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Zinc

Evidence Fact Sheet

Zinc is an essential trace mineral and cofactor for >300 enzymes and >2000 zinc-finger proteins. Human evidence is strongest for shortening common-cold duration and for primary dysmenorrhea and childhood diarrhea; honest negatives include no benefit on male fertility/live birth and no cold-prevention effect.

Also known as: Zn · Zinco · Zinc bisglycinate · Zinc gluconate · Zinc citrate · Zinc picolinate · Zinc sulfate · Zinc acetate · Zinc oxide · Zinc monomethionine

Overview

Zinc is an essential trace mineral that acts as a catalytic cofactor for more than 300 enzymes (including carbonic anhydrase, alkaline phosphatase and Cu/Zn-superoxide dismutase) and as a structural component of over 2000 zinc-finger transcription factors governing DNA synthesis, cell division and gene expression. It modulates innate and adaptive immunity and is required for spermatogenesis, vitamin A metabolism and insulin handling. Typical supplemental intake is 8-25 mg/day elemental zinc (adult RDA 8-11 mg/day); short-term cold-symptom studies used 75-100 mg/day as lozenges. Tolerable upper limits are 40 mg/day (US IOM) and 25 mg/day (EFSA); chronic excess risks copper deficiency, anemia and neutropenia. Zinc carries 18 EFSA-authorized Article 13.1 health claims and ANVISA functional claims; in the US it is a DSHEA structure/function ingredient with no FDA-authorized disease claim, and intranasal zinc gluconate carries an FDA anosmia warning.

Mechanism of Action

catalytic cofactor for >300 enzymes including carbonic anhydrase, alkaline phosphatase, superoxide dismutase (Cu/Zn-SOD), and matrix metalloproteinases · structural component of >2000 zinc-finger transcription factors regulating gene expression, DNA synthesis and cell division · modulator of innate and adaptive immunity (neutrophil chemotaxis, NK cell activity, T-lymphocyte maturation, thymulin activation) · antioxidant via Cu/Zn-SOD activity and stabilization of protein thiols against free-radical oxidation · required cofactor for retinol dehydrogenase in vitamin A metabolism and for delta-6-desaturase in fatty acid metabolism · essential for spermatogenesis, testosterone biosynthesis and reproductive function · regulator of insulin storage, secretion and signaling in pancreatic beta cells (carbohydrate metabolism) · structural role in keratin/collagen synthesis supporting skin, hair, nail and bone matrix

Body systems: IMMUNITY · Skin & Connective Tissue · REPRODUCTIVE · Endocrine & Metabolic · Neurological & Cognitive · MUSCULOSKELETAL · METABOLISM

Evidence-Based Benefits

Each benefit below is anchored to a specific PubMed-indexed study. Effect sizes, sample sizes, and p-values are reported as published; no values are inferred. Honest negatives and null results are kept alongside the positive findings, and disease-research populations are described as such — Zinc is not characterized as a treatment for any disease.

Common Cold — Symptom Duration

Meta-analysis supported
  • -1.65 daysoverall duration · 95% CI -2.50 to -0.81
  • -2.63 daysadults · 95% CI -3.69 to -1.58
  • 17 trials / 2121RCTs / participants

In a pooled meta-analysis of 17 randomized trials, starting zinc within 24 hours of symptom onset shortened cold duration by about 1.65 days overall and 2.63 days in adults. The effect was a research finding in otherwise healthy adults; no significant shortening was seen in children.

Reported effect: Mean difference -1.65 days overall (95% CI -2.50 to -0.81); adults -2.63 days (95% CI -3.69 to -1.58); 17 trials, 2121 participants

“those receiving zinc had a shorter duration of cold symptoms (mean difference -1.65 days, 95% confidence interval [CI] -2.50 to -0.81) ... Zinc shortened the duration of cold symptoms in adults (mean difference -2.63, 95% CI -3.69 to -1.58) ... We included 17 trials involving a total of 2121 participants”

Source: PMID 22566526 · Science 2012 · CMAJ

Common Cold — Prevention (Honest Negative)

Null / no benefit Meta-analysis supported
  • RR 0.93cold risk · 95% CI 0.85-1.01
  • 9 studies / 1449low-certainty evidence
  • -2.37 daysduration if treated · 95% CI -4.21 to -0.53

The 2024 Cochrane review found zinc may have little or no effect on preventing colds (risk ratio 0.93, CI crossing 1.0, low certainty). It may shorten an ongoing cold by roughly 2.37 days, but heterogeneity was very high (I2 97%) and the authors graded all benefit findings as low-certainty.

