Background: Vitamin D status affects musculoskeletal health. More recently, the nonmusculoskeletal actions of vitamin D have become increasingly documented including endocrine effect on kidneys and intestine, local autocrine effects on cell differentiation, proliferation and immune modulation, and cell membrane effects including promotion of the intestinal absorption of calcium and the secretion of insulin.
Objective: This article discusses the actions, sources and measurement of vitamin D, and the treatment of established deficiency.