A new study identifies a possible link between artificial sweeteners and Type 2 diabetes.

By Real Simple
Updated September 18, 2014
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While diet soda might seem like an innocent way to satisfy your sugar cravings, those artificial sweeteners could come with their own set of risks.

Research has been conflicting as to whether dieters are actually successful at losing weight when they switch to sugar substitutes, and some studies have even linked diet soda to increased risk of heart disease or stroke. Now, scientists have found that these sweeteners may lead to Type 2 diabetes, as well. The reason? Surprisingly, it might come down to changes in the composition of your gut bacteria.

The study, published Wednesday in the journal Nature, showed that when mice were fed artificial sweeteners, they developed higher levels of glucose intolerance after just 11 weeks. Glucose intolerance is known to cause high blood sugar, and can be a precursor to Type 2 diabetes. Scientists believe that artificial sweeteners affect the body’s ability to use sugar in the bloodstream, and that this chemical change occurs in the intestines (and, indeed, the researchers tested this hypothesis on the mice).

To understand the impact of these findings on humans, study leaders Drs. Eran Elinav and Eran Segal of the Weizmann Institute of Science analyzed the data of about 400 non-diabetic people from their Personalized Nutrition Project, specifically focusing on artificial sweetener consumption. They isolated 40 individuals from the sample who consumed the most artificial sweetener, and found that they also had higher blood sugar. As another test, the researchers added in a sweetener to the diets of seven volunteers, and found that within a week, their gut bacteria had changed. Humans, they concluded, have two different variations of bacteria in their digestive tracts: one that became glucose-intolerant when exposed to sweeteners, and one that remained unaffected. Throughout the seven days, four of the seven participants suddenly found it more difficult to handle sugar.

While the findings require further testing, Elinav says the initial associations are compelling.

“Our relationship with our own individual mix of gut bacteria is a huge factor in determining how the food we eat affects us,” Elinav said in a press release. “Especially intriguing is the link between the use of artificial sweeteners…to a tendency to develop the very disorders they were designed to prevent; this calls for a reassessment of today’s massive, unsupervised consumption of these substances.”

For more on the difference between the real and the fake stuff, see our Guide to Natural and Artificial Sweeteners.