FAMILY MEDICINE® COLUMN
By John C. Wolf, D.O.
Associate Professor of Family Medicine®
Ohio University College of Osteopathic Medicine

READER NOT LIKELY TO OVERDOSE ON ZINC

Question: I have been taking 50 mg of zinc every day for thin hair for the past year. It seems to have helped. Is taking this much zinc too much?

Answer: Nutrition is an area in which I often receive questions. The regular use of supplemental vitamins and minerals is portrayed as absolutely essential in some quarters but is decried by other folks as a diabolical scheme to bilk millions of dollars from the concerned but uninformed public. There is some data to support both positions, but. as in most cases, the truth probably lies somewhere between the two extremes.

Quite a number of substances are necessary for good health. I think almost everyone is aware that iron is needed to form blood and that calcium is a vital part of our bone structure. In addition, each is essential for other body functions as well. Because of their diverse roles in human metabolism, iron and calcium are needed in abundance.

Other elements, such as the zinc you ask about, copper, magnesium, chromium, iodine, selenium, and others are also essential for good health. The necessary amount of these "trace minerals" is much lower than for calcium or iron. In fact, the levels are so low that the U.S. Food and Drug Administration has not been able to establish the so-called "minimum daily requirements" for most of them.

A normal healthy diet usually contains sufficient amounts of most trace minerals. Fruits and vegetables absorb them from the soil and the animals we slaughter for meat obtain them the same way we do.

Although most Americans do not need to take mineral supplements, there are specific situations in which it may be desirable. These can include persons who have inadequate diet, difficulty absorbing minerals and other nutrients, or suffer from specific side effects of certain drugs.

As you might guess, the minerals that most frequently need to be taken are those that are needed by our metabolism in the greatest quantities calcium and iron. And unfortunately, deficiency in these is fairly common. Deficiency in other minerals, including zinc, is less frequently a problem, but it's still not a rare phenomenon.

Zinc deficiency may occur as a complication of illness that causes persistent diarrhea. In these unfortunate few individuals, the classic signs of zinc deficiency syndrome develop an "acne-like" rash around the mouth, nose and rectum; depression; difficulty with coordination; loss of the senses of taste and smell; and the loss of hair. In milder cases the symptoms are much less severe. Slow wound healing, a mild thinning of the hair, and some loss of the sense of taste and smell are common complaints. But all these symptoms can be caused by many other illnesses or even by advancing age without illness. Perhaps this is, in part, why we physicians fail to diagnose zinc deficiency very often.

The 50 milligrams of zinc you take every day is a safe amount of this mineral. In fact, taking three times this much is also safe. It is possible to have more zinc than is beneficial for good health, but the exact amount necessary to cause problems varies quite greatly and is rarely encountered even in those who take large supplemental amounts even if they are taken every day for years.

This sounds like an endorsement for everyone to take supplemental zinc, but it isn't. While it's generally safe, I can find no scientific studies that support the widespread use of zinc.

Family Medicine® is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Grosvenor Hall, Athens, Ohio 45701.