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Fake Sugar Might Be Making Us Sick

Put down that wake-me-up diet soda for a second: A controversial new study has demonstrated a link between artificial sweeteners and a condition that can lead to diabetes. At the heart of it is the complex jungle of gut bugs that live in our digestive...
Photo via Flickr user Roey Ahram

Sugar might not be the devil, but we all know that spoonful after spoonful of sugar is definitely not doing our bodies good, either. But as the sweet-hungry public increasingly turns to sugar substitutes out of fear of good ol' fashioned sucrose, there's now evidence that the sweeteners in diet soda might be doing just as much damage to your body as sugar can.

A new study published in Nature is making waves in the medical community this week, as it is the first do suggest a link between artificial sweeteners and metabolic disorders like diabetes through gut bacteria. While there is a body of research that suggests a link between diet soda consumption and diabetes, gut bacteria have not been specifically examined as a cause.


The gut microbiome is the latest playground for biologists, who have suggested that the naturally present bacteria in our digestive systems can alter everything from our weight to our mental state. A couple years back, researchers discovered a method of effectively treating a particularly nasty form of infectious diarrhea by giving patients "fecal transplants"—enemas made of a sort of fecal slurry sourced from healthy people—with the idea that the typical collection of gut bugs would restore balance to a diseased GI tract.

The fake sugar study, led by a group of researchers at Weizmann Institute of Science in Rehovot, Israel, specifically examined the relationship between artificial sweeteners and glucose intolerance, a condition that can lead to diabetes, with gut bacteria. In the first of a series of experiments, mice were fed common artificial sweeteners, including saccharin, sucralose, and aspartame, which had the effect of raising their blood sugar levels. When the researchers gave them antibiotics, their glucose levels returned to normal.

In the second experiment, healthy mice were given fecal transplants from other mice that had been fed on a diet of saccharin. In turn, those mice developed high blood sugar, too.

The researchers also examined data from an ongoing nutrition study of 400 people and found a correlation between signs of metabolic disorders and their consumption of artificial sweeteners. Wanting to test that themselves, the researchers then gathered a group of seven human volunteers, who each consumed the maximum recommended daily intake of saccharin—enough to sweeten about 40 cans of soda—each day for one week. At the end, four of them had developed glucose intolerance and collection of gut flora that resembled those of the mice fed saccharin in the previous experiment.

In the final experiment, healthy mice were given fecal transplants from those human volunteers who developed high blood sugar. Guess what? The mice developed glucose intolerance, too.

It's important to point out that, as with all preliminary research, the study has its limitations and more work needs to be done. One of the paper's lead researchers, Eran Elinav, admitted to Scientific American the exact relationship between fake sugar and disease "is a bit chicken-and-egg." He added, "If you are putting on weight, you are more likely to turn to diet food. It doesn't necessarily mean the diet food caused you to put on weight."

Other scientists viewed the study even more cautiously, with some suggesting that the human experiments were too small and the mouse studies too far removed to be applicable to people. Brian Ratcliffe, a professor of nutrition at Robert Gordon University in Aberdeen, told the Guardian, "Most of the effects that they report relate to saccharin with little or no effect of aspartame. Their paper ought to be limited to 'saccharin' in the title rather than attributing the effects to all artificial sweeteners."

So take it all with a grain of salt. Or even sugar.