The evidence for the health and longevity benefits of melatonin is enormous and is growing at unprecedented speed. There are now 4,000 to 5,000 studies on melatonin in the scientific literature, with hundreds of new studies published every month. There is now strong evidence that melatonin is an all-purpose anti-aging therapy. That melatonin has potent anti-cancer effects. That it can help to prevent and treat heart attacks. And that it may be beneficial for other chronic diseases. In addition to all this, the main reason most people take melatonin -- to get a good night's sleep -- makes it likely that millions of people will soon be taking melatonin on a daily basis for many years.
With such imminent popularity on the horizon, it's prudent to make sure that melatonin is safe to take on a long-term basis. The Life Extension Foundation has been offering melatonin to its members for several years. During this time, tens of thousands of people have taken melatonin, without any evidence of serious, adverse side effects.
Who Shouldn't Take Melatonin
The only people who shouldn't take melatonin, or who should only take it very carefully under the care of a physician, are patients with leukemia, lymphomas, or other immune system cancers, or who have auto immune diseases such as lupus or rheumatoid arthritis. Such patients need to be careful about taking melatonin because it is a strong immune system stimulant, which is beneficial for most people, but can cause problems in patients whose immune system has gone awry. There is also some evidence suggesting that patients with ovarian cancer should not take melatonin.
The only other people who should be careful about taking melatonin are women who are pregnant, or who want to become pregnant. The reason for this is that melatonin is involved in the control of reproductive function, and studies are underway to use it as a contraceptive. Even though much higher doses of melatonin are being used in these studies than are used for anti-aging purposes, caution should be exercised.
No Evidence Of Toxicity
For all others, it appears as if melatonin is as benign a therapy as can be found. None of the thousands of scientific papers on melatonin in the scientific literature have found any evidence of harm or risk of any kind in anyone taking melatonin for any reason at all.
To get some idea of how safe melatonin is, let's take a look at several clinical trials in which exceptionally high doses of melatonin were used. In one such study, 40 malignant melanoma patients were given up to 700 mg. a day of melatonin in 4 divided doses for up to 33 weeks. The toxicity encountered in this trial was "minimal" and consisted primarily of fatigue in 17 of the 40 patients.
In a study of melatonin's contraceptive action at Dijkzigt University Hospital in Rotterdam, Holland, 12 women received 300 mg. a day of melatonin for 4 months. The scientists commented on the lack of toxicity in these women as follows:
"No requests for study discontinuation were reported by the women. There were no complaints about altered night/day sleep, and activity patterns, altered emotional well-being, or mood changes. The results of all hematological and biochemical determinations were normal before, during, and after treatment."
In a third study at the Yale University School of Medicine, five adult patients with hyper pigmented skin were given 1,000 mg. (one gram) of melatonin a day (in four divided oral doses) for 25-30 days. Because of the extraordinarily high doses of melatonin used in this study, there was extremely careful monitoring of the subjects. The scientists found that, at this super-high dose of melatonin, which is 333.3 times higher than the most commonly used dose for anti-aging purposes, there was no evidence of toxicity!
"All subjects were watched carefully for signs of toxicity. Slit lamp examinations, direct and indirect fundoscopy, visual acuity, and visual fields showed no evidence of retinal toxicity. Blood pressure and pulse rate were unchanged. Electrocardiograms were not affected. All hematologic tests including white blood cell counts, hemoglobin, hematocrit, platelet count, reticulocyte count, differential white counts were normal throughout the trials. All of the blood chemistry tests including urea nitrogen creatinine, uric acid, calcium, phosphorus, SCOT (serum glutamic oxalcetic transaminase) LDH (lactic dehydrogenase), bilirubin, total proteins and albumen, were normal. Urinalyses were normal."
In an article by Russel J. Reiter of the University of Texas Health Center in San Antonio in the Annals Of the New York Academy Of Science it was stated that:
"Melatonin, even when given in massive amounts (300 mg. daily) for prolonged periods (up to 5 years) to humans does not produce untoward side effects."
The Importance Of Purity
The evidence cited above demonstrates that melatonin is an extraordinarily safe substance. The main risk to consider when purchasing melatonin is how pure is it. The Foundation only sells melatonin of the highest (99.8%) purity. However, some companies sell melatonin that is only 98.5% pure. So beware and only buy the best!