Think zinc, but not too much

Philip J. Goscienski, M.D.

September 2010

Even if you pay attention to your diet it's not likely that you've given much thought to zinc. It's present in lots of foods, multivitamin/multimineral supplements usually contain about as much as most people need and to most physicians zinc deficiency is about as rare as beri-beri or scurvy — not to be found in modern society.

Severe zinc deficiency is rare in the Unites States but mild deficiency is not at all uncommon among certain groups. A government survey suggests that about 12 percent of the general population is at risk of zinc deficiency and that women, children and older persons are even more likely to be deficient. Even mild zinc deficiency during pregnancy can lead to birth defects and other complications of childbirth.

In spite of these findings, most nutritionists do not encourage the use of zinc supplements, for the data are not always conclusive. No nutrient acts alone within the body and zinc is not an exception. It is involved in hundreds of metabolic processes in conjunction with other dietary components. Genetic differences also account for some of the mixed findings. No wonder that teasing out significant data from this jumble is a challenge.

Zinc occurs naturally in a variety of foods. High levels are found in shellfish (oysters, clams, crabs) and red meat (beef, lamb). Whole grains, nuts and beans are fairly good sources but many of these foods contain phytates, substances that interfere with the absorption of zinc (and iron). Although cooking can reduce the zinc-binding effect of phytates, nutritionists recommend that vegetarians, especially vegans, supplement their diet with a multivitamin/multimineral that includes about 15 milligrams of zinc.

Until further scientific evidence becomes available there is no place for stand-alone zinc supplements except in developing countries where severe deficiency leads to growth failure and mental retardation. Zinc lozenges are promoted for reducing the symptoms of the common cold but the results are mixed and nasal sprays have been associated with significant side effects, including the permanent loss of smell.

Persons who follow a prudent diet are not likely to develop zinc deficiency but adolescents, seniors and women in the childbearing age should ensure that their diet matches their needs. This isn't difficult with a regular intake of whole grains, beans, low-fat dairy products, green leafy vegetables, several servings a week of fish or shellfish and a couple of servings a week of red meat.

Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.