The research did not find a negative relationship between soy and sperm mobility or sperm quality, which are both key factors to fertility.Caution: headlines claiming "soy products may lower sperm count" do not tell the whole story. The small scale, preliminary study that Dr. Jorge Chavarro from the Harvard School of Public Health in Boston presented at the American Society for Reproductive Medicine was based on recollected intake of soyfoods and not on specific diets containing soyfoods.
"This study is confounded by many issues, thus I feel the results should be viewed with a great deal of caution," warned Dr. Tammy Hedland, a researcher on male fertility issues, including soy, from the Health Sciences Center, Department of Pathology at the University of Colorado.
The research did not find a negative relationship between soy and sperm mobility or sperm quality, which are both key factors to fertility. The study also did not determine directly what other foods, medications, supplements, existing medical conditions, sexual activities or environmental factors may have directly affected the drop in sperm count.
Generations of Asians have regularly consumed soyfoods without fertility disorders, and Asian countries have prodigiously produced very healthy, highly functioning children for centuries. According to New Scientist, "Chavarro admits that many East Asian men consume much more soya than the participants in his trial and do not develop fertility problems. He speculates that his study found a link between soya and low sperm count because many of the participants were overweight or obese. Men with high levels of body fat produce more oestrogen than their slim counterparts."
Chavarro's study conflicts with the large body of U.S. government and National Institute of Health-sponsored human and primate research, in which controlled amounts of isoflavones from soy were fed and no effect on quantity, quality or motility of sperm were observed. Upon hearing of Chavarro's findings, Dr. Stephen Barnes, a pharmacologist at the University of Alabama at Birmingham, noted "This study is the first to find this correlation. The research on soy in men has not found a negative impact on male hormones but rather has suggested a preventive effect in prostate cancer."
Learn the facts about healthy soyfoods. Studies have indicated soyfoods may lower cholesterol, may boost cognitive function and may protect against prostate cancer.
By Soyfoods Association of North America
This page is updated on May 11, 2013.