I recently posted an article on the benefits of vitamin D, and the recent realization that a high percentage of people are deficient. Research is showing that among other functions, vitamin D has the ability to up-regulate and down-regulate genes. In other words, when we have suboptimal levels of vitamin D our genes are not turned and off appropriately. Genes are used to create proteins which are the building blocks of nearly everything in our body--from our structure (bone, ligament, tendon, etc) to neurotransmitters, hormones, blood, etc.
This wide range of effects translates a host of problems linked to vitamin D deficiency including poor immune function, less vitality, and decreased athletic function. Specific to athletic function, a recent New York Times article highlighted the following:
I highly recommend having your vitamin D level checked with your next blood work. If it is low supplement with 2,000IU of vitamin D for 6 weeks and recheck. With my family I have everyone supplement with about 1,000IU for about three weeks, then we take about a three week break. WE also get plenty of sunshine! If you are local, I have an excellent product in my office.