A new study in the British Medical Journal has found an association between increased risk of cancer and “ultra-processed foods,” including sodas, mass-produced bread, instant noodles, candy, and ready meals.

As with many health studies you see pop up in the news, it's important to pay attention, but also to take them with a pinch of salt.

Scientists at the Sorbonne in Paris looked at the medical records and eating habits of over 105,000 middle-aged French people. Their findings suggest that a 10 percent increase in the proportion of ultra-processed foods in a person’s diet was correlated with a 12 percent higher risk of cancer.

They also noted that the people who had the highest ultra-processed food intake were also more likely to be smokers, had lower levels of education, were less physically active, and consumed more calories.

This study was also only looking for a correlation, not a causation, so the researchers did not explicitly find that certain foods cause cancer. 

So, what counts as ultra-processed?

Well, for this study it was based on “the nature, extent, and purpose of the industrial processing.” This included packaged breads and buns; sweet or savory packaged snacks; industrialized confectionery and desserts; sodas and sweetened drinks; meatballs, poultry and fish nuggets, and other reconstituted meat products; instant noodles and soups; frozen or shelf stable ready meals.

However, their classification of “ultra-processed foods” appears to be vague and fairly loose, meaning it's not very useful for consumers looking to eat healthier or policymakers wanting to lower the risk of disease.

“That’s the problem with terms like ‘ultra-processed’. It’s a label that tends to be deployed very selectively. Being posh or fashionable somehow gives food a get-out-of-jail card,” tweeted botanist and food expert James Wong. 

Undoubtedly, diet has a profound effect on your health and it can affect the risk of cancer, as numerous studies have shown. However, it's always important to carefully consider any of the sensational claims that spring out of these studies like this.

“What people eat is an expression of their lifestyle in general, and may not be causatively linked to the risk of cancer. So it is necessary to rule out what are called confounding factors – things already known to cause cancer such as smoking, obesity, alcohol intake and low intakes of fruit and vegetables,” Tom Sanders, Professor Emeritus of Nutrition and Dietetics at King’s College London, who was not directly involved in the study, cautioned.

“The approach of categorising dietary patterns that depend on industrially processed food in relation to disease risk is novel but probably needs refining before it can be translated into practical dietary advice.”