Two recent observational studies conducted in France suggest an association between higher consumption of specific food preservatives and an increased risk of developing certain cancers and type 2 diabetes. The findings, derived from extensive data collected through the NutriNet-Santé study over more than a decade, were published in Nature Communications and The BMJ.
Study Background and Methodology
The investigations utilized dietary and health data from the ongoing NutriNet-Santé cohort, which tracks the habits and medical data of over 170,000 French participants. Specific analyses involved over 100,000 individuals who were followed between 2009 and 2023. Researchers aimed to determine associations between exposure to various food preservatives and the incidence of type 2 diabetes and cancer in adults.
The methodology involved detailed, repeated 24-hour food questionnaires to assess brand-specific preservative intake. Researchers controlled for potential confounding factors such as physical activity, tobacco and alcohol use, medication, and lifestyle. While 58 preservatives were generally considered, detailed analysis focused on 17 individual preservatives consumed by at least 10% of participants.
Cancer Study Findings
The study published in The BMJ reported that no overall link was established between total preservative consumption and cancer incidence. However, higher consumption levels of several specific preservatives correlated with increased cancer risks when compared to non-consumers or lower consumers. These associations included:
- Potassium sorbate: Associated with a 14% increased risk of overall cancer and a 26% increased risk of breast cancer.
- Sulfites (including potassium metabisulfite): Linked to an overall 12% increased risk of cancer. Potassium metabisulfite specifically was associated with an 11% higher risk of all cancers and a 20% increase in breast cancer.
- Sodium nitrite: Associated with a 32% increased risk of prostate cancer.
- Potassium nitrate: Linked to a 13% increased risk of overall cancer and a 22% increased risk of breast cancer.
- Acetates (including total acetates and sodium acetate): Total acetates were associated with a 15% increased risk of overall cancer and a 25% increased risk of breast cancer. Sodium acetate was also linked to these risks.
- Acetic acid: Associated with a 12% increased risk of overall cancer.
- Sodium erythorbate and other erythorbates: Linked to a 12% increase in overall cancer risk and a 21% higher incidence of breast cancer.
Researchers hypothesized that certain compounds could modify immune and inflammatory pathways, potentially contributing to cancer development. It was also suggested that isolating substances from their original food matrix might alter their health effects. Six of the preservatives found to be associated with increased cancer risk are classified as "generally recognized as safe" (GRAS) by the US Food and Drug Administration.
Type 2 Diabetes Study Findings
The study published in Nature Communications found associations between higher preservative intake and an increased incidence of type 2 diabetes. Among approximately 109,000 participants who did not have the disease at the start of the study, higher intake was associated with:
- A 47% increased incidence of type 2 diabetes for overall preservative intake.
- A 49% increased incidence for non-antioxidant preservatives.
- A 40% increased incidence for antioxidant additives.
Out of the 17 individual preservatives examined, higher consumption of 12 was associated with an increased risk of type 2 diabetes. Five preservatives also linked to cancer risk (potassium sorbate, potassium metabisulfite, sodium nitrite, acetic acid, and sodium acetate) were associated with a nearly 50% higher risk of type 2 diabetes. Additionally, calcium propionate was connected to an increased risk. More than two antioxidant additives, including alpha-tocopherol, sodium ascorbate, rosemary extracts, sodium erythorbate, phosphoric acid, and citric acid, were also associated with a 42% increased risk of type 2 diabetes.
Mathilde Touvier, a study coordinator and senior author, stated that these are the initial global studies to investigate associations between these specific food additives and type 2 diabetes incidence, noting consistency with existing experimental data.
Limitations and Future Research
Both investigations were observational studies, which can identify correlations but do not establish direct cause-and-effect relationships. The potential influence of unmeasured factors on the results was also acknowledged. However, the studies were large-scale, utilizing extensive dietary records linked to food databases over 14 years, and their findings align with existing experimental data suggesting adverse effects from certain compounds. Researchers also considered existing data on the impact of these chemicals on animal models, cellular models, gut microbiota, oxidative stress, and inflammatory processes.
Anaïs Hasenböhler, a first author of both studies, indicated that more research is necessary to confirm and expand these findings. Professor William Gallagher, who was not involved in the studies, commented that while the observed increases in cancer rates may appear modest, their impact becomes significant when considered at a population level.
Recommendations
Researchers involved in the studies advocated for a re-evaluation of food additive safety regulations by health agencies and suggested that manufacturers limit the use of unnecessary preservatives. They also advised consumers to prioritize fresh, minimally processed foods.