A comprehensive prospective study drawing from the NutriNet-Santé cohort has identified potential associations between the consumption of certain food preservatives and a higher incidence of cancer.
Published in The BMJ, the research analyzed dietary habits and health outcomes among more than 105,000 French adults followed for an average of about 7.5 years. During this period, 4,226 participants developed cancer, with breast cancer, prostate cancer, and colorectal cancer among the most common diagnoses.
Researchers focused on 58 preservatives detected in participants’ diets, narrowing their analysis to 17 that at least 10% of the cohort consumed regularly. They estimated exposure by matching detailed 24-hour dietary records, submitted every six months, with food composition databases that detail additive levels in branded products. Adjustments accounted for confounding factors such as age, sex, body mass index, smoking, alcohol use, physical activity, and overall diet quality.
Key Findings on Preservatives and Cancer Associations
The study revealed that higher intake of several non-antioxidant preservatives correlated with elevated cancer risks, while 11 of the 17 analyzed showed no significant link.
- Sorbates (including potassium sorbate, E202): Associated with a 14% higher risk of overall cancer and a 26% increased risk of breast cancer. These compounds, used to inhibit mold and yeast, appear in products like cheeses, dried fruits, and some beverages.
- Nitrites (such as sodium nitrite, E250): Linked to a 32% higher risk of prostate cancer. Nitrites, common in processed meats for color preservation and botulism prevention, can form nitrosamines in the body, recognized carcinogens by agencies including the International Agency for Research on Cancer.
- Sulfites (E221-E228, including potassium metabisulfite, E224): Tied to a 12% increase in overall cancer risk and a 20% higher breast cancer risk. Sulfites prevent oxidation and microbial growth in wine, beer, dried fruits, and condiments.
- Other notable mentions: Potassium nitrate, acetic acid (found in vinegars and pickled foods), and sodium erythorbate showed associations with higher overall or specific cancer risks in certain analyses.
Antioxidant preservatives generally showed weaker or inconsistent links, though some, like sodium erythorbate, correlated with modest increases in certain cancers.
The absolute risk difference remained relatively small. For instance, absolute cancer risk at age 60 was about 13.3% among higher consumers of non-antioxidant preservatives compared to 12.1% among lower or non-consumers. Relative increases, such as 16% overall in some aggregated reports, often stem from small baseline differences amplified in percentage terms.
Broader Context: Benefits Versus Potential Risks
Food preservatives serve essential functions in modern food supply chains. Nitrites prevent deadly botulism in cured meats, sorbates guard against mold in bread and dairy, and sulfites maintain freshness in beverages and dried goods. Since their widespread introduction, foodborne illness rates have declined significantly.
However, certain preservatives have documented mechanisms of concern. Nitrites convert to nitrosamines under acidic conditions or during high-heat cooking, a process linked to DNA damage. Sulfites and sorbates may contribute to oxidative stress or inflammation in susceptible individuals, though direct evidence remains limited outside observational data.
Experts emphasize that these associations may partly reflect broader dietary patterns. Foods high in preservatives often contain elevated levels of salt, saturated fats, sugars, and other additives like emulsifiers, all independently tied to chronic disease risks.
The NutriNet-Santé findings align with prior research on ultra-processed foods (UPFs), which the cohort has linked to higher type 2 diabetes incidence. Another analysis showed 12 preservatives associated with elevated diabetes risk and other conditions.
Expert Perspectives and Limitations
Investigators, led by researchers including Mathilde Touvier from the Nutritional Epidemiology Research Team, stress that the results are observational and require replication in other populations. Confidence intervals for some associations were wide, indicating uncertainty, and self-reported dietary data carry inherent inaccuracies. The study could not fully isolate preservatives from co-occurring compounds or lifestyle factors.
Oncology dietitians and surgeons note that while the data suggest caution, they do not imply causation. Inflammation, gut microbiome alterations, and metabolic disruptions represent plausible pathways, but more mechanistic studies, including ongoing molecular analyses of inflammation markers and microbiota in the cohort, are needed.
Health authorities, including the European Food Safety Authority, have previously restricted additives like titanium dioxide. Nitrites face scrutiny for colorectal cancer links, and the new evidence may prompt reevaluation of others, such as sulfites and sorbates.
Practical Implications for Consumers
Public health recommendations encourage prioritizing fresh, minimally processed foods. Shopping perimeter aisles for produce, fresh meats, and dairy reduces exposure to additives prevalent in center-aisle packaged items.
Occasional consumption of preserved foods within a balanced diet remains reasonable for most people, especially when paired with protective habits like regular exercise, no smoking, limited alcohol, and ample fruits and vegetables rich in antioxidants.
The study reinforces messages from programs like France’s National Nutrition and Health Program: favor homemade or seasonal foods when possible to limit unnecessary additives. Manufacturers may face pressure to reformulate with cleaner-label alternatives, such as naturally derived preservatives, to maintain shelf life without synthetic compounds.
In summary, while certain preservatives show concerning associations with cancer in this large cohort, the evidence calls for a balanced perspective. Preservatives provide critical safety benefits, but reducing reliance on ultra-processed foods offers a prudent step toward lowering potential risks. Further research will clarify these links and guide regulatory decisions to protect public health.