Vitamin D supplementation: Pearls for practicing clinicians.

Vitamin D supplementation is common in the United States, with about one-fifth of the adult population taking a daily supplement in one form or another. Although the detrimental effects of insufficient sun exposure in childhood was established centuries ago, the beneficial effects of vitamin D sufficiency have only recently been established, given the myriad investigations associating vitamin D deficiency with numerous chronic diseases. But it is far less clear precisely how to replete low 25-hydroxyvitamin D (25[OH]D) levels, how long treatment should be continued, if there are potential hazards in doing so, and how to assess and counsel patients regarding the use of vitamin D. This article provides a brief historical review, examines how to assess and counsel patients on the use of vitamin D, presents scenarios that clinicians are likely to encounter, and reviews the literature on recommendations for vitamin D supplementation.