Vitamin D - a review.

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. It explores what is known about vitamin D, what remains to be discovered, and how clinicians should manage their patients in the interim.

Discussion: Vitamin D is produced by the same solar radiation that causes skin cancer and aging. Levels in breast milk are low in vitamin depleted breastfeeding women. Despite these realities, there is an opportunity to use existing public health messages to treat the widespread deficiency of vitamin D.