Artificial sweeteners may increase the tendency to diabetes

A new study published today in the scientific journal Nature shows that these sweeteners may increase glucose intolerance and the risk of adult-onset diabetes and other components of the metabolic syndrome.

Although artificial sweeteners are marketed as a sugar substitute for those who wish to reduce their weight, or for diabetics, a new study published today in the scientific journal Nature shows that these sweeteners may increase glucose intolerance and the chance of developing diabetes in adults and the other components of the metabolic syndrome. "The widespread consumption of artificial sweeteners in drinks and foods can cause obesity and even diabetes," says the chief researcher.
For years, researchers have wondered how it is possible that low-calorie artificial sweeteners do not cause a reduction in body weight. In fact, some studies have hypothesized that their effect may be the opposite. The research led to the discovery that even though artificial sweeteners do not contain sugar, they have a direct effect on the human body's ability to channel and process glucose. Glucose intolerance, which develops when the body is unable to handle a large amount of sugar, is the first sign of the development of adult-onset diabetes and other aspects of the metabolic syndrome.
In the first phase of the study, the scientists gave mice water mixed with the three most common types of artificial sweeteners, in doses equivalent to the guidelines approved by the US Food and Drug Administration for use. These mice developed greater glucose intolerance, compared to mice that drank water and sugar water. When the scientists repeated the experiment with different types of mice and with different doses of the same sweeteners, they predicted similar results: these substances caused glucose intolerance.
Later, the scientists tested the hypothesis that the intestinal bacteria are involved in this phenomenon and may even be responsible for it. This is because they react to substances such as artificial sweeteners, which the body may not recognize as "food". Although artificial sweeteners are not absorbed in the digestive tract, when they pass through it, they come into contact with the trillions of bacteria in the intestine.

The scientists treated the mice with antibiotic drugs that eliminate different populations of their gut bacteria. Following the treatment, the glucose intolerance, which was created due to the exposure to the artificial sweeteners, was completely avoided. The scientists then transferred entire populations of gut bacteria from mice that consumed artificial sweeteners to sterile mice, raised in special bacteria-free facilities. As a result, glucose intolerance was also fully transferred to the recipient mice. This finding provided proof that the changes in gut bacteria directly mediate the harmful effects of artificial sweeteners on sugar levels in mammals. The research group even found that growing the population of intestinal bacteria outside the body under oxygen-free conditions, while exposing it to artificial sweeteners, caused changes in the composition and function of the bacteria, which caused glucose intolerance when they were transplanted into sterile mice. A careful examination of the genetic composition and metabolic activity of the intestinal bacteria in mice showed that exposure to artificial sweeteners results in significant changes in the population and function of the bacteria in the intestine, including activities known to cause a tendency to obesity, diabetes and the metabolic syndrome in animals and humans.

Do the intestinal bacteria of humans function in a similar way? The researchers also examined this issue. In a first step, they examined collected data As part of the personal nutrition project (). The goal of the project, which is the most comprehensive of its kind in the world, is to test the relationship between nutrition and gut bacteria. Among these data, they found a direct and distinct relationship between the level of consumption of artificial sweeteners (as reported by the project participants), to individual-unique configurations of the intestinal bacteria and a tendency to glucose intolerance. In the next step, the scientists conducted a controlled experiment, in which they asked a group of volunteers, who do not usually eat or drink artificial sweeteners, to consume these substances for a week. During that entire week, the glucose levels and the composition of the intestinal bacteria in the bodies of the volunteers were tested.
These findings showed that many of the volunteers, but not all, began to develop glucose intolerance, after just one week of consuming sweeteners. The composition of the volunteers' gut bacteria explained the sudden change: the scientists discovered two different populations of gut bacteria in humans - one population that increased glucose intolerance after consuming sweeteners, and a second population that did not affect sugar levels in any way. The main researcher believes that the reaction of the bacteria in the intestine to the artificial sweeteners, as far as the volunteers who developed glucose intolerance were concerned, was expressed in the secretion of substances that caused an inflammatory reaction - reminiscent of a sugar overdose. This is how changes occurred in the body's ability to use sugar.
"The results of the experiments we performed emphasize the importance of personalizing medicine and nutrition for our health," say the researchers. "We believe that a comprehensive examination of personal data - collected from the genome, gut bacteria and dietary habits - may change our ability to understand how food and food supplements affect human health, and the risk of contracting various diseases."
"The relationship each of us has with our personal gut bacteria is a significant factor in understanding how the food we consume affects us, including our predisposition to diseases such as obesity and diabetes." "The research findings indicate that the consumption of artificial sweeteners leads to the development of the same health problems they were intended to prevent in the first place. These findings require a re-examination of the massive and unsupervised consumption of these substances".

Researchers from Sourasky Hospital, Tel Aviv University, the Center for Mental Health at Kfar Shaul Hospital and the Weizmann Institute participated in the study.