Even Diet Soda May Increase Risk of Diabetes

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Drinking diet soda instead of regular might spare you scads of empty calories, but still may increase your risk of type 2 diabetes. A new study from Israel found that the artificial sweeteners aspartame, saccharine, and sucralose alter the balance of bacteria in the gut, which messes with glucose metabolism. This can eventually lead to glucose intolerance, a precursor to diabetes.

To reach this conclusion, the researchers conducted a series of experiments on mice and on a small group of people. First they gave some of the mice drinking water spiked with artificial sweeteners, and gave the rest of them plain water or water laced with sugar. After 11 weeks, the animals given artificial sweeteners had developed glucose intolerance while those given sugar water or plain water had not. Next the researchers gave the mice with glucose intolerance antibiotics, essentially killing off the gut bacteria that had been altered by the artificial sweeteners. Their glucose intolerance returned back to normal. The scientists aren't sure exactly how these synthetic sweeteners impact the bacterial balance, but they think it has to do with the fact that the body doesn't recognize these substances as food.

The researchers found similar results in humans. They had adults who didn't normally eat or drink artificially sweetened foods or beverages to consume them for one week. By week's end, half of them had developed glucose intolerance.

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Since this study was conducted on mice and a very small group of humans, more research must be done before experts can say definitely that artificial sweeteners increase risk of diabetes. However, the results are convincing enough to pay attention to. "Because the study found effects on gut microbiota using different methods, it increases our confidence that there really is an effect of artificial sweeteners on these microorganisms inhabiting the digestive tract, at least in some cases," says Lisa Lefferts, senior scientist at the Center for Science in the Public Interest. "But what that means for a person's health over the long-term has yet to be determined."

Still, there are other reasons to cut back on artificial sweeteners, says Lefferts. "We recommend you avoid aspartame and saccharin (as well as acesulfame-K, not included in this study) anyway, primarily because of evidence from animal studies that they may cause cancer," she explains. "While still preliminary, this study might give people one more reason to switch to water or seltzer. Or to use a little juice mixed into seltzer. Skim milk, tea, and coffee are also good beverage choices."

And definitely don't ditch diet sodas in favor of regular. "These findings are significant and interesting, but not enough to change the fact that diet sodas still beat regular soda," Lefferts says. "Don't use this study as an excuse to consume beverages with sugar or high-fructose corn syrup. This research does not overturn previous well-designed studies that show that people who drink regular soda have a higher risk of type 2 diabetes, while diet soda drinkers do not. Nor does it override research finding that people are more likely to gain weight on sugar-sweetened beverages that diet drinks." 

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