Some commonly used food preservatives found in processed foods and drinks may be associated with a slightly higher risk of developing cancer and type 2 diabetes, according to two large French studies.
While the findings raise fresh concerns about the long-term effects of certain food additives, researchers and independent experts have stressed that the studies show an association rather than proving that the preservatives directly cause disease.
Two large French studies examine food preservatives
The findings come from two separate studies involving more than 100,000 participants enrolled in an ongoing French nutrition research project. Participants regularly reported details about their diet through questionnaires, allowing researchers to analyse long-term eating patterns and health outcomes.
One study, published in The BMJ, examined links between food preservatives and cancer, while the second, published in Nature Communications, investigated whether certain food additives were associated with the development of type 2 diabetes.
Study links some preservatives to higher cancer risk
According to the study published in The BMJ, researchers observed "multiple associations between preservatives that are widely used in industrial foods and beverages on the European market... and higher incidences of overall, breast and prostate cancers", AFP reported.
Among the preservatives highlighted were nitrites and nitrates, which are widely used to preserve processed meats such as bacon, ham and sausages.
Researchers found the strongest association between sodium nitrite and prostate cancer, with the risk estimated to be around one-third higher among people with greater exposure. However, the researchers noted that the increase in risk remained moderate.
For comparison, AFP reported that heavy smoking increases the risk of lung cancer by more than 15 times.
Diabetes study identifies possible link with potassium sorbate
The second study, published in Nature Communications, found that some food additives were also linked to a higher risk of developing type 2 diabetes.
According to AFP, one of the strongest associations was seen with potassium sorbate, a preservative commonly used to prevent mould and bacterial growth in food and beverages. The study linked higher consumption of potassium sorbate with roughly double the risk of developing type 2 diabetes.
The researchers said further investigation is needed to better understand the biological mechanisms behind these associations.
Researcher urges people to choose less processed foods
Mathilde Touvier, the French epidemiologist who supervised both studies, cautioned against interpreting the findings as proof that preservatives directly cause disease.
"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," she added.
According to AFP, Touvier advised consumers to choose foods that are less processed whenever possible.
"The message for the general public is to choose the least processed foods when shopping in the supermarket," she said.
Experts say more research is still needed
Independent researchers welcomed the scale and methodology of the studies but emphasised that observational research cannot establish a direct cause-and-effect relationship.
Tom Sanders, a nutrition expert at King's College London who was not involved in the research, said the findings could be influenced by other known risk factors.
According to AFP, Sanders noted that processed meat consumption and alcohol intake are already strongly linked with an increased risk of cancer, making it difficult to isolate the effects of individual preservatives.
He suggested that, in some cases, the observed cancer risk may be related to overall dietary habits rather than a specific additive. For example, sodium metabisulphite is used in winemaking, but the increased risk could instead reflect alcohol consumption rather than the preservative itself.
Sanders also told AFP that one possible policy option would be introducing health warnings on foods containing nitrates and nitrites, although he stressed that further evidence is needed before making firm recommendations.
What do the findings mean for consumers?
The researchers and outside experts agree that these studies should not be interpreted as evidence that eating foods containing preservatives will inevitably lead to cancer or diabetes.
Instead, the findings add to growing evidence suggesting that diets high in ultra-processed foods may carry long-term health risks. More studies, including clinical research, will be needed to determine whether these preservatives directly contribute to disease.
The studies were published shortly after the UK introduced restrictions on daytime television, radio and online advertising for foods and drinks high in fat, salt and sugar, reflecting broader efforts to encourage healthier eating habits, AFP reported.
Disclaimer: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.
