Moms Who Eat Beef Cause Low Sperm Count in Sons

Research shows that U.S. women who eat a lot of beef while pregnant give birth to sons with low sperm counts.

The researchers believe that pesticides, hormones, or contaminants in cattle feed may be what causes it. Chemicals can build up in the fat of animals that eat contaminated feed or grass. Cattle are also given hormones to boost their growth.

"In sons of 'high beef consumers' (more than seven beef meals/week), sperm concentration was 24.3 percent lower," the researchers wrote in their report, published in the journal Human Reproduction.

The researchers at the University of Rochester Medical Center in New York studied data on the partners of 387 pregnant women in five U.S. cities between 200 and 2005. They also studied the mothers of the fathers-to-be.

Of the 51 men whose mothers ate the most beef, 18 percent had sperm counts classified as sub-fertile.

"The average sperm concentration of the men in our study went down as their mothers' beef intake went up. But this needs to be followed carefully before we can draw any conclusions," said research team leader Shanna Swan.

Swan and her colleagues set up a study of pregnant women and their partners with funding from the U.S. National Institute of Health.

"They came in, we got a sperm count, they did an interview," Swan said.

Then, starting in 2000, they also gave questionnaires to the mothers of the men.

"Earlier this year I became more aware of the controversy about growth hormones in beef," she added.

Swan admits that the study is limited. The study, called a retrospective study, is not as conclusive as one that follows people in real-time.

She does believe, however, that women can remember accurately what they ate while pregnant.

"When you are pregnant you are very aware of what you eat - you are watching your weight and some things make you sick and you need to get enough of x and y so you focus on that," she said.

The men's mothers were only asked if they ate beef more than once a day, something easy to remember accurately.

She now wants to test men who grew up in Europe, where hormones have been banned in beef since 1988.

According to Swan, beef consumption was the only real link between the women whose sons had low sperm counts. She said that nobody ate much of any other kind of meat.

Sources:
http://www.sciencedaily.com/releases/2007/03/070328073237.htm
http://abcnews.go.com/Health/wireStory?id=2987502