As consumption of ultra-processed foods increased and consumption of fresh food decreased, the likelihood of having shortened telomeres rose dramatically, the researchers found. Short telomeres indicate biological changes at a cellular level and are associated with ageing.
In short, the findings suggested the modern diet was likely to be causing the cells to age faster, said the authors.
Those eating the most ultra-processed foods were also found to be more likely to have a family history of heart disease and diabetes. Depression, high blood pressure and mortality were linked with high consumption of them, too.
Modern processed food has a long history. From preserving it in cans (a technique invented almost 200 years ago) to pasteurising it (a process discovered in 1864), we have continually sought ways to keep comestibles fresh, attractive, safe and tasty.
But during the second half of the 20th century, a new type of food crept into western diets: that was made mostly or wholly from substances "extracted from foods or derived from food constituents". This food commonly contains ingredients you wouldn't have in your own kitchen cupboard: things like sweeteners, preservatives and colourings. It typically goes through multiple processes in the factory.
It's quick, it's moreish - and it's everywhere. It's the mass-produced sliced bread you stick in the toaster each morning; the ham in your workday sandwich; the biscuit with your afternoon tea. It's the supermarket ice-cream you enjoy at the weekend; the carbonated drink you grab on the go. It's hard to avoid and, eaten in large quantities, it's apparently doing us untold damage.
The problem is it makes our lives easier. "Cooking from scratch is more labour intensive," says Sam Bilton, a food historian. "So with women going into the workplace, it's not surprising it took hold as it did. If you had to hold down a job and look after kids then it was a godsend."
Other societal advances came into play, too. In 1970, only three per cent of Britons owned a freezer. By 1995, more than 96 per cent of households had one. The first domestic microwave oven was sold in the UK in 1974. Today, they are ubiquitous.
These technologies allowed for the storage and quick reheating of mass-produced, highly processed food, developments that have been credited with liberating women from the kitchen.
But at what health cost? Last year, a study of 45,000 middle-aged people led by Paris-Sorbonne University found that every 10 per cent increase in intake of ultra-processed food was linked to a 14 per cent increased risk of death within the next eight years. This was the first major investigation connecting high consumption of processed foods to higher overall mortality rates.
The findings were attributed to the fact they tend to be energy-dense, rich in refined carbohydrates, saturated fats and salt, and contain low dietary fibre - features associated with various life-threatening diseases.
The researchers also raised concerns about the industrial processes these foods undergo, and the "potential harmful health consequences of newly-formed contaminants or food additives."
Says Dr Razak: "People don't tend to eat them in moderation because they are often high in carbohydrate and so don't fill you up, The body craves more, so it becomes a vicious cycle.
"The answer is obvious: eat more fresh food. But why is it people aren't able to do that? That's the discussion we need to have.
"It may not be affordable or accessible, and it's not as easy for people who haven't cooked before to know how to cook. People have very busy lives. We don't sit around the table as much as we used to, we might eat in front of the telly."
But for Anthony Warner, the self-styled Angry Chef and food writer, the case against ultra-processed food is less clear cut. Just because those who eat more of them have worse health outcomes isn't proof the food itself is to blame, he argues. Correlation, in other words, is not causation.
"I can think of all sorts of factors that would influence it, including socio-economic [ones]," he says. "It's not to say there's not a problem with certain types of processed foods, but to lump them all together I think is ridiculous and unscientific."
Instead of demonising food people turn to often because they're busy or poor, or perhaps less able to cook for themselves due to old age or disability, we'd be better off trying to understand their reasons for doing so, he suggests.
"We look at the lifestyle of people who are healthier and assume that if we translate that on to people who are less healthy then they'll magically become healthier. That ignores things like public health inequalities."
It's perhaps too soon to say if the tide has started to turn. Many of those who, pre-pandemic, lost several hours of their week to commuting say working from home has given them more time to cook healthy meals from scratch. The Government is meanwhile trumpeting its plans to reduce obesity and type 2 diabetes in Britain (conditions associated with worse coronavirus outcomes).
On the other hand, in-home consumption of crisps, chocolate and biscuits also increased during lockdown.
There is no consensus regarding the responsibility of the individual, as opposed to the role of government in changing behaviour by nudging, legislating and taxing, or how much we should blame the food industry. Last week, however, action to tackle obesity was stepped up when cafes, restaurants and takeaways were handed new Public Health England guidelines asking them to reduce the calorific content of their wares by 20 per cent by 2024.
Dr Razak believes the role of the health service meanwhile needs to change from just treating illness when it happens to focusing more on preventing it.
So doctors need to promote healthier lifestyles, including cooking our own meals from scratch? "Yes, that is 100 per cent our role," she says.
"There are cheap options for quick, nutritious, healthy foods. A stir fry takes 10 minutes. We say it's hard but maybe we make it hard. We say people are too busy, but we're rushing now only to die younger.
"I think what people don't realise is eating more healthily gives them their time back later, in the form of a longer life."
What counts as processed food?
1. Packaged supermarket sliced bread
If it contains emulsifiers or colourings, this bread counts as ultra-processed. Mass produced bread can contain up to 26 ingredients and additives and white bread can contain highly processed white flours with a higher glycaemic index (GI), meaning they are digested quicker, giving you a raised blood glucose level and spiking your insulin levels.
2. Pre-packaged ready meals
These commonly contain high levels of salt, sugar and fat and low levels of other nutrients your body needs.
3. Breakfast cereal
These often make health claims such as being high in fibre. The unhealthier ones (we're not talking about porridge or Shredded Wheat here) are also high in additives and sugar.
4. Sausages and bacon
Processed meat has been classified by the World Health Organisation as a group 1 carcinogen as evidence has linked their consumption to stomach and bowel cancer.
5. Fruit flavoured yoghurt
Plain yoghurt is fine, but yoghurt that contains preservatives, sweeteners, stabilisers or colourings counts as ultra-processed
