Infertility is not an insignificant problem, and sperm-related issues play a part in about half of all cases. Low levels or sperm numbers, malformed sperms and sperms that are not mobile enough all can contribute to ‘subfertility’ in men. One factor that is thought can lead to sperm issues is ‘oxidative stress’ – essentially damage caused by entities known as ‘free radicals’ that are a natural by-product 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.
A recent review by the Cochrane Collaboration (an international collective of researchers dedicated to objective reviews of the evidence) recently published a review of 34 studies in which antioxidants were used to treat male subfertility. The antioxidant agents in each of these studies varied a lot. In some, a single agent was used. In others, more than one agent 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 fertilisation (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 per cent increased risk of live birth (in other words, antioxidant takers were about 5 times as likely to have a live birth compared to those taking placebo). Admittedly, though, 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 418 per cent higher in those taking antioxidants (in other words, antioxidant takers were about 4 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.
So-called ‘meta-analyses’ of this nature are never perfect, especially when amassing studies which quite different methodologies (e.g. 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.