Zinc is a metal. It is called an “essential trace element” because very small amounts of zinc are necessary for human health.
Zinc is used for treatment and prevention of zinc deficiency and its consequences, including stunted growth and acute diarrhea in children, and slow wound healing.
It is also used for boosting the immune system, treating the common cold and recurrent ear infections, and preventing lower respiratory infections. It is also used for malaria and other diseases caused by parasites.
Some people use zinc for an eye disease called macular degeneration, for night blindness, and for cataracts. It is also used for asthma; diabetes; high blood pressure; acquired immunodeficiency syndrome (AIDS); and skin conditions such as psoriasis, eczema, and acne.
Other uses include treating attention deficit-hyperactivity disorder (ADHD), blunted sense of taste (hypogeusia), ringing in the ears (tinnitus), severe head injuries, Crohn’s disease, Alzheimer’s disease, Down syndrome, Hansen’s disease, ulcerative colitis, peptic ulcers and promoting weight gain in people with eating disorders such as anorexia nervosa.
Some people use zinc for benign prostatic hyperplasia (BPH), male infertility, erectile dysfunction (ED), weak bones (osteoporosis), rheumatoid arthritis, and muscle cramps associated with liver disease. It is also used for sickle cell disease and inherited disorders such as acrodermatitis enteropathica, thalassemia, and Wilson’s disease.
Some athletes use zinc for improving athletic performance and strength.
Zinc is also applied to the skin for treating acne, aging skin, herpes simplex infections, and to speed wound healing.
There is a zinc preparation that can be sprayed in the nostrils for treating the common cold.
Zinc sulfate is used in products for eye irritation.
Zinc citrate is used in toothpaste and mouthwash to prevent dental plaque formation and gingivitis.
Note that many zinc products also contain another metal called cadmium. This is because zinc and cadmium are chemically similar and often occur together in nature. Exposure to high levels of cadmium over a long time can lead to kidney failure. The concentration of cadmium in zinc-containing supplements can vary as much as 37-fold. Look for zinc-gluconate products. Zinc gluconate consistently contains the lowest cadmium levels.
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
The effectiveness ratings for ZINC are as follows:
More evidence is needed to rate zinc for these uses.
Zinc is needed for the proper growth and maintenance of the human body. It is found in several systems and biological reactions, and it is needed for immune function, wound healing, blood clotting, thyroid function, and much more. Meats, seafood, dairy products, nuts, legumes, and whole grains offer relatively high levels of zinc.
Zinc deficiency is not uncommon worldwide, but is rare in the US. Symptoms include slowed growth, low insulin levels, loss of appetite, irritability, generalized hair loss, rough and dry skin, slow wound healing, poor sense of taste and smell, diarrhea, and nausea. Moderate zinc deficiency is associated with disorders of the intestine which interfere with food absorption (malabsorption syndromes), alcoholism, chronic kidney failure, and chronic debilitating diseases.
Zinc plays a key role in maintaining vision, and it is present in high concentrations in the eye. Zinc deficiency can alter vision, and severe deficiency can cause changes in the retina (the back of the eye where an image is focused).
Zinc might also have effects against viruses. It appears to lessen symptoms of the rhinovirus (common cold), but researchers can’t yet explain exactly how this works. In addition, there is some evidence that zinc has some antiviral activity against the herpes virus.
Low zinc levels can be associated with male infertility, sickle cell disease, HIV, major depression, and type 2 diabetes, and can be fought by taking a zinc supplement.
Zinc is LIKELY SAFE for most adults when applied to the skin, or when taken by mouth in amounts not larger than 40 mg daily. Routine zinc supplementation is not recommended without the advice of a healthcare professional. In some people, zinc might cause nausea, vomiting, diarrhea, metallic taste, kidney and stomach damage, and other side effects. Using zinc on broken skin may cause burning, stinging, itching, and tingling.
Zinc is POSSIBLY SAFE when taking by mouth in doses greater than 40 mg daily. There is some concern that taking doses higher than 40 mg daily might decrease how much copper the body absorbs. Decreased copper absorption may cause anemia.
Zinc is POSSIBLY UNSAFE when inhaled through the nose, as it might cause permanent loss of smell. In June 2009, the US Food and Drug Administration (FDA) advised consumers not to use certain zinc-containing nose sprays (Zicam) after receiving over 100 reports of loss of smell. The maker of these zinc-containing nose sprays has also received several hundred reports of loss of smell from people who had used the products. Avoid using nose sprays containing zinc.
Taking high amounts of zinc is LIKELY UNSAFE. High doses above the recommended amounts might cause fever, coughing, stomach pain, fatigue, and many other problems.
Taking more than 100 mg of supplemental zinc daily or taking supplemental zinc for 10 or more years doubles the risk of developing prostate cancer. There is also concern that taking large amounts of a multivitamin plus a separate zinc supplement increases the chance of dying from prostate cancer.
