure called energy intake rate. And it's very much like a surrogate. So it's a way of looking at how the structure has changed. And basically, energy intake rate is a measure of telling you how fast you're eating your calories. So is that like your apples versus your apple juice and your puree example? So it's exactly like the apples and the apple puree, they would have entire. different energy intake rate. Your apples would have a very low energy intake rate. Your apple puro would have a really high energy intake rate, which means you're going to over consume

it, which means you're going to consume excess calories. And that is the biggest problem that we have. We're dealing with a problem for the most of the US and most of the UK, not everyone, but internationally overconsumption of calories for many people is a problem. And so that's what we need to tackle with these processed foods where it is a problem. So we have the future of energy intake rate and it's the surrogate at the moment for food matrix because it's not possible to tell exactly has every cell been broken down. This is a really good measure for us to use instead. And then we brought in a third measure and the third measure is something called the hyper palatibility index. What is hyper palatibility? So hyper palatibility is basically a term

to describe it being too yummy, too good to be true. And so what we know is, is that in many processed foods, there's kind of like this magic mix of nutrients of, for example, salt and fat or sugar and fat that wouldn't typically be found in nature. But when it's added in particular ratios, makes that food so yummy that it bypasses these kind of sensory specific areas of the brain that would normally say, well, hold on, you've had enough. And so if you think of, I don't know, what's your favorite ultra-process food? Pringles. Okay, if you think of Pringles, they're salty, they've got lots of, like, really refined carbohydrates. So you can just eat and eat them. Like, it isn't their advert, you can't.

Once you pop, you just can't stop. I used to really like them, and now you ruined this for me over the last few years. But is that an example? So you're saying it's not just because it's soft. So it's not just that it's soft. So we're assessing the softness in a surrogate way with the energy intake rate. What we're doing here is we're looking at how yummy that food is in such a way that it's kind of tricking our brain to overeat it. So there's some research that's been done by external researchers over the years that's looked at a particular mixture of different nutrients that wouldn't be typically found in.

nature that we know seems to be associated with overconsumption of a food. So, for example, and I don't remember the exact proportions. For example, a particular cutoff of salt alongside refined carbohydrate or a particular cut off of fat alongside a particular amount of sugar, for example. And when you say refined carbohydrate? So your pringles is refined. So carbohydrate, where the structure has been destroyed, so refined carbohydrate like white, red, for example. Oh, so this is where it's a carbohydrate, but once I eat it gets turned into sugar almost immediately. Yes, so really what I call a quick carbohydrate. I've heard this term bliss point mentioned before as like nutrition scientists creating this sort of bliss point between sugar and fat and salt.

Is that the same thing? Yeah, so it's sort of the same. There's this idea that it activates these reward centres in your brain, that it gives you this kind of dopamine hit. It is, I need to caveat, as I always do, a new area of research. There are some skeptics out there about whether hyper palatable index is, you know, is there yet enough science to support it? But I think what science is out there to date is quite supportive of the fact that there does seem to be something going on that activates these awards centres that just means that you go on wanting more. There's very few people, I think, after having an apple that are left thinking, oh my God, I just want another apple. I would say there's far more people that eat those pringles of yours and say, oh, I would like a few more of those.

I was thinking about, you know, potato chips or crisps as a great example. So I do really like those as I think about like one of the things. And I'm quite careful about trying to choose a healthier one. So it might just say, like potato and some sort of oil and salts are only three ingredients. But what's interesting is I can eat a really big bag. I wouldn't eat that many potatoes. I certainly wouldn't drink oil. and if it was salt on its own, it'd be disgusting.

So it's something about the combination in just the right proportions that is making me just want to keep on taking it. And I do, right? You eat it really fast and it's delicious and you want more and more and more. Is that this hyper-pallotability? Yeah, so it's having exactly that, the combinations in just the right amount that hits those reward centres in your brain that leaves you wanting more. Let's say regular potato chips or crisps for those in the UK

that quite often might just have potatoes, might just have oil and just a bit of salt. That's a great example. You've just got three ingredients, which individually are fine. But when you put them together, becomes so delicious that they surpass your normal kind of fullness signals, that they hit those bliss points, as you call it, that leave you just wanting more and more. I think it's really interesting because I know that there's been a lot of stuff in the media from big food, but also certain nutrition scientists pushing back on the idea that there is anything different about processed food beyond the fact that it just happens to be like junk food, as I was told as a kid, which means it's like it's got sugar in it, it's got saturated fat. So in other words, there's no difference between that and anything, you know, that was like a treat in the past. And I think what you're saying is it's not just the ingredients. It's not just whether or not it has sugar in it. or, you know, that it's got sort of saturated fats in it, actually, if you can design the product

