What is new in vitamin D: 2006–2007Bikle, Daniel DCurrent Opinion in Rheumatology: July 2007 - Volume 19 - Issue 4 - p 383–388 doi: 10.1097/BOR.0b013e32818e9d58 Metabolic bone disease Abstract Author Information Purpose of review This review focuses on recent developments in a number of areas to bring the reader up to the current state of knowledge in this field. Recent findings A number of studies have revealed new insights into the regulation of the vitamin D receptor and new targets for its action. The mechanism by which a number of drugs can reduce circulating 25OHD has been clarified. New drug targets including increased bone by inhibition of osteoclasts, improvement in diabetes mellitus, and stimulation of innate immunity to combat infections such as tuberculosis have been found. Summary The wide distribution of the vitamin D receptor provides a number of clinical targets for vitamin D and its analogs. The wide distribution of CYP27B1, the enzyme required to convert circulating 25OHD to 1,25(OH)2D enables a number of cells to make their own 1,25(OH)2D3 if circulating 25OHD levels are maintained. These newer studies emphasize that vitamin D is not just for bones, and maintaining adequate levels is important for many tissues. Medicine and Dermatology, University of California and Veterans Affairs Medical Center, San Francisco, California, USA Correspondence to Daniel D. Bikle, Professor of Medicine and Dermatology, University of California and Veterans Affairs Medical Center, San Francisco, California, USA E-mail: firstname.lastname@example.org © 2007 Lippincott Williams & Wilkins, Inc.