Partners of men who take antioxidant supplements are more likely to conceive than those of men who take no such supplements, a Cochrane Review has concluded. But there is no evidence yet on which particular antioxidant(s) may be most beneficial.
Researchers conducted a fairly small systematic review of 34 trials involving 2876 couples who were having treatment to assist reproduction, such as in vitro fertilisation or sperm injection. Most of the male partners in these studies had poor sperm counts and/or low sperm motility.
The trials examined in the review were looking at the effects of many different antioxidants taken orally; they included vitamin E, L-carnitine, zinc and magnesium. Antioxidants help to reduce cell damage thought to be caused, especially to sperm cell number and function, by certain chemicals (reactive oxygen species).
Couples in which the man took antioxidant supplements were more likely to become pregnant and to have a live birth than control couples, in which the man did not take antioxidants. But the authors of the review are at pains to point out that these figures are based on just 964 couples for pregnancy, and 214 couples for live births.
Antioxidants also appeared to be beneficial in the trials that looked at their effect on sperm concentration and motility, but again the group sizes on which these conclusions were based were small.
“When trying to conceive as part of an assisted reproductive programme, it may be advisable to encourage men to take oral antioxidant supplements to improve their partners’ chances of becoming pregnant,” said the lead researcher, Marian Showell from the University of Auckland in New Zealand. “However, these conclusions are currently based on limited evidence.”
She added that there were insufficient data on the relative effectiveness of individual antioxidants to draw any conclusions about which were ‘best’. “We need more head-to-comparisons to understand whether any one antioxidant is performing better than any other,” she said.