January 2007: Melatonin for Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) is a condition in which some or all of the following symptoms occur: alternating diarrhea and constipation, excessive or painful intestinal gas, bloating and cramping, abdominal pain, painful bowel movements, mucus discharge, and undigested food in the stool. Intestinal examination in people with IBS reveals no structural abnormalities; this distinguishes IBS from other, more dangerous conditions such as ulcerative colitis.
Rather, something in the function of the digestive tract appears to have gone awry. Some people with IBS have a tendency to develop spasmodic contractions of the muscles in the intestinal wall. People with IBS may also display an increased ability to detect sensations in the digestive tract. This enhanced perceptual ability is unfortunate because it causes experiences of discomfort under circumstances in which a person without IBS would not experience anything at all.
Due to the absence of objective findings in IBS, conventional medicine has found it difficult to develop effective treatments. For this reason, many people turn to alternative medicine for treatment options. The best known and best supported alternative treatment for IBS is peppermint oil . More recently, the supplement melatonin , has shown some promise.
While melatonin is best known as a sleep aid, it is also hypothesized to play a role in the neurological regulation of the intestinal tract. Some evidence suggests that it can influence pain sensation as well as muscular contraction.
In three small double-blind, placebo-controlled studies enrolling a total of over 100 people with irritable bowel syndrome, use of melatonin appeared to improve IBS symptoms independent of its effects on sleep. The most recent of these studies was performed by Indian researchers and published in the Journal of Clinical Gastroenterology in 2007. In this trial, eighteen people with IBS were given either placebo or three milligrams of melatonin before bed over an eight-week period. The results showed that compared with placebo, melatonin markedly improved IBS symptoms as measured by total symptom scores.
Similar results were seen in the preceding two studies. However, note that while these results are promising, much larger studies will be necessary to actually establish melatonin as a treatment for IBS.
Lu WZ, Gwee KA, Moochhalla S, et al. Melatonin improves bowel symptoms in female patients with irritable bowel syndrome: a double-blind placebo-controlled study. Aliment Pharmacol Ther. 2005;22:927-34.
Saha L, Malhotra S, Rana S, et al. A preliminary study of melatonin in irritable bowel syndrome. J Clin Gastroenterol. 2007;41:29-32.
Song GH, Leng PH, Gwee KA, et al. Melatonin improves abdominal pain in irritable bowel syndrome patients who have sleep disturbances: a randomised, double-blind placebo-controlled study. Gut. 2005 May 24 [Epub ahead of print].
Last reviewed January 2007 by Steven Bratman, MD
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