{"@context":"https://schema.org","@type":"DietarySupplement","id":"https://nutripedia.co.uk/items/zinc","url":"https://nutripedia.co.uk/items/zinc","name":"Zinc","category":"Minerals","tagline":"Essential trace mineral for immunity, testosterone, and wound healing.","verdict":"promising","evidenceRating":4,"verdictSummary":"Good evidence for immune support and deficiency correction. Testosterone benefits are mainly seen in those who are zinc-deficient.","dosage":{"recommended":"15–30","unit":"mg","timing":"With food to reduce nausea","notes":"Zinc picolinate and citrate have better absorption than oxide. Long-term high doses can deplete copper."},"keyBenefits":["Supports immune cell function and defence","Important for testosterone production in deficient individuals","Aids wound healing and tissue repair","Supports skin health"],"warnings":["Chronic supplementation above 40 mg/day may cause copper deficiency","Can cause nausea on an empty stomach","May interfere with antibiotic absorption"],"evidenceSummary":null,"dosing":null,"safety":null,"whoMightBenefit":[],"whoShouldAvoid":[],"regulatoryNotes":null,"faqs":[{"question":"What does the research say about zinc and the common cold?","answer":"A 2015 meta-analysis of zinc lozenges (both acetate and gluconate forms) found that when initiated within 24 hours of cold symptom onset, zinc lozenges shortened cold duration by approximately 33%. A double-blind RCT (n=50) found cold duration reduced from 7.1 to 4.0 days with zinc acetate lozenges. Effectiveness appears highly dependent on the zinc salt used and lozenge formulation — effect is not seen with zinc syrup or nasal sprays in the same way."},{"question":"What dosage ranges have been studied for zinc?","answer":"The NHS RNI for adults is 9.5 mg/day (men) and 7 mg/day (women). Cold treatment trials have used 75–150 mg/day of elemental zinc in lozenge form for short durations. Long-term supplementation studies have used 15–30 mg/day. EFSA has established a tolerable upper intake level of 25 mg/day for adults from all sources combined; the AREDS trial used 80 mg/day but noted copper supplementation was required to prevent induced deficiency."},{"question":"What side effects have been reported in zinc trials?","answer":"Nausea and GI discomfort are the most commonly reported adverse events in zinc supplementation trials, particularly on an empty stomach. Chronic supplementation above 25–40 mg/day consistently reduces copper absorption, with risk of copper deficiency anaemia and potential neurological effects. The EFSA tolerable upper intake of 25 mg/day accounts for this copper interaction. Zinc nasal sprays have been associated with anosmia (loss of smell) in case reports."},{"question":"Is there evidence for zinc and testosterone?","answer":"A landmark study found testosterone roughly doubled in marginally zinc-deficient elderly men given 25 mg/day for 6 months, and young men on a zinc-restricted diet experienced approximately 73% testosterone decline. However, a 2021 systematic review found inconsistent effects across studies and concluded benefits were primarily confined to those with confirmed zinc deficiency at baseline. In zinc-replete individuals, supplementation has not reliably raised testosterone in clinical trials."},{"question":"Which form of zinc has the strongest evidence base?","answer":"For common cold treatment, zinc acetate lozenges have the most consistent evidence. For general supplementation, zinc picolinate and zinc citrate show better bioavailability in absorption studies compared to zinc oxide. A single-dose crossover study found zinc picolinate produced higher plasma and erythrocyte zinc levels than zinc gluconate or zinc oxide. Zinc oxide, while cheap, has substantially lower bioavailability and is less preferred in clinical studies."},{"question":"What do NHS and EFSA say about zinc?","answer":"EFSA has authorised health claims for zinc's contribution to normal DNA synthesis, acid-base metabolism, carbohydrate metabolism, cognitive function, fertility and reproduction, macronutrient metabolism, maintenance of bones/hair/nails/skin, normal protein synthesis, normal testosterone levels, normal vision, and immune function. NHS notes that most people get sufficient zinc through diet; the main at-risk groups are those with malabsorption conditions, vegetarians (who absorb less plant-source zinc due to phytates), and heavy drinkers."},{"question":"What does research say about zinc and eye health (AMD)?","answer":"The landmark AREDS trial (n=3,640, 6.3 years) found that high-dose zinc (80 mg/day elemental) combined with antioxidant vitamins reduced progression to advanced age-related macular degeneration by 25% in high-risk individuals (those with intermediate AMD or advanced AMD in one eye). This is one of the few large RCTs demonstrating a meaningful clinical outcome for zinc supplementation. AREDS formulas are specifically formulated for AMD risk reduction under ophthalmic guidance."