Some other studies have suggested that antioxidant supplements can boost male fertility, but the results haven't been consistent. A 2008 review of nine studies that looked at the fertility effects of vitamins C and E concluded that the jury was still out. However, an analysis of 34 published studies that appeared in Cochrane Reviews in January suggests that men with fertility problems could roughly quadruple their chances of a pregnancy by taking antioxidants.
It makes some sense that antioxidants could help protect sperm, says Dr. Mark Sigman, co-author of the 2008 report and a urologist on the faculty of the Warren Alpert Medical School of Brown University in Providence, R.I. He explains that vitamins C and E should help clean up free radicals that can slow down and stress out the sex cells. But many men already get plenty of antioxidants in their diet, he says, and not everyone has enough free radicals to hamper fertility.