FROM cocktail sausages to ready meals, ultra-processed food has long been suspected of being nutritionally inferior. Most dietary guidelines say this is because it tends to be high in fat, sugar and salt. But that is missing something vital, says doctor, academic and TV presenter Chris van Tulleken in his new book, Ultra-Processed People: Why do we all eat stuff that isn’t food… and why can’t we stop?
What really determines a meal’s nutritional value, says van Tulleken, is how it is made: in the home or a factory. This idea puts a spotlight not on individual ingredients, but on how the way they have been processed, reformulated and cooked affects our health. The industrial techniques used to make many modern foods not only add unhealthy ingredients, but also change the way the foods themselves interact with our body, says van Tulleken – and with ultra-processed food now making up more than half of all food eaten in many Western countries, the consequences for much of the world’s health are catastrophic. He tells żěè¶ĚĘÓƵ what we can do to turn this trend around.
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Clare Wilson: Why is ultra-processed food worse than the food we cook from scratch at home?
Chris van Tulleken: The industrial processes involved in food manufacturing change its chemical and physical structure. They reduce food crops to their core constituents, such as high fructose corn syrup made from corn starch or hydrolysed vegetable protein from soya beans, which are then reformulated into substances that are highly palatable and calorific. These processes strip out fibre and micronutrients. Then ingredients are added that our bodies haven’t evolved to cope with, such as artificial flavourings and emulsifiers. We have evolved to eat naturally arranged matrices of different chemical constituents and when you separate them into their molecular components and chemically modify them, they seem to interact with the body in a very different way. For instance, a study has shown that .
This contradicts common advice to focus on fat, salt and sugar. How much evidence is there that processing is more important?
The epidemiological evidence (data from big groups of people) has piled up – we now have more than 100 really good-quality studies showing diets high in ultra-processed food go hand in hand with worse health, whether you’re looking at mortality, cancer, inflammatory bowel disease, dementia, obesity, stroke and on and on. When you statistically adjust the results to take into account socioeconomic factors, and to take account of the fact that highly processed food has more sugar and fat and less fibre, the size of the effect remains the same. Most of the studies that link eating sugar, salt or fat to poor health outcomes don’t make this same adjustment. There are also plausible biological mechanisms for all the different ways that this food might harm us. For instance, we know that emulsifiers harm the gut.
What are emulsifiers and why do they harm the gut?
Emulsifiers are a wide variety of chemicals that bond fat to water – like soap, which lets you wash oil off your hands. There is something about these artificial emulsifiers in food where they act a bit like detergents and scrub out your intestines. Our intestines are covered in a layer of mucus and in that are trillions of bacteria, which are intimately linked to health. Studies show that certain emulsifiers, like carboxymethyl cellulose, seem to increase the permeability of the gut barrier and increase the amount of bacteria that enter the bloodstream from the gut. They may also , going from broadly health-promoting ones to health-limiting bacteria, and .
How about sweeteners?
Sweeteners are really intriguing because they exemplify the whole problem. The traditional way of thinking about nutrition is that sugar is harmful, it’s a source of calories. It ought to be the case that if we replace sugar with zero-calorie sweeteners, we should see a pretty significant loss in weight. But at best, trials show that it has no effect. That should raise alarm bells. It may be the case that if you put a sweet taste in the mouth, that tells the body that sugar is on its way and you get insulin release. If the sugar never arrives, that insulin stimulates appetite.
We know that epidemiological and animal studies can mislead. Are your ideas supported by randomised clinical trials?
The strongest evidence comes from a small of 20 people that was run in a very convincing way. Each person ate ultra-processed food for 14 days and then unprocessed food for 14 days, or vice versa. The meals contained the same amount of fat, salt, sugar and fibre and people could eat as much as they liked. Despite rating the foods as equally palatable, people ate many hundreds of calories more per day on the ultra-processed diet than they did on the unprocessed diet. And they put on weight exactly as you would predict in line with that excess calorie consumption. That was very persuasive.
Isn’t it premature to advise people to change their diet based on one small trial?
The argument doesn’t hinge on that trial – it is just a cherry on the top. If we didn’t have it, the epidemiological evidence is now sufficient to show causality. We only have epidemiological data to link smoking with cancer, and most scientists agree on that.
Why does most official dietary advice from around the world ignore whether food is highly processed or made from scratch?
There are people who are unpersuaded, but this idea is becoming more widely accepted. I think we are fast approaching this being in Public Health England’s dietary recommendations, which, at the moment, do not mention processing. Advice to avoid ultra-processed food is in French national dietary guidance and Canadian guidance, as well as some other countries, such as Brazil and Chile. It is mainly accepted in countries where food policy-makers have a less close relationship with the food industry.
