Zinc

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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 provider.

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 HbA 1c 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)

Grading rationale

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 healthcare provider.

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.

Dosing Related terms
NS_patient-zinc Portions of this document last updated: Sept. 1, 2012

THIS EVIDENCE-BASED MONOGRAPH WAS PREPARED BY
THE NATURAL STANDARD RESEARCH COLLABORATION
(www.naturalstandard.com)

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