Effect of Different Vitamin D Vitamers on Vitamin D Status

Background: Dietary intake of vitamin D includes vitamin D3 (VitD3), 25-hydroxyvitamin D3 (25OHD3) and vitamin D2 (VitD2). However, the bioactivity of the different species is currently not scientifically established. Objective: The aim of this study was to test the hypothesis that VitD3, 25OHD3 and VitD2 affected vitamin D status equally in humans and if rejected, to estimate the difference in activity. Design: This study was designed as a 3 x 6 weeks (with 4 weeks run-in) double-blinded randomized cross-over study with 12 young, apparently healthy male volunteers and was performed during wintertime at 55 degree N. during the 4 weeks run-in period all volunteers received 10 ug/d VitD3 in order to achieve steady-state in vitamin D status. During the 3x6 weeks intervention periods the subjects received 10 ug/d VitD3, 10 ug/d 25OHD3 or 10 ug/d VitD2 in random order. Content of vitD3, VitD2, 25OHD3 and 25-hydroxyvitamin D2 (25OHD2) in serum were quantified my LC-MS/MS using 0.1 mL serum.