}],"research":{"totalCount":14,"papers":[{"title":"Zinc — Health Professional Fact Sheet","year":2026,"journal":"NIH Office of Dietary Supplements","doi":null,"pmid":"","url":"https://pubmed.ncbi.nlm.nih.gov//","studyDesign":"position-stand","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Systematic review and meta-analysis of the effect of zinc on wound healing","year":2025,"journal":"BMJ Nutrition, Prevention & Health","doi":"10.1136/bmjnph-2024-000952","pmid":"40771531","url":"https://doi.org/10.1136/bmjnph-2024-000952","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Comparative Absorption and Bioavailability of Various Chemical Forms of Zinc in Humans: A Narrative Review","year":2024,"journal":"Nutrients","doi":"10.3390/nu16244269","pmid":"39770891","url":"https://doi.org/10.3390/nu16244269","studyDesign":"systematic-review","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Zinc Toxicity: Understanding the Limits","year":2024,"journal":"Molecules","doi":"10.3390/molecules29133130","pmid":"38999082","url":"https://doi.org/10.3390/molecules29133130","studyDesign":"systematic-review","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Zinc for prevention and treatment of the common cold","year":2024,"journal":"Cochrane Database of Systematic Reviews","doi":"10.1002/14651858.CD014914.pub2","pmid":"38719213","url":"https://doi.org/10.1002/14651858.CD014914.pub2","studyDesign":"systematic-review","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Correlation between serum zinc and testosterone: A systematic review","year":2023,"journal":"Journal of Trace Elements in Medicine and Biology","doi":"10.1016/j.jtemb.2022.127124","pmid":"36577241","url":"https://doi.org/10.1016/j.jtemb.2022.127124","studyDesign":"systematic-review","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Zinc Deficiency","year":2023,"journal":"StatPearls [Internet]. StatPearls Publishing","doi":null,"pmid":"29630283","url":"https://pubmed.ncbi.nlm.nih.gov/29630283/","studyDesign":"position-stand","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Zinc supplementation and immune factors in adults: a systematic review and meta-analysis of randomized clinical trials","year":2022,"journal":"Critical Reviews in Food Science and Nutrition","doi":"10.1080/10408398.2020.1862048","pmid":"33356467","url":"https://doi.org/10.1080/10408398.2020.1862048","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Effects of zinc supplementation on inflammatory biomarkers and oxidative stress in adults: A systematic review and meta-analysis of randomized controlled trials","year":2021,"journal":"Journal of Trace Elements in Medicine and Biology","doi":"10.1016/j.jtemb.2021.126857","pmid":"34560424","url":"https://doi.org/10.1016/j.jtemb.2021.126857","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Serum zinc levels and efficacy of zinc treatment in acne vulgaris: A systematic review and meta-analysis","year":2020,"journal":"Dermatologic Therapy","doi":"10.1111/dth.14252","pmid":"32860489","url":"https://doi.org/10.1111/dth.14252","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Zinc levels in seminal plasma and their correlation with male infertility: A systematic review and meta-analysis","year":2016,"journal":"Scientific Reports","doi":"10.1038/srep22386","pmid":"26932683","url":"https://doi.org/10.1038/srep22386","studyDesign":"meta-analysis","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Scientific Opinion on Dietary Reference Values for zinc","year":2014,"journal":"EFSA Journal","doi":"10.2903/j.efsa.2014.3844","pmid":"","url":"https://doi.org/10.2903/j.efsa.2014.3844","studyDesign":"regulatory","fields":[],"conclusion":"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.","abstract":"","citationCount":0},{"title":"Zinc absorption by young adults from supplemental zinc citrate is comparable with that from zinc gluconate and higher than from zinc oxide","year":2014,"journal":"Journal of Nutrition","doi":"10.3945/jn.113.181487","pmid":"24259556","url":"https://doi.org/10.3945/jn.113.181487","studyDesign":"rct","fields":[],"conclusion":"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).","abstract":"","citationCount":0},{"title":"Comparative absorption of zinc picolinate, zinc citrate and zinc gluconate in humans","year":1987,"journal":"Agents and Actions","doi":"10.1007/BF01974946","pmid":"3630857","url":"https://doi.org/10.1007/BF01974946","studyDesign":"rct","fields":[],"conclusion":"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.","abstract":"","citationCount":0}]},"machineReadable":{"markdownUrl":"https://nutripedia.co.uk/items/zinc/markdown","jsonUrl":"https://nutripedia.co.uk/items/zinc/json","llmsTxt":"https://nutripedia.co.uk/llms.txt"},"disclaimer":"Informational supplement research only. Not medical advice. Consult a qualified healthcare professional before taking supplements.","lastReviewed":"2026-04-20T00:00:00.000Z","updatedAt":"2026-04-20T00:00:00.000Z"}