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Zinc

 

Natural Standard Monograph, Copyright © 2013 (www.naturalstandard.com). Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified health care professional before making decisions about therapies and/or health conditions.

Related Terms

  • A-84, Articulin-F®, Astra, atomic number 30, Curiosin® (zinc and hyaluronic acid), Herpigon, Indian tin, Nels Cream®, Orazinc®, pewter, polaprezinc, Solvezink®, Virudermin Gel®, Zeta N®, Zicam® Nasal Gel, zinc acetate, zinc acexamate, zinc aspartate, zinc carbonate, zinc chloride, zinc citrate, zinc gluconate, zinc methionate, zinc methionine, zinc monomethionine, zinc oxide, zinc picolinate, zinc sulfate, Zincolak®, Zincomed, Zineryt®, Zink, Zinvit-C250, ZN, Zn.

Background

  • Zinc is necessary for the functioning of more than 300 different enzymes and plays a vital role in a large number of biological processes. Zinc is a cofactor for the antioxidant enzyme superoxide dismutase (SOD) and is in a number of enzymatic reactions involved in carbohydrate and protein metabolism.
  • Its immune-enhancing activities include regulation of T lymphocytes, CD4 cells, natural killer cells, and interleukin-2. In addition, it has been claimed that zinc possesses antiviral activity. Zinc is necessary for the maturation of sperm and normal fetal development. It is involved in sensory perception (taste, smell, and vision) and controls the release of stored vitamin A from the liver. In the endocrine system, zinc has been shown to regulate insulin activity and promote the conversion thyroid hormones thyroxine to triiodothyronine.
  • Zinc has been used since ancient Egyptian times to enhance wound healing, although the usefulness of this approach is only partially confirmed by clinical data today. In available research, it has been shown to play a role in wound healing, especially following burns or surgical incisions. Based on available scientific evidence, zinc may be effective for the treatment or management of a number of conditions, including diarrhea in malnourished children, skin conditions (such as acne vulgaris, eczema, and psoriasis), gastric ulcers, attention-deficit hyperactivity disorder (ADHD), immune disorders, sickle cell anemia, leg ulcers, infertility, Wilson's disease, herpes, taste or smell disorders, diabetes, and diabetic neuropathy. Zinc has also gained popularity for its use in the prevention of the common cold.
  • The role of zinc is controversial in some cases, as either the results of published studies provide contradictory information and/or the methodological quality of the studies does not allow for a confident conclusion regarding the role of zinc in the diseases in question.

Evidence

 

Uses based on scientific evidence 

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare professional.

Grade* 

Diarrhea (children) 

Multiple studies in developing countries found that zinc supplementation in malnourished children with acute diarrhea may reduce the severity and duration of diarrhea, especially in children with low zinc levels.

A 

Gastric ulcers 

The healing process of gastric ulcers may be enhanced through treatment with zinc, although further studies will be needed to determine to what extent zinc may be beneficial for patients with this condition. Most studies report no or few adverse effects associated with its use.

A 

Zinc deficiency 

Zinc deficiency is caused by inadequate intake or absorption, increased zinc excretion, or increased bodily need for zinc. Zinc deficiency symptoms include growth retardation, hair loss, diarrhea, delayed sexual maturation, impotence, eye and skin conditions, and loss of appetite. Additional symptoms may include weight loss, delayed wound healing, taste changes, and mental lethargy. Zinc can be measured in plasma, red blood cells, white blood cells, and hair.

A 

Acne vulgaris 

Based on high-quality studies, topical or oral use of zinc seems to be a safe and effective treatment for acne vulgaris. However, some studies report no or negative effects of zinc. Additionally, many studies used combination treatments. Several studies have identified a positive correlation between serum zinc levels and severity of acne, while others did not. It remains to be determined to what degree internal zinc levels may correlate with the severity of acne.

B 

Attention-deficit hyperactivity disorder (ADHD) 

Early studies have shown a correlation between low serum free fatty acids and zinc serum levels in children with attention-deficit hyperactivity disorder. Additional studies found that zinc supplements reduced hyperactive, impulsive, and impaired socialization symptoms but did not reduce attention-deficiency symptoms. Zinc supplementation may be a more effective treatment for older children with higher body mass index (BMI) scores. Further research is required before conclusions may be drawn.

B 

Herpes simplex virus 

Low-quality studies have been conducted to assess the effects of zinc (topical or taken by mouth) on herpes types 1 or 2. Several of these studies used combination treatments or permitted the continued use of other medications, so the exact role of zinc in those studies is unclear. However, the positive results obtained in most trials suggest that zinc may represent a safe and effective alternative treatment for herpes types 1 and 2 and should encourage further research into the topic using well-designed studies.

