Study shows melatonin, commonly used to improve sleep, can aggravate bowel inflammation (Worsens colitis by hurting gut bacteria)

Medical Xpress / FAPESP / Microorganisms ^ | May 9, 2023 | Ricardo Muniz / Jefferson Luiz da Silva et al

[ConservativeMind]

An article shows that melatonin, despite its antioxidant effects and role in regulating sleep cycles, can worsen inflammation of the intestine and impair the action of gut microbiota.

Melatonin is popularly known as the "sleep hormone" and is often taken as a so-called food supplement without a doctor's prescription by people with sleep problems.

"It's generally thought to be harmless. However, our study shows that the ingestion of melatonin supplement can have adverse effects on health," said Cristina Ribeiro de Barros Cardoso.

Melatonin can act as an antioxidant and improve several physiological or pathological conditions. "We started out in this study with the assumption that we might be able to develop a novel treatment for Crohn's disease and ulcerative colitis, but to our surprise, we found exactly the opposite, and patients should be made aware of this danger," she said.

The study involved an experiment in which colitis was induced in mice, and they were treated with melatonin. Their condition became worse instead of improving. "The animals' bowel inflammation became much, much worse," Cardoso said.

"We then began trying to understand why. We found that melatonin had a positive effect on the disease if the effect on gut microbiota was ignored and the mice were treated with wide-spectrum antibiotics to eliminate all the bacteria."

The negative effect of melatonin, therefore, depends on the bacteria that live in the intestine and are also associated with inflammatory diseases of the region. Certain features of gut microbiota increase inflammation and dysregulate the immune system in response to treatment with melatonin, damaging the digestive system.

"We should take great care with medications, hormone supplements or hormones offered as food supplements. It's a hormone, and regulation of the interaction between all hormones and the immune system is very delicate," Cardoso said.

[MayflowerMadam]

“I wonder if it impacts the urinary tract, too, that would make UTIs an issue.”

I did some research online, and it appears that melatonin can have negative effects on the bladder, including causing UTIs.