Zinc is an essential trace mineral, so you get it through the foods you eat. Next to iron, zinc is the most common trace mineral in the body and is found in every cell. It has been used since ancient times to help heal wounds and plays an important role in the immune system, reproduction, growth, taste, vision, and smell, blood clotting, and proper insulin and thyroid function.

Zinc also has antioxidant properties. Therefore it helps protect cells in the body from damage caused by free radicals. Free radicals may contribute to the aging process, as well as the development of a number of health problems, including heart disease and cancer. Antioxidants, such as zinc, can neutralize free radicals and may reduce or even help prevent some of the damage they cause.

Your body doesn't need a large amount of zinc; the recommended daily allowance for adults is 8 - 11 mg. A mild zinc deficiency isn't uncommon but taking a multivitamin, plus eating a healthy diet, should give you all the zinc you need. It's rare for people in industrialized countries to be seriously deficient in zinc. Low zinc levels are sometimes seen in the elderly, alcoholics, people with anorexia, and people on very restricted diets. People who have malabsorption syndromes, such as Crohn's disease or celiac disease, may also be deficient in zinc.

Symptoms of zinc deficiency include loss of appetite, poor growth, weight loss, lack of taste or smell, poor wound healing, skin problems (such as acne, atopic dermatitis and psoriasis), hair loss, lack of menstrual period, night blindness, white spots on the fingernails, and depression. It is very common among the elderly, especially those over 75.

Zinc lessens the amount of copper your body absorbs, and high doses of zinc can cause a copper deficiency. For that reason, many doctors recommend that you take 2 mg of copper along with a zinc supplement.

Acne

Some studies suggest that taking oral zinc supplements may help improve acne. However, most studies used a high dose of zinc that could have toxic effects, and not all studies found any benefit. There is some evidence that a topical form of zinc, used in conjunction with the topical antibiotic erythromycin, might be helpful.

Age-Related Macular Degeneration

Physicians often recommend zinc to slow the progress of age-related macular degeneration, an eye disease that occurs when the macula, the part of the retina that is responsible for central vision, starts to deteriorate. A major clinical trial, the Age Related Eye Disease Study (AREDS1), found that people who had macular degeneration could slow its progression by taking zinc (80 mg), vitamin C (500 mg), vitamin E (400 mg), beta-carotene (15 mg), and copper (2 mg). But not all studies have found zinc to be helpful. One 2007 study found that people with macular degeneration had deposits with high levels of zinc, leading some researchers to wonder if zinc actually contributes to macular degeneration. A new study, AREDS2, is examining exactly what role zinc plays in macular degeneration.

Colds

Many people believe that taking zinc lozenges or using zinc nasal spray when they first show signs of a cold can reduce the duration and severity of symptoms, but the evidence is mixed. In one study, normal zinc status among nursing home elderly was associated with a lower risk of pneumonia, fewer new antibiotic prescriptions and fewer days of antibiotic use. More and better studies are needed that examine which kinds of zinc may be effective and against which kinds of cold viruses.

Immune Response

Zinc is necessary for a healthy immune system, and people who are deficient in zinc tend to be more susceptible to a variety of infections. For that reason, health care professionals sometimes suggest zinc supplements to improve your overall immunity and ward off infections, but that may only work if you are deficient in zinc to start with. Some physicians warn that taking too much zinc can have a negative impact on the immune system.

Sickle Cell Disease

People who have sickle cell disease are often deficient in zinc. Studies suggest that taking zinc supplements may help reduce symptoms of the disease. Children who took zinc showed improvements in height and weight, and had fewer sickle-cell crises.

Stomach Ulcers

Some studies suggest that zinc may help speed the healing of gastric ulcers.

Attention Deficit Hyperactivity Disorder (ADHD)

Evidence suggests that taking zinc may cause a slight improvement in symptoms, reducing hyperactivity, impulsivity, and impaired socialization in children. However, there was no change in attention deficit symptoms, and zinc may only benefit children who are deficient in zinc to start with. Zinc may be most helpful to children with a high body mass index, low levels of free fatty acids in their blood, and low levels of zinc.

Herpes simplex

Topical preparations of zinc have shown benefit in relieving symptoms and preventing recurrences of oral herpes lesions (canker sores).

HIV/AIDS

Zinc deficiency is common in people with HIV (even before symptoms appear) or AIDS. In people with AIDS, low levels of zinc may be a result of poor absorption, medications, and loss of this important nutrient through vomiting or diarrhea. Zinc deficiency leads to increased susceptibility to infection in people with AIDS (called an opportunistic infection). Some studies show that HIV positive people who take zinc have fewer infections, gain more weight, and have a better immune system response. But not all studies agree, and one even suggests that taking zinc may be associated with higher death rates. If you have HIV or AIDS, talk to your doctor before taking zinc or any supplement.

Wilson's Disease

Some early research suggests that zinc may be beneficial in treating Wilson's disease, a condition which causes copper to build up in the body. Because zinc lessens the body's absorption of copper, it may help reduce levels of copper in people with Wilson's disease.

Other

Other conditions may increase the need for zinc or affect how your body absorbs or uses this mineral. It is not known, however, whether taking zinc will help treat any of these conditions:

• Acrodermatitis enteropathica (a skin disorder due to an inherited inability to absorb zinc properly)
• Alcoholism
• Cirrhosis (liver disease)
• Kidney disease
• Celiac disease
• Inflammatory bowel disease (ulcerative colitis and Crohn's disease)
• High blood pressure
• Pancreatic conditions
• Pregnancy

Your body absorbs 20 - 40% of the zinc present in food. Zinc from animal foods like red meat, fish, and poultry is more readily absorbed by the body than zinc from plant foods. Zinc is best absorbed when taken with a meal that contains protein.