Reported effect: Prevention RR 0.93 (95% CI 0.85 to 1.01; 9 studies, 1449 participants); treatment duration MD -2.37 days (95% CI -4.21 to -0.53; 8 studies, 972 participants), low-certainty evidence

“There may be little or no reduction in the risk of developing a cold with zinc compared to placebo (risk ratio (RR) 0.93, 95% CI 0.85 to 1.01; I2 = 20%; 9 studies, 1449 participants; low-certainty evidence). ... When zinc is used for cold treatment, there may be a reduction in the mean duration of the cold in days (MD -2.37, 95% CI -4.21 to -0.53; I² = 97%; 8 studies, 972 participants; low-certainty evidence).”

Source: PMID 38719213 · Nault 2024 · Cochrane Database Syst Rev

Primary Dysmenorrhea (Menstrual Pain)

Meta-analysis supported
  • Hedges g -1.541pain severity · 95% CI -2.27 to -0.81
  • 6 RCTs / 739trials / participants
  • p < 0.001vs placebo

A 2024 meta-analysis of 6 RCTs (739 participants) found zinc supplementation significantly reduced menstrual pain severity versus placebo, with a large effect size. Longer courses (8 weeks or more) were associated with greater pain reduction, and adverse-event rates did not differ significantly from placebo.

Reported effect: Hedges's g = -1.541 for pain severity (95% CI -2.268 to -0.814; p < 0.001); 6 RCTs, 739 participants

“Six RCTs involving 739 participants met the inclusion criteria. ... Zinc supplementation significantly reduced pain severity compared to placebo (Hedges's g = -1.541; 95% CI: -2.268 to -0.814; p < 0.001).”

Source: PMID 39683510 · Hsu 2024 · Nutrients

Childhood Acute Diarrhea

Meta-analysis supported
  • -13.27 hduration · 95% CI -17.66 to -8.89
  • 38 RCTssystematic review
  • RR 1.46 vomitingAE · 95% CI 1.22-1.76

In a 2024 systematic review of 38 RCTs, zinc shortened acute diarrhea duration by about 13 hours and increased the proportion of children who recovered (moderate certainty). The benefit was larger in persistent diarrhea (RR 1.75), but zinc also significantly increased vomiting versus placebo.

Reported effect: Duration MD -13.27 hours (95% CI -17.66 to -8.89, moderate certainty); recovery RR 1.07 (95% CI 1.03-1.1); vomiting RR 1.46 (95% CI 1.22-1.76); 38 RCTs

“We included 38 RCTs in this systematic review. ... a reduction in the duration of diarrhoea (mean difference (MD) = -13.27 hours; 95% CI = -17.66, -8.89; moderate certainty of evidence) ... A significant number of children in the zinc group compared to placebo experienced vomiting (RR = 1.46; 95% CI = 1.22, 1.76; moderate certainty of evidence)”

Source: PMID 39641338 · Ali 2024 · J Glob Health

Age-Related Macular Degeneration (AREDS)

RCT supported
  • OR 0.72antiox+zinc vs placebo · 99% CI 0.52-0.98
  • OR 0.75zinc alone · 99% CI 0.55-1.03
  • 3640 / 6.3 yrparticipants / follow-up

The landmark AREDS RCT (3640 participants, ~6.3-year follow-up) found that antioxidants plus zinc reduced the odds of progression to advanced macular degeneration (OR 0.72). Zinc alone showed a smaller reduction whose confidence interval crossed 1.0 (OR 0.75, 99% CI 0.55-1.03), so a zinc-alone benefit was not statistically conclusive.

