WEDNESDAY, March 19 (HealthDay News) -- The benefits of folate for women in preventing birth defects are well known, but new research suggests the nutrient also boosts sperm health.
Men with relatively low levels of folate had increased risks for sperm containing either too few or too many chromosomes, according to researchers at the University of California, Berkeley. These types of deficiencies can cause birth defects and miscarriages, the experts noted.
Folate is one of the B vitamins and is found in leafy green vegetables, fruit and beans, chickpeas and lentils. By law, breads and grains sold in the United States are also now specially fortified with added folate to help ward off birth defects.
"We looked at sperm to find different kinds of genetic abnormalities," said lead researcher Brenda Eskenazi, 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 said.
Normally, 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.
If a normal egg was fertilized with one of these abnormal sperm, it could result in a birth defect, such as Down's syndrome, Eskenazi said. "This can also result in an increase in miscarriage," she said.
The researchers looked at 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.
The study findings are published in the March 20 issue of the journal Human Reproduction.
In the study, Eskenazi's group analyzed sperm from 89 healthy men. In addition, the researchers asked the men about their daily consumption of zinc, folate, vitamin C, vitamin E and beta-carotene.
The researchers found that men who had the highest intake of folate had the lowest incidence of sperm abnormalities. In fact, men who had the highest intake of folate -- 722 to 1,150 micrograms a day -- had a 20 percent to 30 percent lower frequency of several types of sperm abnormalities, compared with men who consumed less folate.
Up till now, birth-defect researchers have typically focused on women's diet in the period around conception, Eskenazi said. "Based on these data, maybe men, too, need to consider their diet when they are considering fathering a child," she said.
Although this study doesn't conclusively prove a link between folate and chromosomal abnormality, Eskenazi advises men who are thinking of becoming fathers to increase their folate intake, perhaps with a supplement or a multivitamin containing folate.
This isn't the first study to find a link between diet and sperm health. A report published last year in Human Reproduction found that women who ate beef seven or more times per week tended to produce sons with lowered sperm counts, perhaps due to the effects of hormones or pesticides on developing testes.
One expert agrees that healthy eating is linked to having healthy babies -- even for men.
"This is another common-sense article that says good nutrition is associated with a better reproductive outcome," said Dr. Jamie Grifo, director of reproductive endocrinology at New York University Medical Center.
Grifo noted that rates of abnormal sperm seen in the Berkeley study were four to six per 1,000, which means that 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 advised prospective fathers.
For more on infertility, visit the American Society of Reproductive Medicine.
SOURCES: Brenda Eskenazi, Ph.D., professor, maternal and child health and epidemiology, director of the Center for Children's Environmental Health, School of Public Health, University of California, Berkeley; Jamie Grifo, M.D., Ph.D., director of reproductive endocrinology, New York University Medical Center, New York City; March 20, 2008, Human Reproduction