Scientists at the Harvard School of Dentistry have found that the dietary supplement melatonin, commonly used to improve sleep, can increase gut inflammation and damage the gut microbiota. The research was published in the journal microorganisms.
Inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis are caused by abnormal activity of immune cells. Most patients usually do not respond to treatment, which causes them to have to remove part of the intestine with side effects.
The scientists did an experiment: they caused colitis in mice and then gave them melatonin. Melatonin is commonly known as the “sleep hormone” and is often taken over-the-counter by people with sleep problems. Melatonin is known to act as an antioxidant and reduce inflammation, so it has been suggested that it may also help with colitis.
But the condition of the mice did not improve, it got worse. The researchers suggested that this paradox has to do with the gut microbiota – bacteria and other gut microbes. Then the scientists destroyed the gut microbiota of the mice with the help of antibiotics and repeated the experiment. At the same time, melatonin positively affected the course of colitis and reduced inflammation.
The results could mean that some gut bacteria increase inflammation by damaging the digestive tract in response to melatonin treatment. Although the study did not include humans, the authors recommended that melatonin not be taken without a doctor’s advice, especially in the presence of inflammatory bowel disease.