Infertility is not an insignificant problem, and sperm-related issues play a part in about half of all cases. Low levels of sperm, malformed sperm, and sperm that are not mobile enough all can contribute to subfertility in men.
One factor that is thought to lead to sperm issues is oxidative stress—damage caused by entities known as free radicals, which are natural by-products of many processes in the body, including metabolism.
Free radicals can be quenched by substances called antioxidants (including many nutrients). This has led some researchers to assess the effect of antioxidant treatments on fertility in men.
“Antioxidants for Male Subfertility” was published in the Cochrane Database of Systematic Reviews 2011, Issue 1. This article was a review of 34 studies that reported the use of antioxidants in treating male infertility.
The antioxidant agents in each of these studies varied a lot. In some, a single agent was used. In others, agents were combined together. The agents themselves varied considerably and included zinc, vitamin E, vitamin C, L-carnitine, and selenium. All couples in these studies were undergoing assisted reproductive technologies (ARTs), such as in-vitro fertilization (IVF) and intrauterine insemination (IUI).
Amassing all the studies together, the Cochrane researchers attempted to assess if antioxidant therapy appeared to have any benefits on fertility outcomes. They found that compared with placebo, treatment with antioxidant supplementation was associated with a 485 percent increased incidence of live birth. (In other words, antioxidant takers were about five times as likely to have a live birth compared to those taking placebo.)
Admittedly, this finding was based on only 20 live births, (small numbers), which make the findings less robust than if we were looking at significantly bigger numbers.
Rate of pregnancy was also assessed, and this time the numbers were larger (96 pregnancies in total, from 15 trials and a total of 964 couples). Here, rates of pregnancy were found to be 418 percent higher in those taking antioxidants. (In other words, antioxidant takers were about four times as likely to impregnate their partners compared to those taking placebo.)
None of the studies reported evidence of harmful effects of the antioxidant therapy.
Meta-analyses of this nature are never perfect, especially when amassing studies of quite different methodologies (for example, different treatments in different combinations). However, this review does at least strongly suggest that antioxidant treatment has significant potential to enhance male fertility and improve the success rates of assisted-reproduction techniques such as IVF.