Eating white bread and ready meals could be killing us, according to the first major study linking "ultra-processed" food with early death.
The study of 45,000 middle-aged people 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.
Previous research has linked the consumption of foods like white bread, ready meals, sausages, sugary cereals, fizzy drinks to a higher risk of high blood pressure and cancer.
But the new study is the first major investigation linking high consumption of processed foods to higher overall mortality rates.
The study, led by Paris-Sorbonne University, tracked the diets and subsequent mortality of 44,451 French men and women, with an average age of 57.
Participants were asked to keep 24-hour dietary records, enabling researchers to measure their intake of more than 3,000 different food items, which were classified into four groups depending on their level of processing.
Overall, "ultra-processed" foods were found to account for 29 per cent of their diet, the study, published in JAMA Internal Medicine, found.
Separate estimates suggest the British diet is far more reliant on highly processed fare, making up around half of the foods consumed.
Such meals often have a higher content of total fat, saturated fat and added sugar and salt along with a lower fibre and vitamin density.
Author Dr Laure Schnabel, a nutritional epidemiologist at Paris-Sorbonne University, said: "Ultra-processed foods contain multiple ingredients. They are usually ready to heat and eat, affordable, and hyper-palatable.
"Examples include mass-produced and packaged snacks, sugary drinks, breads, confectioneries, ready-made meals and processed meats."
Such foods can also contain additives such as sodium nitrite and titanium oxide, which have been linked to high blood pressure and cancer.
Research has also suggested that artificial sweeteners present in such foods may alter gut bacteria - increasing the risk of type 2 diabetes and other metabolic diseases which are major causes of premature mortality.
Dr Schnabel said: "Nutritional characteristics of ultra-processed foods could partly explain the development of non-communicable chronic diseases among those who consume them.
"Ultra-processed foods are generally energy dense, rich in refined carbohydrates, saturated fats and salt, and contain low dietary fibre.
"These features have been associated with several non-communicable diseases that are the leading causes of mortality.
"Beyond their nutritional aspects, ultra-processed foods have specific characteristics, owing to the industrial processes they undergo.
"Thus, concern is rising about the potential harmful health consequences of newly-formed contaminants or food additives."
Dr Schnabel said: "A 10 per cent increase in the proportion of ultra-processed food consumption was statistically significantly associated with a 14 per cent higher risk of all-cause mortality."
Last year a study of 19 European countries found 50 per cent of food sold in the UK is ultra-processed compared with 46 per cent in Germany, 45 per cent in Ireland - and 14 per cent in France.
Dr Schnabel and colleagues also took into consideration other risk factors such as age, gender, lifestyle, physical activity and BMI (body mass index).
She said: "Ultra-processed foods are mostly consumed in the form of snacks, desserts or ready-to-eat-or-heat meals."
During seven years of follow-up 602 (1.4 per cent) of the participants died - with 219 caused by cancer and 34 by cardiovascular disease.
Prof Nita Forouhi, from the Medical Research Council Epidemiology Unit, University of Cambridge, said: "The case against highly processed foods is mounting up, with this study adding importantly to a growing body of evidence on the health harms of ultra-processed foods."
She said more evidence was needed to confirm the findings, which came from an observational study, but stressed "we would ignore these findings at public health's peril."
Dr Ian Johnson, Nutrition researcher and Emeritus Fellow, Quadram Institute Bioscience, said the findings were statistically significant. But he said the observational study could not prove that the increased mortality rates were caused by the intake of processed foods, and to fully separate out other lifestyle factors like exercise or smoking.
Prof Kevin McConway, Emeritus Professor of Applied Statistics at The Open University, said:
"It's important to understand that the differences in death rates in this study were not very large. On average, participants were followed up for an average of about seven years, which isn't very long in terms of picking up deaths from the sort of chronic diseases most likely to be affected by diet. Out of every 1000 participants (all aged at least 45), about 14 died during the follow-up period," he said.
Cutting cancer risks | 10 recommendations
1. Be a healthy weight. Keep your weight within the healthy range and avoid weight gain in adult life
2. Be physically active. Be physically active as part of everyday life – walk more and sit less
3. Eat a diet rich in wholegrains, vegetables, fruit and beans. Make wholegrains, vegetables, fruit, and pulses (legumes) such as beans and lentils a major part of your usual daily diet
4. Limit consumption of 'fast foods' and other processed foods high in fat, starches or sugars. Limiting these foods helps control calorie intake and maintain a healthy weight
5. Limit consumption of red and processed meat. Eat no more than moderate amounts of red meat, such as beef, pork and lamb. Eat little, if any, processed meat
6. Limit consumption of sugar-sweetened drinks. Drink mostly water and unsweetened drinks
7. Limit alcohol consumption. For cancer prevention, it's best not to drink alcohol
8. Do not use supplements for cancer prevention. Aim to meet nutritional needs through diet alone
9. For mothers: breastfeed your baby, if you can. Breastfeeding is good for both mother and baby
10. After a cancer diagnosis: follow our recommendations, if you can. Check with your health professional what is right for you. - Source: World Cancer Research Fund