Nutrition scientist: This is why you're confused about ultra processed food | Prof. Sarah Berry

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?

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.

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Transcript

Jonathan Wolf: 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 actually just thought it'd be really amazing to let our listeners actually hear that.

Hopefully, we can talk a bit about it, and I will ask some questions when I don't understand, and really bring, literally, the cutting edge of science around processed food, to anyone who's listening today. 

Sarah Berry: I’d 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. 

Jonathan Wolf: So, what was the talk called? 

Sarah Berry: So it was called Processed Food: the Good, the Bad, and the Ugly. 

Jonathan Wolf: Tell me about it.

Sarah Berry: It was very much bringing together all of the science that I've 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 demonization that we've been using around ultra-processed food and actually understanding how different processes involved in processing food can impact our health differently. That 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-processed 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 that are so bad for us, but demonizing all old 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 more complicated. 

Jonathan Wolf: So now I'm intrigued. Tell me about it. 

Sarah Berry: 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-feel of fat, the melt profile of fat, impacts our health. 

And so this is something, as scientists, we've been doing for many, many years. We've been looking at how processing food and therefore processed food can impact our health.

Jonathan Wolf: 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 Frankenstein food that's really bad for me. 

But I think you are using this in some different way. 

Sarah Berry: When we think about processing food, you know, even cooking rice is processing it. Even cooking your carrots is processing in some way because you are 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 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 uses. There are really simple techniques, just like grinding. So you're just grinding something down into a powder. 

There are techniques called extrusion that sound a bit scary, and it's pushing these things through at high heat, at high pressure. So think of Wotsits, for example, or cheese puffs. They use various processes, including exclusion, 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? 

Jonathan Wolf: 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 making cakes: I'm not a big baker, but  I've done a little bit of this with my little girl, because it's really fun. 

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 that you realize you do all this weird stuff with eggs, right? 

You separate out the yolks and the whites, and then you realize you 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. It brought out my inner physicist. 

Would that count as processing, when you're just 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 completely raw and natural?

Sarah Berry: 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 are 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 going to kill us, going to cause all of these awful things, and not all 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 that once you break down into food groups, you see that they're not all the same. 

So, for example, sugar-sweetened beverages, fizzy drinks, processed red meat, salamis, hams, those kind of things, they're driving a lot of the association, and so some ultra-processed foods 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 the NOVA classification. It was created about 20 years ago.

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. 

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-processed food, and ultra-processed 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-processed food, shouldn't even be allowed at a nutrition conference, because we all know the term UPF is nonsense.  

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, ultra-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. 

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. You might be told, Okay, Jonathan, peanut butter is healthy, go have some peanut butter. 

Well, actually, you can have a huge diversity, 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 U.S. and the U.K., that's got a few extra bits added in it.

And then you can have these kind of more homemade style of peanut butters like Pip and Nut, and you know, the very kind of whole food style of peanut butters that are literally the peanuts 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. 

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 helpfulness of that food? 

But more importantly, how can we guide consumers in order to choose the good rather than the bad and the ugly? 

Jonathan Wolf: 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?

Sarah Berry: So, processing food can impact the healthiness 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 are 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 at ZOE how central our microbiome is to all of our health. 

Jonathan Wolf: 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 of those things at the same time. 

Sarah Berry: So there's regulatory bodies that look at the safety of different additives, different kinds of commercially or industrially created ingredients. And they do all of these kinds of toxicology studies where they feed them at certain doses, typically quite high doses, to mice.

They look at does it affect cancer? Does it affect cardiovascular disease? Et cetera, et cetera. 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, does it affect these novel parameters or novel features that we haven't typically thought about, such as the microbiome, which is a new area of research.

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Jonathan Wolf: So you're saying there is this way of checking whether something's sort of toxic, right? So you're saying you're feeding it to mice at very high levels, you would realize that it was poisonous or that it was going to cause your liver to fail or something that you could really measure.

So, is this the sort of thing that would capture, hopefully, whether something is causing cancer? But then you are saying what it doesn't do is catch maybe subtler effects, 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. 

Sarah Berry: Yeah, absolutely.

Jonathan Wolf: And does that help to explain why, particularly in Europe, where those regulations are quite tight, 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, it did sort of pass this test, but obviously, something has happened because we're all feeling less healthy. 

