While we know that ultra-processed foods are bad for our health, a new study warns that they appear to be particularly harmful to cancer survivors.

After 15 years of follow-up, Italian researchers found that cancer survivors whose diets were highest in ultra-processed foods had a 59 per cent increased risk of cancer recurrence and a 48 per cent increased risk of all-cause mortality compared to survivors who consumed the least.

Just over a third of these associations, or 37 per cent, “could be explained by high levels of inflammatory markers and resting heart rate,” wrote the study authors.

“We knew there was an increased risk of developing cancer linked to ultra-processed foods,” said David Labbé, a scientist with the cancer research program at the McGill University Health Centre Research Institute.

“Now there is evidence that there is an increased risk of dying, either from cancer or other causes.”

That said, he continued, even though the study authors attribute about one-third of the observed association to significant inflammation and accelerated resting heart rate, the mechanisms involved are not fully understood.

It is also possible that the study results are influenced by selection bias, he noted.

“Perhaps (the participants are) patients in poorer health,” said Labbé. “That may be why they consume more ultra-processed foods. Perhaps they are people who have had cancer or more aggressive treatment. Perhaps they are no longer able to cook at home with higher quality ingredients.”

Substances used in industrial food processing can interfere with metabolic processes, disrupt the gut microbiota, and promote inflammation, the study authors explained in a press release.

Therefore, they added, “even if an ultra-processed food has, on paper, a similar calorie content and nutritional composition to a minimally processed or ‘natural’ food, it may nevertheless have a more harmful effect on the body.”

“We can’t really prevent cancer, but we can reduce the risk of developing it,” said Labbé. “We need to limit our consumption of processed foods high in added sugars, processed meats, sugary soft drinks, etc.”

Ultra-processed foods are those that have been industrially produced and contain ingredients not typically found in home cooking, such as emulsifiers, preservatives, artificial colors, and artificial flavors.

This broad category includes products such as soft drinks, instant noodles, and potato chips, as well as less obvious foods such as flavored yogurts and commercially prepared whole grain breads.

At this point, Labbé believes that even if we don’t fully understand why and how ultra-processed foods are harmful to health, “there is enough smoke to say that we, as individuals and as a society, should start making choices or supporting people to move away from ultra-processed foods.”

“It’s a bit like cigarettes,” said Labbé. “We didn’t know exactly which chemical compound increased the risk of lung cancer in smokers, but that didn’t stop us from starting to legislate and then adopting regulations and laws to regulate and reduce smoking.”

According to the most recent data available, ultra-processed foods account for nearly 45 per cent of the daily energy intake of Canadians aged 20 and over.

The authors of the Italian study used the Nova food classification, which is not well known in Quebec, even though studies have shown its effectiveness in contributing to weight loss and combating problems such as diabetes.

The Nova classification divides foods into four categories: minimally processed or unprocessed foods (green category); processed food ingredients (yellow category); processed foods (orange category); and ultra-processed foods (red category).

The findings of the new study were published in the journal Cancer Epidemiology, Biomarkers & Prevention.

–This report by La Presse Canadienne was translated by CityNews