A glance at the periodic table of elements will show that zinc is a metallic element. But for humans it is an essential mineral in the diet. For your biological system to function, you need to take in zinc either from food or in a supplement. Zinc deficiency was first clinically diagnosed in 1961, and now when you walk down your drugstore aisles, you will see zinc being touted as a way to do everything from improve immune systems to heal wounds.
Causes of Zinc Deficiency
Zinc deficiency has several different causes, but the primary reason is inadequate consumption. Although deficiency is not common in younger adults, data from the National Health and Nutrition Examination Survey found that the majority of adults over the age of 60 have zinc intakes below the estimated average requirement. Supplemental iron, 38 to 65 mg per day of elemental iron, may decrease zinc absorption. Dietary intake of iron does not have this same effect. For individuals with gastrointestinal disorders that decrease absorption, such as Crohn's or celiac disease, zinc deficiency is more common. Severe wounds and extended periods of diarrhea will also deplete zinc stores.
Daily Zinc Requirements
Men over the age of 14 need 11 mg of zinc per day. Women over the age of 14 require 8 mg. If a woman is pregnant, she needs to increase this to 11 mg, and during lactation, to 12 mg. If a doctor has already diagnosed a deficiency, he will not recommend a supplemental zinc dose greater than 50 mg. High doses can cause gastrointestinal distress including vomiting, diarrhea and nausea and can also interfere with your ability to absorb copper.
Negative Consequences of a Zinc Deficiency
Zinc is intimately involved with cellular metabolism, the production of enzymes, protein synthesis, wound healing and immune function. It is required for normal growth and development in young children and adolescents. A zinc deficiency will also alter your senses of taste and smell. Severe zinc deficiency results in cessation of growth in children, delayed sexual maturation, skin rashes, night blindness, diminished appetite,
chronic and severe diarrhea, immune system deficiencies and impaired wound healing.
Food Sources of Zinc
Zinc is found abundantly in nature. Oysters are the richest source, providing 77 mg per serving. In the standard American diet, red meat and poultry are the greatest sources. It is also found in crab, lobster, beans, nuts, whole grains, fortified cereals and dairy products. The bioavailabilty of zinc in plant foods is much lower than in animal products because natural phytates bind zinc and limit its absorption. You can reduce phytates by soaking beans and grains before cooking them. Because the daily recommended intake of zinc is not extremely high, consuming a variety of foods will greatly reduce the risk of a deficiency.
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