Sarah Berry: Yeah. So I don't think it's just to do with the additives, and I can come onto 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? 

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 sweeteners, for example, negatively impact the microbiome, and how they impact the microbiome may in the long-term cause insulin resistance and change how you process glucose, et cetera.

So, I think it's something that we are going to start to see more and more evidence appear. 

Jonathan Wolf: One of the things that I understand is that the restrictions in the U.S. have not been as high as the restrictions in Europe in terms of these additives. Is that right, and is it a meaningful difference? 

Sarah Berry: So from what I understand, that's right.

It's at this point, as always, Jonathan, I caveat with that's not my area of expertise, and I don't fully understand all of the legislation around the additives that are allowed in the U.S. versus the U.K.

But generally speaking, in the U.K., we've been stricter around what we allow compared to the U.S. But there have been, in recent months, a lot of discussions around now really clamping down in the U.S. on some of the additives and some of the added chemicals they put in food.

So I think things are starting to change now in the U.S. 

Jonathan Wolf: I think you were saying it isn't just a story about additives, however. 

Sarah Berry: 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, et cetera. 

But in addition to that, and in addition to the fact that ultra-processed foods all tend to have a lot more of these unhealthy ingredients like the salt, sugar, saturated fat, they also tend to be really low in really healthy nutrients. 

They tend to be really low in fiber, really low in bioactives. So by 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. 

Jonathan Wolf: To translate that from your nutrition science, that means that in a small amount of this food, there are a lot of calories compared to a normal food that our ancestors would've been able to eat.

Sarah Berry: Absolutely. So it means, therefore, you can get a lot more food and 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. 

So the way I often think about how processing impacts our health, I think about it in two broad buckets: one is the nutrients, the chemicals, which we just talked about. And the other is the structure of the food.

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 calories we digest. It changes the rate at which we digest it. It changes where we digest it in our gastrointestinal tract. 

Jonathan Wolf: Could you just explain for a minute what this food matrix was that you've now destroyed by grinding? 

Sarah Berry: So, food matrix really simply puts 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. 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 that have quite a rigid structure that encapsulate the nutrients of the nuts. So this means the protein, and the carbohydrate, and the fat from the nuts.

So what that means is, if I were to give you a whole almond, 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 are 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 a 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… 

Jonathan Wolf: You get to do all the most glamorous studies, Sarah. 

Sarah Berry: 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 come out the other end.

So what's on the back of pack labeling 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 are delaying the postprandial, so these post-meal responses that you see in circulating fat that also happen after a meal.

So 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… 

Jonathan Wolf: That's different from an at-home grinding? 

Sarah Berry: 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, that are used to make maran, for example, into a flour. 

Now you are breaking all the cell walls. So you've destroyed that matrix, 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 are not getting that 30% difference. 

And so you could have two foods. They have identical back-of-pack labeling, 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.

Jonathan Wolf: Oatmeal for some of us. 

Sarah Berry: Yes. If you are 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 are packed full of these fullness receptors. So saying you are full. 

Yet, if I were to feed you and we've done this experiment at Kings, if I were 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% 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 GLP-1, 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. 

Jonathan Wolf: So if I understand rightly, what you're saying is it's not just about the additives in this processed food, you're saying that this process of 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. 

Sarah Berry: Absolutely. It's changing how much you digest, it's changing how quickly you digest it, and it's changing where you digest it.

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 or calories you go on to consume.

And actually, there was a study that was done in 1977 by a guy called Haber. It 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’s 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 pureed them 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 eating 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. 

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Jonathan Wolf: Wow. 

Sarah Berry: That's a huge difference. Now, I've actually repeated this experiment at my kid's school on one of those take your mom to school day and got all the kids to do it, and they replicated these results almost identically.

So what he did was he then said to everyone, Okay, can you come back, and Can you all eat these at exactly the same time? So firstly, you are 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 ZOE research that if you have a dip in circulating blood sugar, you go on to eat a hundred calories more at your next meal, 300 calories more over the day, you feel more hungry, you have less energy, et cetera. 

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'd done is change the structure, all we'd done is change the texture, and I think this whole area of texture research is fascinating.

This is something that, when we are 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 or how quickly we are 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.

Jonathan Wolf: 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. 

