Yikes! If you're a man with fertility problems, stay away from soy products. That's the message from a study out of the Harvard School of Public Health in Boston. The study is in the current issue of the journal Human Reproduction, and this is how the lead author summarized their findings for Yahoo News:
"What we found was men that consume the highest amounts of soy foods in this study had a lower sperm concentration compared to those who did not consume soy foods," said Dr. Jorge Chavarro.
The Guardian, a British paper, also covered this story. This study is apparently the largest study (99 men) of soy on human fertility. The thing is that soy contains chemicals that mimic the effects of estrogen. So it's not a huge stretch of the imagination that these substances might not be good for the sperm-producing capacity of an adult male especially, as Dr. Chavarro explains, it's already been determined that his sperm count is a little low. The interesting thing is that the difference in sperm counts between men who did and didn't eat soy was pretty significant, again from Yahoo News:
"Men in the highest intake category had 41 million sperm per milliliter less than men who ate no soy foods. A normal sperm count ranges from 80 million and 120 million per milliliter, and a sperm count of 20 million per milliliter or below is considered low."
The effect was even more pronounced in men who were overweight. Guess what? Fat tissue converts male hormones to female hormones.