just right, you get this sort of combination of these ingredients that sort of overrides my natural tendency to say, oh, I've had enough, I'm a bit bored, I'm not going to eat that anymore. Yes, I think that's just one component. I think it's less important personally than the texture and the energy intake rate and less important than the macronutrient composition. So I think we shouldn't be too obsessive about this hyperpalatomy index, particularly given that we're still waiting to see more research about this. But I think certainly it's something that we need to pay attention to. So it's like one component in the overall understanding. Yeah, absolutely. So what do you tell

all these scientists after all of that? We've developed this new score that we've been working on as a science team that takes into account all of these factors, and it weighs these different features in such a way that it can categorize processed food into those good, the bad and the ugly. And I think for me, what's most empowering about this, and this is as a scientist that has hated the turmoil to processed food, hates the demonization of processed food, is that through the score that we've developed, we've been able to see in the U.S. and the UK, it's not so. 65% of processed food that we should be worried about. It's actually only about 20 to 25% of the food

that's on the supermarket shelves in the US, in the UK, that is actually processed in such a way that it's quite bad for our health. I'm guessing that in your science and you don't call it ugly processed food. How does this end up being categorised? So we've generated a scale and this scale goes from being high risk to medium risk to low risk to no risk. And so what we have is this incredible food database where we've got millions of foods that are in our food database that are at brand level. And if you remember when I talked about peanut butter, it's really important to think of the brand level, i.e. the recess peanut butter versus the sum pat versus the pipa nut.

And are they all the same processed food risk? Absolutely not. So the recess would come in at high risk, the sum. compact comes in at medium risk and the pipin nut at no risk. And so we have millions of foods that we're funneling through this pipeline that we first categorize them according to, okay, what additives emulsifies colorants are in them? Are they fine? Are they ones we should be a little bit more concerned about?

Then we look at what's their hyper palatibility index. Then we look at what's their energy intake rate, is that surrogate of that matrix. And then these foods fall across this classification system, across being whether it's high, medium, low or no. And I think the best thing that's come out of this is the fact that we're not demonising every packaged food out there. And that also we're enabling people to make choices that are informed based on the predicted health effects across food groups.

So for example, someone could go into a supermarket and could look at breakfast cereals and they could say, okay, my kid likes cocoa pops. And that would, I assume, would come up at high risk. But I could scan and look at other kind of chocolate-covered cereals. And it might be that there's ones that are very similar, but actually coming up at low risk because they have different additives or they have different energy intake rate. And so I think having this kind of tool is really empowering for people to make healthy choices.

But for me, as a scientist, it's really exciting because also now we can move forward this science on how food processing impacts our health. Is someone you know trying to make healthier food choices, but potentially getting confused by misleading food labels. Perhaps they're struggling to know what's truly healthy when they're surrounded by food that makes claims that it is, even when it isn't. If so, why not share this episode with them right now to help them understand what healthy food really looks like from a world-leading nutrition scientist? What is the response that you're getting from all the scientists as you're describing this? because it sounds like you're saying, in general, none of them like this idea of the word ultra-processed. How are they responding to this idea that there is really an issue around processed food, but it's more complex?

So this is what scientists love to hear that it's more complex. And so if it's a scientist, we're agreeing with other scientists that it's more complex. Absolutely. And I think that it's the oversimplification. It's using a classification that's based on the extent rather than the impact on health of processing has been the real problem. And I think it's also the fact that we're not demonising all the food because the pushback there is in the nutrition community as well around the term ultra-processed food. In addition to the fact it's using a classification system in the past that is pretty rubbish or not for the purposes of looking at the healthfulness of the food is the fact that we have to recognize that many processed foods, out there are significantly cheaper. And there's been modelling work showing on average they're

50% cheaper than the unprocessed equivalent within the same food group. So if you take an old processed bread, for example, versus an unprocessed bread, that there's about a 50% price differential. And that's really important to acknowledge that because many people therefore don't have the budget to make the healthiest choice. And that's what I think is really empowering about having a tool that's not demonising everything that we're saying, okay, there's a particular a problem with this 20%, see if you can avoid it. If you can't, having it now and then isn't going to be a major issue, but try to make sure that the majority of your diet is not heavily dependent on that. And I think it's also recognizing as well, there are some things that are added

