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Antioxidants linked to improved quality of sperm DNA

October 9, 2012

A new US study suggests that an adequate intake of antioxidants such as vitamin C, vitamin E and zinc is strongly associated with less sperm DNA damage in older men.

In the study, 80 healthy men aged between 20 and 80 filled out a 100­item questionnaire that estimated their average daily vitamin intake, both from food and from supplements (1). In addition, their sperm DNA quality was assessed via a lab analysis in which a voltage gradient pulls broken DNA strands from intact strands within the sperm nucleus. Each participant's intake of a micronutrient was classified as low, moderate or high based on how they compared to other participants. The study results showed that many participants, even those who reported being healthy, consumed much less than the recommended dietary allowance for vitamin C, vitamin E, beta-carotene, folate and zinc. Concerning men aged 44 and over, those who consumed the most vitamin C had 20 percent less sperm DNA damage than those who consumed the least vitamin C. The same was true for vitamin E, zinc and folate.

The researchers commented that it appears that consuming adequate amounts of antioxidant micronutrients can help turn back the clock for older men. Men aged 44 and over who consumed at least the recommended dietary allowance of the antioxidants had sperm with a similar amount of DNA damage as the sperm of younger men. Studies have shown that increased consumption of antioxidant-rich fruits and vegetables and dietary supplementation with antioxidants can decrease the amount of oxidative DNA damage. The scientists noted that future studies should help us to determine whether increased antioxidant intake in older fathers will improve fertility, reduce the risk of genetically defective pregnancies, and result in healthier children. This study also raises a broader question beyond sperm DNA: How might lifestyle factors, including a higher intake of antioxidants and micronutrients, protect somatic as well as germ cells against age-related genomic damage?

Previous research has found that the older a man is, the more likely he is to have increased sperm DNA fragmentation, chromosomal rearrangements, and DNA strand damage (2). Older men are also more likely to have increased frequencies of sperm carrying certain gene mutations, such as those leading to dwarfism. These findings help explain why aging men are less fertile and why their sperm are predicted to result in more chromosomally-defective pregnancies and a higher proportion of offspring with genetic defects.

References

  1. Schmid T. E. et al. Micronutrients intake is associated with improved sperm DNA quality in older men. Fertility and Sterility. Published online August 2012.
  2. Sloter E. et al. Effects of male age on the frequencies of germinal and heritable chromosomal abnormalities in humans and rodents. Fertility and Sterility. 2004; 81(4):925–943.