Zinc
PromisingEssential trace mineral for immunity, testosterone, and wound healing.
Not medical advice
Nutripedia summarises published peer-reviewed research. This content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before taking any supplement.
Zinc is an essential trace mineral involved in over 300 enzymatic reactions, including immune function, protein synthesis, wound healing, DNA synthesis, and cell division. It plays a role in testosterone production and is commonly supplemented by athletes and those with restricted diets. Dietary sources include red meat, shellfish, legumes, and seeds. Absorption is inhibited by phytates in plant foods, meaning vegetarians and vegans may require higher intakes.
EFSA-authorised health claims for immune function and normal testosterone levels. Cochrane-level evidence for cold duration reduction with lozenges. Testosterone benefit is primarily seen in deficient individuals, not in zinc-replete populations. Long-term supplementation above 25 mg/day risks copper depletion.
Immune Function & Respiratory Infections
16 studies · 1,360 participants
Wound Healing
9 studies · 490 participants
Age-Related Macular Degeneration (AMD)
4 studies · 3,600 participants
The Evidence
14 peer-reviewed papers, updated 5 days ago
5 meta-analyses · 4 systematic reviews · 2 RCTs · 2 position stands · 1 regulatory document
Zinc — Health Professional Fact Sheet
National Institutes of Health Office of Dietary Supplements
NIH Office of Dietary Supplements
Adult RDAs are 8 mg/day (women) and 11 mg/day (men). The US tolerable upper intake level is 40 mg/day for adults. Deficiency manifests as growth retardation, immune impairment, delayed wound healing, and reproductive dysfunction. Oysters, red meat, and legumes are primary dietary sources.
Systematic review and meta-analysis of the effect of zinc on wound healing
Arribas Lopez E, Zand N, Ojo O et al.
BMJ Nutrition, Prevention & Health
Meta-analysis of five RCTs (178 participants) found zinc treatment associated with a 41% higher probability of favorable ulcer healing outcomes versus control (RR 1.41, 95% CI 1.04–1.92, p=0.03). Authors caution that study quality was moderate and further RCTs are needed.
Comparative Absorption and Bioavailability of Various Chemical Forms of Zinc in Humans: A Narrative Review
Devarski PP, Mao Q, Grant RW et al.
Nutrients
Review of clinical evidence comparing zinc supplement forms concludes that zinc glycinate and zinc gluconate demonstrate superior absorption over zinc oxide and other forms. Zinc citrate and gluconate showed comparable fractional absorption (~61%) versus oxide (~50%) in controlled crossover studies.
Zinc Toxicity: Understanding the Limits
Schoofs H, Schmit J, Rink L
Molecules
Excess zinc intake induces copper deficiency, anemia, and neutropenia. EFSA sets the tolerable upper intake at 25 mg/day; the US UL is 40 mg/day for adults. Toxicity can result from oral, inhalation, or topical routes and chronic low-level excess is clinically relevant.
Zinc for prevention and treatment of the common cold
Nault D, Machingo TA, Shipper AG
Cochrane Database of Systematic Reviews
Zinc supplements may reduce cold duration by approximately two days compared to placebo (8 studies, 972 people), but evidence quality is low. Little or no reduction in cold incidence was found. Non-serious adverse events (nausea, bad taste) were probably increased with zinc treatment.
Correlation between serum zinc and testosterone: A systematic review
Te L, Liu J, Ma J et al.
Journal of Trace Elements in Medicine and Biology
Across 38 eligible studies (8 clinical, 30 animal), zinc deficiency consistently reduced testosterone levels and supplementation restored them. Effect size varied by baseline zinc and testosterone status, supplementation form, elemental dose, and treatment duration.
Zinc Deficiency
Maxfield L, Shukla S, Crane JS
StatPearls [Internet]. StatPearls Publishing
Zinc deficiency is a major global health burden affecting an estimated 2 billion people. Clinical features include growth retardation, alopecia, diarrhoea, delayed wound healing, hypogonadism, and immune dysfunction. Deficiency is most prevalent in South Asia and Sub-Saharan Africa.
Zinc supplementation and immune factors in adults: a systematic review and meta-analysis of randomized clinical trials
Jafari A, Noormohammadi Z, Askari M et al.
