PT - JOURNAL ARTICLE AU - Neil JL Gittoes TI - Vitamin D – what is normal according to latest research and how should we deal with it? AID - 10.7861/clinmedicine.15-6-s54 DP - 2015 Dec 01 TA - Clinical Medicine PG - s54--s57 VI - 15 IP - Suppl 6 4099 - http://www.rcpjournals.org/content/15/Suppl_6/s54.short 4100 - http://www.rcpjournals.org/content/15/Suppl_6/s54.full SO - Clin Med2015 Dec 01; 15 AB - Vitamin D deficiency is a public health concern. Mediated by classical endocrine effects, vitamin D deficiency is causally linked with bone and calcium disorders. Non-endocrine actions of vitamin D are also widely recognised and these effects are mediated by local tissue activation of vitamin D bringing about intracrine effects in non-classical sites. Supported by large volumes of observational studies linking low circulating vitamin D with negative outcomes for many common disease states, there is growing interest that vitamin D may be central to the pathology and outcomes of many common diseases, including cardiovascular, cancer and autoimmune conditions. This article explores the quality of evidence linking vitamin D and various disease outcomes, and furthermore describes some of the cellular and molecular mechanisms of vitamin D action that may help explain some of the incongruity of data observed in observational versus interventional studies of vitamin D supplementation.