Recently there has been a resurgence of interest in the role of vitamin D3, or cholecalciferol, supplementation in disease prevention and health maintenance. Systematic reviews have recently been published with a focus on specific groups, such as those over 50 or by body mass index. Studies have been carried out on serum vitamin D levels to evaluate the role of supplementation on risk for multiple health conditions, ranging from bone health to cancer. However, the benefits and risks of cholecalciferol supplementation are under debate after the publication of a 2010 Institute of Medicine Report that recommended supplementary and dietary reference levels for Vitamin D. From an epidemiological perspective, cholecalciferol is unique, as it can be obtained not only through food and supplementation, but also from ultraviolet radiation, specifically UVB (280-320 nm). Thus, some groups have suggested that people increase time in the sun and forgo sunscreen in an effort to increase their serum 25-(OH)D levels. However, because over exposure to UVB rays can also lead to an increase in skin cancer incidence, the health effects associated with UV exposure may be problematic.