Zinc has been known for more than 50 years to be an essential mineral. It is found in almost every cell in the body and is contained within more than 200 enzymes, substances needed for biochemical reactions. Zinc is important for a healthy immune system, for healing cuts and wounds, and for maintaining your sense of taste and smell. Zinc also supports normal growth and development during pregnancy, childhood, and adolescence.

A medical doctor can evaluate the need for a zinc supplement if diet alone fails to maintain normal zinc levels in the body.

Zinc, infections, and wound healing
The immune system is adversely affected by even moderate degrees of zinc deficiency. People who are zinc-deficient have a more difficult time resisting infections. T-cell lymphocytes, white blood cells that help fight infection, do not function efficiently when zinc stores are low. When zinc supplements are given to individuals with low zinc levels, the numbers of T-cell lymphocytes circulating in the blood increase and the ability of lymphocytes to fight infection improves. Studies show that poor, malnourished children in India, Africa, South America, and Southeast Asia experience shorter courses of infectious diarrhea after taking zinc supplements. Zinc supplements are often used to treat skin ulcers or bed sores , but they do not increase rates of wound healing when zinc levels are normal.

Zinc and the common cold
A study of over 100 employees of the Cleveland Clinic showed that zinc lozenges decreased the duration of colds by one-half. Some of the participants reported fewer days of congestion and nasal drainage, but no differences were seen in how long their fevers lasted or in the level of muscle aches they experienced. However, this study has been criticized by some researchers who believe that since zinc lozenges often have a bad taste, the participants may have known the difference between the supplement and placebo, which would compromise the results. Also, since other studies have shown no benefit the debate continues on the true value of zinc supplements for cold symptoms.