Save Your Sperm┆Men's Health

When the day comes that you want kids—a long, long time from now, of course—you’ll want your swimmers in Michael Phelps-shape, right?

Then drop that donut. Two new Harvard studies show that diet can significantly hurt the quantity and speed of your sperm.

In one study, researchers found that men with the lowest trans-fatty acid intake had roughly double the average sperm concentration as other men—79 million sperm per mL compared to 48 million among those with the highest intake of trans-fatty grub.

More research is needed, but it’s possible that trans fats may accumulate in sperm and wipe them out over time, says study author Audrey Gaskins, a Ph.D. candidate at the Harvard School of Public Health.

In a second study, Crimson researchers examined the semen of 188 college-aged guys (proof that students will do almost anything for beer money) and found that those who ate a healthy diet—with lots of fruits, veggies, whole grains, legumes, and fish—had more motile sperm than those dudes who were regularly snacking on stuff like pizza. Sperm motility rates deal with the ability of your boys to swim successfully toward an egg. The healthy guys’ motility rates were nearly 7 percent higher than those of the less-healthy men.

“A healthy diet with lots of plant foods tends to be packed with antioxidants,” Gaskins explains. “Oxidative stress can impair sperm, but eating antioxidant-rich foods may protect semen quality.”

The easiest way to boost your diet quality without counting servings, Gaskins advises, is to cut down on chow that come in packages, which tend to be high in trans fats and low in antioxidants. Along with eating plenty of fruits and vegetables, you should also aim for an antioxidant-packed, Mediterranean-style diet, which is rich in fish and olive oil, Gaskin says.