Reported effect: Antioxidants plus zinc vs placebo OR 0.72 (99% CI 0.52-0.98); zinc alone OR 0.75 (99% CI 0.55-1.03); 3640 participants, 6.3-year average follow-up

“Average follow-up of the 3640 enrolled study participants, aged 55-80 years, was 6.3 years ... odds ratio [OR], 0.72; 99% confidence interval [CI], 0.52-0.98 ... The ORs for zinc alone and antioxidants alone are 0.75 (99% CI, 0.55-1.03)”

Source: PMID 11594942 · Age-Related Eye Disease Study Research Group 2001 · Arch Ophthalmol

Male Fertility / Live Birth (Honest Negative)

Null / no benefit RCT supported
  • 34% vs 35%live birth · RD -0.9% (CI -4.7 to 2.8)
  • n = 2370couples
  • +2.4%DNA fragmentation · CI 0.5-4.4

In a large JAMA RCT of 2370 couples, folic acid plus zinc did not improve live birth (34% vs 35% placebo) or any semen-quality parameter, and it modestly increased sperm DNA fragmentation. The authors explicitly concluded the findings do not support zinc/folic-acid supplementation for male infertility.

Reported effect: Live birth 404/34% (zinc+folic acid) vs 416/35% (placebo); risk difference -0.9% (95% CI -4.7% to 2.8%); semen parameters not significantly different; DNA fragmentation mean difference +2.4% (95% CI 0.5% to 4.4%); n = 2370 couples

“Live birth was not significantly different between treatment groups (404 [34%] in the folic acid and zinc group and 416 [35%] in the placebo group; risk difference, -0.9% [95% CI, -4.7% to 2.8%]) ... A statistically significant increase in DNA fragmentation was observed with folic acid and zinc supplementation (mean of 29.7% ... and 27.2% in the placebo group; mean difference, 2.4% [95% CI, 0.5% to 4.4%])”

Source: PMID 31910279 · Schisterman 2020 · JAMA

Acne Vulgaris (Adjuvant)

Meta-analysis supported
  • Lower serum zincacne vs controls

A systematic review and meta-analysis reported that people with acne had significantly lower serum zinc than controls, and that zinc treatment significantly improved mean inflammatory papule count versus no zinc, without more side effects. The abstract describes the direction of effect but does not report a numeric pooled effect size.

Effect size: this study reports the direction of the finding but does not state a specific numeric effect size, so none is given here rather than estimated.

“Subjects with acne had significantly lower serum zinc levels compared to controls. ... Patients who were treated with zinc had a significant improvement in mean inflammatory papule count compared to those who were not treated with zinc. ... There was no significant difference in the incidence of side effects in zinc supplementation vs comparators.”

Source: PMID 32860489 · Yee 2020 · Dermatol Ther

Gestational Diabetes & Serum Zinc (Honest Negative/Borderline)

Null / no benefit Meta-analysis supported
  • SMD -0.40overall · 95% CI -0.80 to 0.00 · P=0.05
  • 15 studies / 4955articles / subjects
  • 1549GDM cases

A meta-analysis of 15 studies (4955 women, 1549 with gestational diabetes) found circulating zinc tended to be lower in GDM, but the overall difference was not statistically significant (SMD -0.40, P=0.05). A serum-zinc subgroup reached significance, illustrating that the zinc-GDM association is inconsistent rather than established.

Reported effect: Overall SMD = -0.40 (95% CI -0.80 to -0.00, P = 0.05, not significant); serum-zinc subgroup SMD = -0.56 (95% CI -1.07 to -0.04, P = 0.03); 15 articles, 4955 subjects, 1549 GDM cases

“Compared with normal control, GDM cases had decreased circulating zinc level on the whole, but the difference was not statistically significant (SMD = -0.40, 95%CI: -0.80 to -0.00, P = 0.05). ... 4955 subjects including 1549 GDM cases were enrolled for quantitative analysis.”

Source: PMID 34350703 · Fan 2021 · Matern Child Nutr

Muscle / Physical Performance in Older Adults (Evidence Thin)

Emerging / indexed
  • 1 studyzinc & physical performance

A systematic review of minerals and sarcopenia found only a single study linking zinc intake to physical performance in older adults (positive association), and none on zinc with muscle mass or strength. The evidence base here is too thin to draw conclusions, in contrast to the stronger cold and dysmenorrhea data.

Effect size: this study reports the direction of the finding but does not state a specific numeric effect size, so none is given here rather than estimated.

“zinc (n = 1) intake were significantly and positively associated with physical performance in older adults.”

