Two studies from French researchers highlight the association between higher consumption of preservatives and an increased risk of cancer and type 2 diabetes.
What are the effects on our health of preservatives added to industrial foods to extend their shelf life? The question has been investigated by scientists from various French institutions within the Nutritional Epidemiology Research Team (Cress-Eren), and the results have recently been published in two studies — one in Nature Communications and one in the British Medical Journal — revealing an association between higher consumption of preservatives and an increased risk of cancer and type 2 diabetes.
"These are the first two studies in the world on the links between preservative additives and the incidence of cancer and type 2 diabetes. Although the results need to be confirmed, they are consistent with experimental data suggesting harmful effects of several of these compounds," explained Mathilde Touvier, research director at Inserm and coordinator of the studies.
Preservatives are widely used by the food industry worldwide. Of the 3.5 million food and beverage products listed in the Open Food Facts World database in 2024, more than 700,000 contain at least one of these substances. For the purposes of the studies, researchers grouped preservatives into two categories: non-antioxidant preservatives, which inhibit microbial growth or slow the chemical changes that lead to food spoilage, indicated on labels with European codes E200 to E299, and antioxidant preservatives, which delay or prevent food deterioration by eliminating or limiting oxygen levels in packaging, indicated with European codes E300 to E399.
The research was based on data provided by more than 100,000 French adults with an average age of 42 who participated in the NutriNet-Santé study. Between 2009 and 2023, volunteers reported their clinical history, sociodemographic data, physical activity habits, as well as information on their lifestyle (such as alcohol and tobacco consumption) and their health status. They also regularly provided detailed information on their food consumption, sending scientists comprehensive 24-hour records including the names and brands of processed foods consumed. This data, combined with several databases (Open Food Facts, Oqali, Efsa) and with measurements of additives in food and beverages, allowed researchers to assess participants' exposure to preservatives during the follow-up period.
Of the 58 preservatives identified in participants' medical records, it was possible to individually analyse 17 substances in relation to the conditions studied — substances consumed by at least 10 per cent of volunteers.
During the follow-up period, 4,226 participants received a cancer diagnosis, including 1,208 breast cancers, 508 prostate cancers, 352 colorectal cancers and 2,158 other cancers. Total consumption of non-antioxidant preservatives was associated with an increase in the incidence of cancer in general and breast cancer in particular. Of the 17 preservatives studied individually, 11 were not associated with cancer incidence. However, higher consumption of several preservatives (mainly non-antioxidant preservatives) was associated with a greater risk of cancer compared to lower levels of consumption. In particular:
Among antioxidant preservatives, only total erythorbates and the specific sodium erythorbate (E316) were found to be associated with a higher incidence of cancer in general (12 per cent) and breast cancer (21 per cent).
Several experimental studies have observed that some of these compounds can alter immune and inflammatory pathways, so the hypothesis is that this could trigger the development of cancer.
During the same follow-up period, 1,131 cases of type 2 diabetes were identified. Higher consumption of preservative additives, non-antioxidant preservatives and antioxidant additives was associated with an increase in the incidence of type 2 diabetes of 47 per cent, 49 per cent and 40 per cent respectively, compared to the lowest consumption levels.
Of the 17 preservatives studied individually, higher consumption of 12 was associated with an increased risk of type 2 diabetes: potassium sorbate (E202), potassium metabisulphite (E224), sodium nitrite (E250), acetic acid (E260), sodium acetates (E262) and calcium propionate (E282), sodium ascorbate (E301), alpha-tocopherol (E307), sodium erythorbate (E316), citric acid (E330), phosphoric acid (E338) and rosemary extract (E392).
According to the researchers' conclusions, these new findings add to a growing body of evidence in support of a reassessment of the regulations governing the general use of food additives by the food industry, with the aim of improving consumer protection. Consumers themselves are encouraged to favour fresh and minimally processed foods, limiting exposure to additives as much as possible.