Do antioxidant supplements improve male fertility?

This review article looked at the effect of antioxidant supplements on male fertility. Low-quality evidence suggests supplements improve birth rates among the male partners of couples with low fertility.

Male infertility contributes to 40 – 50% of infertility cases. One of the causes of male infertility is oxidative stress (OS). OS is when there is an imbalance between reactive oxygen species and the capacity of the body to detoxify. Because sperm do not create antioxidant enzymes, they are more easily damaged by OS than other cells. OS can make the sperm less flexible, preventing them from moving normally. OS can also damage the DNA of sperm. Antioxidants from food or supplements can prevent OS and may improve male fertility. However, the effects of different antioxidants on males in couples with low fertility are uncertain.

This article reviewed 61 studies. The studies included 6264 men with infertility and examined the effects of 18 antioxidants. The authors rated the studies for biases which could lead to false results.

Out of 100 couples similar to those studied, 12 would have a baby if the men were not taking antioxidants. If the men were taking antioxidants, between 14 and 26 would have a baby.

Men who took coenzyme Q10 were 2.16 times more likely to have a live birth. Men who took both zinc and folic acid were 3.86 times more likely to get pregnant. Partners of men who took zinc alone were also significantly more likely to get pregnant and give birth.

Men who took vitamin E were 8.51 more likely to have a live birth. However, this study had a high risk of bias. Studies of carnitines and vitamin D plus calcium found no benefit. 

The main side effect of antioxidant supplements was an upset stomach.

This review looked at the effect of antioxidant supplements on male fertility. It found that supplements including coenzyme Q10 and zinc improved pregnancy rates.

The authors rated the studies for biases including whether the subjects knew they were receiving an antioxidant or a placebo, and whether all results were reported. The evidence was judged to be of low quality. More studies are needed.