Zinc: benefits, dosage, contraindications
Other name(s)
Zn
Family or group:
Minerals and trace elements
Indications
Scoring methodology
EFSA approval.
Zinc Deficiency ✪✪✪✪✪
Oral or intravenous zinc administration prevents and treats zinc deficiency. However, routine zinc supplementation is not recommended. rnrnTraditionally, zinc supplementation has been usedrnrnto treat or prevent deficiency in certain conditions such as anorexia nervosa, malabsorption syndromes, conditions associated with chronic and severe diarrhea, alcoholism and hepatic cirrhosis, diabetes, AIDS, during recurrent infections, severe burns, after major surgery, in Wilson's disease or during long-term administration of total parenteral nutrition. rnrnZinc supplementation (136 mg of elemental zinc per day) in patients with cirrhosis and zinc deficiency appears to improve liver function and glucose tolerance, possibly by increasing insulin-like growth factor.rnrn
Posologie
Oral
12.7 - 136 mg
Osteoporosis ✪✪✪✪✪
Reduced zinc intake and low serum zinc levels appear to be associated with lower bone mineral density (BMD) in men and women.rnrnSome clinical evidence suggests that taking zinc in combination with copper, manganese, and calcium may slow bone loss in postmenopausal women.rnrnA combination of 1000 mg of calcium per day (as calcium citrate malate) plus a trace element mixture containing 15 mg of zinc (as zinc sulfate), 0.5 mg of copper and 5 mg of manganese (as the gluconate salt) for 2 years has been used.rnrn
Posologie
Oral
15 mg
2 - years
Zinc sulfate
Synergies
Acid-base balance ✪✪✪✪✪
EFSA has established that zinc contributes to normal acid-base metabolism.
Posologie
Oral use
25 mg
Adults
Oxidative stress ✪✪✪✪✪
EFSA has established that zinc can contribute to the protection of cells against free radicals.
Posologie
Oral use
25 mg
Adults
Healthy aging ✪✪✪✪✪
EFSA recognizes zinc's contribution to normal DNA synthesis and to the maintenance of cognitive functions.
Posologie
Oral use
25 mg
Adults
Skin health ✪✪✪✪✪
EFSA recognizes zinc's contribution to the maintenance of hair, nails and skin.
Posologie
Oral use
25 mg
Adults
Diarrhea ✪✪✪✪✪
Oral zinc supplementation reduces the duration and severity of acute and persistent diarrhea in malnourished children or those deficient in zinc. Oral zinc supplementation may also reduce diarrhea-associated mortality, particularly from persistent diarrhea. Elemental zinc (10 to 40 mg per day) has been used with an oral rehydration solution for 7 to 15 days to treat diarrhea in children aged 6 months to 5 years who are malnourished or zinc-deficient. In undernourished pregnant women, zinc taken at 15 mg per day from the first or third trimester and for one month after delivery significantly reduces the incidence of diarrhea in infants during the first year of life compared with placebo.
Posologie
Oral
10 - 40 mg
15 - days
Pregnant women, Children
Wilson's disease ✪✪✪✪✪
Wilson's disease is characterized by accumulation of copper in vital organs, including the liver and brain. Zinc blocks the absorption of copper and increases copper excretion in the stool in people with Wilson's disease. Zinc sulfate supplementation, at 220 mg three times daily for 3 months, in patients with Wilson's disease resulted in an increase in hepatic glutathione and a decrease in oxidation, compared with those using penicillamine.
