Vitamin D regulates the expression of hundreds of genes and is integral to biological functions that affect every bodily system. Vitamin D insufficiency or deficiency can trigger several generalized symptoms that you may have associated with other health conditions. It’s also called the sunshine vitamin since your skin makes vitamin D when exposed to ultraviolet light from the sun.[1] Vitamin D performs many functions within the body, including maintaining adequate levels of calcium and phosphate, essential for normal bone mineralization.[2] It helps reduce inflammation, which is necessary for the modulation of cell growth and immune function. Vitamin D also affects genes that help regulate cell differentiation and apoptosis (routine cell death). The main indicator of your vitamin D level is 25-hydroxyvitamin D (25OHD). Data collected from the National Health and Nutrition Examination Survey in 2005-2006 showed a deficiency prevalence of 41.6 percent in the U.S. population.[3] However, as I discuss …