Sperm seems to move fastest in men who have high levels of vitamin D, according to a new study. The finding could someday offer hope for a treatment for male infertility.

Researchers found that the sperm of men who were deficient in vitamin D (with less than 25 nanomoles per liter of blood) was less motile than the sperm of men who had more than 75 nanomoles of vitamin D per liter of blood, said study researcher Martin Blomberg Jensen, of the Department of Growth and Reproduction at Copenhagen University Hospital in Denmark.

Researchers also found that by exposing men's sperm to activated vitamin D , the "activated vitamin D was able to induce sperm motility," Jensen told MyHealthNewsDaily. Exposing vitamin D in the skin to the sun activates it.

The study, which was conducted on 300 healthy men, was published recently in the journal Human Reproduction.

The study demonstrates that vitamin D is necessary for proper male reproduction , Jensen said, but he added that more studies are needed before vitamin D can even be considered as a treatment to improve male sperm quality.

"By supplementing vitamin D orally, you may be able to increase the amount of activated vitamin D," Jensen said, "but this has not been shown in the testes so far."

Furthermore, faster sperm speed is not guaranteed to improve male fertility . Male fertility "depends on the reason for low fertility, such as low motility, number or morphology" of the sperm, Jensen said.

However, sperm speed "is a very important parameter, and the proportion of motile sperm is positively associated and a predictor of the chance of achieving a pregnancy."

There are no scientifically sound methods for improving sperm quality, though past research has shown an association between sperm speed and antioxidants, zinc and vitamins, Jensen said.

For example, research presented in 2003 at a meeting of the American Society for Reproductive Medicine showed that sperm speed was faster in men who drink coffee, which is known to be high in antioxidants, compared with men who don't.

Pass it on: Men with high vitamin D have faster sperm than men with low vitamin D levels.

Follow MyHealthNewsDaily staff writer Amanda Chan on Twitter @AmandaLChan.