If scientists told you that there's one lifestyle factor that might 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, their results showed that eating processed food is 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, sweets, cooldrinks, frozen food items like fish fingers, two-minute 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.
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 their eating plan looked like.
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.
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. But given the fact that the research controlled for factors like family history, age, sex, prescription birth control (in the case of breast cancer), body mass index, and education, it's hard to imagine what other factors might explain the bump in cancer rates among packaged-food eaters.
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 restaurant kitchen, and also don't have nearly as much stomach-filling fiber and important nutrients.
Sugar is 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 tumor growth in people who already have cancer.
Some of the packaging that processed foods come in might also be cause for alarm. Materials in the plastic wrapping can include Bisphenol A (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 pre-made foods.