Can antioxidants boost men's fertility? A recent study suggests that it's worth looking into.

In a study analyzing 34 separate clinical trials of couples with fertility problems, couples where men took antioxidant supplements had both more pregnancies and more live births.

In couples where the men took antioxidants, the pregnancy rate was four times higher than in couples where the men took no supplements.

The researchers stop short of saying that antioxidants increase male fertility. Couples where men took antioxidant supplements were likelier to become pregnant and to give birth. Answering whether the antioxidants caused this is beyond the scope of the study.

Much of male infertility is thought to be due to the damaging effect of oxidative stress on sperm cells, lowering their number and quality. In theory, antioxidants could help counteract this problem.

The study looked at published randomized control trials comparing any type or dose of antioxidant supplement taken by the male partner of a couple seeking fertility assistance to a placebo, no treatment or another antioxidant. It found 34 such studies with 2,876 couples in total.

In 15 of these trials, there were 96 total pregnancies reported. In couples where the men took antioxidants, the pregnancy rate was four times higher than in couples where the men took no supplements. In the three trials that reported live births, couples where men took antioxidant supplements had a five-time higher birth rate. There were 20 live births among 214 couples in these three studies.

None of the studies reported evidence of any harmful side effects from antioxidants.

Mark Sigman is an associate professor at Brown University with more than 20 years of experience in the diagnosis and treatment of male reproductive problems. Dr. Sigman, who was not associated with the study, is cautious about making too much of the study results. In an e-mail to Reuters Health, Sigman points to the small number of live births in the studies and also notes that the studies did not use the same types or numbers of antioxidants and so offer no clue as to which particular antioxidants might be effective.

A 2009 study of visitors to a Spanish fertility clinic found that men with poor sperm quality tended to eat a diet high in meat and dairy and low in fruits and vegetables. This suggests that men looking to boost their antioxidant level could simply eat more fruits and vegetables and not worry about which specific antioxidant might be helping them out.

The study on antioxidant supplementation was published online January 19, 2011 by the Cochrane Library.

Mark Sigman, MD, is an Associate professor of urologic surgery at the Warren Alpert Medical School of Brown University. He is a member of the urology staff at five hospitals: Rhode Island Hospital, Providence VA Medical Center, The Miriam Hospital, Women & Infants Hospital and Memorial Hospital of Rhode Island. Dr. Sigman is also the Co-Director of the Men’s Health Clinic based out of the Miriam Hospital.