B 

Immune function 

Zinc appears to be an essential trace element for the immune system, but research on the effect of zinc supplementation on immune function is scant and mostly focuses on patients with specific diseases. Zinc gluconate appears to have beneficial effects on immune cells. There are relatively few studies that examine zinc levels and the effects of zinc supplementation on the health of the elderly population. Further research is needed before a recommendation can be made.

B 

Sickle cell anemia (management) 

There is good scientific evidence to suggest that zinc may help manage or reduce symptoms of sickle cell anemia. Most of these studies reported increased height, weight, immune system function, and testosterone levels, and decreased numbers of crises and sickled cells following zinc treatment.

B 

Wilson's disease 

Wilson's disease is an inherited disorder of copper metabolism characterized by a failure of the liver to excrete copper, which leads to its accumulation in the liver, brain, cornea, and kidney, with resulting chronic degenerative changes. Early research suggests that zinc treatment may be effective in the management of Wilson's disease. Relatively few cases of adverse effects have been reported, including one case report presenting a fatality. However, it is unclear whether or not the death was caused by zinc. Several studies have been conducted by the same authors, resulting in possible bias. More well-designed trials are needed to confirm these early results. Galzin® (zinc acetate) is an U.S. Food and Drug Administration (FDA)-approved drug used to inhibit the absorption of copper in patients with Wilson's disease. It is not indicated as an initial therapy for Wilson's disease in symptomatic patients but rather for maintenance treatment in patients who have already been treated with a chelating agent.

B 

Age related macular degeneration 

Most studies examining the relationship between dietary zinc intake and macular degeneration over many years have not reported positive correlations. However, some high-quality research, which examined the efficacy of zinc supplements in preventing loss of visual acuity, found that zinc supplements helped prevent the occurrence of age-related macular degeneration. Since study results are conflicting, additional well-designed clinical trials are needed before a conclusion can be made.

C 

Alopecia areata (hair loss) 

A few studies that examined the efficacy of zinc in treating alopecia reported conflicting results. Additional information is needed before a conclusion can be made.

C 

Aphthous stomatitis (canker sores) 

Zinc sulfate has been studied for the treatment of recurrent aphthous stomatitis (canker sores). However, the results are conflicting, and a clear conclusion may not be drawn at this time.

C 

Appetite stimulation (in HIV-infected children) 

In preliminary clinical research, multimacronutrient supplementation in HIV-infected children improved appetite. However, the effects of zinc alone cannot be determined from this study. More well-designed trials using zinc alone are needed before a conclusion may be made.

C 

Beta-thalassemia 

Limited research has noted that children with beta-thalassemia (a blood disorder that reduces the production of hemoglobin) who took oral zinc supplements for 1-7 years increased in height more than those who did not take zinc. More studies are needed to confirm these findings.

C 

Blood disorders (aceruloplasminemia) 

Data from case reports suggest a potential role for zinc supplementation in aceruloplasminemia, a neurodegenerative disease caused by a gene mutation. Further research is required before conclusions may be drawn.

C 

Burns 

Studies of zinc sulfate supplements given to burn victims to increase healing rate have yielded mixed results. Further research is needed before a conclusion can be made.

C 

Cancer 

In preliminary clinical research, patients with head and neck cancers receiving radiotherapy had a better clinical outcome following zinc supplementation compared to those who did not take zinc. More high-quality research is needed to confirm these findings.

C 

Celiac disease 

In a very small study, oral zinc supplements did not seem to improve the clinical condition of patients with unresponsive celiac syndrome. More research is needed in this area.

C 

Chronic inflammatory rheumatic disease 

Early studies found that zinc supplementation did not seem to benefit patients with chronic inflammatory rheumatic disease. Further research is needed before a conclusion can be made.

C 

Chronic prostatitis (prostate inflammation) 

Early studies suggest that zinc supplements taken with antibiotics may be more effective than antibiotics alone in reducing pain, urinary symptoms, quality of life, and maximum urethra closure pressure for patients with chronic prostatitis (prostate inflammation). Further research is needed to confirm these results.

C 

Closed head injuries 

Early poorly designed studies indicate that zinc supplementation may enhance neurological recovery in patients with closed head injuries. Further research is needed to confirm these results.

C 

Cognitive disorders (children) 

Early studies indicate that daily supplementation with zinc may be of limited usefulness for improving cognition in adolescent girls and lead-exposed schoolchildren. Further research may be warranted in this area.