Posologie
Oral
660 mg
3 - months
Zinc sulfate
Acne ✪✪✪✪✪
Clinical trials suggest that taking zinc orally, in the form of zinc sulfate or zinc gluconate, may improve acne compared with placebo.rnrn
Posologie
Oral
30 - 150 mg
3 - months
zinc acetate, lotion, zinc gluconate, zinc sulfate
Anorexia ✪✪✪✪✪
Taking zinc supplements orally may help promote weight gain and alleviate depressive symptoms in adolescent and adult patients with anorexia nervosa.rnrn
Posologie
Oral
14 - 50 mg
Adults, Adolescents
Common cold ✪✪✪✪✪
The majority of clinical trials and clinical research analyses show a significant reduction in the duration of common cold symptoms when adults take zinc gluconate or zinc acetate lozenges providing 9 to 24 mg of elemental zinc per dose.rnrn
Posologie
Oral
9 - 184 mg
Adults
zinc acetate, zinc gluconate
Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges.
Zinc gluconate and the common cold: a controlled clinical study.
Two randomized controlled trials of zinc gluconate lozenge therapy of experimentally induced rhinovirus colds.
Warts ✪✪✪✪✪
Preliminary clinical studies suggest that applying a zinc sulfate solution three times a day for 4 weeks improves flat warts, but not common warts, compared with distilled water. rnrnAnother clinical study suggests that the local application of a zinc oxide ointment twice a day may be just as effective in curing warts as a salicylic acid and lactic acid ointment.rnrn
Posologie
Topical
4 - weeks
zinc oxide, zinc sulfate
Male fertility disorders ✪✪✪✪✪
Preliminary clinical research shows that zinc supplementation increases sperm count, testosterone levels, and pregnancy rates in idiopathic infertile men with low testosterone levels.rnrn
Posologie
Oral
25 - 66 mg
6 - months
Men
Attention deficit disorders ✪✪✪✪✪
Some research suggests that children with attention-deficit/hyperactivity disorder (ADHD) have lower serum zinc levels than children without ADHD. Other research suggests that patients with ADHD who have lower zinc levels may not respond adequately to stimulant treatment. Based on this evidence, zinc may be of some interest for improving symptoms in children with ADHD. Oral zinc taken in combination with conventional treatment may slightly improve symptoms of hyperactivity, impulsivity, and socialization difficulties in some children with ADHD. There is evidence that zinc may be more useful in children with a high body mass index (BMI), low zinc levels, and low levels of free fatty acids. Zinc sulfate has been used at 55 mg (15 mg elemental zinc) to 150 mg (40 mg elemental zinc) per day for 6 to 12 weeks.
Posologie
By mouth
15 - 40 mg
12 weeks
Children
Zinc sulfate
Zinc deficiency in attention-deficit hyperactivity disorder.
Does hair zinc predict amphetamine improvement of ADD/hyperactivity?
Methylphenidate for children and adolescents with autism spectrum disorder.
Double-blind, placebo-controlled study of zinc sulfate in the treatment of attention deficit hyperactivity disorder.
Double-blind, placebo-controlled study of zinc sulfate in the treatment of attention deficit hyperactivity disorder.
AMD ✪✪✪✪✪
Supplementation with antioxidants including vitamins A (15 mg), C (500 mg), E (400 IU) and zinc oxide (80 mg) reduces the risk of vision loss by 27% and slows disease progression.
Posologie
By mouth
80 - 500 mg
10 - years
zinc oxide
Synergies
Long-term effects of vitamins C and E, ß-carotene, and zinc on age-related macular degeneration: AREDS report no. 35.
Age-Related Eye Disease Study Research Group. Potential public health impact of age-related eye disease study results: AREDS report no. 11.
Skin healing ✪✪✪✪✪
To help wound healing, topical zinc may improve re-epithelialization and collagen synthesis, reduce inflammation, and inhibit bacterial growth.
Posologie
Topical
Herpes ✪✪✪✪✪
Topical application of zinc appears to help treat herpes simplex infection. Zinc sulfate appears to reduce the severity and duration of symptoms of orolabial and genital herpes.
