Here’s another reason to soak up more of the sunshine vitamin: Not having enough D may put you at greater risk for muscle injury, according to research presented at the annual meeting of the American Orthopaedic Society for Sports Medicine (AOSSM) this past weekend. Researchers looked at New York Giants football players and found that those who suffered a muscle injury during the season had lower vitamin D levels at the start of pre-season than those who didn’t get hurt (19.9 ng/mL versus 24.7 ng/mL). A vitamin D level less than 20 ng/mL is considered deficient; levels between 21 and 30 ng/mL are still considered insufficient.

“People just think about bone health when talking about vitamin D, but it plays a myriad of roles,” says Scott Rodeo, MD, a co-author of the study. “It plays a role in bone growth, muscle function, and the immune system. There is the suggestion that low vitamin D levels could have a role to play in injury prevention, even for the average person.”

Problem is, most of us aren’t getting nearly the amount of vitamin D that we should. While vitamin D levels tend to rise during the summer and fall in the colder months due to changing sun exposure, 41% of men and 53% of women in the United States are vitamin D deficient. There aren’t many natural sources of vitamin D, although a few good sources include salmon, halibut, tuna, and fortified milks and cereals.

But protecting against muscle injury isn’t all that vitamin D may do. Here, four more compelling reasons to increase your levels of D.

Build Stronger Bones 
Vitamin D deficiency is associated with low bone density and rickets (soft bones), and has been used in tandem with calcium to help stave off osteoporosis. In a 2011 study of adolescent twins, Australian researchers found that the sibling who took a calcium/vitamin D supplement had better bone density 6 months later than the one who received a placebo.

Help Lose Weight 
University of Minnesota researchers found that dieters with higher levels of vitamin D dropped more pounds than those who had lower levels. People lost about half a pound more for every increase of 1 ng/mL.

Strengthen Your Immune System 
Step aside, vitamin C. A study in the Archives of Internal Medicine found that people with the lowest levels of vitamin D (less than 10 ng/mL) were 36% more likely to catch a cold than those with levels greater than 30 ng/mL.

Improve Athletic Performance 
A 2010 review published in Medicine and Science in Sports Exercise concluded that athletic performance rises as vitamin D levels rise, the effect peaking at about 50 ng/mL. Part of the reason: Vitamin D increases the both the size and number of fast-twitch muscle fibers.