Source: PMID 28711425 · van Dronkelaar 2018 · J Am Med Dir Assoc

Dosage (research context · not a recommendation)

Adult RDA: 11 mg/day (men), 8 mg/day (women, non-pregnant); pregnancy 11 mg/day; lactation 12 mg/day. Common supplemental range: 8-25 mg/day elemental zinc. Therapeutic short-term ranges studied for cold symptom shortening: 75-100 mg/day elemental zinc as lozenges (acetate or gluconate) for up to 7 days. NOAEL/Upper Limit (IOM): 40 mg/day total elemental zinc for adults; EFSA UL: 25 mg/day. ANVISA IN 28/2018 maximum permitted dose in supplements: 35 mg/day for adults. Sustained intakes above the UL risk copper deficiency, sideroblastic anemia and neutropenia.

Regulatory Status · 4 Markets

US · FDA
No FDA-authorized SSA (Significant Scientific Agreement) health claim exists for zinc under 21 CFR Part 101 Subpart E. Zinc is regulated as an essential nutrient with Daily Value 11 mg (21 CFR 101.9) and as a dietary supplement ingredient under DSHEA (21 USC 343(r)(6)). Structure/function claims (e.g., "supports immune health", "supports normal taste and smell", "supports skin health") are permitted under DSHEA provided the manufacturer (a) has substantiation, (b) notifies FDA within 30 days of first marketing the claim, and (c) includes the disclaimer "This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease." Intranasal zinc gluconate products were the subject of an FDA warning (June 2009) due to anosmia reports.
EU · EFSA
Regulation (EU) No 432/2012 (Annex, consolidated under Article 13(1) of Regulation 1924/2006) authorizes 18 health claims for zinc, each conditional on the food being at least a "source of zinc" per Annex of Regulation (EC) No 1924/2006 (>=15% of the NRV per 100 g/100 ml/portion). Maximum supplemental level not harmonized at EU level; EFSA NDA Panel UL = 25 mg/day for adults (re-evaluated 2024). See the EFSA authorized health claims for the verbatim list.
CN · China
Approved in China as a nutrient-supplement raw material under the SAMR Catalogue of Health-Food Raw Materials — Nutrient Supplements, and as a permitted nutrient fortifier under GB 14880-2012. Supplement-grade claims limited to nutrient-supplement filing ('zinc supplementation'); specific SAMR health-function claims (e.g. immunity) require the registration pathway.
BR · ANVISA
Brazil regulates zinc as a supplement constituent under Instrução Normativa DC/ANVISA No. 28/2018 (suplementos alimentares). Anexo III sets minimum daily limits and Anexo IV maximum daily limits (35 mg/day for adults). Anexo V lists authorized functional claims (alegações funcionais) for zinco; each verbatim claim begins with the official pattern "O zinco auxilia ..." and is restricted to products providing at least double the Anexo III minimum without exceeding the Anexo IV maximum.

Authorized Claims

ANVISA — “O zinco auxilia no funcionamento do sistema imune.” (IN 28/2018 Anexo V)

Safety

Doses above 40 mg/day elemental zinc (IOM UL) chronically can induce secondary copper deficiency, sideroblastic anemia, neutropenia and impaired iron status; case reports of myelopathy with chronic megadose use (often from denture-cream exposure). Acute oral doses >50 mg may cause nausea, vomiting, epigastric pain, and dysgeusia. Zinc lozenges frequently cause bad taste and nausea (RR ~1.6 versus placebo per PMID 22566526). Intranasal zinc gluconate is contraindicated due to FDA-recognized risk of anosmia (FDA advisory 2009, Zicam). Zinc reduces absorption of tetracyclines, fluoroquinolones, penicillamine and integrase-strand-transfer inhibitors; separate dosing by >=2 hours. High-dose zinc decreases HDL cholesterol. Pregnancy: do not exceed RDA without medical supervision. Pediatric dosing must follow weight-based pediatric guidance.

Goals: inflammation-relief · cognitive-support · skin-beauty

Lifestyles: plant-based · athletic-performance

References

PubMed-indexed citations anchoring the benefit findings above. Effect sizes are reported as published.