C 

Cognitive function 

Based on one randomized controlled trial, zinc supplementation in younger adults (<70 years) may have beneficial effects on cognitive function. More well-designed trials are needed before a conclusion may be made.

C 

Common cold 

There are conflicting results regarding the effect of zinc formulations in treating the duration and severity of common cold symptoms. Although zinc may be beneficial in the treatment of cold symptoms if taken at the onset of symptoms, more studies are needed to clarify which zinc formulations may be most effective, which rhinoviruses are affected by zinc, and if nasal sprays provide a useful alternative application route for zinc treatment. Negative results may be caused by using doses of zinc that are too low, or they may be affected by the presence of compounds like citric or tartaric acid, which may reduce efficacy due to chelating of the zinc ion.

C 

Continuous ambulatory peritoneal dialysis (CAPD) 

Zinc supplementation did not improve the nutritional status in patients on CAPD in a well-designed trial. Further research is needed to confirm these results.

C 

Critical illness 

Zinc is required for a functional immune system and is a necessary cofactor for many enzymes. In noncritically ill patients, zinc supplementation has been associated with an improvement in markers of immune function. Further research is required in patients with critical illness before conclusions may be drawn.

C 

Cutaneous disorders (leishmaniasis) 

In a few studies of varying quality, patients with cutaneous leishmaniasis were injected with zinc sulfate intralesionally. Zinc sulfate was shown to be better than meglumine antimoniate for the first four weeks, but significant differences were not observed after six weeks. Overall, results of the studies are mixed, and more research is needed in this area.

C 

Cystic fibrosis 

Zinc supplementation does not seem to affect clinical status, growth velocity, or lung function in children with cystic fibrosis. Further research is needed to confirm available study results.

C 

Dandruff 

Shampoo containing 1% of zinc pyrithione has been shown to reduce dandruff in some people. More high-quality research is needed in this area.

C 

Dementia 

In a small study, zinc supplementation did not have any effects on the psychological functioning of adults with senile dementia. Larger, more well-designed trials are needed.

C 

Diabetes 

Diabetic patients typically have significantly lower serum zinc levels compared with healthy controls. In early high-quality studies, zinc supplementation in type 2 diabetics may have beneficial effects in elevating serum zinc level and in improving glycemic control, shown by decreasing HbA1c concentrations. Further research is needed before a conclusion can be made.

C 

Diabetic neuropathy (nerve damage) 

Oral zinc supplementation may improve glycemic control and severity of peripheral neuropathy. Further research is needed before a conclusion can be made.

C 

Diaper rash 

Zinc may reduce the incidence of diaper rash and have a preventive effect. More well-designed trials are needed before a conclusion may be made.

C 

Down's syndrome 

In several studies, zinc supplements seemed to counteract hypothyroidism and slightly reduce the number of infections in children with Down syndrome. However, zinc did not seem to improve depressed immune systems. Additional human research is needed before a firm conclusion can be made.

C 

Dysentery (adjunct therapy for shigellosis) 

Based on clinical research, zinc may be beneficial in children with shigellosis, as an adjunct to therapy. More well-designed trials are needed before a conclusion may be made.

C 

Eating disorders 

Reports of zinc's effectiveness in treating symptoms of anorexia nervosa observed in young adults are based on small, low-quality studies. Well-designed trials with a larger number of participants are needed to confirm these results.

C 

Eczema 

There are conflicting data regarding the correlation of zinc serum levels and eczema. One study noted that zinc might have caused an increase in itching after several weeks of supplementation. Additional information is needed to help clarify these results.

C 

Exercise performance 

Zinc may improve exercise performance in athletes with low serum zinc or zinc deficiencies. Additional evidence is needed before a conclusion can be made.

C 

Furunculosis (boils) 

In preliminary research, boils in patients treated with zinc did not reappear. Well-designed clinical trials are needed to confirm this potential benefit.

C 

Gilbert's syndrome 

Gilbert's syndrome, named after a French gastroenterologist, is a common, often inherited, disorder that affects processing by the liver of the greenish-brown pigments in bile (called bilirubin). The resulting abnormal increase of bilirubin in the bloodstream can lead to jaundice (yellowing of the skin), but the liver itself remains normal. It is more common in men than women. Zinc sulfate supplementation seemed to decrease serum unconjugated bilirubin levels in a small study. Well-designed clinical trials are needed to confirm these results.

C 

Goiter 

Zinc supplementation may alter thyroid hormone profiles in patients with goiter. Better-designed trials are needed before a conclusion may be made.

