January 21, 2011

Can Sub-fertility Be Eased With Antioxidants?

Couples who have trouble conceiving could find help from antioxidants such as vitamin E and zinc, according to a new review of more than 30 studies.

The research focused on men who were sub-fertile -- less fertile than average but still capable of making a baby -- and found that those who took antioxidants were more than four times as likely to impregnate their partners than those who did not take the supplements.

The researchers did not go as far as to say that antioxidants actually improve fertility, however. They say more research is needed to be sure.

Sub-fertility affects about 5 percent of men and is responsible for half of delayed conceptions. Up to 80 percent of cases are thought to be due to the effects oxidative stress on sperm cells, lowering both the number of sperm produced and the quality.

Oxidative stress occurs when molecules known as free radicals damage DNA and cells' ability to function. Antioxidants help to protect cells by stabilizing free radicals.

This discovery has led some experts to wonder if antioxidants might help sperm stay healthy.

"Oral supplementation with antioxidants may go some way to improve a couple's chance of conception," lead researcher Marian Showell of the University of Auckland, in New Zealand, told Reuters Health by email.

To see if the research backs up that idea, Showell and her colleagues reviewed 34 studies that involved nearly 3,000 couples undergoing fertility treatments, including in vitro fertilization (IVF) and intrauterine insemination. Each study probed the potential role of one or more antioxidants.

Based on 96 pregnancies among 964 couples in 15 of those studies, the team found that antioxidants used by the male partner increased the odds of conception four-fold.

Furthermore, men using antioxidants improved the likelihood of their partners giving birth to a live baby five-fold, the researchers said. However, only three of the studies contained data on live births.

"The findings of increased live birth rates with antioxidants are based on a total of only 20 births -- a relatively small number," Dr. Mark Sigman of Brown University, in Providence, R.I., who was not involved in the review, told Reuters Health in an e-mail.

Sigman, whose research found no improvement in semen quality with the antioxidant carnitine, would not put too much strength into the results of the review.

He said the studies included in the review did not use the same types of numbers of antioxidants. As a result, the researchers could not determine the effectiveness of any individual supplement.

Both Sigman and Showell did caution that couples should not rely on antioxidants to overcome their fertility shortfalls. Even if certain supplements prove effective, more research is needed to determine which couples could reap the benefits.

"It is unrealistic to think one treatment will be good for most couples," noted Sigman.

"There is no evidence that antioxidants cause harm "¦ But since we also don't know which antioxidants or doses are beneficial -- and none have FDA approval for infertility -- consumers are left with purchasing these based on very limited data," he added.

The research was published in the Jan. 19th issue of The Cochrane Library.

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