Posologie
Topical
Zinc sulfate
Topical treatment of recurrent herpes simplex and post-herpetic erythema multiforme with low concentrations of zinc sulfate solution
A randomized clinical trial on the treatment of oral herpes with topical zinc oxide/glycine
Use of topical zinc to prevent recurrent herpes simplex infection: review of literature and suggested protocols
Type 2 diabetes ✪✪✪✪✪
Oral zinc may slightly improve glycemic control in some patients. Although animal studies have shown improved glycemic control with zinc, results from human studies are less consistent.rnrnA meta-analysis of 12 clinical trials in diabetic patients shows that taking zinc supplements reduces fasting blood glucose and glycated hemoglobin (HbA1c) compared with the control group. The reduction in blood glucose appears to be greater with inorganic zinc, at doses of at least 30 mg per day for at least one month. rnrn
Posologie
Oral
50 mg
Zinc acetate
Zinc supplementation improves glycemic control for diabetes prevention and management: a systematic review and meta-analysis of randomized controlled trials
The influence of zinc supplementation on the pancreas of streptozotocin-diabetic rats
Diabetes, metallothionein, and zinc interactions: a review
Depression ✪✪✪✪✪
Some preliminary clinical studies have shown that taking zinc at 25 mg per day for 12 weeks, in addition to an antidepressant treatment, improves depression scores in patients with major depression. However, zinc may not be beneficial for all patients diagnosed with major depression. This would indeed depend on the patient's resistance to antidepressant treatments.rnrn
Posologie
Oral
25 mg
12 weeks
Leg ulcer ✪✪✪✪✪
Clinical research suggests that the application of a zinc-hyaluronate gel once a day may improve ulcer healing time compared with conventional treatment in type 2 diabetic patients with foot ulcers. According to another randomized, double-blind, placebo-controlled study, applying a gauze with zinc oxide for 8 weeks to people with leg ulcers resulted in healing in 83% of treated individuals, compared with 42% healing for those treated with the placebo.
Posologie
By topical application
220 mg
8 weeks
zinc oxide
Properties
Essential
The total amount of zinc in the body is estimated at 2 g. It is a cofactor in many biological processes, including DNA, RNA (the messenger between DNA and proteins) and protein synthesis. It is believed that a large number of proteins involved in the regulation of gene expression contain zinc. European health authorities (EFSA, European Food Safety Authority and the European Commission) have determined that products containing zinc contribute to normal DNA synthesis, normal acid-base metabolism, the normal metabolism of food, carbohydrates (sugars), fatty acids and vitamin A, normal cognitive function, normal fertility and reproduction, protein synthesis, the maintenance of bones, the maintenance of hair, nails and skin, the maintenance of normal testosterone concentrations in the blood, normal vision, the normal functioning of the immune system, cell division, the protection of cells from free radicals (antioxidant effect), if and only if these products contain at least 1.5 mg of zinc per 100 g, 100 ml or per package if the product contains only one serving.
Usages associés
Antioxidant
Zinc limits damage induced by oxidants through various mechanisms. Indeed, it protects against vitamin E depletion, controls the release of vitamin A, contributes to the structure of the extracellular antioxidant enzyme SOD, limits endogenous production of free radicals and promotes their trapping.
Wound healing
To aid healing, topical application of zinc strengthens collagen synthesis and epidermal regeneration, reduces inflammation and limits bacterial proliferation.