C 

Halitosis (bad breath) 

Chewing gum containing zinc or rinsing out the mouth with a solution containing zinc seemed to reduce bad breath (halitosis) in early studies. More well-designed trials are needed before a conclusion may be made.

C 

Hepatic encephalopathy 

Hepatic encephalopathy is abnormal brain function caused by passage of toxic substances from the liver to the blood. Early high-quality trials of zinc for this indication have yielded conflicting results.

C 

Hepatitis (chronic) 

Early studies have shown that zinc in combination with interferon, or interferon and ribavirin, for hepatitis C viral infection did not show significant benefits, except for a lower incidence of gastrointestinal side effects in one study. Further research may be warranted in this area. Recent high-quality evidence suggests that supplementation with polaprezinc in patients undergoing treatment with pegylated interferon alpha-2b and ribavirin may decrease damage to liver cells.

C 

HIV/AIDS 

Patients with HIV/AIDS, especially those with low zinc levels, may benefit from zinc supplementation. Some low-quality studies cited a reduction in infections, weight gain, and enhanced immune system function, including increased CD4 and CD8 cells. However, other low quality studies conflict with these findings. Further research is needed before a conclusion can be drawn.

C 

Hyperlipidemia (high cholesterol) 

Zinc may improve blood cholesterol levels in hemodialysis patients. There is some evidence that zinc may improve the ratio of HDL ("good cholesterol") to LDL ("bad cholesterol"), which would be considered a positive effect. Well-designed clinical trials are needed before a conclusion can be made.

C 

Hyperprolactinemia (high levels of prolactin in the blood) 

Early research did not report an inhibitory effect of zinc on prolactin release in hyperprolactinemic patients. Further research is required before conclusions may be drawn.

C 

Hypothyroidism (low thyroid hormone production) 

Case report data suggest that zinc supplementation may improve thyroid hormone levels (particularly T3) among women with hypothyroidism. More well-designed trials are needed before a conclusion may be made.

C 

Impaired glucose tolerance 

Zinc supplementation may improve glucose tolerance in patients with cirrhosis. More research is needed before a conclusion may be made.

C 

Incision wounds 

Although zinc is frequently thought to have beneficial effects on incision wound healing, few studies have investigated this use. Further research is needed before a conclusion can be made.

C 

Infant development / neonatal care 

Clinical trial results suggest a lack of positive benefit from zinc on the mental and physical development of infants. More well-designed trials of zinc therapy alone are needed before a conclusion may be made.

C 

Infections (children) 

Zinc may decrease incidence of infection, although this may depend on the type of infection. More research is needed in this area.

C 

Infertility 

Many studies report beneficial results of zinc supplements on infertility, as expressed in improved sperm quality and number, although this effect may depend on the cause of infertility. A minor increase in abnormal spermatozoa in subfertile males taking zinc was noted in one study. Additional information is needed before a firm conclusion can be drawn.

C 

Inflammatory bowel disease 

Studies of zinc supplementation for inflammatory bowel disease have had mixed results. One small clinical study found positive effects of zinc supplementation on thymulin levels in patients with Crohn's disease. However in another study, zinc supplementation did not report an improvement inflammatory bowel disease. Well-designed clinical trials are needed to confirm these results.

C 

Kidney function 

Early studies show potential improvement in uremic patients taking zinc supplements. Zinc supplementation may be recommended only in patients with proven zinc deficiency, but for all chronic renal failure patients, it is questionable. Further research is needed to confirm available study results.

C 

Kwashiorkor (malnutrition from inadequate protein intake) 

Short-term zinc supplementation may increase weight gain and decrease infections, swelling, diarrhea, anorexia, and skin ulcers in children with extreme malnourishment. More research is needed in this area.

C 

Leg ulcers 

There are conflicting findings regarding the potential benefit of zinc for healing leg ulcers. All studies, however, reported a lack of or few adverse effects. The healing process of leg ulcers may be enhanced through treatment with zinc, although further studies are needed to determine to which extent zinc may be beneficial for patients with leg ulcers.

C 

Leprosy 

A few studies have examined the efficacy of zinc treatment in leprosy. Studies of zinc taken by mouth have reported positive results, while other research on topical zinc has reported negative results. Further research is needed before a conclusion can be drawn.

C 

Liver cirrhosis 

People with alcoholic liver cirrhosis may be deficient in zinc. Preliminary studies suggest that zinc may benefit these patients. Further evidence is needed to confirm these findings.

