Gut serotonin linked to obesity

While serotonin is a chemical that is commonly associated with feelings of happiness in the brain, high levels of gut serotonin have recently been linked to obesity.

Serotonin is a neurotransmitter that chemically transmits messages to nerve cells in the body, but NHMRC Research Fellow Professor Damien Keating from Flinders University and the South Australian Health and Medical Research Institute (SAHMRI) explained that over 90% of the body’s serotonin is made in the gut and does not enter the brain. Instead, elevated levels of gut serotonin have a negative impact on our metabolism and can increase the risk of developing diabetes and obesity.

“Our gut wall is lined by a protective layer of cells similar to skin cells. But scattered amongst these exists a variety of hormone-producing cells that play important roles in controlling our metabolism, fat mass, and even telling our brain when to stop or start eating,” Keating said.

“We know from a raft of recent high-profile publications that gut-derived serotonin causes diabetes and obesity, but we didn’t know if this was relevant to such disorders in humans. Our findings are the first work implicating serotonin as a driver of worsening obesity in humans.”

Keating was part of a team of researchers that found human obesity is characterised by an increased capacity to produce and release serotonin, as obese individuals had double the amount of gut serotonin.

University of Adelaide Senior Research Fellow, co-author and Associate Professor Richard Young also said the results suggest that obese humans not only secrete excess serotonin from the upper gut when eating a meal, but also during rest.

“This has revealed new ways that we may be able to control the release of serotonin from within the gut, and in turn, further improve the outlook for people living with obesity,” he said.

The researchers plan to build on these results to understand what causes such high levels of serotonin, such as certain foods or diet, and develop treatments that target the cells in the gut that produce this hormone.

The findings were published in the International Journal of Obesity.

Image credit: ©stock.adobe.com/au/carballo