Usages associés
Immunomodulatory
A severe zinc deficiency weakens immune function. Even a mild to moderate zinc deficiency can impair the functions of macrophages and neutrophils and natural killer cell activity. The body needs zinc to develop and activate T lymphocytes. rnrnIndividuals with low zinc levels have shown a reduced lymphocyte proliferative response to mitogens and other immune response disturbances that can be corrected by zinc supplementation. These alterations in immune function may explain why zinc deficiency has been associated with increased susceptibility to pneumonia and other infections in children in developing countries and in the elderly.rnrn
Usages associés
Effect on fertility
Zinc affects male fertility. For example, cases of male infertility have been associated with low zinc levels in seminal plasma. Clinical studies suggest that a transient zinc deficiency leads to a decrease in serum testosterone concentration as well as a reduction in seminal volume. rnrnZinc supplementation improves parameters such as sperm count in infertile men, primarily those with low testosterone levels.rnrn
Usages associés
Neurological
Zinc levels are decreased in people who suffer from depression. In the brain, zinc plays a role in the hippocampus in communication between neurons. Clinical studies have shown that zinc potentiates the action of antidepressants. In Alzheimer's disease, zinc appears to play a protective role due to its antioxidant properties, but on the other hand, it also seems to contribute to the aggregation of beta-amyloid (a small protein whose aggregate is one of the characteristic signs of Alzheimer's).
Usages associés
Antiviral
Zinc may have effects on the rhinovirus. In vitro, it inhibits its replication, but its effects in humans are not clear. Indeed, the rhinovirus (responsible for conditions like the common cold) replicates in the nasal mucosa. Furthermore, the bioavailability of zinc at the level of the nasal mucosa and nasal secretions, when administered orally, varies depending on the formulation used, which can influence zinc's effectiveness for the common cold. Zinc could have effects on other viruses, such as respiratory syncytial virus (RSV) or herpes simplex.
Usages associés
Bone density
Zinc plays a role in the prevention of osteoporosis, as it appears to be involved in bone mineralization. There is a direct relationship between bone strength and zinc levels in bone. Also, in people with osteoporosis, zinc loss is greater due to bone breakdown.
Usages associés
Hypoglycemic
Preliminary research suggests that people with type 2 diabetes may have altered zinc metabolism and, consequently, zinc deficiency. Studies show that zinc potentiates the action of insulin by increasing glucose transport into cells. Zinc can increase IGF-1 (insulin-like growth factor 1) levels by up to 30% (a growth factor that stimulates glucose metabolism, cell proliferation, and differentiation). In a more recent study of patients with prediabetes, taking 30 mg of zinc sulfate daily for 6 months improved fasting blood glucose compared with the control group. Zinc supplementation also improved insulin sensitivity and reduced insulin resistance.
Usages associés
Dermatological effect
Clinical research suggests that zinc has beneficial effects on the skin when used orally or topically. Indeed, zinc appears to improve acne through anti-inflammatory activity and by reducing sebum secretion.
Usages associés
Vision
Zinc plays a key role in maintaining vision. Zinc is present in significant amounts in the retina and choroid. A zinc deficiency can therefore impair vision. In addition, zinc interacts with vitamin A and taurine in the retina and acts as an antioxidant in the retina and the retinal pigment epithelium (involved in light absorption, and its dysfunction is found in diseases such as AMD). Some studies have shown that zinc may slow certain types of degenerative eye diseases.
Usages associés
Safe dosage
Adults 18 years and older: 12.7 mg - 25 mg
For adults, the zinc intake likely to meet the needs of nearly all healthy individuals in a population is provided for four levels of phytate intake (LPI): 300 mg/day (7.5 mg/day of zinc), 600 mg/day (9.3 mg/day of zinc), 900 mg/day (11 mg/day of zinc), and 1200 mg/day (12.7 mg/day of zinc).
Infants 7 to 11 months: 2.9 mg
The zinc intake that meets the needs of nearly all healthy individuals in a population is 2.9 mg/day for infants 7 to 11 months old.
