March 21, 2008

Folate Deficiency In Men May Cause Birth Defects

Researchers at University of California, Berkeley, report that men with low levels of folate are at an increased risk for sperm containing too many or too few chromosomes, which can cause birth defects and miscarriages. 

The research is the first study to find a link between diet and sperm health.

While the benefits of folate for women in preventing birth defects are widely known, the Berkeley research suggests it also boosts sperm health. In fact, the research found that folate deficiency increases the chance a man will have sperm with either too few or too many chromosomes.

Found in fruits and beans, leafy green vegetables, chickpeas and lentils, folate is one of the B vitamins. By law, breads and grains sold in the U.S. are also now specially fortified with added folate to help stem birth defects.

"We looked at sperm to find different kinds of genetic abnormalities," said Brenda Eskenazi, the study's lead researcher and a professor of maternal and child health and epidemiology and director of the Center for Children's Environmental Health at Berkeley's School of Public Health. "The abnormalities we looked at here were having too few or too many chromosomes," she told the Washington Post. Healthy human sperm have 23 pairs of chromosomes.

"In sperm you normally have one of each, but sometimes there are two and sometimes there are none of a particular chromosome," Eskenazi said.

Eskenazi said that if a normal egg was fertilized with one of these abnormal sperm, it could result in a birth defect such as Down's syndrome.

"This can also result in an increase in miscarriage," she said.

In conducting the study, researchers examined three specific chromosomes: X, Y and 21.

"We saw an association between [male] folate intake and how many abnormal sperm there were, in terms of the chromosome number for these three different chromosomes," Eskenazi said.

In the study, Eskenazi's group analyzed sperm from 89 healthy men, and surveyed the men about their daily consumption of zinc, folate, vitamin C, vitamin E and beta-carotene.

The researchers discovered that men with the highest folate intake, 722 to 1,150 micrograms a day, had a 20 percent to 30 percent lower frequency of sperm abnormalities. 

Until now, researchers in birth defects have focused on women's diet during the conception period, Eskenazi said. "Based on these data, maybe men, too, need to consider their diet when they are considering fathering a child," she said.

Eskenazi advises men who are thinking of becoming fathers to increase their folate intake, perhaps with a supplement or a multivitamin.

"This is another common-sense article that says good nutrition is associated with a better reproductive outcome," Dr. Jamie Grifo, director of reproductive endocrinology at New York University Medical Center, told the Washington Post.

He added, however, that abnormal sperm rates seen in the Berkeley study were four to six per 1,000, meaning that even men with poor nutrition still had more than 99 percent normal sperm.

"Even though this may be the case, don't smoke, drink modestly, eat healthy unprocessed food and take your vitamins," Grifo said.

The study findings are published in the March 20 issue of the journal Human Reproduction.  The full report can be viewed here.


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