The best sources of zinc are oysters (richest source), red meats, poultry, cheese (ricotta, Swiss, gouda), shrimp, crab, and other shellfish. Other good, though less easily absorbed, sources of zinc include legumes (especially lima beans, black-eyed peas, pinto beans, soybeans, peanuts), whole grains, miso, tofu, brewer's yeast, cooked greens, mushrooms, green beans, tahini, and pumpkin, and sunflower seeds.

Zinc is available in several forms. Zinc sulfate is the least expensive form, but it is the least easily absorbed and may cause stomach upset.

More easily absorbed forms of zinc are zinc picolinate, zinc citrate, zinc acetate, zinc glycerate, and zinc monomethionine. If zinc sulfate causes stomach irritation, you can try another form, such as zinc citrate.

The amount of elemental zinc is listed on the product label (usually 30 - 50 mg). To determine the amount to take in supplement form, remember that you get about 10 - 15 mg from food.

Zinc lozenges, used for treating colds, are available in most drug stores. There are also nasal sprays developed to reduce nasal and sinus congestion. Nasal gels seem to work better than the spray.

You should take zinc with water or juice. However, if zinc causes stomach upset, it can be taken with meals. Don't take zinc at the same time as iron or calcium supplements.

A strong relationship exists between zinc and copper. Too much of one can cause a deficiency in the other. Long-term use of zinc (including zinc in a multivitamin) should be accompanied by copper.

Do not give zinc supplements to a child without talking to your doctor.

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

Pediatric

• Infants birth - 6 months: 2 mg (AI)
• Infants 7 - 12 months: 3 mg (RDA)
• Children 1 - 3 years: 3 mg (RDA)
• Children 4 - 8 years: 5 mg (RDA)
• Children 9 - 13 years: 8 mg (RDA)
• Males 14 - 18 years: 11 mg (RDA)
• Females 14 - 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 - 18 years: 12 mg (RDA)
• Pregnant females 19 years and older: 11 mg (RDA)
• Breastfeeding females 14 - 18 years: 13 mg (RDA)
• Breastfeeding females 19 years and older: 12 mg (RDA)

Therapeutic ranges (elemental zinc):

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

You should not take high doses of zinc for more than a few days unless your doctor tells you to. Talk to your doctor before taking more than 40 mg of zinc per day.

Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

Research has shown that less than 40 mg a day is a safe amount to take over time, but researchers are not sure what happens if more is taken over a long period.

Common side effects of zinc include stomach upset, nausea, vomiting, and a metallic taste in the mouth. High doses of zinc can cause dizziness, headache, drowsiness, increased sweating, loss of muscle coordination, alcohol intolerance, hallucinations, and anemia.

Very high doses of zinc may actually weaken immune function. High doses of zinc may also lower HDL ("good") cholesterol and raise LDL ("bad") cholesterol.

If you are being treated with any of the following medications, you should not use zinc without first talking to your health care provider.

Amiloride (Midamor) -- Amiloride is a potassium-sparing diuretic (water pill) that may increase the levels of zinc in your blood. Do not take zinc supplements if you take amiloride.

Blood pressure medications, ACE Inhibitors -- A class of medications called ACE inhibitors, used to treat high blood pressure, may decrease the levels of zinc in your blood. ACE inhibitors include:

• Captopril (Capoten)
• Benazepril (Lotensin)
• Enalapril (Vasotec)
• Lisinopril (Zestril)
• Fosinopril (Monopril)
• Ramipril (Altace)
• Perindopril (Aceon)
• Quinapril (Accupril)
• Moexipril (Univasc)
• Trandolapril (Mavik)

Antibiotics -- Zinc may decrease your body's absorption of two kinds of antibiotics, quinolones and tetracyclines. These include:

• Ciprofloxacin (Cipro)
• Levofloxacin (Levaquin)
• Ofloxacin (Floxin)
• Moxifloxacin (Avelox)
• Norfloxacin (Noroxin)
• Gatifloxacin (Tequin)
• Tetracycline
• Minocycline (Minocin)
• Demeclocycline (Declomycin)

However, doxycycline (Vibramycin) does not seem to interact with zinc.

Cisplatin (Platinol-AQ) -- This drug, used for chemotherapy to treat some types of cancers, may cause more zinc to be excreted in your urine. If you are undergoing chemotherapy, do not take zinc or any other supplement without talking to your oncologist.

Deferoxamine (Desferal) -- This medication, used to remove excess iron from the blood, also increases the amount of zinc that is lost in urine.

Immunosuppressant medications -- Since zinc may make the immune system stronger, it should not be taken with corticosteroids (such a prednisone), cyclosporine, or other medications intended to suppress the immune system.

Nonsteroidal anti-inflammatory drugs (NSAIDs) -- Zinc interacts with NSAIDs and could reduce the absorption and effectiveness of these medications. Examples of NSAIDs, which help to reduce pain and inflammation, include ibuprofen (Advil, Motrin), naprosyn (Aleve), piroxicam (Feldene), and indomethacin (Indocin).

Penicillamine -- This medication, used to treat Wilson's disease (where excess copper builds up in the brain, liver, kidney, and eyes) and rheumatoid arthritis, decreases the levels of zinc in your blood.

Thiazide diuretics (water pills) -- This class of medications lowers the amount of zinc in your blood by increasing the amount of zinc that is passed in your urine. If you take thiazide diuretics, your doctor will monitor levels of zinc and other important minerals in your blood:

• Chlorothiazide (Diuril)
• Hydrochlorothiazide
• Chlorthalidone (Hygroton)
• Indapamide (Lozol)
• Metolozone (Zaroxolyn)
• Polythiazide (Renese)
• Quinethazone (Hydromox)
• Trichlormethiazide (Metahydrin, Naqua, Diurese)

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