Lowest dietary intake of these nutrients is associated with decreased sperm motility, study finds.
There is increasing evidence that higher intake of fruits and vegetables may help ensure better sperm quality, researchers say.
They conducted a study showing that low intake of dietary antioxidants correlates with poor sperm motility. “I was somewhat surprised by the strength of the correlation,” said lead investigator Vivian Lewis, MD, professor of obstetrics/ gynecology in the department of reproductive endocrinology at the University of Rochester Medical Center in New York. “Other studies have found an association with folic acid. We did not find that association.”
Reactive oxygen species contribute to male infertility by damaging sperm DNA and motility. It is theorized that dietary antioxidants may reduce these adverse effects, but clinical trials of vitamin C and E supplementation have yielded inconsistent findings.
Dr. Lewis and her colleagues recruited 48 men with abnormal semen parameters whose partners had been trying to conceive for more than 12 months. As controls, the researchers enrolled 10 men with normal semen analyses who had fathered a pregnancy within the previous 12 months. Men were excluded from this study if they had taken vitamin supplements with more than 45 IU of vitamin E within the previous three months.
The mean age of the infertile men was 35 years, whereas the fertile controls were significantly younger, with a mean age of 27.5 years. Both groups were predominantly Caucasian with similar mean BMI and proportion of smokers. Forty percent of the infertile men and 50% of controls took vitamin supplements. The investigators used Block Food Frequency questionnaires with photos of typical portion sizes to characterize the men’s diets.
The proportion of men who consumed fewer than five servings a day of fruits and vegetables was much greater among the infertile group compared with controls (80% vs. 40%). The mean intake of vitamin C was lower among the infertile men compared with controls (104 vs.152 mg a day), and the proportion of men with vitamin C intake below the recommended dietary allowance was greater among the infertile men compared with controls (48% vs. 20%). No differences were observed in vitamin E or selenium intake.
Overall, men with the lowest intake of dietary antioxidants had lower sperm motility, Dr. Lewis said. Low vitamin C intake was associated with reduced total sperm count and motility. Reduced glutathione intake correlated with decreased sperm motility.
Urologists should encourage patients to consume an overall healthy diet and concentrate on a variety of fruits and vegetables, Dr. Lewis said.