New study finds zinc and folic acid supplements are ineffective at improving male fertility

A new study has revealed that taking zinc and folic acid supplements do not improve male fertility as has previously been suspected.

folic acidImage Credit: Jinning Li /

Male fertility supplements disproven by wide-scale study

Researchers at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), part of the National Institutes of Health, conducted a four-year-long study in which they investigated the impact of taking dietary supplements of zinc or folic acid on the fertility of male participants.

The supplements, which have been marketed as a treatment for male infertility, were found not to have any impact in improving pregnancy rates or increasing sperm count or sperm function.

No signs of fertility improvement found after four-year study

Previously, scientists had been conflicted over whether zinc and folic acid supplements could genuinely boost male fertility. While it is known that the mineral of zinc is essential for sperm formation, and folic acid uses zinc to help form DNA in the sperm, the impact of taking dietary supplements had not been proven. Numerous earlier studies can generate discordant results.

This week, the US team published findings of their latest study into the effectiveness of these supplements in the Journal of the American Medical Association. The team had enlisted 2,370 couples who were seeking infertility treatments in four different US cities.

While previous studies have looked into the effectiveness of these kinds of supplements, the current study was one of the very first to use randomized, placebo-controlled trials.

The researchers allocated couples into one of two groups, the experimental group, where the male was given a daily supplement containing 5 milligrams of folic acid and 30 milligrams of zinc, and a placebo group, where the male was instead given placebo supplements that were designed to match the real supplements in appearance, size, taste, and weight. This ensured that couples were unaware of which group they had been assigned to.

The men took the supplements for a period of six months to test whether zinc and folic acid supplements would have a significant impact on various measures of fertility. Researchers found that there was no significant difference between the live birth rates of the experimental group or the placebo group (34% vs. 35%, respectively).

Nor did they find any improvement in semen quality, which was measured six months later. Researchers found that no significant difference was measured between other measures of sperm health, such as movement, shape, or total sperm count.

However, interestingly the team found that sperm DNA fragmentation, which is associated with male infertility, was actually higher in the supplement group in comparison with the placebo group. If the supplements were to improve fertility, it would be expected that DNA fragmentation would be lower, not higher, as a result of taking them.

Pregnancy supplements have also been found to be ineffective

This study comes just a few years after a study into the effectiveness of pregnancy multivitamins for women revealed that the supplements were ineffective at improving mothers’ or babies’ health. The scientists involved in this study dubbed the supplements as an expensive waste of time. They also criticized the marketing for the products for not being founded on actual scientific fact.

Other than folic acid, which has been proven to have a therapeutic role in the prevention of neural tube disorders, all other pregnancy supplements have failed to yield significant results in the lab.

The overall message is that the claims of dietary supplements for both male fertility and maternal/baby health are mostly not backed up by strong scientific evidence. While there is often no harm associated with taking them, the benefits are not supported, leading to people laying their hopes on products that don’t work.

Journal reference:

Schisterman, E.F. et al. (2020). Effect of Folic Acid and Zinc Supplementation in Men on Semen Quality and Live Birth Among Couples Undergoing Infertility Treatment. JAMA. DOI: 10.1001/jama.2019.18714

Sarah Moore

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Sarah Moore

After studying Psychology and then Neuroscience, Sarah quickly found her enjoyment for researching and writing research papers; turning to a passion to connect ideas with people through writing.


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