The Role of Antioxidants in Male Fertility (Updated)

In the past, it was commonly accepted that antioxidants serve as a boost for male fertility. In fact, antioxidant supplements are commercially available for that exact purpose. But why exactly did that practice become so commonplace?

Back in 2009, the Cleveland Clinic wrote a scientific article detailing the role of antioxidants in the treatment of male fertility. Antioxidants were thought to be helpful because of something called oxidative stress, or the imbalance between free radicals and antioxidants in our bodies. 

So, oxidative stress is induced by the presence of too many free radicals in our body. What does that have to do with male fertility? Well, too many free radicals have been correlated with decreased sperm motility, increased sperm DNA damage, and other detriments to sperm quality. 

In the study from the Cleveland Clinic, researchers identified antioxidants as one potential way to lower oxidative stress. However, even in 2009 the scientists admitted some faults in the study. There was conflicting data from two different centers- in one case, an antioxidant supplement proved to be significant over a placebo, and in the other, no significant change in sperm quality was found.

Since that report, other studies have been conducted on antioxidants, and antioxidants came to be believed to improve male fertility. Roughly ten years later, though, we have a new perception on antioxidant supplements for male fertility.

The Study

Published in February of this year, this new study comes from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, or NICHD. They studied the effects of antioxidant supplements on male fertility through a double-blind, randomized, placebo-controlled clinical study. 

These studies were conducted at nine sites across the United States, enrolling 171 couples total. For each couple, the male partner had at least one abnormal reading in sperm count, motility, shape, and DNA quality. However, the female partners all had normal fertility results. From there, the male partners received either an antioxidant supplement or a placebo. In the case of the supplement, the supplement also contained other vitamins and minerals such as Vitamin C, E, and D, zinc, and folic acid.

The men in the study took their assigned supplement for at least three months, with a maximum of six months total. During this time period, researchers collected data on sperm quality, and intended to collect further data on pregnancy rates and live birth rates.

Key Findings

When looking at the data between the placebo group and the antioxidant group, there was no statistical significance in the difference in sperm quality between the two groups. So, the results on antioxidant supplements’ effect on sperm quality were conclusive. Antioxidant supplements do not improve semen quality in males with infertility. 

However, what about pregnancy and live birth rates? Well, researchers at NICHD had initially set out to measure that data as a part of this study. However, this aspect of the study was cut short due to the study design. 

After no benefits of the antioxidants were found in the antioxidant group, further recruitment for the study was stopped. As a repercussion of that event, the study was stopped before they had acquired enough participants to study pregnancy and live birth rates. 

So, while the live birth rates did not appear to differ at six month between the antioxidant and placebo groups, that data cannot be taken as conclusive. Further studies will need to be done on pregnancy and live birth rates in order to draw conclusions about antioxidants’ full effect on male fertility.

Big Takeaways

This study is groundbreaking for a number of reasons. For one, is significant because of its methodology. Thus far, this study was the largest randomized, placebo-controlled trial to examine the effects of antioxidants on male infertility without additional assisted reproductive technology! 

However, this study is even more impactful because of its conclusive findings. This study finally dispels the idea that antioxidants have a significant positive effect on male infertility. This was such a widely-accepted idea for a long time, and disproving it can only have positive effects on the future of fertility science. Hopefully now we can refocus our treatment efforts on other supplements or medications, and better help people on their fertility journeys in the future.