A Single Wintertime Dose of Vitamin D3 to Prevent Winter Decline in Vitamin D Status in Healthy Adults

The purpose of this study is to determine if a single dose of vitamin D administered orally in the fall will provide adequate vitamin D in healthy individuals for the duration of the winter, during which vitamin D levels are known to decrease. The investigators are also interested in finding out if this level of vitamin D will provide adequate levels for the remainder of the year. While the benefits of once-yearly vitamin D administration are clear for patients with osteoporosis, osteomalacia, rickets, and other conditions associated with vitamin D deficiency and high bone turn-over, studies have not been performed in which high doses of vitamin D were used to prevent the seasonal decline of vitamin D concentrations in healthy individuals. These findings could provide evidence to support vitamin D administration to healthy individuals in the wintertime to improve health outcomes, and provide the basis for additional studies in both healthy and sick populations.