Eshre.com – Researchers have found an association between the B vitamin folic acid – found in leafy green vegetables, fruit and pulses (beans, chickpeas, lentils) – and levels of chromosomal abnormalities in men’s sperm. Men who consumed high levels of folate (found naturally in food) and/or folic acid (found in supplements) tended to have lower levels of abnormal sperm where a chromosome had been lost or gained known as aneuploidy. Aneuploidy can cause genetic anomalies such as Down’s syndrome.

Writing in Europe’s leading reproductive medicine journal, Human Reproduction (March 20, 2008), the authors say estimates suggest that between 1 to 4 percent of sperm in a healthy man have some type of aneuploidy, but there are large variations among individuals, the mechanisms are poorly understood and little is known about the effects of men’s diet on their sperm.

In the first study of its kind to investigate the relationship between sperm aneuploidy and paternal diet, they analyzed sperm samples from 89 healthy, non-smoking men and questioned them about their daily total intake (from diet and from vitamin supplements) of zinc, folate, vitamin C, vitamin E and beta-carotene.

One of the principal investigators of the study, Brenda Eskenazi, University of California, Berkeley, said: “We found a statistically significant association between high folate intake and lower sperm aneuploidy: there was increasing benefit with increasing intake, and men in the upper 25th percentile who had the highest intake of folate between 722-1150 micrograms, had 20 to 30 percent lower frequencies of several types of aneuploidy compared with men with a lower intake.

“However, this study cannot prove that high folate intake caused the lower sperm aneuploidy levels, only that there is an association. This is the first study of its kind and the results indicate the need for further research, especially a randomized controlled trial, on this topic.”

The researchers found no consistent associations between intakes of zinc and the other vitamins and sperm aneuploidy.

Prof Eskenazi said: “While the importance of maternal diet on reproduction, especially folate intake, is well known, the results of our study suggest the importance of studying paternal nutrition when considering male-mediated developmental consequences. In previous studies, we and others have shown that paternal micronutrient intake may contribute to successful conceptions by improving the quality of the sperm. This study is the first to suggest that paternal diet may play a role after conception in the development of healthy offspring.” Sperm aneuploidy can have a number of consequences ranging from failure to conceive, miscarriages or children born with conditions such as Down’s syndrome, Turner’s syndrome and Klinefelter’s syndrome.

The current recommended daily intake (RDA) for men aged over 19 is 400 micrograms, and the authors say that if other studies confirm their findings of the link between folate intake and aneuploidy, then a possible intervention would be to increase the RDA for men considering becoming fathers for at least three months before trying to conceive in order to reduce the risk of chromosomal abnormalities in their children.

Ms Suzanne Young, a researcher in Prof Eskenazi’s group, said: “Increasing folate intake can be as simple as taking a vitamin supplement with at least 400 micrograms of folate or eating breakfast cereal fortified with 100% of the RDA for folic acid. In addition, green leafy vegetables, such as spinach, can have up to 100 micrograms of folate per serving.”

Disentangling the effects of folate from other micronutrients (e.g. the other vitamins) can be difficult, but the authors think they have succeeded in doing this by looking at several different nutrients in statistical analyses. Ms Young said: “The results of the different analyses were different, which gave us some confidence that we could look at the effect of these micronutrients separately. The definitive way to answer this question would be with a randomized control trial with folate supplementation.”

Folate is a water-soluble B vitamin that occurs naturally in a wide range of foods, particularly liver, leafy green vegetables, citrus fruits and legumes. It is needed during the synthesis of DNA, RNA and proteins, and it is necessary for the production of new cells. Folate also helps keep in check levels of homocysteine, an amino acid that, when elevated, is linked to heart disease.

Studies have shown that adequate intake of folate by women just before and during pregnancy significantly reduces the risk of neural tube birth defects, such as spina bifida or anencephaly.

Reference: The association of folate, zinc and antioxidant intake with sperm aneuploidy in healthy non-smoking men. Human Reproduction journal. Doi:10.1093/humrep/den036