Soy Does Not Affect Fertility, U of G Study Finds

March 16, 2011 - News Release

Men no longer have to fear that eating soy-based foods will jeopardize their chances at fatherhood.

A new University of Guelph study has revealed that, contrary to a widely held perception, consuming soy does not harm male fertility.

Soy contains isoflavones, which function similarly to estrogens in the body.

“It is perceived that soy can increase estrogen levels, which is why there is a concern that it will have an adverse effect on male fertility,” said Alison Duncan, the study's author and a professor in Guelph's Department of Human Health and Nutritional Sciences.

“But we found that consuming soy on a regular basis had no effect on semen quality, which is a direct measure of fertility.”

Published recently in the American Society for Reproductive Medicine’s official journal, Fertility and Sterility, the study is the largest to look at the impact of soy consumption on male fertility.

As part of the research, participants were asked to drink a soy protein beverage high in isoflavones, a soy protein beverage low in isoflavones and a milk protein beverage each for 57 days each. There was a four-week break between participants switching drinks.

Duncan found the participants’ semen volume, sperm count, sperm motility and sperm morphology remained the same throughout.

Although previous studies on animals have shown soy consumption to have adverse effects on fertility, the current study reveals that this does not apply to humans, she said.

“These findings are important because soy consumption has many benefits for men, such as reducing the risk of cardiovascular disease and prostate cancer.”

For media questions, contact Communications and Public Affairs: Lori Bona Hunt, Ext. 53338,, or Deirdre Healey, Ext. 56982,

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