The impact of 1-year vitamin D supplementation on vitamin D status in athletes: a dose–response study

Background/Objectives: To assess the prevalence of vitamin D deficiency in Dutch athletes and to define the required dosage of vitamin D 3 supplementation to prevent vitamin D deficiency over the course of a year. Subjects/Methods: Blood samples were collected from 128 highly trained athletes to assess total 25(OH)D concentration. Of these 128 athletes, 54 male and 48 female athletes (18–32 years) were included in a randomized, double blind, dose–response study. Athletes with either a deficient (