Two large-scale French studies have reignited debate over the health impacts of food preservatives, suggesting that higher consumption of certain widely used additives may be linked to an increased risk of cancer and type 2 diabetes.
Published this week in leading scientific journals, the findings add to growing concerns about ultra-processed foods, while also prompting calls from experts for caution and further research.
The studies, published in BMJ and Nature Communications, analyzed dietary and health data from more than 100,000 adults participating in Franceβs long-running NutriNet-SantΓ© study.
Participants regularly completed detailed questionnaires about their food intake over 14 years, allowing researchers to track long-term associations between diet and disease.
Cancer risk and common preservatives
The cancer-focused study examined 17 commonly used preservatives found in industrial food and beverages across Europe.
While no overall association was found between preservatives as a group and total cancer risk, higher consumption of several specific additives was linked to increased incidences of certain cancers.
One of the strongest associations is with sodium nitrite, a preservative commonly used to cure processed meats, including ham, bacon, and sausages.
Higher intake of sodium nitrite was associated with a roughly 32% increased risk of prostate cancer. Potassium nitrate, another curing agent, was linked to a 13% increase in overall cancer risk and a 22% higher risk of breast cancer.
Potassium sorbate, commonly used to inhibit mold and bacterial growth, was associated with elevated risks of overall and breast cancers, while sulfites and acetates were also linked to modest increases in cancer incidence.
Researchers emphasized that these increases are moderate at an individual level. For perspective, heavy smoking raises the risk of lung cancer by more than 15 times.
Nonetheless, even modest increases can translate into significant public health impacts when applied across entire populations.
Links to type 2 diabetes
The second study, published in Nature Communications, explored the relationship between preservatives and type 2 diabetes.
It found that higher overall intake of preservatives was associated with a 47% increased risk of developing the disease compared with the lowest levels of consumption.
Non-antioxidant preservatives and antioxidant additives were linked to 49% and 40% higher risks, respectively.
Of the 17 preservatives examined individually, 12 were associated with increased diabetes risk.
Potassium sorbate again stood out, being linked to roughly double the risk of developing type 2 diabetes among high consumers.
Mathilde Touvier, the French epidemiologist who coordinated both studies, stressed that the findings do not mean consuming foods with preservatives will inevitably lead to disease.
Rather, she said, they highlight the importance of limiting exposure over time and favoring minimally processed foods.
Observational limits and expert caution
Despite the scale and methodological rigor of the research, scientists not involved in the studies urged restraint in interpreting the results.
Because the research is observational, it cannot prove that preservatives directly cause cancer or diabetes. Other lifestyle and dietary factors may also play a role.
Tom Sanders, a nutrition expert at King’s College London, noted that it is difficult to completely adjust for confounding factors such as alcohol consumption or processed meat intake, both of which are already strongly linked to cancer risk.
He suggested that, in some cases, it may not be a preservative like sodium metabisulfite causing harm, but the broader dietary context in which it is consumed, such as wine or processed foods.
However, Sanders added that clearer labeling, including potential health warnings on foods containing nitrates and nitrites, could help consumers make more informed choices.
Implications for policy and consumers
The findings arrive amid growing regulatory scrutiny of unhealthy foods. In the United Kingdom, authorities recently announced bans on daytime television, radio, and online advertising for foods high in fat, salt, and sugar.
While the new studies do not directly drive policy changes, researchers argue they should prompt a re-evaluation of preservative regulations worldwide.
Professor William Gallagher of University College Dublin, who was not involved in the research, said the increased risks observed were modest but meaningful at a population level.
He noted that even small shifts in disease incidence can have substantial implications for public health systems.
In their conclusions, the researchers called on manufacturers to reduce the use of unnecessary preservatives and encouraged consumers to prioritize fresh, minimally processed foods.
While further studies are needed to confirm these associations and clarify biological mechanisms, the message emerging from the evidence is consistent: diets centered on whole foods remain the safest choice for long-term health.
