Do Soy Foods Affect Sperm Quality?

Ample evidence in animals demonstrates that isoflavones, with their weak estrogenic activity, can negatively affect the male reproductive system, but evidence in humans is scarce. Boston investigators assessed whether intake of isoflavone-rich soy foods affected sperm quality in 99 men who presented with their partners for evaluation of infertility.

The men completed questionnaires that addressed their intake of 15 soy-based foods during the 3 months before semen analysis. There was an inverse association between soy food intake and sperm concentration that remained significant after adjusting for potentially confounding variables. Results for individual soy isoflavones were similar but did not achieve statistical significance. This inverse …