Consumption of some commonly used food preservatives may be associated with a slightly higher risk of developing cancer and type 2 diabetes, according to two large-scale French studies published on Thursday. Researchers and independent experts, however, cautioned that the findings do not establish a direct cause-and-effect relationship and called for further investigation.
The first study, published in the BMJ, reported multiple associations between widely used preservatives in industrial foods and beverages across Europe and an increased incidence of overall cancers, including breast and prostate cancer. The preservatives examined included nitrites and nitrates, which are commonly used to cure processed meats such as ham, bacon and sausages.
A second study, published in Nature Communications, found that consumption of certain food additives was also linked to a higher risk of developing type 2 diabetes.
Both studies are part of an ongoing French research programme tracking the dietary habits of more than 100,000 participants who regularly provide detailed information through questionnaires.
Mathilde Touvier, a French epidemiologist who supervised both studies, said the findings should not be interpreted as an immediate health threat. “Consuming products with preservatives does not mean you will immediately develop cancer,” she told AFP. “But we need to limit how much we are exposed to these products.”
Touvier advised consumers to prioritise minimally processed foods while grocery shopping, stressing that moderation and overall dietary patterns remain key.
Among the findings, the strongest association in the cancer study was observed between sodium nitrite and prostate cancer, with the risk estimated to rise by around one-third. Researchers noted, however, that the absolute increase in risk was still moderate. By comparison, heavy smoking increases the risk of lung cancer more than 15-fold.
The diabetes study found that potassium sorbate—commonly used to prevent mould and bacterial growth in food and beverages—was associated with roughly double the risk of developing type 2 diabetes.
Independent experts welcomed the robust methodology of the studies but urged caution in interpreting the results. Tom Sanders, a nutrition expert at King’s College London, warned that the associations could be influenced by other lifestyle and dietary factors that are difficult to fully account for in observational research.
Processed meats and alcohol consumption, both already known to increase cancer risk, could partly explain the findings, Sanders said. He added that in some cases, the health risks attributed to additives may actually be linked to the food or drink itself rather than the preservative used.
Sanders suggested that clearer labelling, including possible health warnings on foods containing nitrates and nitrites, could be one policy option worth considering.
The studies were published shortly after the UK announced a ban on daytime television, radio and online advertising for foods and drinks high in fat, salt and sugar, underscoring growing regulatory scrutiny of ultra-processed foods and their impact on public health.