Taking 450 mg or more of zinc daily can cause problems with blood iron. Single doses of 10-30 grams of zinc can be fatal.
Infants and children: Zinc is LIKELY SAFE when taken by mouth appropriately in the recommended amounts. Zinc is POSSIBLY UNSAFE when used in high doses.
Pregnancy and breast-feeding: Zinc is LIKELY SAFE for most pregnant and breast-feeding women when used in the recommended daily amounts (RDA). However, zinc is POSSIBLY UNSAFE when used in high doses by breast-feeding women and LIKELY UNSAFE when used in high doses by pregnant women. Pregnant women over 18 should not take more than 40 mg of zinc per day; pregnant women age 14 to 18 should not take more than 34 mg per day. Breast-feeding women over 18 should not take more than 40 mg of zinc per day; breast-feeding women age 14 to 18 should not take more than 34 mg per day.
Alcoholism: Long-term, excessive alcohol drinking is linked to poor zinc absorption in the body.
Diabetes: Large doses of zinc can lower blood sugar in people with diabetes. People with diabetes should use zinc products cautiously.
Hemodialysis: People receiving hemodialysis treatments seem to be at risk for zinc deficiency and might require zinc supplements.
HIV (human immunodeficiency virus)/AIDS: Use zinc cautiously if you have HIV/AIDS. Zinc use has been linked to shorter survival time in people with HIV/AIDs.
Syndromes in which it is difficult for the body to absorb nutrients: People with malabsorption syndromes may be zinc deficient.
Rheumatoid arthritis (RA): People with RA aborb less zinc.
Interaction Rating = Minor Be watchful with this combination.
Talk with your health provider.
Amiloride (Midamor) is used as a "water pill" to help remove excess water from the body. Another effect of amiloride (Midamor) is that it can increase the amount of zinc in the body. Taking zinc supplements with amiloride (Midamor) might cause you to have too much zinc in your body.
Interaction Rating = Moderate Be cautious with this combination.
Talk with your health provider.
Zinc might decrease how much antibiotic the body absorbs. Taking zinc along with some antibiotics might decrease the effectiveness of some antibiotics. To avoid this interaction, take antibiotics at least 2 hours before or 4-6 hours after zinc supplements.
Some of these antibiotics that might interact with zinc include ciprofloxacin (Cipro), levofloxacin (Levaquin), ofloxacin (Floxin), moxifloxacin (Avelox), gatifloxacin (Tequin) enoxacin (Penetrex), norfloxacin (Chibroxin, Noroxin), sparfloxacin (Zagam), trovafloxacin (Trovan), and grepafloxacin (Raxar).
Zinc can attach to tetracyclines in the stomach. This decreases the amount of tetracyclines that can be absorbed. Taking zinc with tetracyclines might decrease the effectiveness of tetracyclines. To avoid this interaction, take tetracyclines 2 hours before or 4-6 hours after taking zinc supplements.
Some tetracyclines include demeclocycline (Declomycin), minocycline (Minocin), and tetracycline (Achromycin, Sumycin).
Cisplatin (Platinol-AQ) is used to treat cancer. Taking zinc along with EDTA and cisplatin (Platinol-AQ) might inactivate cisplatin (Platinol-AQ) therapy. It is not known for sure, though, if the amount of interference caused by zinc is significant.
Zinc might decrease blood sugar in people with type 2 diabetes. Diabetes medications are also used to lower blood sugar. Taking zinc along with diabetes medications might cause your blood sugar to go too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.
Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.
Interaction Rating = Major Do not take this combination.
Penicillamine is used for Wilson's disease and rheumatoid arthritis. Zinc might decrease how much penicillamine your body absorbs and decrease the effectiveness of penicillamine. Take zinc and penicillamine at least 2 hours apart.
High doses of zinc can lower beta-carotene blood levels.
Metals such as zinc might reduce the effects of bromelain. However, there are no reports of this interaction.
Calcium supplements might decrease dietary zinc absorption. This usually doesn't seem to be much of a problem. However, this interaction can be avoided by taking calcium supplements at bedtime instead of with meals.
There is early evidence that chromium and zinc could each reduce the absorption of the other. This is probably not a problem when usual supplemental doses of zinc and chromium are taken.
Large amounts of zinc can reduce copper absorption. Taking zinc in high doses can cause significant copper deficiency and anemia, a condition in which the blood cannot carry enough oxygen. Some signs of copper deficiency have also occurred in people taking 150 mg/day or more of zinc for 2 years.
EDTA is a chemical compound that is given to people to remove excess metals in their systems, especially lead. EDTA works by binding with (chelating) the metal. Repeated high doses of EDTA, as used in chelation treatment, can reduce blood zinc levels by up to 40%. Symptoms of zinc depletion have been reported, even when supplemental zinc (15mg/day) was given. People receiving chelation therapy should be monitored for zinc depletion.
