Q: Can I take melatonin to improve my irritable bowel syndrome?
A: Although I can't answer definitively, it seems like supplementing with melatonin should help you out. Melatonin is a hormone produced by the pineal gland located in the brain. It assists in regulating sleep and also helps regulate gastrointestinal motility and sensation. As such, it has been used in recent trials to see if it would improve bowel symptoms and sleep disturbances in IBS patients.
In one study, 40 IBS patients with sleep disturbances were randomly assigned to receive either 3 mg melatonin or placebo for two weeks. Compared with placebo, melatonin significantly decreased abdominal pain. However, it did not seem to affect bloating and stool frequency, nor, surprisingly, sleep disturbances.1 A second study took 17 female patients with IBS and randomly assigned them to receive either 3 mg melatonin or placebo for eight weeks, and then switch. Of those taking melatonin, 88 percent (versus 47 percent on placebo) reported mild to excellent response in IBS symptoms, but again, no changes in sleep.2 A third study showed essentially the same results.3 So, from these preliminary studies, it appears that melatonin has a potentially positive effect on IBS, but not in improving sleep for those with the syndrome. Certainly more studies are in order, but a trial run of this seemingly safe dose may show improvements.
Q: I know green tea is good for you, but as a woman, how much do I really have to drink for a protective effect against heart disease?
A: Green tea polyphenols have been extensively studied as cardiovascular protective agents in test tubes and animals. Human research over the past few years encouragingly supports the former studies' positive findings. A few years ago a study came out of Japan suggesting 10 cups of green tea per day was needed for human cardiovascular benefits. (Depending on the source, a "cup" is defined as 100 ? 150 ml, or about 3.4 ? 5.1 oz.) In that study of about 8,000 adults, those consuming more than 10 cups per day experienced a protective cardiovascular effect compared with adults who consumed less than three cups per day (although it should be noted there was a more protective effect for men than women).4
A more recent and larger study in Japan tracked more than 40,000 Japanese adults for up to 11 years. Researchers found green tea consumption was inversely associated with cardiovascular disease—women drinking one to two cups per day had a .84 relative risk of dying from heart disease, while drinking three to four cups a day reduced the relative risk to .69. This number did not improve by drinking more—it was still .69 for those drinking five or more cups per day.5 (In this study, the volume of a typical cup of green tea is 100 ml.) So, generally speaking, the more the better, but probably at least three to five cups per day to get a reasonable benefit.
Science editor's note: The green tea effect has so far been observed in Asian populations only. We don't have enough dedicated green tea drinkers outside of Asia to fill a teapot. But one cannot assume that if it is effective in preventing disease in Asians it will work in people in other populations, because they have not historically consumed it in large quantities over their life span.
1. Saha L, et al. A preliminary study of melatonin in irritable bowel syndrome. J Clin Gastroenterol. 2007;41(1):29-32.
2. Lu WZ, et al. Melatonin improves bowel symptoms in female patients with irritable bowel syndrome: a double-blind placebo-controlled study. Aliment Pharmacol Ther. 2005;22(10):927-34.
3. Song GH, et al. Melatonin improves abdominal pain in irritable bowel syndrome patients who have sleep disturbances: a randomised, double blind, placebo controlled study. Gut. 2005; 54(10):1402-7.
4. Nakachi K, et al. Preventive effects of drinking green tea on cancer and cardiovascular disease: epidemiological evidence for multiple targeting prevention. Biofactors. 2000;13(1-4):49-54.
5. Kuriyama S, et al. Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study. JAMA. 2006;296(10):1255-65.
Natural Foods Merchandiser volume XXVIII/number 9/p. 106