Zinc is an essential trace mineral, which, next to iron, is the second most abundant trace mineral in the body. Zinc is stored primarily in muscle but is also found in red and white blood cells, the retina of the eye, bones, skin, kidneys, liver, and pancreas. In men, the prostate gland contains more zinc than any other organ.

Recent research has attempted to determine the true value of zinc lozenges in preventing or reducing cold symptoms, with some studies showing good results. You can buy zinc lozenges in any pharmacy now to treat the common cold.

Zinc supplements can help the body in the following ways:

• Helps prevent cancer
• Prevents and treats colds
• Boosts the activity of immune system
• Speeds healing of wounds
• Treats and may prevent acne
• May prevent macular degeneration (eyesight deterioration that happens as people age)
• Treats some cases of anorexia nervosa (anorexia is a symptom of zinc deficiency, and the teenage population is at higher risk for zinc deficiency due to poor dietary habits)
• Improves male fertility, especially among smokers
• Treats rheumatoid arthritis (may have anti-inflammatory effects)
• Treats Wilson's disease (a disorder of excess copper storage)
• Decreases changes in the sense of taste during cancer treatments
• Heightens sense of taste and smell
• May increase lean body mass and reduce or keep fat mass stable 

Some conditions may affect how your body absorbs zinc, or may increase your need for zinc. If you have one of the following conditions, you may benefit from zinc supplements:

• Acrodermatitis eteropathica (the inherited disease that causes zinc malabsorption)
• Alcoholism
• Diabetes
• Kidney disease
• Celiac disease
• Inflammatory bowel disease, ulcerative colitis
• Chronic diarrhea
• Pancreatic conditions
• Prostate problems (BPH, prostatitis, cancer)

Women who are pregnant or are breastfeeding, and those who take oral contraceptives may also have an increased need for zinc.

We absorb 20 to 40% of the zinc that is in our food. Zinc from animal foods like red meat, fish, and poultry is the most readily absorbed form. Zinc in vegetables is less available to our bodies, and vegetable fiber itself lessens how much zinc we can absorb and use. Dairy products and eggs contain fair amounts of zinc, but it is less easily absorbed from these sources.

The following foods are the best sources of usable zinc: oysters (richest source), red meats, shrimp, crab, and other shellfish.

Other good, though less easily absorbed sources, include legumes (especially lima beans, black-eyed peas, pinto beans, soybeans, peanuts), whole grains, miso, tofu, brewer's yeast, cooked greens, mushrooms, green beans, and pumpkin seeds.

Zinc sulfate is the most frequently used supplement. This is the least expensive form, but it is the least easily absorbed and may cause stomach upset. Health care providers usually prescribe 220 mg zinc sulfate, which contains approximately 55 mg of elemental zinc. More easily absorbed forms are available: zinc picolinate, zinc citrate, zinc acetate, zinc glycerate, and zinc monomethionine.

These different forms contain different amounts of zinc. Always look for the amount of elemental zinc listed in milligrams on the label. Usually this will be between 30 and 50 mg of elemental zinc. Remember that you take in about 10 to 15 mg of zinc from food every day. Your healthcare provider should take this into account when prescribing how much supplemental zinc you should take. Zinc lozenges are also available in most drugstores and grocery stores, and are used for treating colds. Zinc lozenges are also available for the treatment of colds.

Consideration of zinc supplementation, particularly for children, should be discussed with your healthcare provider. The most benefit comes from taking zinc supplements with water or juice (not milk) in between meals; however, if the zinc bothers your stomach, you can take it with a meal. Avoid taking at the same time as iron or calcium supplements.

Daily intake of dietary zinc (according to the U.S. RDA) are listed below:

Pediatric

• Infants birth to 6 months: 2 mg (AI)
• Infants 7 to 12 months: 3 mg (RDA)
• Children 1 to 3 years: 3 mg (RDA)
• Children 4 to 8 years: 5 mg (RDA)
• Children 9 to 13 years: 8 mg (RDA)
• Males 14 to 18 years: 11 mg (RDA)
• Females 14 to 18 years: 9 mg (RDA)

Adult

• Males 19 years and older: 11 mg (RDA)
• Females 19 years and older: 8 mg (RDA)
• Pregnant females 14 to 18 years: 13 mg (RDA)
• Pregnant females 19 years and older: 11 mg (RDA)
• Breastfeeding females 14 to 18 years: 14 mg (RDA)
• Breastfeeding females 19 years and older: 12 mg (RDA)

Therapeutic ranges (elemental zinc):

• Men: 30 to 60 mg daily
• Women: 30 to 45 mg daily

Doses over this amount should be limited to only a few months under the supervision of a healthcare professional.

Most trace minerals are toxic if you take too much, and this is true of zinc. Symptoms of toxicity are stomach upset and vomiting, usually occurring if 2,000 mg or more has been swallowed. Studies have stated that up to 150 mg is fairly safe, but that much is usually not needed and may interfere with your body's use of other minerals. Research has shown that less than 50 mg a day is a safe amount to take over time, but researchers are not sure what happens if you take more than that over a long period. Talk with your health care provider before taking zinc or any other supplement.

One known negative side effect of too much zinc is that it lowers HDL (good) cholesterol and raises LDL (bad) cholesterol. Some research has shown that megadoses of zinc lower immune function, but other studies have not confirmed this. If zinc sulfate causes stomach irritation, try another form, such as zinc citrate. Check with your health care provider first. Other reported side effects of zinc toxicity are dizziness, headache, drowsiness, increased sweating, loss of muscle coordination, alcohol intolerance, hallucinations, and anemia.

Zinc decreases the absorption of oral quinolones, a class of antibiotics that includes ciprofloxacin, norfloxacin, ofloxacin, and levofloxacin, as well as tetracycline antibiotics. Similarly, zinc interacts with nonsteroidal anti-inflammatory drugs (NSAIDs), and could reduce the absorption and effectiveness of these medications. If you take NSAIDs and are considering taking zinc supplements, talk with your healthcare provider first.

Penicillamine, a medication used to treat Wilson's disease and rheumatoid arthritis, decreases zinc levels.

Since zinc supports immune function, it should not be taken with corticosteroids, cyclosporine, or other medications intended to suppress the immune system.

Hormone replacement therapy consisting of estrogen and progesterone derivatives may reduce loss of zinc in the urine, particularly in women with osteoporosis.

There has been at least one report of an interaction between zinc and hydralazine, a medication used to treat high blood pressure, which resulted in a lupus-erythematosus-like syndrome (characterized by a facial butterfly rash, fever, leg and mouth ulcers, and abdominal distress). It would be wise to refrain from using zinc supplements with hydralazine.

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