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 diarrhoea 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 sulphate 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 one other 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.
How does it work?
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. 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, diarrhoea, 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.
- Preventing and treating blood levels of zinc that are too low (zinc deficiency).
- Zinc deficiency may occur in severe diarrhoea, conditions that make it hard for the bowel to absorb food, liver cirrhosis and alcoholism, after major surgery, and during long-term use of tube feeding in the hospital.
- Taking zinc by mouth or intravenously (by IV) helps to restore zinc levels to the right level.
- But as a rule, routine use of zinc supplements is not recommended.
Likely Effective for:
- Reducing diarrhoea in malnourished children, or in children who have low zinc levels.
- Severe zinc deficiency in children is common in developing countries.
- Treating Wilson’s disease, a rare genetic disorder.
Possibly Effective for:
- Decreasing the length of time the common cold lasts, when taken by mouth as a lozenge. However, using zinc as a pill or a nose spray doesn’t seem to help prevent colds.
- Acne. Taking zinc by mouth or applying it to the skin in an ointment that also contains erythromycin seems to help clear up acne.
- Weak bones (osteoporosis). Low zinc intake seems to be linked to lower bone mass. Taking a zinc supplement in combination with copper, manganese, and calcium might also decrease bone loss in women who have passed menopause.
- Treating an eye disease called age-related macular degeneration (AMD) when taken with other medicines. Taking zinc by mouth in combination with antioxidant vitamins (vitamin C, vitamin E, and beta-carotene) might slow the worsening of advanced age-related macular degeneration (AMD).
- There isn’t enough information to know if zinc plus antioxidants helps people with less advanced macular disease or prevents AMD. Taking zinc supplements alone does not seem to benefit people with existing AMD.
- Treating attention deficit-hyperactivity disorder (ADHD). Taking zinc by mouth in combination with conventional treatment might slightly improve symptoms of hyperactivity, impulsiveness, and socialization problems in some children with ADHD. But zinc might not improve attention span. Some research suggests that children with ADHD have lower zinc levels in their blood than children without ADHD. Other research suggests people with ADHD with lower zinc levels might not respond well enough to prescription medications for ADHD (stimulants). Studies using zinc for ADHD have taken place in the Middle East where zinc deficiency is relatively common compared to Western countries. It’s not known if zinc would have the same potential benefits when used for ADHD in people from Western countries.
- Treating an inherited disorder called Acrodermatitis enteropathica.
- Leprosy, when used with other medications.
- Herpes simplex virus when zinc preparations made for the skin are applied directly to the mouth or genitals.
- Promoting weight gain and improving depression in people with eating disorders such as anorexia nervosa.
- Treating hypogeusia, a rare condition where the sense of taste is abnormal.
- Preventing and treating stomach ulcers.
- Preventing complications related to sickle cell anaemia in people who have low zinc levels.
- Preventing muscle cramps in people who have low zinc levels.
- Treating leg wounds in people with low zinc levels.
- As a mouthwash or toothpaste for preventing tartar and gingivitis.
- Improving healing of burns.
- Increasing vitamin A levels in underfed children or in children with low zinc levels.
- Preventing and treating pneumonia in undernourished children in developing countries.
Possibly Ineffective for:
- Preventing prostate cancer. Some preliminary research suggests that some men might benefit from taking zinc along with other vitamins and minerals for preventing prostate cancer. But other research suggests that taking zinc can increase the risk of developing prostate cancer and increase the risk of dying from prostate cancer.
- Raising blood iron levels in pregnant women, when taken with iron and folic acid supplements.
- Skin conditions including eczema, psoriasis, or hair loss.
- Many kinds of arthritis.
- Preventing or treating cataracts.
- Malaria in underfed children.
- Inflammatory bowel disease.
- “Ringing in the ears” (tinnitus).
- AIDS diarrhoea-wasting syndrome.
- Preventing the flu.
- Increasing birth weight and gestation time in infants born to HIV-infected women.
Insufficient Evidence for:
- Alzheimer’s disease. Some limited research has shown zinc supplements may slightly slow the worsening of symptoms in people with Alzheimer’s disease.
- Wrinkled skin. A skin cream containing 10% vitamin C as L-ascorbic acid and acetyl tyrosine, zinc sulphate, sodium hyaluronate, and bioflavonoids (Cellex-C High Potency Serum) applied for 3 months to facial skin aged by sun exposure seems to improve fine and coarse wrinkling, yellowing, roughness, and skin tone.
- Infections related to AIDS. There is some limited evidence that taking zinc supplements by mouth in combination with zidovudine (AZT, Retrovir, a component of Combivir) might prevent certain bacterial and yeast infections that can occur in people with AIDS because their immune system is less active than it should be. However, taking zinc supplements might lower the overall survival of people with AIDS.
- Male sexual problems. Taking zinc orally to treat male sexual problems caused by disease or medical treatment has produced varying results.
- Crohn’s disease.
- Ulcerative colitis.
- Treating the common cold when used as a nose spray.
- Down syndrome.
- Recurrent ear infections.
- Preventing cancer.
- Head injury.
- Helping babies that are too small when born.
- Preventing oesophageal cancer.
More evidence is needed to rate zinc for these uses.
- Zinc is LIKELY SAFE for most adults when applied to the skin, or when taken by mouth in amounts not larger than 40 mg per day. Routine zinc supplementation is not recommended without the advice of a healthcare professional. In some people, zinc might cause nausea, vomiting, diarrhoea, metallic taste, kidney and stomach damage, and other side effects. Using zinc on broken skin may cause burning, stinging, itching, and tingling.
- 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.
- Zinc nose sprays (Zicam, Cold-Eeze) are POSSIBLY UNSAFE. These products may cause loss of ability to 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 zinc nose sprays.
Special Precautions & Warnings:
- Pregnancy and breast-feeding: Zinc is LIKELY SAFE for most pregnant and breast-feeding women when used in the recommended daily amounts (RDA). 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.
- HIV (human immunodeficiency virus)/AIDS: Do not take zinc if you have HIV/AIDS. Zinc might shorten your life.
- Moderate Interaction Be cautious with this combination
- Antibiotics (Quinolone antibiotics) interact with ZINC – 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 zinc supplements at least 1 hour after antibiotics.
- Some of these antibiotics that might interact with zinc include ciprofloxacin (Cipro), enoxacin (Penetrex), norfloxacin (Chibroxin, Noroxin), sparfloxacin (Zagam), trovafloxacin (Trovan), and grepafloxacin (Raxar).
- Antibiotics (Tetracycline antibiotics) interact with ZINC -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 zinc 2 hours before or 4 hours after taking tetracyclines.
- Some tetracyclines include demeclocycline (Declomycin), minocycline (Minocin), and tetracycline (Achromycin).
- Cisplatin (Platinol-AQ) interacts with ZINC – Cisplatin (Platinol-AQ) is used to treat cancer. Taking zinc along with EDTA and cisplatin (Platinol-AQ) might increase the effects and side effects of cisplatin (Platinol-AQ).
- Penicillamine interacts with ZINC – 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.
- Minor Interaction Be watchful with this combination – Amiloride (Midamor) interacts with ZINC 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.
APPLIED TO THE SKIN:
For acne vulgaris: zinc acetate 1.2% with erythromycin 4% as a lotion applied twice daily.
For herpes simplex infections: zinc sulphate 0.25% applied 8 to 10 times daily or zinc oxide 0.3% with glycine applied every 2 hours while awake.