Those who eat more food with preservatives—the chemical and plant-based ingredients that keep processed food from becoming rancid and making us sick—are at a 40 percent to 49 percent higher risk of developing Type 2 diabetes, according to a new study.
The diabetes finding and a separate cancer risk study conducted by researchers in Paris add to a growing body of evidence that the more preservative-rich foods you eat, the more your body is prone to unfavorable metabolic and inflammatory states that lead to chronic disease.
More than half the calories in the average American diet come from ultra-processed foods.
The food industry’s widespread use of preservatives and other chemical ingredients—often with no testing of long-term chronic disease risk—motivated the studies, Mathilde Touvier, research director at the French National Institute for Health and Medical Research, told The Epoch Times in an email.
Type 2 Diabetes Findings
Researchers from Sorbonne Paris Nord University followed 108,723 participants between 2009 and 2023, during which 1,131 were diagnosed with Type 2 diabetes, according to results published in Nature Communications.
Those with higher risk ate foods high in non-antioxidant food preservatives, which work either by preventing microbial growth or by slowing down chemical reactions that affect food color and texture. Those with a 40 percent higher risk had a diet high in antioxidant food preservatives, which prevent free radicals from causing oxidation that makes food rotten, discolored, or lose nutrients.
Seventeen preservatives were included in the study, 12 of which were associated with an increased risk of Type 2 diabetes, including potassium sorbate, sodium nitrite, sodium acetates, potassium metabisulfite, acetic acid, calcium propionate, sodium ascorbate, alpha-tocopherol, sodium erythorbate, citric acid, phosphoric acid, and rosemary extracts.
Possible mechanisms the researchers noted include interference with insulin signaling and glucose regulation, while other preservatives may trigger chronic low-grade inflammation or alter gene expression involved in metabolism. Changes to the gut microbiome also emerged as a plausible mechanism, as shifts in microbial balance can influence blood sugar control and insulin sensitivity over time.
Cancer Risk Study
In another study published in BMJ, the researchers also found that those who ate more food preservatives from the same cohort of participants were also more likely to be diagnosed with cancer.
Researchers discovered multiple associations between non-antioxidant preservatives (potassium sorbate, potassium metabisulfite, sodium nitrite, potassium nitrate, acetic acid, and sodium erythorbate) and antioxidant preservatives (total erythorbates and specific sodium erythorbate) with higher incidences of overall, breast, and prostate cancers.
Of the 105,260 study participants, 4,226 developed cancer in a 14-year period at an overall rate of 4 percent. Risk rates varied between specific cancers and preservatives; six of 17 preservatives studied were linked to an increased risk of cancer. Rates ranged from a 12 percent increased risk for overall cancer associated with total sulfites to a 32 percent increased risk for prostate cancer associated with sodium nitrite.
The preservatives used in both studies are also found in the U.S. market in products such as sauces, pickled foods, wine, beer, dried fruits, salad dressings, cheese, and yogurt, as well as cured meats such as bacon, hot dogs, deli meats, and sausage.
The authors of a BMJ editorial noted that more research is needed, pointing out that the study does not establish causality, shows only a modest increased risk of cancer, and is unclear about whether synthetic preservatives are more harmful than natural ones. They added that because multiple chemicals and additives are added to foods, it is difficult to tell whether health effects are the result of preservatives alone or a combined or interactive effect with other ingredients.
Why Preservatives May Be Harmful
The danger in food preservatives is that, however they affect the food, they may also affect the human body—especially when eaten in large amounts, according to gastroenterologist and leading gut health expert Will Bulsiewicz, who was not involved in the studies.
The antimicrobial action of some preservatives could have an effect similar to that of antibiotics and wipe out good bacteria in the gastrointestinal tract.
“Type 2 diabetes has been very clearly associated with changes to the gut microbiome,” he told The Epoch Times.
A complication to the issue is that seemingly healthy or innocuous ingredients could be problematic because of the way food is adulterated—extracting and isolating elements from natural foods and then combining them with other extracted and isolated parts of other foods, Bulsiewicz said.
“The food matrix contains all these other nutrients along with that one nutrient,” he said. “You extract it, and it doesn’t necessarily behave the way that it used to. We have to be careful.”
The Challenge of Avoidance
Unlike other food additives, such as colors and sweeteners, preservatives aren’t classified as markers of ultra-processed foods. Although they are common in processed items, they appear across many food categories. The authors of the Type 2 diabetes study noted that preservatives are “ubiquitously used across many food groups, with a huge variability in ingredient lists.”
Such ubiquity creates challenges for consumers trying to limit exposure, particularly for those managing health conditions.
For patients with inflammatory bowel diseases, dietitian Cassie Madsen uses dietary guidance issued by the International Organization for the Study of Inflammatory Bowel Diseases, which suggests limiting several food additives but doesn’t address preservatives. It can be a nuanced issue for some and lead to fear of food, she told The Epoch Times.
“If processed foods are what they tolerate when they first come to me and I tell them, ‘Nope, you can’t have that,’ what are they going to eat?” Madsen asked. “I think we have to be a bit careful of fear-mongering that makes people afraid to eat and increases the confusion.”
Simply adding more restrictions to such dietary recommendations is unrealistic, the authors of the new studies said. All additives need to be reevaluated, and if necessary, new regulations should remove risks from food, they said.
What Regulators Say
The U.S. Food and Drug Administration told The Epoch Times in an email that it is poised to remove unsafe food from the market with its newer review process.
However, preservatives were not among the examples it provided of additives that it is currently attempting to remove from the food supply.
The study authors noted there have been broad efforts to educate consumers to limit preservatives in processed meats and alcohol, but they said much more work is needed.
What You Can Do Now
The researchers noted that their findings suggest that it is safest to eat fresh, minimally processed food, cook at home, and choose preservative-free alternatives whenever possible.
Touvier and Anais Hasenbohler, a doctoral student assisting in the studies, told The Epoch Times that a food matrix includes composition, structure, acidity, and other compounds that interact with the gut microbiome and determine what our bodies will absorb and use.
Preservatives need more research, they acknowledged. Ongoing studies include investigations into food preservatives and cardiovascular risk, food dyes and chronic disease risk, and the combined effects of food packaging contaminants and food processing on chronic disease risk.
The research team has already published studies linking food additives such as emulsifiers and artificial sweeteners to cancer, cardiovascular disease, and Type 2 diabetes.
Anyone can take action, the researchers said in the study. Manufacturers can start limiting preservatives, health care providers can improve food recommendations to patients, and government leaders can improve access to fresh, homemade food.
“If confirmed, our findings reveal a potential for modifiable risk factor for several key chronic diseases,” Touvier said.