Artificial sweeteners may hasten the development of glucose intolerance and metabolic diseases including obesity and diabetes, according to a new study by Weizmann Institute of Science in Israel.

The researchers said that the sweeteners alter the composition and function of the gut microbiota - the population of bacteria residing in intestines. The different mix of microbes changes the metabolism of glucose, causing levels to rise after eating and decline in a slower pace than they normally would.

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

Elinav said that there is not enough evidence to change the current recommendations relating to artificial sweeteners. But, he hopes that it would trigger a healthy discussion.

Glucose intolerance, which is characterised by body's inability to deal with large amounts of sugar, causes serious illnesses like metabolic syndrome and Type-2 diabetes.

For the study, the researchers added saccharin, sucralose or aspartame to the drinking water of 10-week-old mice. Other groups of mice drank either plain water, water mixed with glucose or with ordinary sugar.

The researchers observed minute changes in the mice who drank water or sugar water after a week. But the group with artificial sweeteners developed distinct glucose intolerance. When the mice were treated with antibiotics, destroying most of the gut bacteria, the glucose intolerance was cured.

The researchers conducted another experiment to test their hypothesis that the change in glucose metabolism was caused by a change in bacteria.

Here, they removed intestinal bacteria from mice who drank saccharin-laced water and injected them in those unexposed to the molecule. The researchers found that these mice developed the same glucose intolerance. The DNA sequencing showed that saccharin modified the diversity of gut bacteria in mice that consumed it.

In the study, the researchers could not explain the direct relationship between sweeteners and bacteria nor did they find out the reasons behind why the three different molecules of saccharin, aspartame and sucralose triggered similar changes in the glucose metabolism.

The finding is published by the journal Nature.