into food for a reason. We need to keep our food stable. We need to keep our food safe. There are additives that are added in to keep our food safe or stable. We don't want to all be going and getting E. coli or some other kind of illness. And so there's some things that are put in food for a reason beyond just to make that food more tasty. And so we need to recognize that and not demonise all of that as well. I feel that on the one hand you're saying don't demonize everything that's being viewed as sort of highly processed or ultra processed. On the other hand, I think you're saying that 20 to 25 percent of the food that we're eating is high-risk processed food. So if I look at it on that side, it seems like at the end of this research, you're also saying

there is a real issue. Yeah, I think that I hope that very few nutrition scientists would ever say there is not an issue with the food that people are eating or the majority of people eating, the food that's on our supermarket shelves. I think that what nearly every nutrition scientists would agree with is that we're not eating enough fiber, we're not eating enough bioactives like polyphenols, we're eating too much salt, we're eating too much saturated, fat we're eating too much sugar. I think that also most nutrition scientists would agree that there are many processed foods that are processed in such a way that are not good for us in addition to how that composition is affected and this is what the score that we've created

is trying to capture. If we're putting something out there, a scientist, putting something out there that people are going to use, it has to be right. So one thing that I am really proud about in relation to this process of score is it's part of a bigger score, it's part of a bigger food score and as part of a bigger picture of how we need to look at the healthfulness of food. So we've created an overall food score that considers multiple features of what shapes the healthiness of that food, how much fibres in there, how much healthy fats in there, how diverse that the plant-based ingredients are, how little salt is in there, how little sugar is in there.

So all the kind of features that we know are really important. some of the very traditional features, some of the more novel features like the quality of the fat rather than the type of fat. And the processing score is one feature of this overall food score. So when someone looks at the healthfulness of something in the supermarket, for example, so like the peanut butter or any food, firstly they're getting an overall picture, not just of the processing, because the processing tells us only a small part of that story. So if we take beef tallow or butter or large as an example, they're not classed as processed as processed foods, but hopefully everyone listening will know they are bad for you, they're packed for

saturated fact, they're not good for you. And so we need a score that captures not just the processing, but also the overall healthfulness of a score. So we have the score that captures the overall healthfulness of the score using all of the science from the last, you know, couple of hundred years. Plus one feature of that is our processing score. And that's what gives me confidence as a scientist in this and that's what gives me the confidence that I've actually started using it myself as well because sometimes again even though I've been a nutrition scientist for 25 years it's so confusing now to work out oh is this healthy for me isn't it's healthy for me beyond the fact that yes I know plant-based foods in their original

format nuts seeds etc are going to be healthy but when I'm trying to grab something on my way home it's six o'clock I'm shattered I've been working all day I need need to feed the kids. I want something quick and easy. I'm not going to start cooking from scratch. That's why I think it's really helpful for me because I'm going to go for a package pre-made meal in that situation is the unfortunate reality. I was thinking that one of the things it's been eye-opening for me over the last eight years at Zoe is realizing how different two foods might be that look the same. And before Zoe, I would never have turned a package over on the back and looked at the ingredients that I just looked at him and being like, oh, that seems fine,

I'm going to get one of those. So I think I am still sometimes a bit amazed that, for example, you could be looking at the bread, you know, in the supermarket, and you could be walking along and there could be one bread with like a couple of ingredients and another one with 20 ingredients. And they don't necessarily really look different, right? Yeah, totally. And I think what's important about the score that I've been working on is that it's not about the number of ingredients either. It's not about the number of additives. because there's now some retailers that are bringing out these single ingredient foods as a way of trying to say, oh, this food is good for you because, you know,

anything that's got loads of ingredients is obviously going to be bad for you. You could have some food that's got 20 ingredients in it, but they might be all of these wonderful nuts and seeds and bioactives. And so I think that's what I like is there's all of these tricks that are being used now to try and capitalize as well on people's fear of ultra-process food. And that's what we've got to stop, the fear of it. Is there anything in this presentation that I've missed as we've been chatting about it? So I do also like to talk about the good of the auto-processed food and some work that I've been involved with

where we can actually harness food processing techniques to make the food even better. And we often call this health by stealth in nutrition. Health by stealth. Yes. There's a body of work that I've been involved with for many years. which has been trying to generate a healthier bread. So we have created this bread that basically is a lot healthier for you than a typical bread, but tastes the same.

And this is because we've been really clever with how we use food processing techniques. So what we've done is we've taken some chickpeas. We finally ground them, but we've ground them in such a way that the cellular structure is intact. So remember those cell walls, the cell walls, or the water balloon? Yep. So you've got thousands of intact water balloons where they have not been burst yet.

