Are preservatives in packaged food linked to type 2 diabetes?

What's actually in it

Preservatives are added to packaged foods to prevent spoilage, extend shelf life, and stop bacteria from growing. Common ones include sodium benzoate, potassium sorbate, sodium nitrite, and calcium propionate. You'll find them in bread, deli meats, sauces, soft drinks, salad dressings, and snack foods.

These chemicals are approved as safe in the amounts used. But "safe" was determined through short-term toxicity tests. Nobody tested what happens when you eat small amounts of multiple preservatives in nearly everything you eat, every day, for decades.

What the research says

A 2026 study in Nat Commun followed a large group of adults in the NutriNet-Santé cohort over time, tracking both their preservative intake and their health outcomes. People who consumed higher levels of food preservatives had a noticeably higher risk of developing type 2 diabetes.

The study was prospective, meaning researchers tracked preservative intake first and then watched who got diabetes later. That's a much stronger design than asking people who already have diabetes what they used to eat. It also controlled for overall diet quality, body weight, physical activity, and other diabetes risk factors.

The link remained even after accounting for the fact that people who eat more preservatives tend to eat more processed food in general. In other words, it wasn't just the junk food. The preservatives themselves appeared to be part of the problem.

The suspected mechanisms include disruption of gut bacteria (which affects insulin sensitivity), interference with glucose metabolism, and promotion of chronic low-grade inflammation. All three pathways are well-established routes to diabetes.

You don't need to memorize every preservative on every label. A simpler rule: the fewer ingredients, the better. Foods that need preservatives to survive months on a shelf are usually the ones you want to eat less of. Fresh, frozen, and minimally processed foods rarely contain preservatives at all.