Preservatives are added to many of the foods we eat every day, including meat, dairy products, sauces, snack foods, frozen meals, and more. These chemicals extend shelf life and keep food from spoiling—but a new study published in the BMJ suggests they may have serious downsides, too.
People who eat lots of certain preservatives may be at increased risk for cancer, the new study found.
“Of course, we need to confirm the results,” said Mathilde Touvier, PhD, one of the study’s authors and a research professor at the French National Institute for Health and Medical Research. But from a precautionary standpoint, she told Health, the study suggests it’s worth avoiding preservatives when possible.
The new paper is based on data from the NutriNet-Santé study, a nutrition research project that began in 2009.
As part of this project, more than 100,000 people submitted detailed food diaries over the course of multiple years. The researchers used those logs to determine which preservatives people in the study consumed, and how often.
Then, the researchers monitored the participants—almost 80% of whom were women—to see how many of them developed cancer. More than 4,200 people received a diagnosis during the study period, which ran from 2009 to 2023.
After accounting for factors like tobacco use, family history of cancer, and overall diet quality, the researchers zeroed in on how 17 commonly eaten preservatives seemed to affect cancer risk. Eleven of them were not linked to cancer. But some preservatives used widely across the food supply did appear to boost cancer risk when eaten frequently.
These included sulfites, potassium sorbate, potassium nitrate, acetates, acetic acid, and sodium erythorbate. Higher intake of these chemicals was associated with 12% to 15% higher overall cancer risks, the researchers found.
Some seemed to be linked especially dramatically to specific cancer types. Sodium nitrite, which is commonly found in cured meats, was associated with a 32% higher risk of prostate cancer. And potassium sorbate, which is used in cheese, snack foods, frozen foods, and more, was linked to a 26% increased risk of breast cancer.
The study was designed to find patterns related to dietary habits and cancer risk—and for that purpose, “it’s a very well-done study,” said Edward Giovannucci, MD, ScD, a professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health. (Giovannucci was not involved in the research, but cowrote an accompanying editorial about it for the BMJ.)
The research, however, was not meant to prove cause and effect or to investigate how preservatives could theoretically cause cancer. But other published studies—many performed on cells or animals rather than people—provide some clues, Touvier said. Studies have linked food preservatives to multiple potentially cancer-causing effects, including cellular toxicity, abnormal cell growth, and increased inflammation.
It’s also possible, Giovannucci added, that some foods containing preservatives increase cancer risk in other ways. For example, sulfites are often consumed in alcoholic drinks. Alcohol is a known carcinogen because it breaks down into a toxic byproduct when digested, so “you can’t say it’s the sulfites that are causing the cancer,” he told Health.
The bottom line is, more research is needed to say for sure if or how preservatives cause cancer. “We cannot say more than what we have here,” Touvier said.
Public health experts already recommend limiting consumption of processed meat and booze, two known carcinogens that contain some of the preservatives identified in the study. But what about the many other foods packed with preservatives?
“In a perfect world, we could grow our own food in the backyard and cook everything from scratch,” Giovannucci said.
But, obviously, that’s not possible for the vast majority of people—and you shouldn’t panic if you end up eating foods that contain preservatives. The study’s findings are preliminary and not dramatic enough to cause immediate alarm, Giovannucci said, though it is worth continuing to study the health effects of preservatives.
That said, based on other research, “is very clear that highly processed foods, including those that contain many additives, have negative health benefits,” said Timothy Rebbeck, PhD, a professor of cancer prevention at Dana-Farber Cancer Institute and the Harvard T.H. Chan School of Public Health, who was not involved in the new study. “Limiting processed foods and eating whole foods that are less processed is always the preferred choice to minimize cancer risks and maximize health benefits for other diseases,” he told Health.
Touvier agreed. Whenever you can, she said, “use minimally processed foods, make your own recipes, and avoid these unnecessary food additives.”
