Artificial sweeteners may lead to glucose intolerance

Portfolio, Science Writing

Those little yellow, pink, and blue packets affect gut microbes and metabolism


Photo credit: Weizmann Institute of Science.

Consumption of artificial sweeteners such as Splenda and Equal may lead to an imbalance of gut bacteria and metabolic changes, report researchers at the Weizmann Institute in Rehovot, Israel.

Although artificial sweeteners are non-caloric, previous studies have found that people do not successfully lose weight by switching from real sugar to artificial sweeteners. The new study, published online in Nature, suggests that artificial sweeteners affect the body’s ability to metabolize blood sugar. Since the body’s resistance to glucose is a factor in adult-onset diabetes, this finding encourages consumers to reconsider the use of artificial sweeteners in their daily tea or coffee.

The research team, led by Eran Elinav of the Immunology Department at the Weizmann Institute and Eran Segal of Computer Science and Applied Mathematics, hypothesized that the body doesn’t recognize artificial sweeteners as food. When artificial sweeteners encounter bacteria in the small intestine, the bacteria secrete substances that provoke an inflammatory response that affects the body’s ability to use blood sugar.

The researchers studied both mice and humans. Mice that drank water with FDA-approved dosages of artificial sweeteners developed glucose intolerance, unlike mice who drank water or even sugar water. Researchers fed the mice the three most common artificial sweeteners: saccharin (commonly sold as SweetN’ Low), sucralose (Splenda), and aspartame (Equal). Next, the researchers treated mice with antibiotics that reversed the effects on glucose metabolism by destroying the “infected” gut bacteria, and they also successfully transmitted glucose intolerance from “infected” mice to “non-infected” mice. This supports a strong link between consumption of artificial sweeteners and harmful metabolic changes.

To study humans, researchers employed the Personalized Nutrition Project, which quantifies participants’ genetic make-up, gut microbiota, and glucose responses. Elinav and Segal compared self-reported artificial sweetener consumption with glucose intolerance, finding a significant association between the two. Next, they ran a controlled experiment in which volunteers’ glucose levels were tested before and after consuming artificial sweeteners for one week. Past research has connected adult-onset diabetes to particular gut bacteria, and accordingly, the results of these human trials showed that some gut bacteria reacted by disrupting glucose metabolism, while some didn’t.

The link between artificial sweeteners and high blood sugar is valuable for researchers interested in obesity and type 2 diabetes. Not only is glucose intolerance a risk factor for diabetes, it also leads to increased insulin secretion by the pancreas, which causes more sugar to be stored as fat. According to Dr. Elinav, “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… calls for a reassessment of today’s massive, unsupervised consumption of these substances.”


J. Suez et al. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature. Published online September 17, 2014. doi:10.1038/nature13793.

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