Additives, preservatives and artificial colorings in food are America's gateway drugs to overconsumption and obesity. Professor Chris van Tulleken, the author of Ultra-Processed People: The Science Behind Food That Isn't Food, explores the effects of ultra-processed food in a world where profit is the goal and purposeful addiction is part of the recipe.
KCRW: How do you boil down the long scientific definition of "ultra-processed foods"?
Chris van Tulleken: It's pretty straightforward. Anything that's wrapped in plastic that has an ingredient that you don't typically find in a domestic kitchen — xanthan gum, an emulsifier, a stabilizer, a humectant, high fructose corn syrup — is very likely to be ultra-processed. There are a couple of other good rules of thumb. If there is any health claim on the pack — "low fat," "high in fiber," "vitamin enriched," "supports weight loss," "benefits your immune system" — that is likely to indicate a food that's ultra-processed. Real food — broccoli, bananas, steak — almost never has a health claim.
It's such an oxymoron.
The logic is easy to understand once you understand the incentives within the food production system. Writing my book, I spoke to a huge number of extremely kind and decent people who work within the food industry. One of the purposes of ultra-processed food is to add value to waste products.
I was looking at a protein bar the other day and it contained a thing called "citrus fiber." Now, citrus fiber is just left over in the peel from making lemon juice, orange juice, grapefruit juice or in the peel when things are canned. If you can, rather than throwing that away or scattering it on a field, take that citrus fiber, make it edible, add it to a protein bar and call it "citrus fiber" (two words we associate with good health), then you've added enormous value to it. A lot of ultra-processed food is about taking stuff that is more or less inedible and making it edible by flavoring it, emulsifying it and coloring it.
When did the use of artificial additives, preservatives, and coloring spike in food manufacturing? Was there immediate regulation of their use?
Saccharin was the first additive, developed in the late 19th century. It became very popular in World War I. It was the first thing to be added in large quantities to food. It became very popular, particularly in the [United] States, but all around the world. It was after World War I and World War II that ultra-processing really took off. Quite early on, Congress in the States realized, in the '50s, that a whole slew of new additives were being added to food that no one had really studied. So they passed a food additives act in the late '50s, which was very robust. It empowered Congress, not simply to consider the safety of one additive but to look at the total number of additives. If a food product contains a safe amount of additive A, B, C and D, in combination, they may no longer be safe. In the '50s, people were really taking this nuanced effect. But they built in this loophole because they didn't want to have to go and do safety trials on vinegar and table salt and olive oil, stuff that we've been adding to our food for centuries or even millennia.
So they built in this loophole about things that are generally recognized as safe. Unfortunately, that loophole created this gateway in the States. I always feel self-conscious talking to American interviewers about this because it is such an indictment of your food safety system. I would be very anxious eating any food with additives in the States. Now, there is no regulation of food additives. There's a sort of Potemkin regulation. There's what looks like regulation because there's the Food and Drug Administration, and they do go through a couple of billion dollars of performance of regulation. But, in fact, if any company wants to add any additive to your food, provided scientists at the company agree that it is generally recognized as safe, then they can add it.
Some activist groups, legal action groups, and environmental groups like the Environmental Defense Fund, have started exploring in detail a few cases. We're seeing, for example, corn oil that is left over from the production of bioethanol being added to food supply chains. What the consumer will never know is that the corn oil is not squeezed directly out of the corncob. It is instead coming from a fermentation mash to which antibiotics and antifungals have been added. It's been through very serious industrial processes normally with no regard for human safety. That's just one example.
By some estimates, there are as few as 5,000 or as many as 15,000 additives that are unknown to the Food and Drug Administration.
Wow. Describe the personal experiment that you conducted on ultra-processed food consumption. What were the results?
I ate a diet of 80% ultra-processed food for a month. I did this in partnership with my colleagues at University College London, where I'm an academic. This wasn't Supersize Me. It wasn't a stunt for a book or a TV show. It was done to get pilot data for a very big study, which we're now running. Various newspaper articles have said, I sort of put my body on the line for science, and I really didn't. I ate a diet that is extremely normal for an American or a Canadian or a British teenager. 20% of people in the US and the UK eat 80% of their calories from ultra-processed food.
Three things happened. First, I gained a huge amount of weight, 6.6 kilos, which means that in a year, I would have doubled my body weight. I'm around 80 kilos.
The second thing was we saw a huge increase in connectivity between the habit-forming areas at the back of the brain, the cerebellum, and the addiction reward ancient parts in the middle of the brain. This was a set of MRI scans that we did under very close supervision with our national neurology hospital. This is a very robust result. We have no knowledge of what is happening to the brains of children who eat this level of ultra-processed food from birth through to when they're fully developed in their mid-20s.
The final thing that happened was that my response to a standard meal changed. At the beginning of the diet, when I drank a standard nutritional milkshake, the kind that we use in these research studies the whole time, I had a normal response (in terms of my hormones) to fullness and hunger. At the end of the diet, when I drank the same standardized meal, my hunger hormones remained sky high.
