Ultra processed foods such as chicken nuggets, ice cream and breakfast cereals have been linked to early death and poor health, scientists say.
Researchers in France and Spain say the amount of such food being eaten has soared. Diet is always key to a healthy life.
Their studies are not definite proof of harm but do come hot on the heels of trials suggesting ultra-processed foods lead to overeating.
Experts expressed caution but called for further investigation.
What are ultra-processed foods?
The term comes from a way of classifying food by how much industrial processing it has been through.
The lowest category is unprocessed or minimally processed foods, which include fruit, vegetables, milk, meat, legumes, such as lentils, seeds, grains, such as rice, and eggs.
Processed foods have been altered to make them last longer or taste better generally using salt, oil, sugar or fermentation.
This category includes cheese, bacon, home-made bread,tinned fruit, and vegetables, smoked fish and beer.
Then come ultra-processed foods, which have been through more substantial industrial processing and often have long ingredient lists on the packet, including added preservatives, sweeteners or color enhancers.
If a product contains more than five ingredients, it is probably ultra-processed, says Prof Maria Bes-Rastrollo, of the University of Navarre, citing a maxim.
How bad were the findings?
The first study, by the University of Navarre, in Spain, followed 19,899 people for a decade and assessed their diet every other year. There were 335 deaths during the study.
But for every 10 deaths among those eating the least ultra-processed food, there were 16 deaths among those eating the most (more than four portions a day).
The second study, by the University of Paris, followed 105,159 people for five years and assessed their diet twice a year.
It showed those eating more ultra-processed food had worse heart health.
Rates of cardiovascular disease were 277 per 100,000 people per year among those eating the most ultra-processed food, compared with 242 per 100,000 among those eating the least.
The rapid increase of ultra-processed foods over less processed foods, may drive a substantial burden of cardiovascular diseases in the next decades, said Dr Mathilde Touvier, of the University of Paris.
So do these foods damage health?
The evidence is accumulating, said Dr Touchier, noting increasing numbers of independent studies. Prof Bes-Rastrollo said she was very certain ultra-processed foods were bad for health.
Last year, a link was made with an increased risk of cancer.
The challenge is being 100% sure. The studies have spotted a pattern between highly processed food and poor health but they cannot prove that one causes the other.
Those who ate the most ultra-processed food were also more likely to have other unhealthy behaviors, such as smoking, which the researchers tried to account for.
Why might ultra-processed foods be bad?
The first trial of ultra-processed foods showed they led people to eat more and put on weight.
Researchers at the US National Institutes of Health monitored every morsel of food that volunteers ate for a month.
And when given ultra-processed food, they ate 500 calories a day more than when they were given unprocessed meals.
Other suggestions include They are energy dense but lacking in nutrients and fiber.
While the additives in food have been safety tested, it may be unhealthy to consume lots of additives from different foods. People eat more because they’re easy to eat.
They push healthier foods such as fruit and vegetables out of diets who wants a banana when you can have ice cream?
These ideas still need researching.
Is there any useful advice?
While the term ultra-processed food may be new, the health advice will be very familiar: adopt a alkaline diet.
Such a diet includes plenty of minimally or unprocessed foods, such as fruit, vegetables, fish, nuts and seeds, beans, lentils and wholegrain, said Victoria Taylor, senior dietitian at the British Heart Foundation.
This, along with exercising regularly and not smoking, has been shown to be beneficial for lowering risk of heart and circulatory disease.
Measures such as taxation and marketing restrictions on ultra-processed foods, should be considered, said Prof Bes-Rastrollo, given the weight of evidence.
Is the ultra-processed label a load of nonsense?
There are certainly a lot of critics.
The labeling of food as ultra-processed could be inconsistent, said Dr Gunther Kuhn, an expert in nutrition and health at the University of Reading.
It is also not obvious why salami is considered to be ultra-processed, yet cheese, which often requires considerably more processing steps and additives, is not. The classification combines a wide range of foods with very different potential impacts on health, which limits its usefulness as a basis for recommendations.