Vitamin D: A D-Lightful Vitamin for Health

Vitamin D is a sunshine vitamin that has been produced on this earth for more than 500 million years. Because foods contain so little vitamin D most humans have always depended on sun exposure for their vitamin D requirement. Vitamin D deficiency has been defined as a serum 25-hydroxyvitamin D concentration < 20 ng/mL (50 nmol/L); vitamin D insufficiency as a serum 25-hydroxyvitamin D of 21-29 ng/mL and vitamin D sufficiency as a serum 25-hydroxyvitamin D of 30-100 ng/mL whereas toxicity is usually not seen until blood levels are above 150 ng/mL. Vitamin D deficiency is a global health problem that increases risk for metabolic bone diseases in children and adults as well as many chronic illnesses including autoimmune diseases, type 2 diabetes, cardiovascular disease, infectious disease, and cancer. The major causes of vitamin D deficiency are lack of adequate sensible exposure to sunlight, inadequate dietary intake and obesity. The United States Endocrine Society recommended that to prevent vitamin D deficiency in those at risk, children 1 year and older require 600-1,000 international unit (IU) of vitamin D daily and adults require 1,500-2,000 IU of vitamin D daily. Obese patients require 2-3 times more vitamin D to both treat and prevent vitamin D deficiency.