Despite sunlight being a primary source, an estimated 40% of U.S. adults have insufficient Vitamin D levels, with higher rates among those who spend most of their time indoors, live in northern latitudes, or have darker skin tones ¹.
Cholecalciferol (D3) is the preferred supplemental form. Research consistently shows D3 raises and maintains circulating 25(OH)D levels more effectively than D2, the plant-derived alternative ².
1. Forrest KY, Stuhldreher WL. Prevalence and correlates of vitamin D deficiency in US adults. Nutr Res. 2011;31(1):48-54. doi:10.1016/j.nutres.2010.12.001
2. Tripkovic L, Lambert H, Hart K, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status. Am J Clin Nutr. 2012;95(6):1357-1364. doi:10.3945/ajcn.111.031070