Sarah Berry: 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 fiber, fat, protein, carbohydrate, and water. 

Jonathan Wolf: So, there's no change in that example of what's in there. It's just the act of breaking down these… I think about this like my school biology,  the cell walls and all this stuff being broken down into sort of this mush, has suddenly completely changed the way my body's responded. 

It sounds like in a very negative way. The way you're describing it sounds like eating this as an apple rather than the apple puree is much better for me. 

Sarah Berry: Absolutely. Because you're eating it more slowly.

You are absorbing it lower down your gastrointestinal tract, where you've got more fullness receptors, so you're feeling more full. You are allowing the time for the fullness receptors to say, Hey Jonathan, you've had enough, rather than this kind of fast food, so to say. 

I think if we bring it back to where we started this conversation around the 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-processed food, and how that impacts our energy intake and our weight.

What they found was that if you feed people ultra-processed food, and this is according to that Nova classification that we talked about, that soft, you eat loads of that, you eat excess calories from that, and you are more likely to put on weight.

If you feed unprocessed, but soft food, you still eat that quite quickly.

Jonathan Wolf: Could you give me an example? 

Sarah Berry: Oh, now you're putting me on the spot. It could be… yogurt is a good example of an unprocessed soft food. So you are still eating it very quickly because of the texture. 

If you then have an ultra-processed hard food, you eat that more slowly, have less overconsumption of calories even than the unprocessed soft food.

So it's a bit complicated. But it's like this step down, where the worst in terms of the rapid rate of eating, the overconsumption, 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.

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 four, which is means it's ultra-processed or not? 

Jonathan Wolf: I'm also struck that it took you a second to think of a soft, unprocessed food, which tells you that there aren't that many of them in our natural environment, I guess. 

Sarah Berry: Yeah. I find this whole segregation of unprocessed and overprocessed actually really hard.

So I think yes, it's partly that. Partly because most foods in nature are quite hard.  I think you've picked up on a really important point.

But I would say if people ask me, Oh, is this ultra-processed, isn't this ultra-processed? I actually don't know. I've had 25 years of training as a nutrition scientist, and I don't know, I'm so confused, and I shouldn't be confused. 

I should be able to tell you that's ultra-processed, that's bad for you, or that's not. 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. 

Jonathan Wolf: You've talked about added ingredients that can be bad, and which maybe we weren't testing for in the way up until now. 

So there are 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. 

Sarah Berry: 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.

Jonathan Wolf: So we've got these additives, and you're saying we shouldn't necessarily be like, Oh, if 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 stripping out all of the nutrients that you would get from a whole food that might be feeding my microbiome and my body in general.

Because I sort of rip that out and then 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.

Sarah Berry: We haven’t been talking about it enough. 

Jonathan Wolf: 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 are full. 

But also that the grinding itself can destroy a lot of those nutrients. So it's not, 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. 

Sarah Berry: 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 fiber, very simply put, is plant cell wall material. So it has a really important structural role. 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 are 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. 

Jonathan Wolf: Got it. So it's still in there, but it's sort of like the, again, I'm thinking back to my little school cell wall picture, it's keeping everything safe inside and delivering it slowly, almost like a little pill, I guess. 

Like when I take medicine, right? It keeps it intact for longer. 

You're saying if 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.

Sarah Berry: Yeah, totally. Imagine a water balloon, for example. So you've got the rubber keeping the water safe inside. So that's just like the fiber is the rubber keeping all the nutrients inside, and then you break that, and it comes out. 

Jonathan Wolf: So this highly process food is like being hit by water balloons. I like this. 

So you took us up to this point. Is it all so complex that we're sort of doomed and it's impossible to sort of differentiate between any of this? 

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Sarah Berry: So I think it is really complex and I think it's a really, really difficult challenge to be able 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 ZOE over the last year.

Working really hard on 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 ZOE 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 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. 

These features include everything that we've just talked about. So it includes things like the additives, the emulsifiers, the colorant, but it grades them. 

A food could have 10 additives, but they could be all low risk. They could even have an additive like inulin for example, which is fiber, which is classed 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 microbiome. Yes, won't give us cancer, but still we feel that it's not something that we should be having regularly. 

So we wanted to create a system where firstly, we looked at these additives, these emulsifiers, these colorants, but graded them according to their predicted impacts on health.

