Ready meals and cereals linked with rise in cancer
Eating factory-made food including cornflakes, pizza and chocolate bars every day increases the risk of cancer by a quarter, the first study of its kind suggests.
Additives in ready meals, packaged snacks and shop-bought cakes may combine to trigger the disease, researchers warned.
Cancer caused by processed food would be over and above the harmful effects of the sugar and fat it contains, scientists fear.
French researchers studied the diets of 105,000 people, of whom 2228 developed cancer over an eight-year period. The quarter who ate the most "ultra-processed" food were 23 per cent more likely to get any type of cancer than the quarter who ate the least, researchers report in The BMJ.
Those in the top quarter obtained a third of their calories from such products, roughly equivalent to a man consuming a chocolate bar, a can of cola, a bowl of cornflakes and a quarter of a pizza daily.
A study revealed last week that half of the food bought in Britain is made in a factory.
Mathilde Touvier, of the Sorbonne Paris Cite Epidemiology and Statistics Research Centre, led the study.
The French research cannot prove that the processing of food directly increases cancer risk and some experts said that the effect was more likely to be a result of the lack of vitamins in the kinds of foods that tend to be sold packaged, or the unhealthy lifestyles of those who tend to eat them.
However, the research underlines the importance of a diet rich in fruit and vegetables rather than crisps and pizza.
The World Health Organisation has classed processed meats such as bacon and ham as carcinogenic but the new study looked more widely at industrialised ultra- processed foods such as factorymade bread, packaged confectionery, nuggets, burgers, breakfast cereals, instant soups and fizzy drinks. This includes ham and sausages when made with preservatives and additives other than just salt.
Canned salted vegetables are considered to be "processed" foods whereas factory-prepared cooked or fried seasoned vegetables, marinated in sauces with added flavourings are considered "ultraprocessed".
Touvier said that adjusting for the higher sugar and salt content of processed food did not appear to account for the findings. Her theory is that additives, compounds that form during processing or chemicals in packaging could be driving the results. "In Europe we have over 400 authorised additives. Most of them are probably safe," she said. "If it is due to some additives we have to say which ones."
Linda Bauld, of Cancer Research UK, said people should not worry about "eating a bit of processed food here and there", but added: "There is good evidence that too little fruit, vegetables and fibre and too much processed and red meat can contribute to the development of some types of cancer. "