If you like to produce mass quantities of sperm, you might do best to avoid tofu and other soy-based foods. No, that's not the first sentence of a spam e-mail, it's from a real scientific study done at Harvard that examined the relationship between sperm count and diets that are high in soy. The little green beans may have the power to deplete sperm because they contain a chemical that emulates estrogen.
Dr Jorge Chavarro, a research fellow in the department of nutrition at Harvard School of Public Health, Boston, USA, and his colleagues found that men who ate the most soy food had 41 million sperm per millilitre less than men who did not consume soy products. (The "normal" sperm concentration for men ranges between 80-120 million/ml).
This doesn't mean you should give up tofu or soy crackers. First of all, a high sperm count is really only necessary if you need to make babies right away. Moreover, the researchers found that soy affected the sperm count of men who were obese in far greater numbers than men of average weight.
On the flip side, this doesn't mean an all-soy diet substitutes for good birth control either.