Couples struggling to conceive may be more likely to have a child if the man takes certain vitamins or other antioxidants, according to scientists.
The finding emerged from a review of 34 randomised controlled trials involving 2,876 couples who were having difficulty conceiving. Most of the men in the trials had low sperm cell counts or sperm which were poor swimmers. Male subfertility affects 1 in 12 men in the UK and between 30 percent (%) to 80% of cases are considered to be due to the damaging effects of highly reactive particles called free radicals, which circulate the body and can adversely affect the health of sperm. The damage can be reduced by the body's own antioxidant defences. These defences may be boosted by our diet or by taking supplements.
The trials assessed the potential benefits on fertility of many different types of oral antioxidants, including vitamin E, L-carnitine, zinc and magnesium. They compared the pregnancy and birth rates in couples when the man took one of these supplements compared to those that took no treatment or a placebo.
Most of the studies looked at the effect of antioxidants on the chances of pregnancy. On average, the chance of couples becoming pregnant increased from 3.1% to 11.8% when antioxidant treatment was taken. Three studies assessed how antioxidants affected the number of live births. The results revealed that antioxidants increased the likelihood from 2% to 8%. Both results were statistically significant.
Lead author of the study, Dr Marian Showell, who works in obstetrics and gynaecology at the University of Auckland, said: 'When trying to conceive as part of an assisted reproductive program, it may be advisable to encourage men to take oral antioxidant supplements to improve their partners' chances of becoming pregnant'.
The review emanates from 'The Cochrane Collaboration', considered to be the 'gold standard' in review and data analysis due to the thoroughness and stringency with which the available data is assessed. In the present analysis however, available studies were limited and showed great variability in outcome, making the conclusions tentative at this stage. Dr Showell acknowledged the need for more studies to confirm the apparent benefits of antioxidants.
Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield described the research as 'encouraging' but added that: 'To date, the research has been controversial with some studies showing evidence of benefit and others showing no improvement. This meta analysis seems to suggest that there is an increased chance of pregnancy in the partners of men who took antioxidant therapy, although the numbers are still small. Clearly more research is needed'.
Next steps in the research are to identify any superiority of one anti-oxidant over another.
The data is published in The Cochrane Library.