Zinc is involved in more than 300 enzymatic & metabolic reactions in the body. It plays a key role in the maintenance of the bodyâs immune, nervous & reproductive systems. Zinc is essential for normal growth & development, taste & smell, & for maintaining healthy vision, skin & nails. Heavy drinkers, the elderly, diabetics, those with gastro-intestinal disorders, people with poor health or diet, pregnant women, vegetarians & vegans may have an increased dietary requirement for zinc.