Critical Reviews in Food Science and Nutrition
Pooling 35 RCTs (1,995 participants), zinc supplementation significantly reduced circulating CRP, hs-CRP, TNF-α, IL-6, and neutrophil counts, while increasing CD3 and CD4 levels, supporting zinc's immunomodulatory role in adults.
Effects of zinc supplementation on inflammatory biomarkers and oxidative stress in adults: A systematic review and meta-analysis of randomized controlled trials
Mohammadi H, Talebi S, Ghavami A et al.
Journal of Trace Elements in Medicine and Biology
Zinc supplementation significantly reduced CRP, IL-6, and malondialdehyde (MDA) levels in adults across randomized controlled trials. No significant effects were observed for TNF-α, total antioxidant capacity, glutathione, or nitric oxide concentrations.
Serum zinc levels and efficacy of zinc treatment in acne vulgaris: A systematic review and meta-analysis
Yee BE, Richards P, Sui JY et al.
Dermatologic Therapy
Acne patients had significantly lower serum zinc than healthy controls. Zinc supplementation as monotherapy or adjunctive treatment significantly reduced inflammatory papule counts. No meaningful difference in adverse effects versus control was observed.
Zinc levels in seminal plasma and their correlation with male infertility: A systematic review and meta-analysis
Zhao J, Dong X, Hu X et al.
Scientific Reports
Seminal plasma zinc concentrations were significantly lower in infertile versus fertile men. Zinc supplementation significantly increased semen volume, sperm motility, and percentage of morphologically normal sperm. Authors note further studies are needed to clarify the causal relationship.
Scientific Opinion on Dietary Reference Values for zinc
EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)
EFSA Journal
Using a two-stage factorial model with saturation response modelling, EFSA derived population reference intakes for zinc of 7.5–12.7 mg/day for women and 9.4–16.3 mg/day for men depending on dietary phytate. The tolerable upper intake level was set at 25 mg/day for adults.
Zinc absorption by young adults from supplemental zinc citrate is comparable with that from zinc gluconate and higher than from zinc oxide
Wegmüller R, Tay F, Zeder C et al.
Journal of Nutrition
Crossover study in 15 healthy adults comparing 10 mg elemental zinc from three forms. Fractional absorption of zinc citrate (61.3%) and zinc gluconate (60.9%) were not significantly different from each other but were both significantly higher than zinc oxide (49.9%, p<0.01).
Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans
Barrie SA, Wright JV, Pizzorno JE
Agents and Actions
Double-blind four-period crossover RCT in 15 volunteers (50 mg elemental zinc/day, 4 weeks each form). Zinc picolinate was the only form to significantly raise hair, urine, and erythrocyte zinc versus placebo (p<0.005). Zinc citrate and gluconate produced no significant changes in these tissue markers.
Evidence Database
Click any row to explore the studies behind each health outcome. Grades reflect the volume and quality of published research, not a recommendation.
| Grade | Health Outcome | |
|---|---|---|
| B | Immune Function & Respiratory Infections16 studies | |
| B | Wound Healing9 studies | |
| B | Age-Related Macular Degeneration (AMD)4 studies | |
| C | Testosterone in Deficient Individuals7 studies |
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General Information
Dosage (Evidence-Reported)
These figures reflect what clinical studies used — not personalised recommendations.
Safety Notes
- Chronic supplementation above 25–40 mg/day can cause copper deficiency
- Nausea commonly reported when taken on empty stomach
- May interfere with tetracycline and quinolone antibiotic absorption — separate by 2 hours
- Zinc nasal sprays associated with anosmia case reports — different risk profile from oral forms
- EFSA tolerable upper intake is 25 mg/day from all sources
Key Benefits
- Reduces common cold duration when lozenges initiated within 24 hours of onset
- Supports normal immune cell function (EFSA-authorised claim)
- Essential for wound healing and tissue repair
- May restore testosterone in zinc-deficient men
- High-dose zinc (AREDS formula) reduces AMD progression risk by 25% in at-risk individuals
Quick Facts
Legal food supplement (UK). Multiple EFSA-authorised health claims covering immune function, testosterone, DNA synthesis, and cognitive function. NHS RNI 7–9.5 mg/day. EFSA tolerable upper intake 25 mg/day.
Frequently Asked Questions
Nutripedia is an educational resource. Content is sourced from peer-reviewed studies and does not constitute medical advice. Consult a healthcare professional before starting any supplement.