Several previous studies have suggested improvements in sperm quality after vitamin supplementation, and several reviews have drawn tentatively positive conclusions:
- The current literature seems to suggest a beneficial effect of antioxidants on male infertility.
- Several studies have reported a significant increase in sperm quality and pregnancy rates when the men were supplemented by specific vitamins and micronutrients
- For those undergoing assisted reproduction, the odds ratio that antioxidant use would improve pregnancy rates was 4.18, with a 4.85-fold improvement in live birth rate also noted.
Most of the primary trials lacked scientific rigour, however. Now a new study has emerged that overcomes many of the flaws of the previous research.
Professor Anne Steiner from the University of North Carolina at Chapel Hill, USA, presented her study yesterday at the 34th Annual Meeting of ESHRE in Barcelona. This clinical trial of 174 couples has found that an antioxidant formulation taken daily by the male partner for a minimum of three months made no difference to sperm concentration, motility or morphology, nor to the rate of DNA fragmentation. The study was performed in eight American fertility centres.
All men in the study had been diagnosed with male factor infertility, reflected in subnormal levels of sperm concentration, motility, or morphology, or higher than normal rates of DNA fragmentation. These parameters were measured at the start of the trial and at three months. In between, the men allocated to the antioxidant intervention were given a daily supplement containing vitamins C, D3 and E, folic acid, zinc, selenium and L-carnitine; the control group received a placebo.
At three months, results showed only a “slight” overall difference in sperm concentration between the two groups, and no significant differences in morphology, motility, or DNA fragmentation measurements. Sub-group analysis (according to different types of sperm abnormality) found no significant differences in sperm concentration (in oligospermic men), motility (in asthenospermic men), and morphology (in teratospermic men).(1) There was also no change seen after three months in men with high rates of DNA fragmentation (28.9% in the antioxidant group and 28.8 in the placebo group).
Natural conception during the initial three month study period did also not differ between the two groups of the entire cohort – a pregnancy rate of 10.5% in the antioxidant group and 9.1% in the placebo. These rates were also comparable at six months (after continued antioxidant or placebo for the male partner and three cycles of clomiphene and intrauterine insemination for the female partner).
The authors concluded that “the results do not support the empiric use of antioxidant therapy for male factor infertility in couples trying to conceive naturally”.
The story about supplements and health claims seems to be strangely repetitive:
- the claim that supplements help for condition xy is heavily promoted, e. g. via the Internet;
- a few flimsy trials seem to support the claim;
- these results are relentlessly hyped;
- the profit of the manufacturers grows;
- eventually a rigorous, independently-funded trial emerges with a negative finding;
- the card house seems to collapse;
- the manufacturers claim that the trial’s methodology was faulty (e. g. wrong does, wrong mixture of ingredients);
- thus another profitable card house is built elsewhere.
In the end, the only supplement-related effects are that 1) the consumers produce expensive urine and 2) the manufacturers have plenty of funds to start a new campaign based on yet another bogus heath claim.