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Study analysis · Urology journal · 2017

This one supplement combo doubled sperm count in infertile men—here's what the science actually says.

Taking folate and zinc together helps men with low sperm count make more sperm with better shapes, but doesn't help them swim better or change their hormones.

Reading level
Very low certainty
Level 1a · Systematic review of RCTs

Overview

What the study found

The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.

In simple terms

This study looked at many smaller experiments where men took folate or zinc and saw if their sperm got better. It found that, on average, their sperm count improved a bit, but it didn't prove that the supplements caused the improvement in every case.

What’s the bottom line?

This study looked at whether taking folate or folate plus zinc pills helps men who have trouble having babies by improving their sperm.

How strong is this study?

This is like checking the report card of several science fair projects and saying, 'Most of them showed improvement.' But we didn't see how each project was done, so we can't be 100% sure they were all fair tests. That's why we need to be careful about trusting the results too much.

Reporting

0 / 100

  • COI disclosureconflicts of interest not disclosed
  • Data availabilitydata not shared
  • Code availabilitycode not shared
Methodology

0 / 100

  • Randomizationrandomization unclear
  • Blindingblinding unclear
  • Control groupno control group
  • Sample sizeno sample size reported
  • Follow-upno follow-up reported
Publication

100 / 100

Statistical

54 / 100

  • P-values+15/15
  • Effect size+20/20
  • Confidence intervalsno confidence intervals
  • Pre-registrationnot pre-registered

Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.

Where it sits

RCT reviews

Max 100

Randomized Trials

Max 90

Reviews of Cohort Studies

Max 85

Cohort Studies

Max 72

Reviews of Case-Control Studies

Max 63

Case-Control Studies

Max 58

Cross-Sectional & Case Series

Max 50

Expert Opinion

Max 5
StrongerWeaker
Reviews of RCTs (Meta-analyses)
Level 1a
33

33 / 100

Probability of being correct

The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.

This design can establish causation. The abstract explicitly states that the systematic review included randomized controlled trials (RCTs), which are the highest-quality studies for establishing causation. However, the review itself does not perform new randomization, so causation is inferred from the included RCTs, not directly tested.

No Conflicts

No conflicts of interest identified

No conflicts of interest or funding information were disclosed in the provided text.

The study is a systematic review and meta-analysis with no disclosed funding sources or author conflicts. However, the absence of a COI or funding statement raises a minor transparency concern, though no evidence of bias or industry influence is present.

Key takeaways

  1. 01

    Folate alone: sperm count went up (P < .001), but shape and movement didn't change.

  2. 02

    Folate + zinc: sperm count and shape improved (both P < .001), but movement and hormones didn't change.

  3. 03

    Yes — for men with low sperm count, taking folate or folate plus zinc may help increase the number of sperm and improve their shape, which could help with fertility.

Surprising findings

  • Folate plus zinc improved sperm morphology (shape) but not motility (movement), despite both being critical for fertility.Most assume that if a supplement improves sperm shape, it should also help them swim better—but this study shows they’re independent effects.
  • Zinc did not increase testosterone levels, contradicting widespread supplement marketing.Zinc is heavily promoted as a testosterone booster, yet this meta-analysis found no statistically significant change in serum testosterone (P = .86).

Practical takeaways

Men with low sperm count may consider taking a folate and zinc supplement combo to improve sperm concentration and shape.

This study only looked at short-term effects in sub-fertile men; no data on pregnancy outcomes, long-term safety, or optimal dosage.

low confidence

Why this study matters

Folate Alone Boosts Sperm Count

Folate supplementation alone increased sperm concentration by a statistically significant margin (P < .001), but had no meaningful effect on sperm shape (P = .056) or movement (P = .652).

Most people think vitamins help all aspects of sperm health—but this shows folate only helps with quantity, not quality or movement.

Folate + Zinc: The Power Duo for Shape and Count

Combining folate and zinc significantly improved both sperm concentration (P < .001) and morphology (P < .001)—but still had zero effect on motility (P = .169) or key hormones like testosterone (P = .86).

It’s rare to find a supplement combo that improves two sperm metrics at once—yet it ignores the most commonly sought-after trait: swimming ability.

No Hormone Changes—Even With Zinc

Despite zinc’s reputation for boosting testosterone, this study found no significant change in testosterone (P = .86), inhibin B (P = .84), or FSH (P = .054) after folate plus zinc supplementation.

Zinc is marketed as a testosterone booster—but here, it didn’t budge hormones at all, even while improving sperm shape and count.

Want the whole report?

Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.