Researchers from France and Brazil have now linked consumption of ultra-processed food with increased risk of cancer.
In addition, processed foods may also raise the risk of obesity, high blood pressure and cholesterol.
Researchers evaluated potential associations between ultra-processed food intake and risk of overall cancer, as well as that of breast, prostate and bowel (colorectal) cancers.
Researchers studied over 104,980 healthy adults (22 percent men and 78 percent women) with an average age of 43 years.
The study investigated “ultra-processed” foods, such as ready meals, fresh bread, chicken nuggets and cakes, which are made in factories with ingredients unknown to the domestic kitchen.
Researchers found that a 10% increase in the amount of ultra-processed foods in the diet was linked to a 12% increase in cancers of some kind.
Several well known risk factors for cancers, such as age, sex, educational level, family history of cancer, smoking status and physical activity levels, were taken into account.
Consumption of fresh or minimally processed foods such as fruits, vegetables, pulses, rice, pasta, eggs, meat, fish and milk was also associated with lower risks of overall cancer and breast cancer.
The researchers emphasized 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.
“To our knowledge, this study is the first to investigate and highlight an increase in the risk of overall and specifically breast cancer associated with ultra-processed food intake,” researchers said.
They added, however, that their results would need to be “confirmed by other large-scale” studies to establish the mechanisms behind this association.
The researchers used data from a large cohort study, called NutriNet-Santé, that tracks the eating habits and health of thousands of French people. The study was published in the British Medical Journal.