Processed foods make up to 50 per cent of the average person's diet in some developed countries and could be contributing to rising cancer levels, researchers working in Brazil and France found.
Teams from the Sorbonne in Paris and the University of Sao Paulo found that a 10 per cent increase in ultra-processed food intake was associated with a 12 per cent increased risk of overall cancer.
The research also indicated an 11 per cent increase in the risk of breast cancer.
The findings, published in the British Medical Journal, were based on a survey of 104,980 healthy French adults with an average age of 43, measuring their intake of 3,300 different food items.
The foods were grouped according to the level of processing, and participants were asked to self-declare any cancer diagnosis, which was then confirmed through their medical records.
Researchers also took into consideration other risk factors such as age, gender, levels of education, whether the participant smoked and family history of cancer.
While a small rise in ultra-processed food intake was associated with an increased risk of cancer, there was no significant link between less processed foods – such as canned vegetables, cheese and fresh bread – and cancer.
Consumption of fresh or minimally processed foods including fruits, vegetables, pulses, rice, pasta and fresh meat, was associated with a lower risk of overall cancer.
The researchers emphasised that at this stage it was just an observational study, and no firm conclusions could be drawn about ultra-processed food consumption and risk of cancer.
Ultra-processed foods often have a higher content of total fat, saturated fat, and added sugar and salt along with a lower fibre and vitamin density.