This is slightly old news, but I wanted to include it anyway because any information that makes vegetarianism sound like a bad choice is worth reporting on. The European Society for Human Reproduction and Embryology has issued a press release telling us that the consumption of soy-based foods has the effect of lowering sperm count.

I guess it’s lucky, then, that most of Asia drinks soy sauce by the bucketfull, or those randy bastards would have completely overridden the world by now. If a population in the billions is a consequence of a handicapped fecundity, one can only imagine the awesomeness of their reproductive power otherwise.

At the core of the issue is the presence of phytoestrogens in soy products. This family of chemicals is characterized by its ability to mimic the effects of estrogen in the body. The effect of diminished sperm was more marked in overweight and obese men.

The study does not reveal why soy foods have this effect on sperm, but Dr Jorge Chavarro, a research fellow in the department of nutrition at Harvard School of Public Health, Boston, USA, and his colleagues speculate that increased estrogenic activity may have an adverse effect on the production of sperm by interfering with other hormonal signals. This effect could be strengthened further in overweight and obese men because men with high levels of body fat produce more estrogen than slimmer men, leading to high overall levels of estrogen in the body and reproductive organs.

Apart from Asians, the other group of people likely to consume a lot of soy are vegetarians. Luckily for them, they’re usually not obese; unluckily, they are pretty annoying.

Those interested in body building should be especially wary of soy products, and avoid soy-based protein supplements. T-nation.com always has plenty of info in this regard, here’s a good article to get you started on The Evils of Soy.