This ability of food to interrupt the way that we handle calorie intake is characteristic of ultra-processed food. It's something lots of listeners are going to recognize. They sort of feel full or they know they've had enough and yet they are unable to stop eating. The evidence that these foods are addictive is now very, very strong. We have a lot of evidence.
"Ultra-Processed People" follows one man's journey into unrecognizable ingredients. Photo courtesy of W.W. Norton & Company.
In terms of pure enjoyment of eating and enjoyment of the meal, what was that like for you at the beginning and towards the end?
In a way, that was the most important thing that happened to me. At the beginning of this diet, I was looking forward to it. I was gonna go and eat all the cereals that I'd eaten as a kid. I was going to eat junk food every day for breakfast, lunch and dinner. I was feeling I could sort of let myself go. I wasn't going to overeat but I could eat what I wanted in a way that I normally sort of don't. I don't necessarily go to fast food restaurants for lunch as a doctor.
Midway through the diet, I spoke to a colleague in Brazil. We were planning a research study about something else. She kept saying to me, "It's not food, Chris. It's an industrially-produced edible substance." That night, I sat down to a meal of Kentucky Fried Chicken. I could not eat the meal. I was disgusted. The rest of the diet was very hard for me. I wanted real food.
The gift I want to give to the reader of my book is the same thing that the "easy way to quit smoking" book does. By the end of the book, I hope that people won't just be more knowledgeable about this food, but they will be unable to eat it.
You're a doctor with the NHS. Do your patients know that you went through this experience? Has it informed your ability to be able to convince them to eat more real food rather than veering towards ultra-processed?
I'm an infectious diseases specialist. I mainly treat patients with tropical infections or systemic infections. Most of my patients live in poverty. They're migrants, refugees. They have no addresses, they're homeless. They are hugely impacted by diet. The reason my patients get infections is because their diets are terrible. We only really see infectious diseases in people who live in poverty. They're often injecting drug users. I talk with them a lot about what they should eat but the conversation has a real edge to it. Because I can tell them to eat fresh, healthy food. "Go and cook some steak, buy some apples." And they're like, "We don't have a refrigerator. I can't keep anything. I can't cook things. I can't afford to batch cook a meal and freeze it. I don't own a freezer."
In the UK, we have, much like the United States, huge levels of inequality. One of the problems about discussing ultra-processed food is that this is the food that people who are disadvantaged are forced to eat. I'm speaking to you from Canada. I'm in a community where there's a large Indigenous population who I know well. Many of them have now read my book. I'm friends with them. They can't stop eating this food. It's the only food available to them. They can't afford to go and get fresh food. They're a really impoverished community. So there is a political edge to this where we're seeing, certainly in the UK. The British government is resisting saying, "Don't eat ultra-processed food" because it's complicated as a government to say, "Don't eat the only food you can afford." Clearly, people are going to take to the streets and go, "Why can't we afford the food that you're telling us to eat?"
I personally think that whatever political stripe you wear, the cheapest thing is to have a population that eats a healthy diet. It is so expensive in the States and in the UK to have childhood obesity and diabetes rates the way they are. So it makes economic sense, it makes moral sense and, if you have any sense of social justice, then it's an imperative that real food is affordable and available.
Part of the marketing of ultra-processed foods is to use recognizable ingredients, like the citrus fiber you mentioned. Are there any redeeming nutrients in these products?
That's such a good question because we have never been able, in the entire history of nutrition, no one has ever extracted a vitamin, a molecule, a mineral, an element, an aspect of any whole food that has conferred a health benefit in healthy people. Whether it's lycopene from tomatoes, vitamin C from citrus fruit, fiber extracted from all-bran, fish oil from fish, walnut oil from walnuts, none of it seems to have any... And yet, tomato is healthy, citrus fruit is good for you, oily fish are good for you, walnuts are good for you. We're very, very certain about that.
So the thing that is hardest for people to understand is that food is a complex substance. It consists of a structural matrix. When you eat an apple, you're not simply eating a long list of thousands of ingredients, you're deconstructing them with your mouth. Your tongue and taste receptors interact with all the different molecules and prepare your body to receive the meal. You start becoming full even as you're chewing, and your liver will prepare to receive the small number of toxins that are present in all fruit, veg and real food. Your kidneys will do the same.
Real food is complex and the human body has evolved to eat it. When you dismantle real food, like a soy bean, and you turn it into a soy protein isolate it in some soil and a bit of soy modified starch, your body hasn't evolved to handle any of them. So the health claims made about individual ingredients are really nonsense.
Michael Pollan had this insight at the turn of the millennium. He said, "Eat food, mostly plants, not too much." The problem with that is the political loading it comes with. It's not affordable for most people. The scientists who developed the ultra-processed food definition used Pollan's idea to develop this work, to formalize it. We now have a decade of data showing that it's correct. We know that eating real food, whether it's a tomato or a piece of beef or a pork chop, is basically good for you. Eating any extract of that really doesn't seem to have a health benefit.