Pregnant women aged 18 years and older: 14.3 mg - 25 mg
Children aged 1 to 3 years: 4.3 mg - 7 mg
For children, the fractional absorption of zinc taken into account in establishing the PRI (Population Reference Intake) was based on data from mixed diets assumed to contain varying amounts of phytate; therefore, no adjustment for phytate intake was made
Child aged 4 to 6 years: 5.5 mg - 10 mg
For children, the fractional absorption of zinc taken into account in establishing the PRI (Population Reference Intake) was based on data from mixed diets assumed to contain varying amounts of phytate; therefore, no adjustment for phytate intake was made
Child aged 7 to 10 years: 7.4 mg - 13 mg
For children, the fractional absorption of zinc taken into account in establishing the PRI (Population Reference Intake) was based on data from mixed diets assumed to contain varying amounts of phytate; therefore, no adjustment for phytate intake was made
Child aged 11 to 14 years: 10.7 mg - 18 mg
For children, the fractional absorption of zinc taken into account in establishing the PRI (Population Reference Intake) was based on data from mixed diets assumed to contain varying amounts of phytate; therefore, no adjustment for phytate intake was made
Child aged 15 to 17 years: 11.9 mg - 22 mg
For children, the fractional absorption of zinc taken into account in establishing the PRI (Population Reference Intake) was based on data from mixed diets assumed to contain varying amounts of phytate; therefore, no adjustment for phytate intake was made
Lactating woman aged 18 and older: 15.6 mg - 25 mg
Interactions
Médicaments
Diuretics: moderate interaction
Amiloride (a potassium-sparing diuretic) can reduce urinary zinc excretion at doses greater than or equal to 10 mg/day. This effect can offset zinc losses caused by thiazide diuretics. Other potassium-sparing diuretics (spironolactone, triamterene) do not appear to spare zinc. Thiazide diuretics increase zinc excretion by 50 to 60%. This phenomenon is observed for at least 3 years of treatment. Serum zinc levels decrease but remain within the normal range due to compensatory mechanisms. However, prolonged diuretic therapy may reduce tissue zinc.
Antidiabetic: moderate interaction
Clinical evidence has shown that zinc can lower blood glucose. Use with caution if the patient is already taking antidiabetic medications; dose adjustments may be necessary.
Antiretroviral: moderate interaction
Zinc can reduce the serum concentrations of atazanavir (Reyataz*), and ritonavir (Norvir*), by a chelating effect, preventing their absorption. A single oral dose of 125 mg zinc sulfate does not alter atazanavir concentrations. However, in patients treated with atazanavir and ritonavir, coadministration of 125 mg zinc sulfate for 2 weeks reduced plasma atazanavir concentrations by 22% and ritonavir by 16%. Nevertheless, atazanavir levels remain sufficiently high to prevent HIV replication. Therefore, this decrease is not clinically significant. Additionally, pharmacologic studies have shown that zinc decreases the blood level and effect of integrase inhibitors. Integrase inhibitors include: dolutegravir (Tivicay*), elvitegravir (Vitekta*) and raltegravir (Isentress*).
Cephalexin: strong interaction
Zinc decreases cephalexin levels by a chelating effect, thereby preventing its absorption. A pharmacokinetic study showed that taking 250 mg of zinc sulfate concomitantly with 500 mg cephalexin reduced the maximum concentration of cephalexin by 31%. However, taking the same dose of zinc sulfate 3 hours before cephalexin reduced its maximum concentration by 11%. This effect is not seen if zinc is taken 3 hours after cephalexin.
Cisplatin: moderate interaction
Some studies suggest that zinc stimulates the production of metalloprotein (a protein characterized by a high affinity for metal ions) by tumor cells. This protein can inactivate cisplatin, but it is unknown whether zinc supplementation or a zinc-rich diet can cause a clinically significant interaction with cisplatin. Furthermore, cisplatin may increase zinc excretion.
Captopril: weak interaction
Some data suggest that captopril increases urinary zinc excretion by chelation through sulfhydryl groups. This excretion appears to be dose- and duration-dependent. Increased losses seem more likely with high doses of captopril (greater than 150 mg/day) taken for several weeks. However, zinc supplementation is not necessary with captopril. Zinc loss is unlikely with other angiotensin-converting enzyme (ACE) inhibitors such as enalapril.
