Author Affiliations: Division of Applied Cachexia Research, Department of Cardiology, Charité Campus Virchow-Klinikum (Drs Anker and von Haehling), and Center for Cardiovascular Research, Charité Medical School, Campus Mitte (Dr von Haehling), Berlin, Germany; and Centre for Clinical and Basic Research, IRCCS San Raffaele, Rome, Italy (Dr Anker).
Dietary vitamin D supplementation is advocated throughout the world, and in recent years it has received substantial public interest.1 Vitamin D metabolism is complex. The active metabolite 1,25-hydroxyvitamin D is involved in calcium and phosphorus homeostasis and the vitamin D receptor is expressed in many tissues, such as skeletal muscle, brain, prostate, breast, colon, and immune cells.2 Vitamin D status is usually assessed by measurement of the inactive metabolite 25-hydroxyvitamin D in serum, but no consensus exists on optimal serum levels.2
Anker SD, von Haehling S. Vitamin D in Chronic Kidney DiseaseMore Questions Than Answers. JAMA. 2012;307(7):722-723. doi:10.1001/jama.2012.159