What is the nature of the relationship between some food policymakers and the food industry?
In the UK, when it comes to food policy, some of our most influential charities are partly funded by companies that make income from ultra-processed food. And as much as the money, there’s a cultural problem. Until we start to see the companies that make ultra-processed food a little bit more like the tobacco industry – and regulate them as such – we’re not going to make progress.
Isn’t that demonising the food industry, to compare it to tobacco companies?
You can’t treat food exactly like tobacco, but you can learn a lot of lessons about how you treat food companies from tobacco control. I do want to acknowledge that this is the only affordable, accessible foods that many families can buy to feed their children. I wouldn’t tax this, I wouldn’t ban it. And I would be conscious that any policy brought in would need to minimise stigma.
Aren’t you increasing stigma when you say in your book’s subtitle that ultra-processed food isn’t actually food?
The forum in which you say something is crucial. In żěè¶ĚĘÓƵ, I’m happy to say it may be a useful mental trick to think of these products as not food, but as a soundbite in a live interview, that idea risks generating stigma and weight shame. The subtitle of my book – “Why do we all eat stuff that isn’t food and why can’t we stop?” – is trying to locate the problem in the food, not in the person.
Is it unrealistic to expect people on lower incomes, working long hours, to make meals from scratch?
People should have the choice. At the moment, they don’t have choice or opportunity because they’re fed false information and they are unable to buy healthy food, due to time and money. . If all we did was fix the problem of poverty in the UK, that could solve more than 50 per cent of obesity.
Fixing poverty seems a tall order.
Of course, but that’s not what I’m proposing. Number one, you point out that there is early evidence showing that ultra-processed foods are linked with poor health. And I would put that in national nutrition guidance. That can sit alongside fat, salt and sugar, as those things are almost certainly harmful, too. Number two is marketing restrictions. Why must we have cartoon characters like a monkey on a cereal box? Number three is to improve institutional food. Schools, hospitals, prisons – all have to make available unprocessed food. Then we need to label whole foods positively (see “Which food is which?”). Finally, we need to label packs of ultra-processed food somewhat negatively. At some point, we have to figure out a way of defining ultra-processed food and that is a real challenge. But there are lots of shorthand ways. If you just define it as food with an artificial emulsifier, a non-nutritive sweetener or high fat, salt and sugar, that wraps up more than 90 per cent of the ultra-processed foods.
Would you accept the modern food industry has some benefits, such as in reducing hunger? In your book, you describe the arrival of obesity and diabetes in Brazil as the diet there became more westernised – but at the same time, life expectancy rose.
The reason people began living longer is because there was improved sanitation and hygiene and public health measures around things other than food, like smoking. The nutrition transition has definitely done a bit of good. You don’t see nearly as much malnutrition in Brazil now. But diet-related disease is still causing people to die earlier than if they were eating less ultra-processed food. There are real benefits to our current food system. I think we can acknowledge progress, while still holding gently in our hands the idea that with that progress came some genuine problems. Like automobiles, the food system has brought incredible benefits to millions of people, while also bringing very significant harms to people and the planet.
How about the benefit of freeing people – often women – from having to cook from scratch several times a day?
Saying that our food system causes diet-related disease isn’t the same as saying we should all go back to cooking for 5 hours a day and women should stay in the kitchen. The food industry uses arguments like these to paint people like me as regressive.
How often do you make homemade meals for your children?
Two or three nights a week I cook them something like a piece of salmon, a lamb chop or pasta bake. We do have ready meals two nights a week and we have takeaway probably one night a week. I want to be able to choose crappy food for my kids sometimes. I have no interest in a nanny state. I don’t think it’s for governments to tell people how to eat. I think it’s to create an environment where good food is affordable, where people aren’t saturated in bad food and where the bad food is clearly labelled.
Clare Wilson is a reporter at New żěè¶ĚĘÓƵ
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Which food is which?
WHOLE FOODS
Foods that haven't been processed or had artificial ingredients added. In reality, most foods undergo some degree of processing, such as washing or boiling, so whole foods often include minimally processed foods such as wholegrain pasta or frozen peas.
PROCESSED FOODS
These are foods that have been changed from their natural state, for instance by being packaged, pasteurised or dehydrated. It also includes foods that have added preservatives, nutrients, flavours, salts, sugars or fats.
ULTRA-PROCESSED FOODS
There is no agreed definition of what makes a food "ultra-processed", but nutritionists tend to apply the term to foods that are the result of intensive manufacturing processes. It includes foods that have added sugars, fats and salts, but they also often have added ingredients taken from other foods such as high fructose corn syrup, maltodextrin, gluten and hydrogenated oils.
