What are ultra-processed foods doing to our bodies?

0:00This is The Guardian.

0:07Today, what are ultra-processed foods doing to your body?

0:17In the last two decades, the rates of bowel and colon cancer diagnosed in young people has skyrocketed around the world. Hi, my name is Megan and I wanted to come on here to share my story of how I've been diagnosed with stage 3 colon cancer at 24 years old. I'd go to the toilet, then I'd like, do I need it again? This was normal. This was around for years, guys. I just thought this was normal. My gastroenterologist tried to reassure me, saying that, no, not bowel cancer. You're too young. And then went in for my colonoscopy and then got the news that it was bowel cancer. I was his youngest patient he's ever had to tell the news to, so he was in complete shock as well.

0:56Until recently, studies couldn't really pinpoint why. But a consensus is growing. And one culprit keeps coming up. Ultra-processed foods. That crumpet at breakfast. Your vegan meat burger. The protein bar you figured would be healthier than a bar of chocolate. Ultra-processed foods are everywhere. They're cheap, convenient and incredibly hard to avoid. In the UK, they now make up more than half of the average diet. But what's in UPFs? And how dangerous are they? From The Guardian, I'm Noshin Iqbal. Today in Focus, are ultra-processed foods causing cancer?

1:42Devi Shridhar, welcome to Today in Focus. You are the Professor and Chair of Global Public Health at Edinburgh University and familiar to many of our listeners for your work during the COVID pandemic. We want to talk to you today about a different threat to our health. it's about cancer rates rising in young people. Yeah, what we are seeing is a pattern in that cancer used to be something that mainly affected people over the age of 60 or 70. It was seen as a disease of the elderly. But we are seeing a rise, the steepest rise in young people. While rates have declined in those over 60, so we're doing better at catching cancer at an earlier stage, what we are seeing is a sharp increase in many developed countries among people under 50.

2:25And in this age group, it's called early onset disease because we're not expecting to see cancer in those age groups. And so there's something happening. And so this rise, is it consistent as a global picture? I would say it's a consistent global picture in developed countries. So what we're really looking here is at G7 countries. If you look across European countries, the United States, Canada, but even places like Japan, though they have better cancer survival rates, actually they also are seeing a rise in cancer rates. And so going beneath the picture of like cancer obviously can affect all different parts of the body, what you're seeing is a steep rise in those linked to the digestive system.

3:03Now, new data shows the number of under 50s being diagnosed with bowel cancer is increasing worldwide. England is among the countries with the biggest rise. The number of colon cancer cases in U.S. adults under the age of 54 has sharply increased over the last decade. Australians under the age of 50 have the highest rate of bowel cancer in the world. according to new research today from the University of Melbourne. And so just so we're all anatomically clear about what we're talking about, could you explain how that internal plumbing works? Yeah, so we have our stomach and then it goes into our small intestine, into our large intestine and then our rectum, basically.

3:39And so there what we're seeing is a steep rise in cancers of the rectum and of the colon. So that's the last part before it comes out. So what a colonoscopy does, because I guess that's what people might have heard of, it actually just sends a tube up through that system where a doctor can look with the light to see are there any polyps, which are small growths. And then they biopsy those to see, are they actually cancerous? And so that is now routine in people who are, depending if you're in England or Scotland over the age of 50 or 55, will you be invited for the screening? And it's just to take a look in that system because the early signs of colon cancer are often, there's no symptoms.

4:16And the problem we're now facing in young people is that they are not invited for these screenings, again, because it's considered a disease of older people. And so when you are getting people going to their GPs or feeling unwell and symptomatic, it's often at quite a later stage. As you say, there is mounting evidence that colon and bowel cancers are rising and that people under 50 now make up one in 20 cases in the UK, which is a stat that has alarmed doctors specialising in this. Devi, what are the factors that scientists are looking at as possible causes to explain it and why have young people become particularly vulnerable to cancer risks?

4:52So every generation that is born later has a higher likelihood of getting cancer at an earlier age. You and I have a higher likelihood of getting cancer than our parents. We have a higher likelihood than our grandparents. So we're kind of going the opposite of progress. And that's any cancer? That generally links the digestive system. There are genetic underpinnings for colon cancer, but that only explains about 25 % of cancers that are out there. 75 % seem to have no linked to family history or kind of genetic underlying basis. So that is where you're like, okay, what has changed in these various generations?

5:25Could it be something environmental? Could it be diet? Because diet is something that has changed quite radically in the last, I would say, 50 years.

