The U.S. researchers, on Wednesday, revealed that even meek consumption of soy-based foods could significantly lower a man’s sperm count.

The study is the largest in humans to scrutinize the relationship between semen quality and a plant form of the female sex hormone estrogen known as phytoestrogen, which is present in abundance in soy-rich foods.

“What we found was 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,” said Dr. Jorge Chavarro of the Harvard School of Public Health in Boston, whose study appears in the journal Human Reproduction.

“It was a relatively large difference,” Chavarro said.

Chavarro’s team studied the intake of 15 soy-based foods in 99 men who went to a fertility clinic between 2000 and 2006.

It was found that m with highest intake of soy-based foods had 41 million sperm per milliliter less than men who ate no soy foods. A normal sperm count ranges from 80 million and 120 million per milliliter, and a sperm count of 20 million per milliliter or below is considered low.

“It suggests soy foods could have some deleterious effect on the reproductive system and especially on sperm production,” Chavarro said.