Studies on the effects of folic acid supplements on dietary zinc absorption are conflicting. Normal supplemental doses of folic acid are not likely to affect zinc balance in people with adequate dietary zinc intake.
Large amounts of zinc might lower blood sugar. Using it along with other herbs and supplements that have the same effect might cause blood sugar to drop too low in some people. Some of these alpha-lipoic acid, bitter melon, chromium, devil's claw, fenugreek, garlic, guar gum, horse chestnut, Panax ginseng, psyllium, Siberian ginseng, and others.
Phytic acid found naturally in foods can bind zinc and reduce its absorption. However, zinc deficiency due to high dietary phytic acid levels has not been reported in Western populations. Avoid IP-6 supplements, which contain phytic acid, if you have other risk factors for zinc deficiency.
Under some circumstances, iron and zinc can interfere with each other's absorption. To avoid this effect, take these supplements with food.
High doses of zinc supplements (142 mg/day), or high dietary zinc intake (53mg/day) seem to decrease magnesium balance. The importance of this isn't known.
Research suggests zinc supplements can more than double the amount of manganese absorbed from supplements.
Research suggests riboflavin can improve zinc absorption. The importance of this isn't known.
Research suggests that zinc supplements can increase blood levels of vitamin A. Theoretically, zinc might increase the effects and side effects of vitamin A.
Research suggests vitamin D is involved in zinc absorption, but it's not clear whether vitamin D improves zinc absorption.
Taking zinc sulfate with black coffee instead of water reduces zinc absorption by half. Researchers aren't sure why this happens or how important the interaction may be.
Calcium can decrease zinc absorption. The risk of losing too much zinc isn't significant unless lots of dairy products are consumed along with calcium supplements. However, the body adapts over the long term, becoming more efficient at absorbing zinc and reducing zinc losses.
Eating fiber can reduce zinc absorption. However, over time the body adapts to increased dietary fiber by increasing zinc absorption.
Phytate is a molecule found in grains (e.g., maize, corn, sorghum), legumes, seeds (e.g., sunflower, pumpkin), and soy. Phytate can reduce zinc absorption. Some foods with higher phytate contents also have a higher zinc content (for example, whole wheat vs. white bread), canceling out the effect in zinc absorption. Some people in Middle Eastern countries have zinc deficiencies because they eat unleavened bread and maize, which contain phytate. People in Western populations most at risk are those with diets high in unrefined grains, legumes, soy protein, and calcium, and low in animal protein. However, the body adapts over the long term, becoming more efficient at absorbing zinc and reducing zinc losses.
Zinc binds to proteins, becoming available for absorption as the protein is digested. The type of protein influences how much zinc is absorbed. Animal proteins generally increase zinc absorption, although a protein in cow's milk slows absorption down. Soy proteins also reduce zinc absorption, possibly due to their phytate content. These effects can influence zinc balance in infants; babies get the most zinc from mother's milk, less from cow's milk, and even less from soy-based milk. It isn't known whether high-protein diets influence zinc balance in adults.
Vegetarian diets are often high in grains and legumes, so they contain more phytate. Zinc absorption is likely to be lower, so this type of diet is considered a risk factor for zinc depletion. However, the body adapts over the long term, becoming more efficient at absorbing zinc and reducing zinc losses.
The following doses have been studied in scientific research:
The Institute of Medicine has established Adequate Intake (AI) levels of zinc for infants birth to 6 months is 2 mg/day. For older infants, children, and adults, Recommended Dietary Allowance (RDA) quantities of zinc have been established: infants and children 7 months to 3 years, 3 mg/day; 4 to 8 years, 5 mg/day; 9 to 13 years, 8 mg/day; girls 14 to 18 years, 9 mg/day; boys and men age 14 and older, 11 mg/day; women 19 and older, 8 mg/day; pregnant women 14 to 18, 13 mg/day; pregnant women 19 and older, 11 mg/day; lactating women 14 to 18, 14 mg/day; lactating women 19 and older, 12 mg/day.
The typical North American male consumes about 13 mg/day of dietary zinc; women consume approximately 9 mg/day.
The Tolerable Upper Intake Levels (UL) of zinc for people who are not receiving zinc under medical supervision: Infants birth to 6 months, 4 mg/day; 7 to 12 months, 5 mg/day; children 1 to 3 years, 7 mg/day; 4 to 8 years, 12 mg/day; 9 to 13 years, 23 mg/day; 14 to 18 years (including pregnancy and lactation), 34 mg/day; adults 19 years and older (including pregnancy and lactation), 40 mg/day.
Different salt forms provide different amounts of elemental zinc. Zinc sulfate contains 23% elemental zinc; 220 mg zinc sulfate contains 50 mg zinc. Zinc gluconate contains 14.3% elemental zinc; 10 mg zinc gluconate contains 1.43 mg zinc.
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