Zinc for Male Infertility

Verdict: Zinc does not treat male infertility

For male infertility, high-quality evidence shows zinc supplementation does not improve live births, pregnancy, or any sperm parameter, so it is not a recommended treatment. A possible exception is men with documented zinc deficiency, in whom supplementation may help.

D 🔴 D Counter-Evidence Counter-Evidence

🔬Why this grade7-layer evidence engine

This claim is graded D (counter-evidence) because the decisive trial is firmly negative. The FAZST randomized, double-blind, placebo-controlled trial (PMID 31910279, n=2,370) tested 30 mg zinc plus 5 mg folic acid for 6 months and found no improvement in live birth (34% vs 35%) and no improvement in any semen measure (concentration, motility, morphology, volume, total motile count). DNA fragmentation was actually slightly higher with supplements, and gastrointestinal side effects were more common.

Later syntheses reinforce this. A 2023 meta-analysis (PMID 37539255, n=2,168) found the zinc-plus-folic-acid arm produced no significant change in sperm motility, concentration, or morphology, and a 2025 meta-analysis of 50 trials (PMID 40431450) concluded there is no convincing evidence that any dietary supplement improves pregnancy or live birth. A 2022 Cochrane review (PMID 35506389) saw an overall antioxidant signal, but zinc was not analyzed separately and the live-birth benefit disappeared (OR 1.22, not significant) once high-bias studies were removed.

Regulators and clinics align with this caution. The AUA/ASRM guideline advises clinicians that supplement benefits are of "questionable clinical utility" in male infertility, while Mayo Clinic and Cleveland Clinic limit any value to men with documented zinc deficiency or oxidative-stress infertility rather than routine use. A 2025 review (PMID 40002352) likewise restricts possible benefit to zinc-deficient men, with evidence weak or inconsistent in those who are zinc-replete.

⚖️

Scoring transparency

All scores computed by a 7-layer evidence engine — fully auditable

Raw score 0.44

← counter-evidence / ineffectiveeffective / strong evidence →

Final grade

D · Counter-Evidence

Confidence

84%

Highly consistent evidence

Evidence level

Cochrane high-quality SR/MA

How strongly each layer supports this effect

lower = less supportive

L11 AI re-checkIndependent read

0.30

L5 Clinical bodiesAuthoritative stance

0.43

L2 PubMedPrimary literature

0.45

L3 MechanismPlausibility

0.45

L1 ExamineGlobal benchmark

0.50

Against Mixed Supports

▸View the full decision path (audit trail)

compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.436
tier_from_score — 依分數區間映射至 tier letter
apply_hec_rules — 高品質 SR/MA 顯示 negative 主導 (2 negative > 1 positive)，下層 RCT 不能推翻
apply_hec_override — HEC-1 高階證據 negative — 強制由 C 改為 D
tier_strict_requirement_check — Tier 條件達標，未降階
detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
decide_status — 依 tier + dispute 結果決定 status

📄PubMed studies (5)L2 · primary research & systematic reviews

Effect of Folic Acid and Zinc Supplementation in Men on Semen Quality and Live Birth Among Couples Undergoing Infertility Treatment: A Randomized Clinical Trial (FAZST)

PMID: 31910279 2020 RCT (double-blind) n = 2,370

Finding: Zinc + folic acid did NOT improve live birth (404/1185, 34% vs 416/1185, 35%; risk difference -0.9%, 95% CI -4.7 to 2.8). NO significant differences in any semen quality parameter at 6 months: sperm concentration, total motility, morphology, semen volume, total motile sperm count all n.s. between groups. DNA fragmentation was paradoxically HIGHER in the supplementation arm (29.7% vs 27.2%, MD +2.4%, 95% CI 0.5 to 4.4). GI side effects more common with active treatment (abdominal pain 6% vs 3%; nausea 4% vs 2%; vomiting 3% vs 1%). Authors conclude findings do not support use of folic acid + zinc supplementation in male infertility.

