While it has been widely known for many decades that Vitamin D3 is necessary for healthy bones(4), the extent to which Vitamin D3 helps optimize other body functions and overall health has only recently been noted(8; 9). As early as the 1970’s scientists knew that activated forms of Vitamin D3 might have a positive effect on muscle protein and energy metabolism(1); however, it has only been over the last 15 years that the importance of Vitamin D3 to muscle function (and strength) has been confirmed(2).
New studies show Vitamin D3 is a vital nutrient for healthy muscle. Serum levels of at least 32 ng/mL or greater of the activated form of Vitamin D (25(OH)D) are necessary for optimal performance and muscle function(10). Most of us, unfortunately, do not have this optimal level of Vitamin D (25(OH)D) in our body. A recent meta-analysis found that over half of all athletes studied had less than an optimal level of Vitamin D3, and that the levels of Vitamin D3 in athletes living and competing farther away from the equator; in spring and winter sports; or those competing in indoors sports (all of whom get less sun exposure) were even much more likely to be Vitamin D3 deficient(6).
In one of the most recent studies, researchers measured the correlation between Vitamin D3 status and strength measures in collegiate athletes. The study found significant correlation between Vitamin D3 status and strength measures. As shown in the graph, athletes with a deficient Vitamin D3 status also had decreased muscle power and strength as measured by their vertical jump, shuttle run, triple hop distance, and 1 rep max in the back squat when compared with athletes that were Vitamin D3 sufficient(12).
Vitamin D3 not only helps to improve muscle function, but also helps strengthen bones to withstand the rigors of strenuous training. A review of stress fractures during military training showed that higher levels of Vitamin D3 were associated with lower incidences of training-induced stress fractures(3).
Vitamin D3 plays a key role in keeping your bones healthy and optimizing muscle function so that you can perform your best each day.