C 

Lower respiratory infections in children 

Results from large clinical trials suggest that supplementation with zinc may reduce the incidence and severity of lower respiratory infections. Some studies suggest that these effects are apparent only in boys and not girls. A trend toward increased respiratory infections in children has been noted in one study. A recent study did not support the use of zinc supplementation in the management of acute lower respiratory infections requiring hospitalization in indigenous children living in remote areas. Due to conflicting results, further research is needed before a conclusion can be drawn. Future studies could examine whether adult populations have a similar response.

C 

Malaria 

Results are contradictory for the effect of zinc on malaria symptoms. Some high-quality studies suggest no effect of zinc supplementation on the severity of malaria. Other studies suggest that zinc supplementation may reduce the number of stays in the hospital and the death rate due to P. falciparum infection. Further well-designed trials are required to address these discrepancies.

C 

Menstrual cramps 

Case report data suggest a possible role for zinc supplementation in menstrual cramps. Additional research is needed to confirm these findings.

C 

Mood disorders 

Zinc supplementation may improve mood states in young women. More well-designed trials are needed before a conclusion may be made.

C 

Mortality reduction 

Evidence from available high-quality studies did not find an association between zinc supplementation and mortality among children. Additional research is needed in this area.

C 

Mucositis (radiation-induced) 

Radiation has the potential side effect of mucositis, which is inflammation of mucous membranes inside of the mouth, nose, and throat. Clinical studies suggest that zinc may lower the degree of mucositis in patients on radiation. Further research is needed to confirm these results.

C 

Muscle cramps (cirrhosis) 

Zinc supplementation may improve muscle cramps in patients with cirrhosis. Further research is needed to confirm available study results.

C 

Parasites 

In a few studies of varying quality, patients with cutaneous leishmaniasis were injected with zinc sulfate intralesionally. One study found zinc sulfate was better than meglumine antimoniate for the first four weeks, but no significant differences were observed after six weeks. Zinc may decrease the severity of infection and reinfection with S. mansoni, but it does not seem to prevent initial infection. More research is needed to examine how zinc affects the S. mansoni life cycle and whether these data can be extrapolated to other species of Schistosoma. The effects of zinc on the rate of parasitic reinfestation have been examined in children. No significant effect of zinc treatment was found. Recent high-quality study data suggest that supplementation with zinc and vitamin A may favorably alter the infection rate and duration among children. Due to conflicting results in this area, more research is needed before zinc can be recommended for the treatment of parasites.

C 

Plaque / gingivitis 

A few studies have reported a significant reduction in plaque accumulation following treatment with zinc rinses and dentifrices. Preliminary research suggests that zinc citrate dentifrice may reduce the severity and occurrence of supragingival calculus formation. However, more well-designed studies are needed to confirm such benefits. More research may help to determine zinc's potential efficacy in other dental applications as well.

C 

Pneumonia 

Studies have found that zinc supplementation does not seem to lessen the duration of abnormally fast breathing, hypoxia (inadequate oxygen), chest indrawing, inability to feed, lethargy, severe illness, or hospitalization in children.

C 

Poisoning (arsenic) 

A combination of spirulina extract plus zinc may be useful for the treatment of chronic arsenic poisoning with melanosis and keratosis. More research is needed to confirm the effects of zinc alone.

C 

Pregnancy 

According to multiple reviews, evidence is lacking to suggest that zinc supplementation offers benefits during pregnancy, although there is a possible reduction in labor complications and preterm deliveries. However, results from individual studies suggest a possible benefit of zinc supplementation on blood pressure during pregnancy. Further research is needed before a conclusion can be drawn.

C 

Psoriasis 

There are only a few studies that examined the efficacy of zinc treatment on symptoms of psoriasis, including psoriasis-induced arthritis-like symptoms. One trial noted a reduction in pain and joint swelling. Other studies did not support a role for zinc in alleviating the symptoms of psoriasis. Further well-designed clinical trials are required to clarify these results.

C 

Respiratory disease (respiratory papillomatosis) 

Evidence from case reports suggests a possible role for zinc supplementation as adjuvant therapy in juvenile-onset recurrent respiratory papillomatosis (JORRP). Further investigation is warranted in this area.

C 

Respiratory tract infections (upper) 

Studies on the effects on zinc on upper respiratory tract infections have produced mixed results. More well-designed trials are needed before a conclusion may be made.

C 

Rheumatoid arthritis 

Most trials did not show significant improvements in arthritis symptoms following zinc treatment. Interpretation of some data is difficult, because patients in the studies were permitted to continue their previous arthritis medication, and most studies used a small number of participants. Well-designed clinical trials are needed before a conclusion can be made.