🟢 High quality Academic Effect size: [object Object]

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Antioxidants for male subfertility (Cochrane Review, pub5 update)

PMID: 35506389 2022 Cochrane SR n = 10,303

Finding: Antioxidants overall may increase live birth (12 RCTs, n=1283: OR 1.43, 95% CI 1.07-1.91) and clinical pregnancy (20 RCTs, n=1706: OR 1.89, 95% CI 1.45-2.47, p<0.00001). When high-risk-of-bias studies removed, live birth signal lost significance (OR 1.22, 95% CI 0.85-1.75, p=0.27). GRADE: very low-certainty for live birth, low-certainty for pregnancy. Zinc-specific subgroup analyses for live birth/pregnancy not reported. Mild GI side effects more common with antioxidants overall (OR 2.70, 95% CI 1.46-4.99).

🟢 High quality Academic Effect size: [object Object]

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Effects of folic acid and folic acid plus zinc supplements on the sperm characteristics and pregnancy outcomes of infertile men: A systematic review and meta-analysis

PMID: 37539255 2023 統合分析 n = 2,168

Finding: Folic acid + ZINC subgroup: NO significant effect on sperm concentration (MD +1.87, 95% CI -1.39 to 5.13, p=0.26), motility (MD +1.67, 95% CI -1.29 to 4.63, p=0.27), or morphology (MD -0.05, 95% CI -0.27 to 0.18, p=0.69). Folic acid ALONE improved motility (MD +3.63, 95% CI -1.22 to 6.05, p=0.003) but not concentration/morphology. Pregnancy rate in transferred embryos higher with folic acid (35.6% vs 20.4%, p=0.082) but not significant. Combined zinc+folic acid arm shows NO benefit over placebo across any sperm parameter — confirms FAZST direction.

Effect size: [object Object]

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The Effect of Dietary Supplements on Male Infertility in Terms of Pregnancy, Live Birth, and Sperm Parameters: A Systematic Review and Meta-Analysis

PMID: 40431450 2025 統合分析

Finding: Across all dietary supplements (including zinc + folic acid), NO effect on pregnancy or live birth was observed. Zinc + folic acid did improve sperm concentration in the surrogate-endpoint pool. Authors conclude there is 'no convincing evidence of an effect of any dietary supplements on male infertility' for the patient-relevant outcomes (pregnancy, live birth). GRADE certainty rated 'generally low or very low' across outcomes.

Academic

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Association Between Zinc Levels and the Impact of Its Deficiency on Idiopathic Male Infertility: An Up-to-Date Review

PMID: 40002352 2025 系統性回顧

Finding: Seminal plasma zinc is consistently lower in infertile vs fertile men. Zinc-DEFICIENT infertile men may benefit from supplementation (improvements in motility, morphology, count); however, in zinc-replete men evidence is weak/inconsistent. Both deficiency and excess can cause oxidative stress harming spermatogenesis. Authors recommend assessing seminal plasma zinc to guide treatment rather than empirical supplementation. No pooled effect size; conclusions described as 'not yet conclusive' for sperm parameters and absent for pregnancy/live birth outcomes.

Academic

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🏛️Regulatory & authoritative positionsL4/L5 · FDA / EMA / NIH ODS / Cochrane / Mayo …

L4b EU EFSA

Supportive

contributes to normal function of the immune system source↗

L4c UK NHS

Cautious

You should be able to get all the zinc you need from your daily diet source↗

L4d TW TFDA / 衛福部

Supportive

鋅之每日最高攝食量不得超過30 mg source↗

L4e WHO

Supportive

zinc has been recommended by WHO and UNICEF as the only treatment to be coupled with oral rehydration salts for the treatment of all diarrhoea episodes source↗

L5a NIH Office of Dietary Supplements

Supportive

Zinc is an essential mineral involved in numerous aspects of cellular metabolism source↗

L5b Mayo Clinic

Cautious

zinc is essential for normal sperm production source↗

L5c Cleveland Clinic

Cautious

Male oxidative stress infertility (MOSI) is really the only condition that can be treated effectively with male fertility supplements. source↗

L5e Specialty Society (condition-mapped)

Cautious

Clinicians should counsel patients that the benefits of supplements (e.g., antioxidants, vitamins) are of questionable clinical utility in treating male infertility. source↗

✓PMID 100% verifiedevery citation checked via NCBI Entrez

🔬5 PubMed studiesindependently re-checked by multiple sub-agents

engine_version: v1.0 claim_id: CLM-COND-male-infertility-INT-zinc-001 繁體中文版 →