Genistein Intake Does Not Alter Male Testicular Development 37960

Genistein Intake Does Not Alter Male Testicular Development

BIRMINGHAM, Ala.Male exposure to dietary genistein does notnegatively affect testicular development, according to animal research out ofthe University of Alabama that was published in the July issue of the Journalof Nutrition (133, 7:2287-93, 2003) (www.nutrition.org).Researchers compared the effects of a phytoestrogen, genistein, and a syntheticestrogen, diethylstilbestrol (DES), on rat testicular development.

For five weeks, rats were given dietary genistein in doses of either 250mg/kg or 1,000 mg/kg, or 75 mcg/kg of DES. The dietary DES intake causedimpaired testicular development, as well as reduced testicular weights, alteredmorphology and increased apoptosis in the seminiferous tubules (essential fortesticular function). Conversely, dietary genistein intakewhich caused ratsto exhibit serum concentrations that approximate or exceed concentrations inAsian men on a soy-containing dietdid not significantly alter testicularweights or morphology. However, researchers did note that the high-dosegenistein diet significantly reduced testicular aromatase activity, which maycontribute to reduced estrogen concentrations and suppress prostate cancerdevelopment.

This research opposes previous research out of the Johns Hopkins BloombergSchool of Public Health in Baltimore, which indicated when pregnant andlactating rats were fed a genistein-enhanced diet, male offspring developedsmaller testes, had lower testosterone concentrations in adulthood anddemonstrated long-term dysfunction in reproductive behavior (J Urol, 169,4:1582-6, 2003). The Baltimore researchers concluded genistein exposure resultedin transient and lasting alterations in masculinization of the ratsreproductive systems.

Contrary to those findings, the Birmingham researchers concluded from theirstudy that exposure to genistein in the diet at concentrations that result inserum concentrations at the upper limit of humans consuming soy products doesnot adversely affect testicular development, but may provide health benefits.