A study of more than 100,000 people has found that one food group is closely linked with cancer

  • A study of more than 100,000 French adults revealed a startling link: People who consumed more processed food were much more likely to develop all kinds of cancers.
  • Most of the ultra-processed products were foods and beverages with a lot of sugar.
  • The finding held true for every category of adults in the study: men and women, exercisers and couch potatoes, younger and older people, smokers and nonsmokers.

If scientists told you there was a single lifestyle factor that may best predict whether you get cancer, you’d want to know, right?

Researchers in France may have found just that. After studying more than 100,000 adults for years, they found that eating processed food was more closely linked with cancer risk than one’s age, sex, body mass index, height, level of physical activity, smoking and drinking habits, calories consumed, or family history.

This harmful “ultra-processed” food, as the researchers called it, may include packaged sweet pastries and muffins, chips, candy, sodas, frozen dinners like meatballs and fish sticks, instant ramen noodles, sugary cereals, and pretty much anything else you can imagine that’s cheap and comes in a ready-to-go packet or container at the store.

The researchers estimate this junk food accounts for 25% to 50% of the total daily energy intake of people who live in rich, developed countries like the US, France, and Canada.

The link between sugary, processed food and cancer

Junk food snacks chips processed

To find the link between processed food and cancer, researchers combed through, on average, five years of medical records and surveys of previously cancer-free adult patients.

All the participants (a cohort of roughly 22% men and 78% women) agreed to fill out an online form detailing everything in their daily diet on about six days each year. Those surveys were meant to serve as comprehensive samples of what the study participants tended to eat in a single 24-hour period, with data from both weekdays and weekend diets.

The researchers then compared that data to the participants’ records in France’s national health system database to find out who was getting cancer and what they ate.

The scientists noticed that participants who reported eating more ultra-processed, packaged foods tended to develop cancer more often than people who ate fresh stuff that was cooked at home or in restaurants. In fact, the study authors wrote that “a 10% increase in the proportion of ultra-processed foods in the diet was associated with significant increases of 12% in the risk of overall cancer, and 11% in the risk of breast cancer.”

On the other hand, French people who ate slightly less processed foods like canned goods, cheeses, and baguettes didn’t tend to report higher instances of cancer. And healthy eaters who ate fresh, unprocessed foods like fish, rice, and veggies were found to have the lowest rates of cancer.

We don’t know that processed food is causing cancer, but there’s a link in the data

It’s important to note that these results don’t mean processed food is definitively causing cancer – the scientists simply found a worrisome trend in the data. The research, however, controlled for a fairly comprehensive number of factors like family history, age, sex, prescription birth control (in the case of breast cancer), body mass index, and education.

It is well established that processed foods aren’t good at keeping people full or providing them with the necessary fuel to get through the day without crashing. Packaged foods contain more sugar, fat, and salt than anything made in a home or a restaurant kitchen, and also don’t have nearly as much stomach-filling fibre and important nutrients.

Sugar is most likely the biggest diet culprit here: sweet drinks and blood-sugar-spiking snacks accounted for more than a quarter of the ultra-processed food that the people in the study ate. Other recent research has suggested that sugar may fuel tumour growth in people who already have cancer.

Some of the packaging that processed foods come in may also be cause for alarm. Materials in the plastic wrapping can include bisphenol A, or BPA, which can disrupt normal functioning of the endocrine system and lead to more birth defects and higher cancer rates. Packaged foods also include additives like sodium nitrite, which preserves meats but has also been shown to cause cancer in animal models.

Scientists would never suggest that a link between data points is the same as a clear indication that one thing is the cause of another. But this new finding is concerning enough that the scientists say the next several decades could be increasingly cancerous times if we continue eating so many sugary premade foods.