Amazing. And you put it into the bread. So firstly, you've got a chickpea flour that's slightly higher in protein than a typical wheat flour. You've got a flower where all the cell walls are intact, all the water balloons are intact. And when you put it into the bread and you feed these to participants, which is what we've done in our studies, you get about a 50% lower post-meal glucose or blood sugar response. you get nearly a hundred percent difference in the feeling of fullness. So when you add it into the bread versus not having it in the bread, and remember I've said we've done all this sensory tasting, they taste the same, you have 100% difference in how full you feel. You have more than 100% difference in gut hormones. It's like this wonder bread.

And that's because we've harnessed the power of processing to our benefit. And there's a whole other body of research that I've been involved with at Kings, which is looking at how you can process wheat. you grind it in such a way that releases the iron. Iron deficiency inemia is a huge problem in the UK, in the US. So many people, about 30% of the population, have insufficient iron stores. It's really difficult to get iron from plant-based foods from wheat because generally it's within a really rigid structure within wheat,

what we call the allurone layer. We've generated this kind of micromilling technique that basically releases the iron so that when you have the bread, whether it's whole grain or white, you're actually getting that iron in a more accessible form. So that's two great examples of how processing can help us. Amazing. This explosion in obesity and diabetes and all these other lifestyle diseases, you know, inflammation and like negative impact on quality of life.

People are actually dying younger now than, you know, a few years ago. To what extent is this link? to this rise in the high-risk processed food that you're talking about today? So I think that the rise in obesity, the rise in chronic diseases that are underpinned by diet are due to lots of factors. They're due to the fact that we have a more sedentary lifestyle. They're due to the fact we're not sleeping like we used to. They're due to the fact that we're more stressed than we were. But they're also a huge part due to the food that we're eating. Now, it's not just the fact that we're eating food that is processed with unhealthy additives

and, you know, devoid of certain nutrients and has extra additional nutrients. I think that overall the quality of the food has changed. But absolutely, yes, the way that the food is processed now compared to 100 years ago absolutely is responsible for some of this increase in obesity, some of this increase in chronic diseases. So if I just swap from like this high-risk processed food to low-risk processed food, do I significantly reduce my personal risks both about health and also about sort of managing to keep control of my weight? I believe, based on the score that we've created, based on very strong science,

that if you swap from the high risk to even the medium risk, you'll reduce your risk. If you swap to the low risk, I believe you'll reduce it more. We're currently doing some quite intensive validation work within our cohorts where we can actually answer this question more clearly. And the initial analysis is really promising. But it's really important to reiterate that the processing score is just one aspect of the healthfulness of a food that we must also consider overall the healthfulness of the food like the fibre, like the salt, like the sugar, for example as well. But yes, I believe when you are thinking about what to feed your child that evening, what you want for your lunch that day, if you're looking at foods within a food group that are broadly similar, like sandwiches, for example, that might have broadly similar nutrient composition, that if you were to choose ones that are lower risk in terms of the processing versus higher risk, that absolutely over time, day after day, that will improve your overall health. The final question I have is coming back to this current explosion in the use of GLP-1s. Is it possible that this high-risk processed food is part of what's causing the damage to our brains around hunger that these GLP-1 drugs then sort of fix?

Yeah, so I think there's some evidence to show that they are overriding our fullness signals, partly through the drug. the speed at which you eat them, but partly through how they might interact or cause feedback to our fullness, our hunger centres in our brain. It's an emerging area of research. There's some evidence around food addiction. Some scientists say it's not a real thing. Some scientists say that actually if you see the dopamine response that goes on, particularly with these processed foods that have this kind of magic mixture of nutrients, it's causing this dopamine hit. It's overriding your natural fullness signals. I think it's emerging science. I think it would be wrong to say for sure, actually, yes, this process or this additive or this technique is definitely a problem

and kind of mucking up our brain's natural way of thinking about food. But I think, you know, there's new research going on in this area at the moment. And so I think we'll have answers in the next five to ten years. I'll end this episode with something I think you'll like, a free Zoe gut health guide. If you're a regular listener, you know just how important it is to take care of your gut. Your gut microbiome is the gateway to better health, better sleep, energy and mood. The list just goes on. But many of us aren't sure how to best support our gut.

I wasn't sure before doing Zoe, which is why we've developed an easy-to-follow gut health guide. It's completely free and offers five simple steps to improve your gut health. you'll get tips from Professor Tim Specter, Zoe's scientific co-founder and one of the world's most cited scientists, plus recipes and shopping lists straight to your inbox. We'll also send you ongoing gut health and nutrition insights, including how Zoe can help. To get your free Zoe gut health guide, head on over to zoie.com slash gut guide. Thanks for tuning in and see you next time. You know,