C 

Sexual function / libido / erectile dysfunction 

Several studies have been conducted in men on chronic maintenance hemodialysis. However, the results are conflicting. More well-designed trials are needed before a conclusion may be made.

C 

Skin damage caused by incontinence 

Early evidence suggests that topical zinc oxide oil may help manage perianal and buttock skin damage in incontinent patients. Further research is needed to confirm these results.

C 

Stress 

Zinc may help reduce stress in the elderly. More well-designed trials are needed before a conclusion may be made.

C 

Taste disturbances 

Results from studies investigating the potential role of zinc in treating taste and smell disorders are contradictory. Well-designed research is needed to determine if zinc contributes to the treatment of taste and smell disorders.

C 

Taste perception (hemodialysis, cancer) 

Results from studies investigating the potential role of zinc in treating taste and smell disorders in patients with cancer or kidney disease are contradictory. Recently, a large high-quality trial showed no evidence of a benefit of zinc supplementation on taste alterations among patients undergoing radiation therapy for head and neck cancer. Well-designed research is needed in this area.

C 

Tinea versicolor 

Zinc pyrithione shampoo may be an effective treatment for tinea versicolor, a fungal infection of the skin. Side effects were not noted in available research. Additional research is needed before a conclusion may be made.

C 

Tinnitus 

Studies on the efficacy of zinc in treating tinnitus have yielded contradictory results based on subjective findings. Further research is necessary before a conclusion can be drawn.

C 

Ulcers (foot ulcers) 

Zinc hyaluronate may help heal foot ulcers in patients with diabetes. More well-designed trials are needed before a conclusion may be made.

C 

Vaginitis (trichomoniasis) 

Little research is available on the efficacy of zinc for the treatment of trichomoniasis, a sexually transmitted disease (STD). One very small study suggested that a zinc sulfate douche and the prescription antibiotic metronidazole may effectively treat patients with recalcitrant trichomoniasis. However, more well-designed human studies are necessary before a firm conclusion can be drawn.

C 

Viral warts 

Preliminary research suggests that zinc sulfate may be effective for recalcitrant viral warts. Well-conducted studies are needed to clarify early study results.

C 

Growth 

Some limited evidence suggests that supplementation with zinc plus iron (but not zinc alone) may improve linear growth (length) of stunted infants with low hemoglobin. Overall studies using zinc alone do not suggest any effect on growth.

D 

 

*Key to grades: 

A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use (it may not work);
F: Strong scientific evidence against this use (it likely does not work).

For full grading rationale, click here.

Uses based on tradition or theory 

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified health care professional

Acrodermatitis enteropathica (metabolic disorder affecting zinc absorption), aging, alcoholism, Alzheimer's disease, anti-inflammatory, antioxidant, antiseptic (skin), aphrodisiac, atherosclerosis (hardening of the arteries), benign prostate hyperplasia, bladder cancer, bone diseases, bowel disorders (short bowel syndrome), bulimia, cataracts, cleansing (douching), contraceptive, eye disorders (night blindness, retinol pigmentation abnormalities), gastrointestinal inflammation, human papilloma virus, Huntington's chorea/disease, hyperglycemia, hypogonadism, hypoxia, liver disease, menopause, non-Hodgkin's lymphoma, osteoarthritis, pancreatitis, Parkinson's disease, poisoning (nickel), postpartum depression, prostate cancer, psychosis, retinopathy, schizophrenia, seizures, skin disorders, spleen disorders (enlargement), tuberculosis, wound healing.


Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy. Consult a healthcare professional immediately if you experience side effects.

Allergies

  • Zinc oxide allergy has been reported. Avoid with known allergy or hypersensitivity to zinc compounds.

