January 19, 2010 — Oral antioxidants for men may help some couples who are experiencing difficulty conceiving to achieve pregnancy, according to a review published online January 19 in the Cochrane Database of Systematic Reviews.
One in 20 men is affected by subfertility. In many cases, the difficulty may be traced to sperm cells altered by reactive oxygen species. Antioxidants may lessen such damage.
"Between 30% to 80% of male subfertility cases are considered to be due to the damaging effects of oxidative stress on sperm," write Marian Showell, MPH, from the University of Auckland, New Zealand, and colleagues. "Oral supplementation with antioxidants may improve sperm quality by reducing oxidative stress."
The reviewers examined 34 randomized controlled trials consisting of 2876 couples. The individuals' mean ages ranged from 20 to 52 years. Each couple was trying to conceive using in vitro fertilization, sperm injections, and other assisted reproductive techniques after 1 year of regular intercourse that did not lead to conception.
Vitamin E, L-carnitine, zinc, and magnesium were among the types of oral antioxidants tested.
Live birth per couple randomized was the primary outcome. To perform statistical analysis of the data, the investigators used Review Manager 5 software.
Results Show Antioxidant Use to Be Statistically Significant
In the 3 studies reporting live birth and the 15 reporting pregnancies, antioxidant supplements were found to have a positive effect, as follows:
20 live births (18 associated with men taking oral antioxidants, 2 in the control group) took place among a total of 214 couples;
a statistically significant increase in live birth was associated with the antioxidants (pooled odds ratio [OR], 4.85; 95% confidence interval [CI], 1.92 - 12.24; P = .0008, I 2 = 0%) compared with control groups;
96 pregnancies (82 associated with antioxidants, 14 from the control group) occurred among 964 couples;
a statistically meaningful increase in pregnancy rates was associated with antioxidant use (pooled OR, 4.18; 95% CI, 2.65 - 6.59; P < .00001; I 2 = 0%); and
analysis of the 2 trials reporting both live birth and pregnancy also showed a significant positive relationship with antioxidants (pooled OR, 9.64; 95% CI, 2.47 - 37.70; P = .001; I 2 = 0%).
"When trying to conceive as part of an assisted reproductive program, it may be advisable to encourage the male partner to take an oral antioxidant supplement to improve his partner's chance of conceiving," the authors write. "More research is required to further substantiate these conclusions."
The researchers acknowledged several limitations to the collection of trials reviewed, including:
the 3 trials reporting live birth had imprecise approaches to sequence generation and allocation concealment;
only 15 of the 34 studies reported pregnancy rate, just 15 reported on sperm motility, and only 16 reported on sperm concentration;
2 trials tested combined antioxidants against controls;
stillbirth, miscarriage, and antioxidant adverse effects seem to be poorly reported; and
there is a lack of comparative data regarding different antioxidants.
"Further randomised controlled trials are needed to assess whether one antioxidant is more effective than another by head to head comparisons," the authors write.
The study authors have disclosed no relevant financial relationships.
Cochrane Database Syst Rev. Published online January 19, 2011.
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