Corticosteroid: weak interaction
The hypothalamic-pituitary-adrenal axis is thought to play a role in controlling serum zinc levels. Thus, disturbance of this axis by high doses of corticosteroids (>= 50 mg of prednisone) or by long-term treatment with lower doses may decrease serum zinc levels. Routine zinc supplementation is not necessary with corticosteroid therapy.
Iron chelator: moderate interaction
* Deferoxamine: It increases urinary excretion of zinc. This effect is dose-dependent. However, symptomatic zinc deficiency due to deferoxamine remains rare. Zinc supplementation is necessary for some patients.rnrn* Dexrazoxane: Some studies show it increases urinary zinc excretion tenfold, but clinical data remain insufficient.rnrn* EDTA (ethylenediaminetetraacetic acid): It is a chelator of metal ions including zinc. EDTA used in the treatment of lead poisoning can increase urinary zinc excretion 10 to 17 times and reduce serum levels by 40%. Levels normalize after stopping treatment. Zinc supplementation is necessary in some cases, although there is concern it may reduce EDTA's effectiveness.
Penicillamine: moderate interaction
Penicillamine (a copper chelator) can also bind to zinc. It can increase urinary zinc excretion but may also increase its intestinal absorption.rnrnOnly a single case of severe zinc deficiency has been reported. If zinc supplementation is necessary, it should be taken 1 to 2 hours apart from penicillamine.
Quinolone: moderate interaction
Quinolones form complexes with zinc in the gastrointestinal tract if taken at the same time, which reduces their absorption. It is recommended to take quinolones 2 hours before or 4 to 6 hours after zinc supplementation. Examples of quinolones include: ciprofloxacin (Cipro*), gemifloxacin (Factive*), levofloxacin (Levaquin*), moxifloxacin (Avelox*).
Tetracycline: moderate interaction
Tetracyclines (achromycine*, sumycine*, déclomycine*) form complexes with zinc in the gastrointestinal tract if taken at the same time, which reduces their absorption. Indeed, tetracycline absorption is reduced by 30 to 40% if it is taken at the same time as 200 mg of zinc sulfate. Furthermore, the interaction of zinc with doxycycline (vibramycine*) is not significant. It is recommended to take tetracyclines 2 hours before or 4 to 6 hours after zinc supplementation.
Plantes ou autres actifs
Zinc: minor interaction
Calcium supplementation may decrease the absorption of zinc from the diet, but there is no clinically significant effect on zinc balance. However, this interaction can be avoided by taking calcium between meals.
Zinc: minor interaction
Large amounts of zinc can reduce copper absorption. Copper deficiency has been observed in subjects taking 150 mg/day or more of zinc for 2 years.
Zinc: minor interaction
If zinc is taken on an empty stomach, it interferes with iron absorption and vice versa, due to competition when binding to transport proteins. If they are taken with meals, these ions complex with food components and no longer compete. Therefore, there is no significant interaction between iron and zinc if they are taken during meals.
Zinc: minor interaction
Clinical data suggest that zinc supplementation can increase plasma retinol levels (one of the three available forms of vitamin A). A significant increase has been observed for doses up to 30 mg/day for 6 months.
Precautions
Type 2 diabetes: use with caution
Taking high doses of zinc can lower blood glucose in diabetic patients. Use with caution and monitor blood glucose.
Alcoholism: use with caution
Long-term excessive alcohol consumption leads to decreased zinc absorption and increased urinary excretion.
Renal failure: use with caution
Patients on hemodialysis have zinc deficiency. Zinc supplementation may be necessary.
HIV infection: use with caution
Some evidence has shown a link between high zinc intake and reduced survival time. Other research suggests that addressing zinc deficiency in patients infected with HIV helps maintain normal immune function. Use with caution.
Malabsorption syndrome: use with caution
These patients have zinc deficiency due to decreased absorption and increased renal elimination.
Rheumatoid arthritis: use with caution
Zinc absorption is decreased in people with rheumatoid arthritis.
