Vitamin D and skeletal muscle tissue and function

This review aims to summarize Current knowledge on the role of vitamin D in skeletal muscle tissue and function, Vitamin D deficiency can cause a myopathy of varying severity. Clinical studies have indicated that vitamin D status is positively associated with muscle strength and physical performance and inversely associated with risk of falling, Vitamin D supplementation has shown to improve tests of muscle function, reduce falls. and possibly impact on muscle fiber composition and morphology in vitamin D deficient older adults. Molecular mechanisms of vitamin D action on muscle tissue include genomic and non-genomic effects via a receptor present in muscle cells. Genomic effects are initiated by binding of 1,25-diliydroxyvitamin D [1,25(OH)(2)D] to its nuclear receptor, which results in changes in gene transcription of mRNA and subsequent protein synthesis. Non-genomic effects of vitamin D are rapid and mediated through a cell surface receptor. Knockout mouse models of the vitamin D receptor provide insight into understanding the direct effects of vitamin D on muscle tissue. Recently, VDR polymorphisms have been described to affect muscle function. Parathyroid hormone which is strongly linked with vitamin D status also may play a role in muscle function: however, distinguishing its role from that of vitamin D has yet to be fully clarified. Despite the enormous advances in recent decades, further research is needed to fully characterize the exact underlying mechanisms of vitamin D action on muscle tissue and to understand how these cellular changes translate into clinical improvements in physical performance. (C) 2008 Elsevier Ltd. All rights reserved.