A new study has revealed that artificial sweeteners could actually hasten the development of glucose intolerance and metabolic disease by changing the composition and function of the gut microbiota.
According to the study by Eran Elinav of the Weizmann Institute's Immunology Department, the widespread use of artificial sweeteners in drinks and food may be contributing to the obesity and diabetes epidemic that is sweeping much of the world.
The scientists gave mice water laced with the three most commonly used artificial sweeteners - in the equivalent amounts to those permitted by the FDA that developed glucose intolerance, as compared to mice that drank water, or even sugar water. Next, the researchers investigated a hypothesis that the gut microbiota are involved in this phenomenon. They thought the bacteria might do this by reacting to new substances like artificial sweeteners, which the body itself may not recognize as "food." Indeed, artificial sweeteners are not absorbed in the gastrointestinal tract, but in passing through they encounter trillions of the bacteria in the gut microbiota.
The researchers treated mice with antibiotics to eradicate many of their gut bacteria; this resulted in a full reversal of the artificial sweeteners' effects on glucose metabolism. Next, they transferred the microbiota from mice that consumed artificial sweeteners to 'germ-free' mice - resulting in a complete transmission of the glucose intolerance into the recipient mice. This, in itself, was conclusive proof that changes to the gut bacteria are directly responsible for the harmful effects to their host's metabolism.
The group even found that incubating the microbiota outside the body, together with artificial sweeteners, was sufficient to induce glucose intolerance in the sterile mice. A detailed characterization of the microbiota in these mice revealed profound changes to their bacterial populations, including new microbial functions that are known to infer a propensity to obesity, diabetes and complications of these problems in both mice and humans.
The findings showed that many - but not all - of the volunteers had begun to develop glucose intolerance after just one week of artificial sweetener consumption. The composition of their gut microbiota explained the difference: The researchers discovered two different populations of human gut bacteria - one that induced glucose intolerance when exposed to the sweeteners, the second that had no effect either way. Researchers believe that certain bacteria in the guts of those who developed glucose intolerance reacted to the chemical sweeteners by secreting substances that then provoked an inflammatory response similar to sugar overdose, promoting changes in the body's ability to utilize sugar.
The study was published in Nature.
