Soy-based foods may lower sperm count

The US researchers have founded that eating a half serving a day of soy-based foods could be enough to significantly lower a man's sperm count. The study is the largest in humans to look at the relationship between semen quality and a plant form of the female sex hormone estrogen known as phytoestrogen, which is plentiful in soy-rich foods.
The 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," according to Dr. Jorge Chavarro of the Harvard School of Public Health in Boston, whose study appears in the journal Human Reproduction.
They were asked how much and how often in the prior three months they had eaten soy-rich foods including: tofu, tempeh, tofu or soy sausages, bacon, burgers and mince, soy milk, cheese, yogurt and ice cream, and other soy products such drinks, powders and energy bars.
Because different foods have different levels of isoflavones in them, the researchers set a standard for serving sizes of particular foods. Then they divided the men into groups according to soy consumption levels. Men in the highest group on average ate half a serving per day.
They also found the association between soy foods and lower sperm count was stronger in overweight men, which might suggest hormones are playing a role.
Men who are overweight or obese tend to have higher levels of androgen-produced estrogen. They are converting a male hormone into a female hormone in their fat. The more body fat you have, the more estrogen you produce in your fat.