Diets high in ultra-processed foods may be harmful to every part of the body, a major review of research found.
Eating a lot of foods such as ready meals, sugary cereals and mass-produced bread is linked to an increased risk of 32 health problems including cancer, type 2 diabetes and mental health disorders.
Often high in fat, salt and sugar and low in vitamins and fibre, researchers found ‘convincing’ evidence higher consumption was associated with a 50 per cent greater risk of dying from a heart attack or stroke.
In the biggest analysis of evidence to date involving 10 million people, researchers found those eating the most had between a 40 and 66 per cent increased risk of dying from heart disease.
They were also significantly more likely to be diagnosed with obesity, lung conditions and sleep problems.
Likening it to tobacco, they said ‘public policies and actions are essential’ to curb intake and called on public health officials to urgently develop guidelines and ‘best practice’ for ultra-processed foods.
In a linked editorial, they suggest foods are clearly labelled when ‘ultra-processed’.
UPFs refer to items containing ingredients people would not usually add when cooking homemade food.
These additions might include chemicals, colourings, sweeteners and preservatives that extend shelf life.
Restrictions should be placed on advertising and sales ‘prohibited in or near schools and hospitals,’ they say.
Governments need to adopt national dietary guidelines recommending varieties of minimally processed foods, they say, while taking steps to make freshly prepared meals cheaper and more accessible to all.
The UK is the worst in Europe for eating ultra-processed foods, making up an estimated 57 per cent of the national diet.
They are thought to be a key driver of obesity, which costs the NHS around £6.5billion a year.
Often containing colours, emulsifiers, flavours, and other additives, they typically undergo multiple industrial processes which research has found to degrade the physical structure of foods, making them rapid to absorb.
This in turn increases blood sugar, reduces satiety and damages the microbiome – the community of ‘friendly’ bacteria that live inside us and which we depend on for good health.
Food additives like non-nutritive sweeteners, modified starches, gums and emulsifiers also seem to affect the microbiome, levels of gut inflammation and metabolic responses to food which may also increase the risk of heart attack and stroke.
An umbrella review conducted by academics in Australia analysed 14 review articles published in the last three years which associated consumption with poor health outcomes.
Evidence was graded as convincing, highly suggestive, suggestive, weak or no evidence.
There was convincing evidence higher intake was linked to a 50 per cent greater risk of death from cardiovascular disease, a 12 per cent greater risk of type 2 diabetes, and a 48-53 per cent greater risk of developing anxiety.
There was ‘highly suggestive’ evidence that eating more ultra-processed foods can increase chances of dying from any cause by a fifth, according to findings published in the BMJ.
This was also the case when it came to obesity, type 2 diabetes, sleep problems and dying from heart disease, which all showed between a 40 to 66 per cent heightened risk.
Researchers from Deakin University, Australia, also found a 22 per cent greater risk of developing depression and a 21 per cent greater risk of death from any cause.
The evidence between UPF intake and asthma, gastrointestinal health, some cancers, and intermediate cardiometabolic risk factors remains limited, they said.
In an accompanying editorial, academics from Sao Paolo, Brazil said: ‘Overall, the authors found that diets high in ultra-processed food may be harmful to most—perhaps all—body systems.’
They wrote: ‘No reason exists to believe that humans can fully adapt to these products.
‘The body may react to them as useless or harmful, so its systems may become impaired or damaged, depending on their vulnerability and the amount of ultra-processed food consumed.’
UPFs refer to items containing ingredients people would not usually add when cooking homemade food. These additions might include chemicals, colourings, sweeteners and preservatives that extend shelf life
They added: ‘It is now time for United Nations agencies, with member states, to develop and implement a framework convention on ultra-processed foods analogous to the framework on tobacco.’
Further research to determine the different mechanisms by which these foods impact health is also vital, they said, but should not delay policymakers from making urgent changes.
Scientists said there were limitations to the study, including inconsistent data collection methods in the original research.
Commenting on the findings, Gunter Kuhnle, Professor of Nutrition and Food Science, University of Reading, said: ‘Many studies also show that people who consume a lot of ultra-processed foods also have an unhealthy lifestyle and therefore a higher risk of disease.
‘Although many studies attempt to adjust for this, it is virtually impossible to do so completely.’
While observing multiple increased health risks due to ultra-processed diets, the study cannot prove that consumption of these foods caused any of the health problems identified.
Part of the problem is that people who eat large amounts of ultra-processed food tend to be both unhealthier in general and poorer, factors that may worsen their health independently and influence or exacerbate the results.
Another factor is the potential that ultra-processed foods may not directly damage health but instead lead people to eat less nutritious foods which could be driving the results.
The other factor is how some ultra-processed foods might be worse than others.
Experts have previously complained about how nebulous the term ‘ultra-processed food’ is and that it doesn’t distinguish between a ready meal packed with fat, salt and sugar and a wholemeal loaf of bread.
Quality of evidence linking diets high in ultra-processed foods to health issues is also an issue. The BMJ review graded the quality of the evidence behind observed rises in health problems on a scale of ‘very low’, ‘low’, ‘moderate’ and ‘high’.
Only a few of the health issues observed reached a ‘moderate’ quality of evidence, the vast majority were ‘low’ or ‘very low’.
A government spokesperson said: ‘We are taking strong action to encourage healthier food choices and to tackle obesity – recognising that it is the second biggest cause of cancer and costs the NHS around £6.5billion a year – while respecting the importance of individual choice.
‘We have introduced calorie labelling on food sold in restaurants, cafes and takeaways to empower people to make informed personal choices about their lifestyle, and thanks to our salt reduction programme, the amount of salt in food has fallen by around 20 per cent.
‘Pre-packed foods are required to set out a variety of information to aid shoppers – including a list of ingredients and nutritional data.’