A recent study has shown that low Vitamin D levels were associated with both prior sports hernias and lower extremity strains. The data was taken from the 2015 NFL combine. Overall 59% of the players had low levels and 13% had severely low levels. Normal is considered 30ng/ml or higher, although most now think that a level closer to 50 is desirable. Vitamin D is gotten most efficiently from the sun, but at northern latitudes such as Chicago, Vitamin D cannot be made on the skin except in the warmer months. Therefore, virtually every Chicagoan should take a Vitamin D supplement except in warmer months when they are out in the sun. It is also important to get sun only in moderation to avoid burning. 2000 units/day is a reasonable dose, but the only way to know for sure is to get your Vitamin D level tested. If it is low, supplements should be started and then it should be rechecked until levels are normal. Vitamin D is needed more in darker skinned people than lighter skinned. It is also associated with greater health in a wide variety of other areas. A high quality vitamin D supplement is available on our website at the "purchase supplements".