  1. PMID 22566526 · Science 2012 · CMAJ — Common Cold — Symptom Duration
  2. PMID 38719213 · Nault 2024 · Cochrane Database Syst Rev — Common Cold — Prevention (Honest Negative)
  3. PMID 39683510 · Hsu 2024 · Nutrients — Primary Dysmenorrhea (Menstrual Pain)
  4. PMID 39641338 · Ali 2024 · J Glob Health — Childhood Acute Diarrhea
  5. PMID 11594942 · Age-Related Eye Disease Study Research Group 2001 · Arch Ophthalmol — Age-Related Macular Degeneration (AREDS)
  6. PMID 31910279 · Schisterman 2020 · JAMA — Male Fertility / Live Birth (Honest Negative)
  7. PMID 32860489 · Yee 2020 · Dermatol Ther — Acne Vulgaris (Adjuvant)
  8. PMID 34350703 · Fan 2021 · Matern Child Nutr — Gestational Diabetes & Serum Zinc (Honest Negative/Borderline)
  9. PMID 28711425 · van Dronkelaar 2018 · J Am Med Dir Assoc — Muscle / Physical Performance in Older Adults (Evidence Thin)

Frequently Asked Questions

1. Does zinc actually shorten a cold?

The strongest pooled evidence (Science 2012, CMAJ, 17 trials / 2121 participants) found zinc started within 24 hours of onset shortened cold duration by about 1.65 days overall and 2.63 days in adults. However, the 2024 Cochrane review graded this benefit as low-certainty (heterogeneity I2 97%) and found no reliable cold-prevention effect (RR 0.93, CI crossing 1.0). So the research supports a modest, uncertain shortening of an active cold in adults, not prevention. These are findings in studied populations, not a cure.

2. Can zinc help with menstrual cramps?

A 2024 meta-analysis of 6 RCTs (739 participants; Hsu 2024, Nutrients) found zinc significantly reduced primary-dysmenorrhea pain severity versus placebo (Hedges's g -1.541, p<0.001), with larger benefit from courses of 8 weeks or more and no significant excess of side effects. This is one of zinc's better-supported quantitative findings, though it concerns pain severity in research settings rather than treating any disease.

3. Does zinc improve male fertility or testosterone?

The largest trial, a JAMA RCT of 2370 couples (Schisterman 2020), found folic acid plus zinc did NOT improve live birth (34% vs 35% placebo) or any semen-quality parameter, and modestly increased sperm DNA fragmentation. The authors concluded the data do not support zinc/folic-acid supplementation for male infertility. EFSA does authorize a structural claim that zinc 'contributes to the maintenance of normal testosterone levels,' but that is a normal-function maintenance claim, not evidence of boosting fertility outcomes.

4. Is zinc useful for children's diarrhea?

Yes, this is one of the most robust uses. A 2024 systematic review of 38 RCTs (Ali 2024, J Glob Health) found zinc shortened acute diarrhea by about 13 hours (MD -13.27 h) and improved recovery (moderate certainty), with an even larger effect in persistent diarrhea (RR 1.75). The trade-off is significantly more vomiting (RR 1.46). This is an evidence summary, not clinical guidance — any use in a child should be directed by a pediatric clinician.

5. How much zinc is safe to take?

Adult RDA is 8 mg/day (women) to 11 mg/day (men); common supplements provide 8-25 mg/day elemental zinc. Tolerable upper limits are 40 mg/day (US IOM) and 25 mg/day (EFSA); ANVISA caps supplements at 35 mg/day. Chronic intake above the upper limit can cause copper deficiency, anemia and neutropenia. High-dose lozenges (75-100 mg/day used in cold studies) commonly cause bad taste and nausea (RR ~1.65 in the Science 2012 meta-analysis). Intranasal zinc gluconate should be avoided due to an FDA anosmia (loss of smell) warning.

6. Does zinc clear up acne?

A systematic review and meta-analysis (Yee 2020, Dermatol Ther) found people with acne had significantly lower serum zinc than controls and that zinc treatment improved inflammatory papule count without more side effects. The abstract reports the direction of benefit but no numeric pooled effect size, so zinc is best viewed as a possible adjuvant rather than a primary acne treatment. Frame this as a research-level association, not a guaranteed result.

Last evidence review: 2026-06-04

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