In one, they gave antibiotics to mice who had been fed sweeteners regularly. Artificial and caloric sweeteners 
 
 The following commercially available NAS were dissolved in mice drinking water to obtain a 10% solution: Sucrazit (5% saccharin, 95% glucose), Sucralite (5% Sucralose), Sweet’n Low Gold (4% Aspartame). So the researchers performed several experiments to test their idea. However, the researchers relied primarily on saccharin in their mouse and human experiments. “Rather, as scientists, we simply point to the immense body of experiments that we carried out in both humans and in mice.
– If you're drinking diet soda or consuming other products with artificial sweeteners to cut your risk of obesity and diabetes, a new study published in Nature has some bad news: You might be doing more harm than good. Researchers found that sweeteners such as saccharin, sucralose, and aspartame can interact in a complex way with bacteria in our gut and lead to higher blood-sugar levels, reports the Wall Street Journal. Scientists say studies on both mice and people back up the assertion, though the findings may not apply to all. In one of the human experiments, for example, researchers gave foods with such sweeteners to seven people who normally never consumed them and found that four of the subjects had markedly higher blood-sugar levels in just four days. "In other words: Some people are more susceptible to the effects of artificial sweetener than others," explains the Verge. It all depends, apparently, on your particular microbiome, which the Washington Post describes as the "vast and enigmatic ecosystem of bacteria in our guts." The sweetener industry is already disputing the research, but "the scope of our discovery is cause for a public reassessment of the massive and unsupervised use of artificial sweeteners," says a study co-author at Israel's Weizmann Institute of Science. Far more research is needed before it's definitive, but NPR grabs this quote from the director of the Human Microbiome Program at New York University: "I can just tell you ... as a middle-aged man who's concerned about his diet and his waistline—and [as] somebody who drinks diet soda—I didn't drink any yesterday." (Meanwhile, US bellies are getting bigger.)