Ultra-processed foods could be making you age faster

A few months ago, I tried my hand, unsuccessfully, at coining a neologism. I was writing a feature about how obesity, stress, heatwaves and pollution accelerate ageing, or senescence, in which I proposed that our modern world should be called the “senesogenic environment”. (I hold my hands up that this was inspired by the well-established idea that we live in an obesity-promoting, or “obesogenic”, environment, but nobody ever invented anything in a vacuum.)

It didn’t stick. The only reference I can find to it online is my article, and a blog post about my article. I’d like to have another go, because I missed an important contributor to premature ageing: ultra-processed foods (UPFs).

For anyone who has been living under a rock for the past few years, UPFs are a class of foodstuffs that have been, er, ultra-processed. The precise definition is disputed, but, as a rule of thumb, they are pre-packaged foods that are created in a factory from purified ingredients such as sugars, fats and proteins, often chemically modified and laced with synthetic chemicals like dyes, emulsifiers and preservatives. They tend to be low in nutritional value – short on healthy nutrients such as fibre and vitamins – and steeped in fat, salt and sugar. Think cheap microwave meals, salty snacks, mass-produced bread, sugary drinks, instant noodles, ice cream, candy, baked goods, processed meats and condiments such as mayonnaise and ketchup.

Over the past 50 years, UPFs have come to make up an ever-larger proportion of the Western diet. In high-income countries, including the UK, where I live, more than half of all calories consumed are in the form of UPFs. This trend has plateaued over the past decade, but globally the appetite for UPFs is still growing. And who can blame us? These foods are widely available, convenient, affordable and undeniably delicious.

It’s a no-brainer to say that we’d be better off avoiding UPFs, and a large body of research backs this up. High UPF consumption has been linked with a long list of chronic health problems, including obesity, cancer, type 2 diabetes, cardiovascular disease, inflammatory bowel disease, fatty liver disease and kidney disease.

Unsurprisingly, it also raises the risk of death from any cause. Three studies conducted in Spain, France and the US, each following tens of thousands of people, independently found that the highest consumers of UPFs were significantly more likely to die than the most moderate consumers during the study periods.

The mechanism by which such a diverse group of foods can cause such a wide range of conditions has proved elusive. One obvious possibility is that they are obesogenic – obesity leads to many other health problems. Other suspects are poor nutritional quality, additives, toxins generated during processing and others that can leach out of plastic packaging. Some scientists claim that the processing itself adds an extra dollop of unhealthiness – of which more later. As yet, however, there is no definitive answer.

But recent research offers a big hint: UPFs drive premature ageing. In 2024, researchers analysed the diets of 16,055 adults in the US aged 20 to 79 from data gathered between 2003 and 2010 as part of the US National Health and Nutrition Examination Survey (NHANES). They estimated what percentage of calories each participant was getting from UPFs and also measured their biological ages, finding that, on average, the higher a person’s UPF intake, the bigger the gap between their actual age and their biological age.

Each 10 per cent increase in calories consumed in UPF form added an average of 0.21 years, or around two and a half months, to that divergence. The difference between the lowest and highest consumers of UPFs – those who ate less than 39 per cent versus more than 68 per cent – was 0.86 years in biological age.

Regular readers of New Scientist may be feeling a sceptical twitch at this point. Biological age measurements are notoriously imprecise: indeed, I poured cold water on them in my previous column. But for research like this – where people are compared against one another rather than being given individual scores – they are fine, as any systematic errors in the measurement apply to all participants.

The gap doesn’t sound like much – what’s two or three months in a lifetime – but the researchers point out that previous research has shown that even modest rises in biological age are linked to small but significant increases in the risk of chronic disease, disability and death over the following two years.

Other researchers have since found similar senescence-promoting effects of UPFs. Last year, for example, a team in China analysed a different dataset from the UK and also discovered that people who eat a lot of UPFs are biologically older and have a higher risk of death than moderate consumers.

Neither the NHANES study nor the Chinese one tracked changes in biological age over time – they simply took a snapshot – but that would be an interesting next step. Even in the absence of this information, we can safely file UPFs alongside obesity, stress, heat and pollution as a component of the senesogenic environment. Indeed, their detrimental effects on health may boil down to their pro-ageing properties: many of the diseases associated with high UPF consumption are classic conditions of old age.

Again, this raises the question of the underlying mechanism. And again, it could be obesity, poor diet in general, toxic contamination or a noxious blend of all three. But these don’t quite cut the mustard.

One of the running debates over UPFs is whether their detrimental effects are simply down to their poor nutritional quality or whether the processing itself also somehow contributes. The NHANES study adds weight to the latter view: when the researchers accounted for the nutritional quality and energy content of UPF-rich diets, they found that these alone didn’t account for the observed increases in biological age. “Other properties of UPF related to processing may contribute to an acceleration of biological processes of ageing,” they conclude.

What it is about processing that may make UPFs ultra-unhealthy remains to be elucidated. But what matters at this point is that two very large studies using different datasets from different countries have both concluded that diets high in UPFs are associated with faster ageing.

The take-home isn’t hard to work out. Where possible, avoid ultra-processed foods. Admittedly, that is easier said than done – UPFs are everywhere, and in both studies the lowest consumers were still eating a fair amount. But in a world where many of the drivers of premature ageing are impossible to avoid, you can at least do yourself a favour and eat actual food. Oh, and do me a favour: spread the word about the senesogenic environment.