Zinc is an essential trace mineral that is found in some foods, fortified in others and available as a supplement. Its major function in the body is its role in cellular metabolism. It is also involved in immune function, DNA synthesis, cell division and protein synthesis. The body does not store zinc, so a steady supply from either the diet or supplements is necessary for proper health.

Zinc is found in a variety of foods, with shellfish, meat and poultry providing the largest amounts per serving. The best dietary sources of zinc include oysters, chuck roast, crab, lobster, ground beef, chicken, cashews, pork chops, chickpeas, kidney beans and flounder. There are very few plant-based sources of zinc unless they are fortified.

Symptoms of zinc deficiency include loss of appetite, slowed growth and problems with the immune system. Severe deficiency can cause sexual problems, hair loss, weight loss and lethargy. Since these symptoms can be associated with many other health problems it is not easy to attribute them to zinc levels. Zinc is also dispersed throughout the body and not stored at high levels, making it rather difficult to accurately test. Groups at highest risk of zinc deficiency include vegetarians and vegans, chronic alcoholics and those with malabsorption disorders.

Some studies have shown that when zinc supplements in the form of lozenges are taken at the first sign of symptoms of the common cold that they can speed recovery. These studies have also been refuted, so more study is needed to determine conclusively. Zinc also plays a role in slowing the advancement of age related macular degeneration, although it has only been shown to slow the process once it has already started and does not appear to be able to halt its formation in the first place.

Consuming too much zinc can lead to toxicity, and too much zinc can also lead to problems with absorbing dietary copper. Several adverse health effects are related to supplemental zinc, so it is recommended that diligence is used to make sure that adequate zinc is consumed through diet.