Where you've got some baddies, 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 is changed, and basically, energy intake rate is a measure of telling you how fast you are eating your calories. 

Jonathan Wolf: So is that like your apples versus your apple juice and your puree example?

Sarah Berry: So it's exactly like the apples and the apple puree, they would have entirely different energy intake rates.

Your apples would have a very low energy intake rate. Your apple puree would have a really high energy intake rate, which means you're going to over-consume it, which means you are going to consume excess calories. And that is the biggest problem that we have. 

We're dealing with a problem for most of the U.S. and most of the U.K., not everyone, but internationally, over-consumption 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 feature 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-palatability index. 

Jonathan Wolf: What is hyper-palatability? 

Sarah Berry: So hyper-palatability is basically a term to describe it being too yummy, too good to be true.

And so what we know is that in many processed foods, there's kind of this magic mix of nutrients, 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, Whoa, hold on you've had enough. 

So what's your favorite ultra-processed food? 

Jonathan Wolf: Pringles. 

Sarah Berry: Okay. If you think of Pringles, they're salty. They've got lots of  really refined carbohydrates, so you can just eat them. Isn't their advert…

Jonathan Wolf: Once you pop, you 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, so that's, it's not just because it's soft, 

Sarah Berry: 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 are doing here is we are 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 over-consumption of a food. 

For example, and I don't remember the exact proportions, for example, a particular cutoff of salt alongside refined carbohydrate or a particular cutoff of fat alongside a particular amount of sugar, for example.

Jonathan Wolf: And when you say refined carbohydrate… 

Sarah Berry: So your Pringles is carbohydrate where the structure's been destroyed. So refined carbohydrate, like white bread, for example. 

Jonathan Wolf: Oh, so this is where it's a carbohydrate, but once I eat it, it gets turned into sugar almost immediately. 

Sarah Berry: Yes, so really what I call a quick carbohydrate.

Jonathan Wolf: I've heard this term, bliss-point, mentioned before as nutrition scientists creating this sort of bliss-point between sugar and fat, and salt. 

Is that this same thing?

Sarah Berry: Yeah, so it's sort of the same. There's this idea that it activates these reward centers 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-palatability index 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 reward centers.

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.  

Jonathan Wolf: Thinking about potato chips or crisps is a great example. So I do really like those. I'm quite careful about trying to choose a healthier one. So it might just say potato and some sort of oil, and salt. So 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’s salt on it's 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-palatability?

Sarah Berry: Yep. So it's having exactly that. 

The combinations in just the right amount that hits those reward centers in your brain, that leaves you wanting more.

Let's say regular potato chips or crisps for those in the U.K, 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, become 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. 

Jonathan Wolf: I think it's really interesting because I know that there's been a lot of stuff in the media from big food manufacturers, 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 junk food, as I was told as a kid, which means 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. 

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 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. 

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Sarah Berry: 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 hyper-palatability index, particularly given that we are still waiting to see more research about this.

But I think certainly it's something that we need to pay attention to. 

Jonathan Wolf: So it's like one component in the overall understanding. 

Sarah Berry: Yeah, absolutely. 

Jonathan Wolf: So what do you tell all these scientists after all of that? 

Sarah Berry: We've developed this new score that we've been working on, as a science team that takes into account all of these factors.

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 term ultra-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., in the U.K., it's not 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 U.S., in the U.K., that is actually processed in such a way that it's quite bad for health. 

Jonathan Wolf: I'm guessing that in your science thing, you don't call it ugly processed food. How does this end up being categorized? 

Sarah Berry: 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. 

Think of the brand level i.e., the Reese's peanut butter, versus the Sun-Pat, versus the Pip and Nut.

Jonathan Wolf: And are they all the same processed food risk? 

Sarah Berry: Absolutely not. So Reese’s would come in at high risk. The Sun-Pat comes in at medium risk, and the Pip and Nut at no risk.

So we have millions of foods that we're funneling through this pipeline, that we first categorize them according to what additives, emulsifiers, 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 palatability index? Then we look at what's their energy intake rate, that surrogate of that matrix, and then these foods fall across this classification system, across being whether it's high, medium, low, or no. 