5:40Well, you wrote very convincingly, I should say, about one of these key factors, these key contributing culprits being ultra-processed foods to explain the staggering rise in colon cancer. Before we get into the why, could you just very quickly lay out some definitions about what counts as an ultra-processed food? So yeah, so this has been a real range of debates within the scientific literature over like, what is it? I think the way I've seen it best explained is that can you make it in your own kitchen? Does it have very long shelf life? will last for six months or a year or three months, as well as the range of additives.

6:20And so when you look at the ingredient list, the very end, you'll see three or four things you won't even be able to pronounce. It's usually a preservative, a coloring, an additive, a flavoring, emulsifiers, these kind of things. We've gone, if you think back 50, 100 years, is consuming kind of what's local, what you can make, what you can cook, to now consuming products that are made in factories thousands of miles away that are shipped all around the globe. And we're eating things that might look like food but are very far from what we might see as original food that our ancestors might've eaten.

6:51So like certain type of breads, if you buy a supermarket loaf that's been baked in their store, it's probably fine. And it goes rock hard after three days, where if you buy a squishy loaf from there that's gonna last for two weeks, that's ultra process. So I think the difficulty for people is not just saying bread is bad. I think it's about how it's made and the ingredients within it. And I think that's where I think it's really hard for people to like pick between things rather than this ruling out entire foods. I think it's quite easy to dismiss ultra-processed foods as just junk food. The kind we've always known has been bad for us.

7:27But it does also include things in the kitchen cupboard that people wouldn't necessarily expect. Yeah, I think one of the things that ultra-processed food has been really good at is marketing itself with those health claims on boxes with really good packaging. I think it comes down to like reading ingredients. Even not all baby foods are made the same. Some you might read and it's 100 % carrots and you're like, okay, it's 100 % carrots and that's it. But if you're getting something and it's 50 % carrots, 20 % additives, and we've added a preservative and we've added a lot of sugar, that's a completely different product.

7:57So there's no easy shortcut to think beyond reading labels, unfortunately. And that goes beyond like reading the packaging on the front, actually you're saying, what is in this product? It basically made me think about my childhood of going to the supermarket with my mom and looking at the cheesy puffs or looking at whatever it was. And my mom always been like, no, I can make that at home. And she insisted she always could, no matter what it was. And so I guess what you're saying is, it's that kind of old school thinking of if your grandmother wouldn't cook it and wouldn't recognize this as an ingredient, perhaps you should rethink about whether you should also be consuming it.

8:28yeah like is it actually food i mean a lot of these things are changed and you know processed beyond any recognition of what the original ingredients even are supposed to be in it but again it's like it's not all equal so even let's say frozen chips some people might think like i just want frozen chips if you go to the supermarket there's a range of 100 potatoes which is like fried maybe two percent sunflower oil and then you get chips that are like 50 potato potato and then 50 % all kinds of other stuff. Exactly. We'll have a look. And so again, it's a challenging one because even coming back to what you said about your mom, probably if you look back at her childhood diet, it'd be completely different to any kind of diet that children would be eating today.

9:10Partly people saw that as progress, right? People saw it as like, you don't have to waste your time cooking. It was an advance for women to be able to have microwave meals. And conversely, when I was growing up, it was cheaper for my mom to cook everything from scratch, whereas that is not the case now. No, I think actually, especially if you are on a limited budget, going to a place like Iceland where you can get bulk food, cheap calories. I mean, there's studies showing that a basket of nutritionally less dense calories is cheaper. We don't really have a problem of food scarcity as we did in the past because we have the opposite problem.

9:40Caloric abundance, healthy calories are what are expensive. You grownups who think there's no time for a hot breakfast. Just wait until you have children. Consider Kellogg's Pop-Tarts, Hot and fast from the toaster.

9:59How much of the average diet in the UK is made up of UPFs? It's really high. So these studies show 50 to 60 percent. And if you go back with the past 10, 15 years, it's gone up every kind of single 10 years. And the place where it's really scary is in school lunches, where actually some school lunches can be 70 to 80 % ultra processed. And that's what children are getting to eat. So yeah, we do have a high dependence. To be fair, it's pretty much every part of the world going down this track. They might be slightly behind us in places like India and Ghana, but actually their diet's shifting for its ultra processed.

