The Medical Posting Journal had the following story recently
Coffee drinkers, smokers can read into what you will.

2003-11-21
Marijuana smokers' sperm goes to pot

But male coffee drinkers have better swimmers

Men who smoke marijuana end up with sperm that swim too fast for their own good. Coffee drinkers, on the other hand, may have a fertility advantage.

Lani Burkman, a researcher at the State University of New York in Buffalo, says her study shows heavy marijuana smokers not only have a lower sperm count, but the sperm move too fast, too soon.

"We saw very vigorous activity, but at the wrong time," she says. "We believe they burn out before the sperm approach the egg."

The study involved 22 men who smoked marijuana for an average of five years.

Women smoking marijuana can also affect sperm, Burkman says. The active ingredient of marijuana -- tetrahydrocannabinol -- is found in fluids in the female reproductive tract, through which sperm passes.

Men who drink coffee, however, appear to have sperm that are better swimmers than those of non-coffee drinkers.

Dr. Fabio Pasqualotto, a reproductive medicine specialist at the University of Sao Paulo in Brazil, says his study of semen samples from 750 men showed men who drank at least one cup of coffee daily had higher sperm motility -- a measure of swimming ability -- than nondrinkers.

The quality and quantity of sperm in both groups were otherwise identical.

A separate study of the same group showed sperm from men who smoked tobacco products were just as healthy as those of nonsmoking men.