Artificial Sweeteners Don’t Mix Well with Our Microbiomes

Artificial sweeteners have long been considered our calorie-cutting allies, but a new study published yesterday in the journal Nature suggests that eating or drinking too much of the saccharine stuff may lead to diabetes.

The counterintuitive result was uncovered when a large team of researchers, led by Eran Segal and Eran Elinav of the Weizmann Institute of Science in Israel, started examining mice fed a diet that included artificial sweeteners. The mice on that diet soon started developing glucose intolerance, a symptom of diabetes. The researchers then carried out a somewhat complicated series of experiments to investigate further.

artificial-sweeteners
Non-caloric sweeteners appear to increase a person's risk for diabetes.

Dan Vergano, reporting for National Geographic News, has a great summary:

In the new study, the team began by adding one of three FDA-approved artificial sweeteners—saccharin, sucralose, or aspartame—to the drinking water of mice. The researchers compared these groups of mice with others that drank only water. Within 11 weeks, the mice drinking sweetened water had developed glucose intolerance, most notably when saccharin was added to their diet.

To see whether the mice’s intestinal bacteria contributed to the problem, the team then used antibiotics to wipe out the mice’s intestinal bugs and found they could return the mice’s blood sugar levels to normal.

Finally, they fed fecal samples from glucose-intolerant mice to normal mice, transferring the unhealthy mice’s gut bugs. The normal mice that got these fecal samples then developed glucose intolerance within six days.

Segal, Elinav, and team also tested the link between artificial sweeteners and diabetes in humans, surveying 381 people who weren’t diabetic. Those who consumed artificial sweeteners not only had higher blood sugar than other participants, but their intestines also housed significantly higher counts of Bacteroides fragilis, a species that might cause intestinal inflammation. Lastly, the scientists gave seven consenting adults 120 mg of saccharin per day, or about the amount in two Tab diet sodas or a little over three Sweet’n Low packets. Four of them—just over half—saw their blood sugar levels spike in just one week.

The researchers acknowledge that they don’t know exactly how artificial sweeteners interact with the microbiome—they’re asking other scientists to replicate the study to learn more—but they do admit that the results of the study have caused them to cut back on their own use. They do caution, though, that the evidence isn’t enough to encourage people to change their habits. Nor should people consuming large quantities of artificial sweeteners switch to sugar, which can also raise your risk for diabetes. If you’re concerned, the best bet seems to be simply reducing or eliminating artificial sweeteners without replacement.