Wednesday, June 22, 2005

Soy isoflavone may damage fertility, finds new research

The soy component genistein, one of the isoflavones in soy, could damage human sperm.

Genistein, and other isoflavones, are marketed as dietary estrogens to women as a natural alternative to hormone replacement therapy (HRT). They are also being investigated for their potential to slow prostate and breast cancer.

But Lynn Fraser, professor of reproductive biology at King's College London, will present evidence today that even tiny doses of the natural compound can cause human sperm to ‘burn out’ and lose fertility.

Speaking ahead of the annual European Society of Human Reproduction and Embryology conference, Fraser said: "Human sperm proved to be even more responsive than mouse sperm to genistein."

Moreover, when the compound is combined with other environmental oestrogens, such as 8-prenylnaringenin (found in hops), and nonylphenol that is found in industrial products like paints, pesticides and cleaning products, the damage to fertility could be even more serious.

In particular, the chemicals stimulated the sperm to undergo an acrosome reaction - when the cap on the head of the sperm ruptures and releases enzymes that enable the sperm to penetrate the coverings of the egg. If the acrosome reaction happens before a sperm reaches the egg, then fertilisation is unable to take place because the sperm has lost special 'docking' molecules that allow it to bind to the egg.

Courtesy of nutraingredients.com

Bonnie - whenever fertility is an issue, I suggest reducing or eliminating soy foods or supplements. They may create a fluctuation of women's hormone levels as well as affect men. While this is one of the first studies of its kind, and more research needs to be done, it is compelling nonetheless.

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