Early research revealed that zinc is indispensable to normal growth. Data from studies of Egyptian and Irani boys identified severe zinc deficiency (defined by low zinc plasma levels) as a major factor and common denominator contributing to the high incidence of dwarfism and hypogonadism in this segment of the population. The findings were replicated with the discovery of less pronounced zinc deficiency among preschool children from low-income households in Denver and other large American cities. It is now firmly established that insufficient zinc in the diet results in impaired growth and delayed sexual maturation. It is also a factor in adult infertility. Studies have shown both the serum and semen zinc levels to be lower in infertile men than in fertile men. Fortunately, all of these conditions can be largely prevented by fortifying many foods with zinc. They can also be reversed if caught early enough, by taking zinc supplements.
Another very important role of zinc is to promote proper immune system functioning. Many of the body’s immune cells depend on zinc. Studies with young children show that zinc deficiency leads to reduced numbers of white blood cells, such as T lymphocytes and suppressed immune system response. Conversely, treatment with zinc supplements can restore the white blood cell count and immune system response to normal. Zinc also results in the improved response of antibodies to vaccines. Furthermore, zinc can act as a potent detoxifying agent when the body is exposed to pollutants in the environment or harmful chemicals that wind up being ingested.
Zinc is also a cofactor for more than 300 enzymes. It enters into chemical reactions involving both the synthesis and decomposition of carbohydrates, proteins, fats, and nucleic acids. Zinc helps balance blood sugar levels and stabilize metabolic rate. When there is not enough zinc in the diet, the pancreas secretes less insulin, which is the hormone that keeps the blood glucose level in check. In addition, the metabolism slows down.
Zinc is a powerful antioxidant, which explains its role in maintaining the structure and functioning of cell membranes. Zinc is especially important in maintaining the structure of different proteins. It serves as an intracellular signal in brain cells and regulates a variety of genetic activities. For example, zinc is needed for DNA and RNA synthesis to occur. Zinc even appears to be a factor in the sense of taste and smell; impairment in those functions often accompanies zinc deficiency.