Side Effects and Warnings

  • Zinc is regarded as relatively safe and generally well tolerated when taken at recommended doses, and few studies report side effects. Occasionally, adverse effects such as nausea, vomiting, or diarrhea have been observed. Reduced levels of high-density lipoprotein (HDL), or "good," cholesterol have been observed following daily supplementation with zinc. Reduced immune responses have also been observed. A slight tingling or burning sensation in the nostril has been reported from zinc nasal gel. A trend toward increased respiratory infections in children has been noted. One case of hypersensitivity pneumonitis has been reported.
  • Unpleasant taste, taste distortion, and abdominal cramping have been occasionally reported, especially in studies examining the efficacy of zinc-containing lozenges in treating symptoms of common cold or treatment of diarrhea in children.
  • Reports of skin conditions have been noted. In one study, worsening of an acne condition was observed following topical application of zinc, although many studies have shown positive effects of zinc on acne. A case report suggested the presence of dermatitis due to zinc deficiency.
  • Use amounts regularly exceeding the recommended upper tolerance levels (greater than 40 milligrams daily) under a physician's guidance only. Sideroblastic anemia, leukopenia, microcytic anemia, neutropenia, bleeding gastric erosion, hepatitis (liver inflammation), liver failure, intestinal bleeding, acute tubular necrosis, and interstitial nephritis have been reported following the ingestion of large amounts of zinc. High-quality studies have found evidence of an association between high-dose zinc supplement use and hospitalization for urinary complications, including benign prostatic hyperplasia or urinary retention, urinary tract infection, and urinary lithiasis. This was especially evident among males.
  • There is one report of death following the ingestion of 400 coins (mostly pennies). Pennies are composed mostly of zinc. There is also one case report of a fatal outcome from cystic degeneration in the putamen and necrosis in the hypothalamus. It was reported as a consequence of zinc treatment for Wilson's disease. However, the patient had received penicillamine, followed by a relatively high daily dose of zinc for several weeks, followed by penicillamine again for an unspecified time, so it remains unclear if zinc was responsible for the death.
  • Zinc may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or those taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
  • Zinc may lower blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.
  • Use cautiously in patients with high cholesterol or blood fats, a high risk of developing heart disease, various skin disorders, gastrointestinal disorders, liver disease, genitourinary conditions, blood disorders, neurological disorders, pulmonary or respiratory disorders, immune disorders, or kidney disease, or in patients taking antidepressants, potassium-sparing diuretics, antibiotics (particularly tetracyclines and quinolones), iron, penicillamine, thyroid hormones, or copper.
  • Avoid in patients who are homozygous for hemochromatosis (a metabolic disorder involving the deposition of iron-containing pigments in the tissues and characterized by bronzing of the skin, diabetes, and weakness).
  • Avoid use of intranasal Zicam®. Numerous reports exist of loss of smell associated with zinc-containing Zicam® products. These zinc-containing formulas have since been withdrawn from the U.S. market.
  • Avoid with known allergy or hypersensitivity to zinc compounds.

Pregnancy and Breastfeeding

  • Zinc is likely safe when consumed in amounts generally found in foods (or as part of a multivitamin or multimineral compound) in nonallergic women. There is insufficient reliable information available about the safety or efficacy of medicinal use of zinc during pregnancy or lactation. The relationship between zinc levels or intake and low birthweight or delivery complications has been studied, but the results are conflicting.
  • The recommended daily allowance (RDA) for zinc during pregnancy and lactation is as follows: for pregnant women 19 years old and older, 11 milligrams daily; for pregnant women 14-18 years of age, 13 milligrams daily; for breastfeeding women 19 years old and older, 12 milligrams daily; and for breastfeeding women 14-18 years of age, 14 milligrams daily.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy.

Interactions with Drugs

  • Zinc may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants (blood thinners) such as warfarin (Coumadin®) or heparin, antiplatelet drugs such as clopidogrel (Plavix®), and nonsteroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
  • Zinc may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. Patients taking insulin or drugs for diabetes by mouth should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
  • Zinc may also interact with acetazolamide, ACE inhibitors, angiotensin-converting enzyme receptor blockers, antibiotics, antidiarrheals, anti-inflammatory agents, anticancer agents, antiulcer agents, antivirals, caffeine, calcium salts, carbenoxolone analog (BX24), cholera vaccine, cholesterol-lowering agents, corticosteroids, deferoxamine (Desferal®), dexrazoxane, disulfiram, diuretics, drugs that affect the immune system, drugs used for osteoporosis, estrogens, ethanol (alcohol), folic acid, H2 blockers, iron salts, magnesium supplements, methylphenidate, niacin, pain relievers, pancreatic enzyme replacements, penicillamine (Cuprimine®), phenytoin, propofol, proton pump inhibitors, thyroid hormones, tricyclic antidepressants, trientine, and zidovudine.

