Zinc facilitates metabolic functions and DNA synthesis, supports a healthy immune system, is required for the healing of wounds, & maintains a sharp sense of taste.
Zinc is a micro-mineral, thought to be involved in more body functions than any other mineral. Zinc's activities are many, and include acting as necessary component of more than 100 enzyme systems, normal growth and development, the maintenance of body tissues, sexual function, the immune system, as well as detoxification of chemical and metabolic irritants. Zinc also influences carbohydrate metabolism and DNA synthesis, and is believed to facilitate healing after surgery or burns.
Other possible therapeutic uses for zinc include the treatment of skin problems, wound healing, male sexual and prostate problems, infertility, alcoholism, anorexia, colds and sore throat, cataracts, hearing loss, environmental sensitivity, fatigue, gastric ulcers, inflammation, high blood pressure, immune suppression, and weak muscles, to name a few.
RDA for Zinc
RDAs are set with the understanding that our body tissue needs are about 4 to 6 mg of zinc daily, and the body absorbs only about 30% to 40% of zinc consumed.
Accordingly, the RDA for zinc for adult females is 8 mg (with up to 50 percent more being required for pregnant and lactating women), and 11 mg for adult males. There are also very specific RDAs designated for infants, children, and adolescents of each sex at varying ages.
Sources of Zinc
Animal Sources of Zinc
Most animal foods contain adequate amounts of zinc, with oysters topping the list with more than ten times as much as other sources. This ultra source may prove problematic, however, as oysters are also high in copper, and may potentially be laden with ocean-polluting chemicals and metals.
Other animal sources of high amounts zinc include:
- Red meats (beef, lamb, pork)
- Liver
- Herring
- Egg yolks and milk products
Other fish and poultry are considered fair sources of zinc.
While zinc is available in both animal and plant food sources, zinc in animal foods is better absorbed than vegetable sources, since fiber foods, bran, and phytates found in grains and vegetables may bind with the zinc in the GI tract, causing less to be absorbed. However, it is possible – although not easy – to obtain adequate zinc by consuming mostly whole grains and beans.
Vegetable sources of zinc include:
- Whole grains (wheat, rye, oats)
- Fortified breakfast cereals
- Nuts (especially pecans and Brazil nuts)
- Pumpkin seeds
- Ginger root
- Mustard, chili powder, black pepper
Fruits and vegetables are generally poor sources, although peas, carrots, beets and cabbage contain some zinc.
Zinc Deficiency
Zinc deficiency is far more common and complex than once believed; major factors contributing to zinc deficiency include aging, and depletion in foods is produced by soil losses, and losses due to food processing. Additionally, a shift from iron- and zinc-containing water pipes to copper ones has resulted in a decrease in zinc intake and absorption. Groups particularly at risk for zinc deficiency due to low intake include infants, adolescents, women (especially those on birth control pills), strict vegetarians, alcoholics, the poor, and the elderly.
Symptoms of zinc deficiency include:
- Poor appetite, slow development, learning disabilities, poor attention span in children
- Slowed growth and delayed or absent sexual development during puberty
- Low sperm count, prostate problems and/or sterility in males
- Delayed menstruation in puberty and menstrual problems
- Morning sickness in pregnancy
- Delayed healing of wounds
- Stretch marks
- Depression
- Lowered resistance and increased susceptibility to infection
- Fatigue
- Exaggerated sensitivity and reactions to environmental chemicals
- Hair loss or thinning
- Dermatitis, dry skin, skin rashes
- Poor sense of taste, appetite and digestion in adults
- Brittleness of nails and/or white spots on nails (leukonychia)
Zinc Toxicity
Zinc is considered fairly nontoxic, since – even with large dosages – only a certain amount will be absorbed into the body.
Toxicity due to excessive supplementation may include symptoms such as immune suppression, premature heartbeats, dizziness, drowsiness, increase sweating, lack of coordination, alcohol intolerance, hallucinations, and anemia. Dosages in excess of 100 to 150 mg daily may interfere with the assimilation of other minerals such as copper and iron. Taking more than 2 g in one dose will usually produce vomiting.
Before you reach for a zinc supplement, consider whether your needs could be adequately met by dietary zinc sources, which are (as with most supplements) the best form. Consult with your health care practitioner before beginning a regimen of therapeutic zinc supplementation, particularly if you are pregnant or lactating, or if you have pre-existing health conditions.
Source: Staying Healthy With Nutrition: The Complete Guide to Diet and Nutritional Medicine, 21st Century Edition, by Elson M. Haas
