Vitamin D2 supplements linked with increased muscle damage after weightlifting

Vitamin D2 supplements were associated with decreased levels of vitamin D3 in the body and higher muscle damage after intense weightlifting in NASCAR pit crew athletes following eccentric exercise.

Researchers randomly assigned NASCAR pit crew athletes to take either vitamin D2 or placebo for 6 weeks. Researchers collected blood samples and conducted muscle function tests before and after the study. Post-study, participants engaged in 90 minute eccentric exercise, with blood samples and delayed onset of muscle soreness ratings obtained immediately after and 1 day and 2 days after exercise.

Although researchers believed taking vitamin D2 supplement would improve performance by reducing inflammation and aiding in recovery from exercise-induced muscle damage, the results indicated that the supplement increased exercise-induced muscle damage in the pit crew members. This was the first documented evidence of exercise-induced muscle damage in athletes taking high doses of vitamin D2.

“This is the first time research has shown that vitamin D2 supplementation is associated with higher muscle damage after intense weightlifting, and thus cannot be recommended for athletes,” David Nieman, DrPH, director of the Human Performance Lab at Appalachian State University, stated. “We know that when you restore vitamin D levels in older people it improves their muscle function. What hasn’t been documented is if the same holds true for younger adults. We were interested in seeing if increasing vitamin D in the pit crew athletes who train heavily in the off season would improve their muscle and immune function. While vitamin D2 levels in the blood increased, we found that levels of the valuable D3 decreased. And to our surprise, those taking vitamin D2 didn’t have just a little more muscle damage, they had a lot more damage.”

Reference:

Nieman D. Nutrients. 2014;doi:10.3390/nu6010063.

Disclosure: The researchers have no relevant financial disclosures.