Research has found that too much soy intake (including tofu, tempeh, tofu or soy “meats,” soy milk, cheeses, yogurts, ice creams, & soy energy bars) may sink a man’s sperm count. A study in the journal HUMAN REPRODUCTION found that men who ate the equivalent of one soy tofu burger or drank one cup of soy milk every 2 days had 41 million fewer sperm per milliliter of semen than those who didn’t eat/drink soy (normal sperm counts are between 80-120 million per milliliter). The reason may lie in the fact that soy products contain plant estrogens which have been found to affect overall fertility.
Although this research is interesting, it does not mean men should stop eating/drinking soy. Critics argue that the researchers who did the above study failed to take into account the subject’s medical histories or other conditions that may have contributed to the lower sperm counts. In addition, generations of Asian men who regularly consume soy products have not been found to have decreased sperm counts. The sperm count decreases may have more to do with a man’s weight than his soy intake. Overweight men produce more estrogen, which can interfere with normal hormone production. Since American men are more likely to be overweight than Asian men, this helps explain why the study found these differences. Balance is the key here – taking care of yourself and eating a healthy diet are both key to healthy sperm production.