10:34It's also in Brazil, where there've been a number of studies. And even Japan, which we always stand out for their food culture, how healthy their diet is, their longevity, a lot of that is being stalled because of the introduction of ultra processed foods, which are appealing to a lot of people for a number of reasons. Like there are reasons that both food production and food consumption, like the whole food system, Oreo, Ounces, they have a lot of appealing attributes. I remember in the States growing up, like my dad was really excited by ultra processed food because he thought this was better because it was packaged and it was American and it was new.

11:07And I think for a lot of young people, they just grew up with it, not thinking that it was bad for them. They just ate it, right? And I, to be honest, didn't even reflect on this until quite recently, I would say five or 10 years when the evidence starts coming out, you know, in the sense of I didn't see a difference between a store-bought cupcake and a homemade cupcake. I didn't see the difference between squishy bread and meal deals and bakery bread. And I think for a lot of people, it's probably like that, right? And then now suddenly that awareness is coming of like, oh, what have I been eating?

11:38Did I even know what I was eating those years? So I think we can't blame people at all. It's the food environment we're then. But I think it's pretty new. I think that now there's this emerging evidence base and more and more studies accumulating about the health costs.

12:01What do we know about what ultra processed foods actually do to your body and what health impacts they do have? So we know, I mean, if we go back 10, 15 years, we learned early on that they do have a higher likelihood of giving you obesity. And so for the same amount of calories, whether you eat it, let's say, biscuits that you make at home or you buy store-bought biscuits, you will more likely get obese on the store-bought biscuits because of the way it changes metabolism and kind of how you process them in your gut or even how hungry you feel afterwards. So I think that's really interesting because first it was a theory was that you eat more ultra processed food.

12:35But now it's actually that for the same amount of calories, you actually process it differently. So that whole calories in, calories out thing is kind of debunked because they're not all equal. Exactly. What we also see is that diabetes has been on the rise, which is basically how we manage insulin in our bodies and our blood sugar levels. And that's been tied to the consumption of these foods. It seems to lead to chronic low-grade inflammation, alterations to our gut microbiome, and all of these are implicated in cancer development. There was a major study in the States, 46 ,000 men. They were tracked over roughly 25 years, and they tried to understand what could be possible risks for developing colorectal cancer.

13:15And they found that the group that consumed most ultra-processed food had rates that were almost 29 % higher, even accounting for weight, which I found really interesting because obesity usually is like the intermediary factor, right? Which is we know their obesity length factors, but that you could be of a healthy body weight or a normal body weight, but your diet affects your cancer risk. I found that really interesting as well from that study. And 2025, there was a review in a journal called Nature Reviews Endocrinology. So they went through all the evidence until 2025 on the rise in colorectal cancer.

13:50And they do come out pointing to ultra-processed foods with the recommendation that actually we try to reduce this in the diet of the general population. Well, Devy, how clear is the science on things like emulsifiers and additives actually being harmful for one's body? Well, I think there it's been tricky to see it in human studies, if I'm honest, probably because we can't really take humans and inject them with large amounts of these and say, do you grow a tumor? I think the only way to do it is to do kind of these large studies, which is you track a population over, you know, 20 years, you track, you know, a lot of attributes, whether it's their age, their activity patterns, smoking patterns, how much alcohol they drank, as well as diet.

14:31And then within that, you try to control for different variables over a long time period and then start to pull out. But I think there, what's really tricky is that we can say as a whole, people who consume these kinds of foods might have a higher likelihood, but what's the exact chemical or is there exact additive? I think It's tricky. So I think the animal studies are pretty convincing, even on things like artificial sweeteners that have now been introduced to replace. So some things say there's zero sugar, but actually there's usually an artificial sweetener that might be worse for your body than sugar.

14:58When these have been tested in mice and rats, they do show reduced immune function, even tumor growth. Of course, those are like at a very high concentration in a small mammal. But I think there you can start to say, okay, the evidence is growing. Probably the most advanced science is on, which we've already kind of banned in Britain and in Europe is the artificial colorings. So artificial colorings would be in sweets, kids lollipops. It would be, you know, in cereals like Froot Loops, in rightly colored, vibrant cupcake frosting. And you're saying that's banned in the UK? No, that's not what you're saying.

15:30So basically what the rule is, is if you use them, you must put on the packaging. This may have an adverse effect on activity and attention in children. And so generally because of that, a lot of food manufacturers have moved to natural colorings like turmeric or spirulina. So actually it's largely been shifted out because the government went to food manufacturers and were like, we're going to ban it unless you change it. And if you don't change it, you need to put kind of a label. No one wants that label on their food. Exactly. Exactly. So I think once that label goes on, a lot of people don't buy it.