Interactions with Herbs and Dietary Supplements

  • Zinc may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
  • Zinc may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
  • Zinc may also interact with antibacterials, anticancer herbs and supplements, antidepressants, antidiarrheals, anti-inflammatory herbs and supplements, antioxidants, antiulcer herbs and supplements, antivirals, ascorbic acid, bromelain, caffeine, calcium, cat's claw, cholesterol-lowering herbs and supplements, chromium, citric acid, copper, dairy foods, diuretics, EDTA, fiber, folic acid, herbs and supplements believed to have estrogenic properties, herbs and supplements that affect the immune system, herbs and supplements that affect the thyroid, herbs and supplements used for acne, herbs and supplements used for osteoporosis, IP-6 (phytic acid), iron, magnesium, manganese, mushroom extracts, niacin, nicotinamide, pain relievers, phosphorous, riboflavin, selenium, tartaric acid, vitamin A, and vitamin D.

Authors

  • This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Selected References

Natural Standard developed the above evidence-based information based on a systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

  1. Al-Awadhi, A. M., Alfadhli, S. M., Al-Khaldi, D., et al. Investigation of the distribution of lymphocyte subsets and zinc levels in multitransfused beta-thalassemia major patients. Int.J Lab Hematol. 2010;32(2):191-196.
  2. Bao, B., Prasad, A. S., Beck, F. W., et al. Zinc decreases C-reactive protein, lipid peroxidation, and inflammatory cytokines in elderly subjects: a potential implication of zinc as an atheroprotective agent. Am J Clin Nutr 2010;91(6):1634-1641.
  3. Barbosa, E., Faintuch, J., Machado Moreira, E. A., et al. Supplementation of vitamin E, vitamin C, and zinc attenuates oxidative stress in burned children: a randomized, double-blind, placebo-controlled pilot study. J Burn Care Res 2009;30(5):859-866.
  4. Bhandari, N., Mazumder, S., Taneja, S., et al. Effectiveness of zinc supplementation plus oral rehydration salts compared with oral rehydration salts alone as a treatment for acute diarrhea in a primary care setting: a cluster randomized trial. Pediatrics 2008;121(5):e1279-e1285.
  5. Cereda, E., Gini, A., Pedrolli, C., et al. Disease-specific, versus standard, nutritional support for the treatment of pressure ulcers in institutionalized older adults: a randomized controlled trial. J Am Geriatr.Soc 2009;57(8):1395-1402.
  6. Hu, D., Sreenivasan, P. K., Zhang, Y. P., et al. The effects of a zinc citrate dentifrice on bacteria found on oral surfaces. Oral Health Prev Dent. 2010;8(1):47-53.
  7. Iannotti, L. L., Zavaleta, N., Leon, Z., et al. Maternal zinc supplementation reduces diarrheal morbidity in peruvian infants. J Pediatr 2010;156(6):960-4, 964.
  8. Latva-Pukkila, U., Isolauri, E., and Laitinen, K. Dietary and clinical impacts of nausea and vomiting during pregnancy. J Hum Nutr Diet. 2010;23(1):69-77.
  9. Lin, Y. S., Lin, L. C., and Lin, S. W. Effects of zinc supplementation on the survival of patients who received concomitant chemotherapy and radiotherapy for advanced nasopharyngeal carcinoma: follow-up of a double-blind randomized study with subgroup analysis. Laryngoscope 2009;119(7):1348-1352.
  10. Orsini, G., Procaccini, M., Manzoli, L., et al. A double-blind randomized-controlled trial comparing the desensitizing efficacy of a new dentifrice containing carbonate/hydroxyapatite nanocrystals and a sodium fluoride/potassium nitrate dentifrice. J Clin Periodontol. 2010;37(6):510-517.
  11. Sawada, T. and Yokoi, K. Effect of zinc supplementation on mood states in young women: a pilot study. Eur J Clin Nutr 2010;64(3):331-333.
  12. Shi, Z., Yuan, B., Qi, L., et al. Zinc intake and the risk of hyperglycemia among Chinese adults: the prospective Jiangsu Nutrition Study (JIN). J Nutr Health Aging 2010;14(4):332-335.
  13. Shidfar, F., Aghasi, M., Vafa, M., et al. Effects of combination of zinc and vitamin A supplementation on serum fasting blood sugar, insulin, apoprotein B and apoprotein A-I in patients with type I diabetes. Int.J Food Sci Nutr 2010;61(2):182-191.
  14. Taneja, S., Strand, T. A., Sommerfelt, H., et al. Zinc supplementation for four months does not affect growth in young north Indian children. J Nutr 2010;140(3):630-634.
  15. Valentiner-Branth, P., Shrestha, P. S., Chandyo, R. K., et al. A randomized controlled trial of the effect of zinc as adjuvant therapy in children 2-35 mo of age with severe or nonsevere pneumonia in Bhaktapur, Nepal. Am J Clin Nutr 2010;91(6):1667-1674.

 

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