Zinc Factoids

• Zinc, the chemical element designated by the symbol Zn, is an essential trace mineral in the human body. Among the trace elements the only one that exists in the body in a larger amount than zinc is iron. The average human body contains between 2 and 3 grams of zinc, all in the form of a positively charged ion (Zn++).

• Zinc is essential for growth, development, and reproduction and a healthy immune system. It also plays a key role in metabolism, serving as the cofactor for more than 300 enzymes. Zinc is needed as well for DNA and RNA synthesis. Zinc even affects taste and smell.

• Research studies have identified zinc as the probable cause of the high incidence of dwarfism and hypogonadism in Egyptian and Iraqi boys.

• Zinc is also a powerful antioxidant. Research studies with young children show that zinc deficiency leads to reduced numbers of T lymphocytes and suppressed immune system response, while treatment with zinc supplements can reverse these effects. Zinc also results in the improved response of antibodies to vaccines. Zinc can act as a detoxifying agent when the body is exposed to harmful chemicals or pollutants.

• Zinc is being successfully used today in the treatment of those with compromised immune systems as well as a variety of other medical problems. Some of the diverse illnesses for which zinc is being given as treatment include colds, sore throats, and other respiratory infections; respiratory allergies; rheumatoid arthritis; herpes; trichomoniasis; burns; skin, hair, and nail problems; male sexual functioning problems; anorexia; HIV; and schizophrenia and senility. Zinc is also being used to help prevent macular degeneration (a serious eye disorder associated with blindness in the elderly) and to speed up recovery from surgery.

• The Recommended Dietary Allowance (RDA) for zinc is 11 mg for men, 8 mg for women, and 11 mg and 12 mg, respectively, for pregnant and lactating women. The Upper Tolerable Limit for zinc has been set at 40 mg per day.

• Zinc can be found in many foods, including meats, poultry, and shellfish; dairy products; whole grains; leafy and root vegetables; legumes; soybean products; nuts; and chocolate. In addition, many cereals and grain products are fortified with zinc to compensate for the zinc lost through processing. 

• The normal serum zinc level is between .66 and 1.10 mcg/ml. Levels outside of that range, in either direction, can create serious health problems. While both zinc toxicity and severe zinc deficiency are rare in this country, mild zinc deficiency remains prevalent.

• Vegetarians, especially vegans, are at increased risk for zinc deficiency since they rely exclusively on plant food sources of zinc. Due to the phytate content, the zinc in legumes and other vegetables can be much more difficult to absorb than zinc from animal sources. Fruits, another mainstay of the vegetarian diet, are not a good source of zinc at all. Others who are at increased risk for zinc deficiency include infants and toddlers, pregnant and lactating women, female athletes, the elderly, severely malnourished persons and those with malabsorption disorders, alcoholics, diabetics, and those with HIV.

• Even mild zinc deficiency can slow down children’s growth and impair immune system functioning. Severe deficiency can also cause learning disabilities and attention deficit disorders; fatigue; poor appetite; diarrhea, nausea and vomiting; reduced sense of smell and taste; frequent colds and infections; skin irritations; delayed wound healing; hair loss; depression; delayed maturity, hypogonadism, impotence, and infertility; and pregnancy complications.

• Zinc toxicity is more likely to be the result of excessive amounts of zinc supplements than too much zinc in the diet. Symptoms of toxicity can include poor immune functioning; low HDL cholesterol; copper deficiency; fever; stomach cramps and loss of appetite; metallic taste; nausea and vomiting; and CNS disturbances.

• Even in healthy individuals, zinc is not absorbed as efficiently as some other minerals, only about 20 to 40% of the total amount ingested. For people with certain gastrointestinal disorders and other serious illnesses, the absorption rates are much less.

• The phytates in such foods as legumes and the oxylates in such foods as spinach, chard, and chocolate interfere with the absorption of zinc.Calcium, phosphorus, copper, iron, and folate also compete with zinc for absorption. Milk is rich in zinc, but it is also rich in calcium which takes away from its usefulness as a source of zinc. Conversely, zinc absorption is facilitated by an acidic environment, glucose, lactose, soy protein, and red wine.

• Zinc supplements are frequently prescribed, both to treat existing zinc deficiencies or as a preventative measure. However, they are best taken on an empty stomach because otherwise, the additional zinc could interfere with the absorption of other vitamins and minerals in the food, thus merely replacing one deficiency with another.

• Zinc is widely used in industry. Because of its ability to resist corrosion, zinc is used to galvanize steel. In addition, zinc oxide is used to make a wide array of commercial products, including batteries, paint, plastics, pharmaceuticals, floor coverings, ink, cosmetics, soaps, and textiles. Zinc oxide is also used in creams and lotions as an insect repellant and to protect the skin against sunburn.