The strongest sperm are the fastest swimmers -- and if your little ones are doing the doggy paddle, don't expect to break into the daddy business anytime soon.
But don't give up, either, because there's an easy way to get your little swimmers speeding along like Michael Phelps -- and that's with a nutrient you should be getting anyway: Vitamin D.
Looks like bikinis aren't the only things at the beach that can kick a man's sex gears into overdrive!
Dutch researchers examined D levels and semen quality in 300 healthy men, and found that those with less than 25 nanomoles of D per liter of blood produced slowpoke tadpoles.
Men with a more robust 75 nanomoles per liter, on the other hand, had hard-charging sperm capable of backstrokes, breaststrokes, and butterflies -- or at least a faster, straighter journey to the egg.
What's more, the researchers found that low-D sperm got a speed boost once they were exposed to the nutrient -- but that shouldn't come as a surprise to anyone who's been keeping up with the science on this.
Several years ago, researchers found that sperm actually have their own vitamin D receptors -- and since sperm don't exactly have room for excess baggage, you know those receptors are there for a reason.
Put it together with the new study in Human Reproduction, and it's increasingly clear that vitamin D is practically fuel for sperm, giving them the turbo charge they need to find, penetrate, and fertilize the egg in the short time they have to get the job done.
Other studies have also exposed the link between low D and male fertility problems -- and the animal science here is even clearer.
In one study, researchers found that rats low in D were less likely to reproduce -- and once that deficiency was corrected, they went on to father pups with typical rodent fruitfulness.
All we need now is an honest-to-goodness clinical trial pitting D against a placebo in men with sperm problems -- but I wouldn't hold my breath waiting for someone to invest the time and money needed to do it right.
Instead, invest in a comfortable beach blanket so you can get the sunlight you need to make your own D -- and a quality supplement to keep those levels high even when the sun is low.
About the author
William Campbell Douglass I.I., M.D. has been called "the conscience of modern medicine."
You can sign up for his "Daily Dose" at DouglassReport.com.