Without zinc, the body can’t grow, develop, or function properly. It’s estimated that more than one hundred different enzymes in the body require zinc in order to function. We require zinc to metabolize alcohol, digest our food, help form bone, provide the body with energy through glycolosis and synthesize the heme structure in hemoglobin. Zinc also helps maintain the structural shape of proteins. If proteins lose their shape, they lose their function. Zinc stabilizes the structure of certain DNA-binding proteins. Zinc has received so much attention for its contribution to immune system health that zinc lozenges have been formulated to fight the common cold.
Zinc also helps turn genes on and off which regulates the body functions that these genes control. If zinc isn’t available to activate certain genes related to cellular growth during the development of the fetus and after the child is born, growth is stunted. Zinc also helps maintain blood glucose levels by interacting with insulin and influencing the way fat cells take up glucose. Zinc is also a critical component of cell replication and normal growth.
Zinc absorption increases during times of growth, sexual development and pregnancy. High non-heme iron intakes can inhibit zinc absorption. Also, the phytates and fiber found in whole grains and beans inhibit absorption. However, dietary protein enhances zinc absorption, especially animal based proteins.
The RDA for zinc for adult men and women aged 19 years and older are 11 mg/day and 8 mg/day. Good food sources are red meats, some seafood, whole grains, and enriched grains and cereals. Zinc deficiency is a concern for people eating a vegetarian or vegan diet because zinc is more absorbable in animal based foods.
Excessive zinc supplementation has been shown to depress immune function and decrease HDL concentrations. High intakes (5-6 times the RDA) can also reduce copper and iron status because zinc absorption interferes with these minerals. Zinc deficiency is uncommon in the United States. A deficiency occurs more often in countries where people consume mostly grain-based foods. Zinc deficiency symptoms include growth retardation in children, diarrhea, delayed sexual maturation, eye and skin lesions, hair loss, and impaired appetite. Also because zinc plays an important part of a healthy immune system, a deficiency can lead to an increased incidence of infections and illnesses. In developed countries, those who are at risk for zinc deficiencies include whose with malabsorption syndromes and adults and children who eliminate high zinc foods from their diet.
Source: Thompson, Janice, Melinda Manore, and Linda A. Vaughan. The Science of Nutrition. San Francisco, CA: Pearson Benjamin Cummings, 2011. Print.