Melatonin is no miracle, but it may be a new snake oil

On Call

June 11, 1996|By Dr. Simeon Margolis | Dr. Simeon Margolis,SPECIAL TO THE SUN

One of my friends is taking melatonin and has urged me to do the same in order to protect against heart attacks and Alzheimer's disease. Do you agree that it is worthwhile to take melatonin?

My short answer: No.

Melatonin is a hormone produced by the tiny pineal gland located deep within the brain. The formation of melatonin is regulated by light -- melatonin is manufactured when it is dark, and its production is turned off by bright light. As a result, blood levels of melatonin follow a daily cyclical pattern. Peak levels are achieved during the night; blood levels fall in the morning and stay low throughout the day. Melatonin formation is highest in children and declines in subsequent years, so that blood levels are quite low in elderly individuals.

Melatonin functions as a kind of internal clock to control and coordinate daily biological rhythms such as the sleep-wake cycle. Studies have provided reasonable evidence that melatonin may be helpful in alleviating jet lag or sleeplessness in shift workers. Even so, more research is needed to know what dose of melatonin to use or when it should be taken.

Unfortunately, grossly exaggerated claims for the benefits of melatonin have appeared in newspaper and magazine articles and particularly in a book, "The Melatonin Miracle," written by two doctors and published in August of 1995. The authors claim melatonin will "delay aging, combat disease (including cancer), prolong sexual vitality."

The notion that melatonin can prolong life is based on the fall in its levels with aging, bolstered by an experiment that showed that nightly injections of melatonin lengthened the life of elderely mice. Various articles have maintained that melatonin can prevent or cure a wide array of other disorders including heart disease, Alzheimer's disease, cataracts, depression, schizophrenia, epilepsy, diabetes and Parkinson's disease. The mere fact that this substance is said to cure or prevent so many diseases should raise a red flag and serve as a reminder of the snake-oil salesmen of the old Wild West. The claims are based solely on animal experiments, anecdotal reports in people, or pure speculations; none has been subjected to careful scientific studies in humans.

Sales of melatonin -- so brisk that many health food stores are unable to meet demand -- provide yet another example of how ready people in this country are to accept claims of "miracle" cures. Melatonin cannot be recommended as a treatment or preventive measure for any disease or to foster longevity or improve sex life. The safety of melatonin is unproven. There is no control over the quality of the melatonin sold, nor any studies on its possible long-range ill effects.

Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.

Pub Date: 6/11/96

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