Higher intake of certain food preservatives may be linked to a greater risk of developing type 2 diabetes and some forms of cancer, according to two large studies that are prompting renewed questions about the safety of widely used food additives.
The research, published in Nature Communications and The BMJ, points to potential public health concerns, especially given how common preservatives are in packaged and ultra-processed foods consumed around the world. While the authors stress that more research is needed, they say the findings should spark a closer look at existing regulations and encourage stronger consumer protections.
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Why Preservatives Are Under Scrutiny
Preservatives are routinely added to packaged foods to prevent spoilage and extend shelf life. Past laboratory experiments have shown that some of these substances can damage cells and DNA. However, solid evidence connecting preservatives to long-term health outcomes such as type 2 diabetes or cancer in humans has been limited.
To explore these possible links, researchers analyzed diet and health data collected between 2009 and 2023 from more than 100,000 adults enrolled in France’s NutriNet-Santé study. The team examined overall preservative exposure as well as the effects of 17 individual additives.
Cancer Risk: Mixed Results, But Notable Signals
In the cancer-focused study published in The BMJ, researchers found no overall association between total preservative intake and cancer incidence. Eleven of the 17 preservatives studied individually were also not linked to cancer.
However, higher consumption of several specific preservatives was associated with increased cancer risk compared with low or non-consumption. Potassium sorbate, for instance, was linked to a 14% higher risk of overall cancer and a 26% higher risk of breast cancer. Sulfites were associated with a 12% increase in overall cancer risk.
Other findings included a 32% increased risk of prostate cancer associated with sodium nitrite, and higher risks tied to potassium nitrate, 13% for overall cancer and 22% for breast cancer. Total acetates were linked to a 15% increase in overall cancer risk and a 25% increase in breast cancer, while acetic acid was associated with a 12% rise in overall cancer risk.
Researchers noted that some of these compounds may interfere with immune or inflammatory pathways, potentially contributing to cancer development. Still, they emphasised that the study was observational, meaning it cannot prove cause and effect, and that other unmeasured factors may have played a role.
Despite these limitations, the study’s size, its 14-year follow-up, and detailed dietary tracking strengthen the findings. The results also align with experimental evidence suggesting harmful cancer-related effects of several preservatives.
"This study brings new insights for the future re-evaluation of the safety of these food additives by health agencies," the researchers wrote, calling for a careful balance between the benefits of food preservation and potential health risks.
Type 2 Diabetes: A Stronger Association
The second study, published in Nature Communications, focused on type 2 diabetes and found a clearer pattern. Higher overall intake of preservatives was associated with a 47% increased incidence of type 2 diabetes compared with the lowest levels of consumption. Similar increases were seen for non-antioxidant preservatives (49%) and antioxidant additives (40%).
When examined individually, 12 of the 17 preservatives studied were linked to a higher risk of developing type 2 diabetes.
"This is the first study in the world on the links between preservative additives and the incidence of type 2 diabetes," said Mathilde Touvier, a coordinator of the research. While she cautioned that the findings need confirmation, she added that they are consistent with experimental data pointing to harmful effects from several of these compounds.
What This Could Mean For Public Health
Experts say the results deserve attention, particularly at a population level. Prof William Gallagher of University College Dublin, who was not involved in the research, described the increased cancer risks as modest but meaningful. "These higher rates of cancer are modest but are significant when taken at a population-based level in terms of potential impact," he said.
For now, the researchers are urging food manufacturers to reduce unnecessary use of preservatives and are reinforcing existing advice for consumers to prioritise fresh, minimally processed foods whenever possible.