A world-first study has offered a never-before-known explanation of the link between gut bacteria and diabetes, concluding from research on mice that the gut microbiome influences serotonin in a way that causes the hormone to negatively affect blood sugar.
The finding builds on years of research suggesting, but not explaining, a link between gut bacteria and blood-sugar related diseases like diabetes and obesity. The gut microbiome is the collection of good bacteria in our digestive tracts that supports nearly all physiological functions; it has been the focus of intense research and is widely considered to be integral to managing various diseases and conditions, from diabetes to lupus — if scientists could just crack how.
“We found that the microbiome worsens our metabolism by signaling to cells in the gut that produce serotonin,” first author Damien Keating, Ph.D., head of molecular and cellular physiology at Flinders University, Australia, said in a statement. “They drive up serotonin levels, which we previously showed to be increased in obese humans, and this rise in blood serotonin causes significant metabolic problems.”
Serotonin is a neurotransmitter, a substance that helps regulate messages sent via the nervous system. In serotonin’s case, it is mostly involved in aiding messages related to (and thus regulating) sleep, mental health and metabolism. While serotonin is popularly thought of as a product of the brain, roughly 90% of any body’s serotonin is produced by the gut.
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The researchers, who hailed from Flinders University, the South Australian Health and Medical Research Institute, and McMaster University in Canada, arrived at this conclusion by experimenting on mice who had been genetically engineered to have diminished serotonin production in the gut. Some of these mice were further fed antibiotics in order to alter their gut health. Researchers then monitored the mice’s blood glucose levels. If the alteration of gut bacteria affected blood glucose levels via a different route, the researchers would expect to see the mice’s health deteriorate — but it didn’t, suggesting that gut bacteria affect blood glucose by working on serotonin-making cells in the gut.
The researchers are calling it an “exciting revelation” but caution it is far from applicable to human health any time soon.
“The next step will be to understand exactly which bacteria do this, and how, in the hope that this could lead to new approaches to regulating blood sugar levels in humans,” Keating said in the statement.
