Haroon M and Fitzgerald O
In last few years we have witnessed an explosion of research revealing the wide spread prevalence of vitamin D deficiency among all ages, communities, and different disease spectrums. Clearly, vitamin D has been shown to have effects beyond its traditional role in mineral metabolisms, which are mediated through the activation of vitamin D receptors distributed in a variety of tissues. There are strong epidemiological links between vitamin D deficiency and chronic diseases and will continue to be a focus of future research. However, this research information has not yet been fully translated into clinical practice. The increased awareness of the level of vitamin D deficiency in the general population and its potential impact on skeletal and extra skeletal health outcomes have highlighted the important need to understand and follow the latest research knowledge in this area. There remains a poor understanding among health professionals as regards the prescribing policy and the provision of appropriate vitamin D supplements. This review will discuss the physiological role of vitamin D, and the available literature on vitamin D deficiency with respect to its definition, associated factors, prevalence, and management recommendations, and the safety of its repletion.