SemenBoost

Supplements

Zinc and male fertility

Zinc is required for sperm production. A large trial of zinc and folic acid did not improve semen quality or live birth.

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Short answer

Zinc is involved in spermatogenesis, and deficiency is harmful. That does not mean a zinc tablet helps men who already have enough. A large randomised trial of folic acid and zinc in couples seeking infertility treatment found no improvement in semen quality or live birth. SemenBoost does not recommend zinc to boost fertility.

Key takeaways

  • The negative trial was published in JAMA in 2020 and is more informative than small positive studies.
  • High-dose zinc can cause nausea and, over time, copper deficiency.
  • Diet and deficiency are different questions from a fertility supplement.
  • No zinc product is listed or affiliated here.

What it is

Zinc is a trace mineral used in many enzymes, including in the testes. Semen contains zinc. Severe deficiency, which is uncommon in people eating a varied diet in the UK or US, can impair sperm production. The marketing step from “zinc is necessary” to “extra zinc improves fertility” is the step the large trial does not support.

What the better evidence shows

The FAZST trial randomly assigned men seeking infertility care to folic acid plus zinc or to placebo. Semen parameters did not meaningfully improve, and live birth did not improve. Gastrointestinal symptoms were more common on the supplement. Smaller, older studies had reported parameter changes. They do not outweigh this trial for the outcome that matters.

Safety

Doses well above ordinary dietary intake can cause nausea, cramps and, with prolonged use, copper deficiency and immune or blood changes. Zinc can interfere with some antibiotics if taken at the same time. People should not stack several zinc-containing “fertility” products.

Limits

The trial does not say zinc repletion is useless in someone who is deficient. It says routine supplementation of this kind, in men attending fertility care in that setting, did not improve semen or live birth. SemenBoost will not quote a fertility dose.

Evidence

Insufficient evidence

A large, relevant randomised trial found no benefit for semen quality or live birth from folic acid plus zinc. Biological necessity is not the same as a treatment effect.

Semen parameters

Insufficient evidence

The best single trial did not show a meaningful semen-quality benefit in men seeking infertility treatment.

Pregnancy and live birth

Insufficient evidence

Live birth was not improved in that trial.

A change in a semen measurement is not the same finding as a pregnancy or a live birth.

Related

Sources

  1. Effect of folic acid and zinc supplementation in men on semen quality and live birth — JAMA, 2020
  2. Antioxidants for male subfertility — Cochrane, 2022
  3. Fertility problems: assessment and treatment (NG257) — NICE, 2026
How this page was prepared

Drafted with automated research assistance and checked against the cited primary sources. A named clinician has not reviewed this page. Medical review is pending. Changes to reference values are not published automatically.