Diabetes concerns over food preservative

A preservative widely used to prevent mould growth in foods has been shown to increase weight-gain and glucose production in mice, and to up diabetes risk in humans – fuelling calls for more research.

In a paper published in the journal Science Translational Medicine, a team of scientists headed by endocrinologist Amir Tirosh from the Sheba Medical Centre in Israel report on mouse experiments and a pilot clinical trial, both looking at the metabolic effects of a preservative known as propionate.

The substance is a naturally occurring short-chain fatty acid. It is common in the human gut, produced by resident bacteria in response to the presence of carbohydrates.

As calcium propionate, it is used as a preservative in many commercially produced foods, especially bread and other baked goods, processed meat and dairy products. Its primary purpose is to restrict the development of fungal colonies. On packaging it is known as E282.

Tirosh and colleagues exposed mice to significant doses of the substance and found that it prompted glycogenolysis – glucose production – and hyperglycemia, high blood sugar, the defining characteristic of diabetes.

A follow-up study in humans found that exposure to propionate increased insulin resistance. The number of people in the trial was too small to provide definitive conclusions, however.

The findings – especially if confirmed in larger studies – could lead to significant changes in food manufacture.

“Our findings may have implications for the current practice of food preservation,” the researchers write.

“Given that the US Food and Drug Administration has declared propionate to be generally recognised as safe with no known adverse effects, there is currently no limitation on its utilisation other than as required by good manufacturing practice.”

Tirosh and colleagues note that in the human trial – wherein participants were exposed to propionate levels equivalent to those found in preserved foods – the hyperglycemic response was lower than in the mice, which were given proportionately larger doses.

Nevertheless, they note, there may be concerns related to “repeated daily exposure” at accepted food industry levels.

“There are alternatives that could be used for food preservation, and if those molecules prove to be neutral in their metabolic activities, then simple alterations in manufacturing practices may yield public health benefits,” they conclude.