Soy products could lower the sperm count in men, articulated a study, published online in Human Reproduction. The study showed that men who ate soy products had a lower sperm count, though it was still within the normal range.

The study based its data on 99 men at the Massachusetts General Hospital Fertility Center, between 2000 and 2006. In the study, the men, who gave semen samples, were asked to complete a questionnaire which asked them how often they had eaten 15 different soy foods such as tofu, soy milk, soy burgers etc in the last three months.

The researchers found that 90% of the men had sperm concentrations that were within the normal range, while 42% of the men had normal semen analysis. Out of the men interviewed only 20 said they ate soy foods at least twice a week, 22 said they ate soy anywhere between twice a month to twice a week, 18 said they ate soy foods less than twice a month while a majority of them, 39 men said they had not eaten any soy foods during the last three months.

In a nutshell, they concluded that men who ate soy foods tended to have a sperm concentration that was lower (though still within normal limits) than men who ate no soy. This seemed to be more significant in men who were overweight or obese. They also felt that the study’s results may not be representative of all men.

Jorge Chavarro, MD, ScD, ScM, of Harvard School of Public Health's nutrition department, who led the study said, "The clinical significance of these findings remains to be determined."