Soda might be especially bad for kids… but it could be even worse for men who hope to have their own kids someday.

A new study finds that young men who drink a quart of cola each day have 30 percent fewer sperm swimming around. A quart may sound like a lot of soda–but it’s really just two of those 16-ounce plastic bottles most people consume easily enough.

Danish researchers looked at 2,500 young men and found that those who didn’t drink soda had a healthy 50 million sperm per milliliter of semen. Those who downed that daily quart, on the other hand, had an average of 35 million sperm per milliliter of semen, according to the study published in the American Journal of Epidemiology.

That’s still enough to make a baby… but since lower sperm is linked to lower fertility, clearly these young men have a higher risk of reproductive problems–especially if those levels continue to fall as they age.

The researchers say cola alone may not be causing the sperm problems, since the soda-slurpers also tended to have unhealthier lifestyles. They were, for the most part, fast- food eaters. And like a lot of cola-loving youths, they didn’t make much time for fresh fruit and veggies.

But while these other reasons might also help explain millions of missing sperm, the researchers believe they know one thing that’s not causing it: caffeine. The study also found that men who drank coffee or tea instead of soda did not suffer from lower sperm levels.

Researchers are interested in what all that pop does to men since Danish youths have been increasing their consumption of this carbonated liquid poison. But if they’re really looking for some answers, they don’t need a study–they just need to look across the sea.

Americans consume more soda than any other people–and we’re also among the most overweight and diabetic. Soda is one of the prime ingredients fueling our problem-packed unhealthy lifestyle.

Soda has also been linked to tooth decay, liver problems and cell damage. Cell damage can actually disrupt your DNA, leading to conditions like Parkinson’s disease and cirrhosis.

And soda can also causes bone loss and poor mineralization, increasing the risk of broken bones and setting the stage for osteoporosis.

All that’s bad enough… but for men–especially young men– none of that may seem as bad as the idea of being less manly.