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High Soy Intake Linked to Low Sperm Counts

No effect on sperm motility or morphology

THURSDAY, July 24 (HealthDay News) -- Men who consume high levels of soy-containing foods tend to have lower sperm counts, with no effect on sperm motility or morphology, according to research published online July 23 in Human Reproduction.

Jorge E. Chavarro, M.D., and colleagues from Harvard Medical School in Boston, surveyed the intake of 15 soy-based foods in the previous three months through a food frequency questionnaire in 99 male partners of subfertile couples undergoing semen analysis.

After adjusting for age and a number of clinical and behavioral factors, the researchers found that men with the highest soy consumption had 41 million fewer sperm per milliliter than men who did not consume soy. Similar trends were observed for individual soy isoflavones. The drop in sperm count was more pronounced for men with higher sperm concentrations and in overweight or obese men. There was no association between intake of soy or soy isoflavones and sperm motility, sperm morphology or ejaculate volume, the investigators report.

"These data suggest that higher intake of soy foods and soy isoflavones is associated with lower sperm concentration," Chavarro and colleagues conclude.

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