What Have We Learned from the Epidemiology of Vitamin D?

Vitamin D deficiency has emerged as a potential risk factor for multiple adverse outcomes, including cardiovascular and cancer related morbidity and mortality. Epidemiological studies have been instrumental in detecting associations between lower serum levels of vitamin D and such outcomes, and by doing so have provided an impetus to examine the mechanisms of action underlying such associations and to design interventional trials of vitamin D supplementation to try and reverse the adverse effects attributed to low serum vitamin D. This chapter reviews in detail observational studies that describe the incidence and prevalence of hypovitaminosis D, and the various adverse outcomes that low serum vitamin D has been linked with. The comprehensive nature of this review will provide the reader with a better understanding of why vitamin D is currently regarded as a very promising area of research to try and lower adverse outcomes in a variety of patient groups and in the general population.

Keywords: All-cause mortality, cardiovascular risk factors, cardiovascular outcomes, cause-specific mortality, epidemiology, malignancies, hypovitaminosis D, National Health and Nutrition Examination Survey (NHANES), vitamin D supplementation.