These common food preservatives may be linked to cancer

A large study from France published by The BMJ reports that people who consume higher amounts of food preservatives may face a slightly increased risk of developing cancer. These additives are commonly used in industrially processed foods and drinks to extend shelf life.

The researchers emphasize that more studies are needed to fully understand the relationship. Still, they say the findings raise important questions about current regulations and suggest that safety standards for food preservatives may need to be re-examined to better protect consumers.

Why Preservatives Are Under Scrutiny

Food preservatives are added to packaged products to prevent spoilage and extend how long foods remain safe to eat. Previous laboratory research has shown that some preservatives can damage cells and DNA. However, until now, there has been limited real world evidence directly linking these additives to cancer risk.

To explore this issue more closely, researchers analyzed long term dietary and health data collected between 2009 and 2023. Their goal was to determine whether exposure to specific preservative food additives was associated with cancer risk in adults.

A Large and Detailed Long Term Study

The study followed 105,260 participants aged 15 years and older (average age 42 years; 79% women) who were part of the NutriNet-Santé cohort. All participants were cancer free at the start and regularly completed detailed 24 hour brand-specific dietary records over an average period of 7.5 years.

Researchers then tracked cancer diagnoses using health questionnaires along with official medical and death records through December 31, 2023.

Preservatives Examined in the Study

The analysis focused on 17 individual preservatives, including citric acid, lecithins, total sulfites, ascorbic acid, sodium nitrite, potassium sorbate, sodium erythorbate, sodium ascorbate, potassium metabisulfite, and potassium nitrate.

These preservatives were categorized into two groups. Non-antioxidants inhibit microbial growth or slow chemical reactions that cause spoilage. Antioxidants help delay food deterioration by reducing or limiting oxygen exposure in packaging.

Cancer Cases Identified

During the follow-up period, 4,226 participants were diagnosed with cancer. These cases included 1,208 breast cancers, 508 prostate cancers, 352 colorectal cancers, and 2,158 other types of cancer.

When researchers looked at all preservatives combined, they found no overall link with cancer risk. In addition, 11 of the 17 preservatives studied individually showed no association with cancer incidence.

Specific Preservatives Linked to Increased Risk

Higher intake of several individual preservatives was linked to a greater risk of cancer, particularly among non-antioxidant preservatives. These included potassium sorbate, potassium metabisulfite, sodium nitrite, potassium nitrate, and acetic acid.

Total sorbates, especially potassium sorbate, were associated with a 14% higher risk of overall cancer and a 26% higher risk of breast cancer. Total sulfites were linked to a 12% increase in overall cancer risk.

Sodium nitrite was associated with a 32% higher risk of prostate cancer. Potassium nitrate was linked to a 13% increased risk of overall cancer and a 22% higher risk of breast cancer.

Total acetates were associated with a 15% higher risk of overall cancer and a 25% higher risk of breast cancer. Acetic acid alone was linked to a 12% increase in overall cancer risk.

Among antioxidant preservatives, only total erythorbates and sodium erythorbate were associated with a higher incidence of cancer.

Possible Biological Explanations

The researchers note that several of the preservatives linked to cancer risk may affect immune function and inflammation. These changes could potentially contribute to cancer development, although more research is needed to confirm these mechanisms.

Because this was an observational study, it cannot prove that preservatives directly cause cancer. The authors also acknowledge that other unmeasured factors could have influenced the results.

Why the Findings Still Matter

Despite these limitations, the researchers point out that the study was large, relied on detailed dietary data linked to food databases, and followed participants for more than a decade. They add that the findings align with existing experimental research suggesting cancer related effects for some of these compounds.

Based on the results, they conclude: “This study brings new insights for the future re-evaluation of the safety of these food additives by health agencies, considering the balance between benefit and risk for food preservation and cancer.”

Implications for Consumers and Policy

The researchers encourage food manufacturers to reduce the use of unnecessary preservatives and support guidance for consumers to choose freshly prepared, minimally processed foods whenever possible.

In a related editorial, US researchers note that preservatives do offer clear benefits, including longer shelf life and lower food costs, which can be especially important for lower income populations. However, they argue that the widespread and often poorly monitored use of these additives, combined with uncertainty about long term health effects, calls for a more balanced regulatory approach.

They suggest that findings from NutriNet-Santé could prompt regulators to revisit existing policies. Possible steps include stricter limits on preservative use, clearer labeling, mandatory disclosure of additive content, and international monitoring efforts similar to those used for trans fatty acids and sodium.

“At the individual level, public health guidance is already more definitive about the reduction of processed meat and alcohol intake, offering actionable steps even as evidence on the carcinogenic effects of preservatives is evolving,” they conclude.