Artificial sweeteners may exacerbate, rather than prevent, metabolic disorders such as Type 2 diabetes, a study suggests.

Calorie-free artificial sweeteners are often chosen by dieters in part because they are thought not to raise blood sugar levels.

In Wednesday’s issue of the journal Nature, researchers report that artificial sweeteners increase the blood sugar levels in both mice and humans by interfering with microbes in the gut. Increased blood sugar levels are an early indicator of Type 2 diabetes and metabolic disease.

The increase in consumption of artificial sweeteners coincides with the obesity and diabetes epidemics, Eran Segal of the Weizmann Institute of Science in Rehovot, Israel, and his co-authors said.

“Our findings suggest that non-caloric artificial sweeteners may have directly contributed to enhancing the exact epidemic that they themselves were intended to fight.”

Link to gut bacteria

The study included a series of experiments.

Mice whose drinking water was supplemented with glucose and a sweetener developed glucose intolerance compared with mice drinking water alone, or water with just sugar in it. The effect occurred both in mice fed normal chow and those on a high-fat diet.

When antibiotics were used to kill off gut bacteria, the artificial sweetener effect on glucose intolerance in mice fed either diet was restored to normal.

Taken together, the data indicate that artificial sweeteners “may contribute to, rather than alleviate, obesity-related metabolic conditions, by altering the composition and function of bacterial populations in the gut,” Cathryn Nagler and Taylor Feehley of the pathology department at the University of Chicago said in a journal commentary.