Why Some Common Food Preservatives May Elevate Cancer and Type 2 Diabetes Risk

Last updated on 13 JAN 2026

Packaged foods are a routine part of daily life for many people, yet few stop to consider how the ingredients that extend shelf life may affect long-term health. Preservatives are added to prevent microbial growth, delay spoilage, and maintain color and texture, making them especially common in processed and ultra-processed foods. Over time, their widespread use has quietly increased overall exposure, often without consumers realizing how frequently these additives appear across different food categories.

A large prospective study published in The BMJ raises concerns about this growing exposure. Researchers followed more than 108,000 adults for over a decade and found that higher intake of several commonly used preservative additives was associated with a higher incidence of type 2 diabetes. The authors note that preservatives are now “massively used by the food industry globally,” with more than 700,000 products in global food databases containing at least one preservative. These findings add to an expanding body of research suggesting that the long-term health effects of food additives deserve closer attention.

What Food Preservatives Are Designed to Do

Food preservatives are added to products to slow deterioration caused by microorganisms or oxidation. According to the study, preservatives “are added to prolong the shelf-life of foods” and to protect against changes such as fat rancidity and color loss. These additives include substances like sorbates, nitrites, propionates, sulfites, and antioxidant compounds that appear under European E-numbers, most commonly in the E200 and E300 ranges.

Many of these substances also occur naturally in small amounts in foods, such as citric acid or vitamin C. However, the researchers explain that “the impact of the substance may depend on the matrix in which it is integrated,” meaning the health effects can differ when these compounds are consumed as additives rather than as part of whole foods. This distinction is important because additives are often consumed repeatedly in processed products throughout the day.

Preservatives are not limited to a single food group. The study shows that they appear across meats, grains, beverages, baked goods, sauces, and even some fruit and vegetable products. As a result, nearly all participants in the study had some level of preservative exposure during the first two years of follow-up, demonstrating how difficult it is to avoid these additives entirely in a modern diet.

How the Study Examined Diabetes Risk

The research was conducted using data from the NutriNet-Santé cohort, which collected repeated, brand-specific 24-hour dietary records over many years. Participants reported detailed information about the exact foods they consumed, allowing researchers to calculate time-dependent exposure to specific preservatives rather than relying on general food categories.

Over a median follow-up of just over eight years, 1,131 new cases of type 2 diabetes were identified. The authors report that “higher intakes of total preservatives” were associated with higher diabetes incidence, even after adjusting for factors such as age, body weight, physical activity, smoking, alcohol intake, and overall dietary quality.

Importantly, the analysis accounted for the proportion of ultra-processed foods in the diet. Even after this adjustment, many preservatives remained independently associated with diabetes risk. This suggests that the additives themselves may contribute to metabolic effects rather than simply acting as markers of unhealthy eating patterns.

Preservatives Most Strongly Associated With Type 2 Diabetes

Several specific preservatives showed consistent associations with higher diabetes risk. These included potassium sorbate, sodium nitrite, calcium propionate, sodium ascorbate, citric acid, phosphoric acid, and certain tocopherols and erythorbates. The study found that people in the highest intake categories for some of these additives had substantially higher hazard ratios compared to those with the lowest intake.

For example, potassium sorbate and sodium nitrite were among the additives most strongly associated with type 2 diabetes incidence. These substances are commonly used in processed meats, baked goods, and packaged foods that are eaten frequently by many consumers. The authors observed that these associations were stable across multiple sensitivity analyses.

The researchers also note that no participant exceeded acceptable daily intake levels for most preservatives, yet associations with diabetes still appeared. This finding raises questions about whether current safety thresholds adequately reflect long-term metabolic effects, particularly when multiple additives are consumed together over many years.

Possible Biological Explanations Behind the Findings

The study discusses several biological mechanisms that may explain the observed associations. Experimental evidence suggests that certain preservatives can disrupt insulin signaling, promote inflammation, and affect pancreatic tissue. The authors reference data showing that some additives are linked to “insulin disruption,” inflammation, and activation of advanced glycation end products.

Nitrite-based preservatives have been associated with compounds that impair pancreatic beta-cell function in animal studies. Other preservatives, such as propionates and sorbates, have been shown to influence gut microbiota composition and liver metabolism, both of which are closely connected to glucose regulation.

The researchers also point out that several preservatives are metabolized into compounds involved in the tricarboxylic acid cycle, which is central to energy metabolism. Alterations in this cycle may influence insulin sensitivity and overall metabolic balance, providing another possible explanation for the observed increase in diabetes risk.

The Role of Ultra-Processed Foods

Ultra-processed foods accounted for 34.6 percent of preservative intake in the study population. These foods are designed for convenience and long shelf life and often contain multiple additives. The authors report that ultra-processed food exposure was associated with higher type 2 diabetes incidence and that “17% of the association between ultra-processed food and type 2 diabetes was mediated by exposure to these preservatives.”

This finding suggests that preservatives may be one of several factors linking ultra-processed foods to metabolic disease. While not all preservatives come exclusively from ultra-processed foods, many are most commonly consumed through products with low nutritional value, such as processed meats and sweetened beverages.

The study emphasizes that reducing preservative exposure is not always straightforward, as the same food item can vary widely in additive content depending on the brand. This variability makes individual choice challenging and highlights the role of broader food system practices in shaping exposure.

What This Research Means for Everyday Eating

The authors are careful to note that this observational study does not prove causation. However, they state that the findings “support recommendations for consumers to favour fresh and minimally processed foods and limit superfluous additives whenever possible.” This guidance aligns with existing dietary advice focused on whole foods.

Reducing intake of processed meats, packaged baked goods, and additive-heavy products may lower exposure to preservatives linked with metabolic disruption. Cooking at home and choosing products with shorter ingredient lists are practical ways to limit cumulative intake over time.

As preservatives continue to be used across a wide range of foods, this research adds weight to concerns about long-term exposure. It also reinforces the importance of transparency, regulatory review, and informed food choices when it comes to protecting metabolic health.

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