I think the best thing that's come out of this is the fact that we are not demonizing every packaged food out there. And that also we are enabling people to make choices that are informed based on the predicted health effects across food groups. 

So, for example, someone could go into supermarket, and could look at breakfast cereals, and they could say, Okay, my kid likes Coco Pops and that, I assume, would come up at high risk, but I could scan and look at other 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. 

Jonathan Wolf: What is the response that you are getting from all these 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. 

Sarah Berry: 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. 

I think it's also the fact that we're not demonizing 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. 

There's been modeling work showing on average they're 50% cheaper than the unprocessed equivalent within the same food group. 

So if you take an ultra-processed bread, for example, versus an unprocessed bread, there's about 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's really empowering about having a tool that's not demonizing everything that we're saying. Okay, there are, there's a particular 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.

I think it's also recognizing, as well, that 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 demonize all of that as well. 

Jonathan Wolf: I feel that on the one hand you're saying, don't demonize everything that's been viewed as highly-processed or ultra-processed. 

On the other hand, I think you're saying that 20 to 25% 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. 

Sarah Berry: Yeah, 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 scientist would agree with is that we are not eating enough fiber. We're not eating enough bioactives like polyphenols.

We are 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. 

This is what the score that we've created is trying to capture. If we are putting something out there as scientists, 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 score is it's part of a bigger score. It's part of a bigger food score, and it's part of a bigger picture of how we need to look at the helpfulness of food. 

So we've created an overall food score that considers multiple features of what shapes the healthiness of that food. How much fiber's in there, how much healthy fat's in there, how diverse the plant-based ingredients are. How little salt is in there, how little sugar is in there. 

So all the features that we know are really important. Some of them are very traditional features, some of them are 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 healthiness 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 lard as an example, they're not classed as processed foods. Hopefully, everyone listening will know they are bad for you. They're packed with saturated fat, 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 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. 

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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 this healthy for me? Beyond the fact that, yes, I know plant-based foods in their original format, nuts, seeds, et cetera, 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 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 packaged pre-made meal in that situation is the unfortunate reality.

Jonathan Wolf: I was thinking that one of the things that'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. 

Before ZOE, I would never have turned a package over on the back and looked at the ingredients. I just looked at it and was 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 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?

Sarah Berry: 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 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-processed food. And that's what we've got to stop: the fear of it.

Jonathan Wolf: Is there anything in this presentation that I've missed as we've been chatting about it? 

Sarah Berry: I do also like to talk about the good of the ultra-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.

Jonathan Wolf: Health by stealth.

Sarah Berry: 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.

What we've done is we've taken some chickpeas, we finely ground them, but we've ground them in such a way that the cellular structure is intact. So remember those cell walls or the water balloon? 

Jonathan Wolf: Yep. 

Sarah Berry: So, you've got thousands of intact water balloons where they have not been burst, 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 flour 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, remember I've said, we've done all this sensory tasting, they taste the same, you have a hundred percent difference in how full you feel. 

You have more than a hundred percent difference in gut hormones. It's like this wonder-bread, and that's because we've harnessed the power of processing to our benefit.

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 anemia is a huge problem in the U.K., in the U.S., 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 aleurone layer.

We've generated this kind of micro-milling technique that basically releases the iron so that when you have the bread, whether it's whole grain or white, you are actually getting that iron in a more accessible form. 

So that's two great examples of how processing can help us. 

Jonathan Wolf: Amazing. This explosion in obesity, and diabetes, and all these other lifestyle diseases, inflammation, and negative impact on quality of life. People are actually dying younger now than a few years ago.

To what extent is this linked to this rise in the high-risk processed food that you're talking about today? 

Sarah Berry: 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 are eating now. It's not just the fact that we are eating food that is processed with unhealthy additives and 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 a hundred years ago, absolutely, is responsible for some of this increase in obesity, some of this increase in chronic diseases. 

Jonathan Wolf: So if I just swap from 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?

Sarah Berry: 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 are 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 fiber, 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 are 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. 

Jonathan Wolf: The final question I have is coming back to this current explosion in the use of GLP-1. 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? 

Sarah Berry: Yeah, so I think there's some evidence to show that they are overriding our fullness signals, partly through the speed at which you eat them, but partly through how they might interact, or cause feedback to our fullness, our hunger centers 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 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 10 years.