15:58So food manufacturers move that way. The States is far behind, though. You can still go to the States and buy all this kind of stuff. And that's what, you know, the Make America Healthy agenda has suddenly gone after. Bizarrely, because I think it's a good cause. We've done it here and in Europe, but it's a led by quite an interesting character. Yeah, RFK. Yeah, exactly. Yeah. If you like a McDonald's cheeseburger or a Diet Coke, which my boss loves, you should be able to get them. If you want to eat Hostess Twinkies, you should be able to do that. But you should know what the impacts are on your family and on your health.

16:33So, I mean, this is what's really tricky about RFK Jr. because he says stuff like America's children are some of the most unhealthy. We have real problems with our food. You know, why are we so sick? Which are all true. So you're like, yes, yes, yes. But then it's about the solutions where I think there's not enough about population interventions. And actually many of the things they're doing are the opposite, right? They're cutting food benefits. They're increasing inequality. All the things that we know go against good health outcomes. And is the science and medical establishment, are they generally agreed on this?

17:05UPFs are dangerous and they're contributing to this rise in cancer. I think there's a general agreement that ultra-processed foods are linked to obesity and that obesity is implicated in the rise in a number of cancers and chronic disease. Would I sit in a room of 30 health experts and they all say it's definitely ultra-processed foods. I don't know, actually, in terms of the strength of evidence, they might say, well, it could be, but it's also physical activity patterns have reduced. People are doing less exercise. Could it be smoking? So I think, but I'm trying to think of any room I've been in with 30 experts where we've had consensus.

17:41And I think the only last topic probably was something like tobacco. We've had that kind of, and that took decades to get to. What, to linking tobacco to lung cancer, essentially? And to get consensus, right? It took like from the earliest studies, If you think back, you know, to kind of the 40s and 50s where they were starting. And again, in animal studies, it was Adele Kroniger's lab that kind of painted tobacco tar on the back of mice and soft tumors growing. So again, started in animals to, you know, the large longitudinal studies by Richard Pito and others who were like, actually, this is linked to lung cancer to actually like the U.S.

18:15Surgeon General or the chief medical officers actually coming out was about 20, 25 years that went by for that. So it sometimes can feel quite slow, but we are heading in that direction in terms of the evidence accumulating first in animal models and in large population studies. So I think we're heading in that way.

18:36Coming up, how is the government taking on the food industry?

18:51Well tobacco industry provides potentially an interesting analogy here because as you've said it took absolutely decades for there to be that recognition acknowledgement that yes it causes lung cancer before the tobacco companies admitted that. Where are we in this trajectory with ultra processed foods. How is the food industry in particular responding to the growing evidence? Oh, they're not happy. I think, you know, they were fine when public health experts were saying, oh, you've got too much salt or you've got too much sugar because then they could reformulate, right? They could do low sugar products.

19:23You could do diet Coke. You could do low sodium ketchup, right? So I think there were ways they could modify in terms of, oh, we can still sell a product. We'll just shift it slightly to appease you, right? And I think now if you're going after of the entire model, which is saying that factory produced foods at bulk in a very cheap way, using additives and chemicals that give you long shelf life and make it more tasty to consumers and can be done much more cheaply than having to actually have supply chains for fresh produce and things. It's their whole business model, right? It's a whole threat.

19:57And I think we've seen in Britain, I mean, I think first when labor was campaigning and then first came in, They said they were going to take this on in a big way, that prevention was going to be a big thing. They were going to bring in regulations on advertising and marketing and multi-buy deals. Since then, it's been watered down a lot. And I think that is due to lobbying by big firms who are constantly pushing and trying to modify the guidance towards their profit model. Well, what about West Streeting's war against obesity? He said it, but what have we seen in terms of changes? To be fair, I mean, actually, some of it's out of their control.

20:31since Brexit, food and vegetable prices have gone up. They've gone up, like cucumbers have gone up 200%. I mean, it's harder to get fresh fruit, vegetables, meat, dairy into supermarkets at an affordable price because they're now largely imported. Fruit's like 70 % to 80%. Vegetable is not far off that. So if you don't want to have people riding because they can't afford food, we already know cost of living is an issue. Can you really take away ultra processed foods, which are the cheapest option? So I feel like we are certainly in this predicament because of the cost of food. That does come to a key question I have about all of this, because for a lot of people, it comes down to cost and convenience, because you know often that these things are bad for you, but you're busy.