Adherence to a vitamin D supplement intervention in urban schoolchildren.

Vitamin D supplementation is an important strategy for preventing low levels of serum 25OHD and improving bone health and consequent associated health risks, especially in children at risk of deficiency. Although vitamin D supplements are recommended, there is limited research on the factors that influence adherence to taking them. In a cross-sectional sample of 256 child (aged 9 to 15 years) and parent pairs in the Boston, MA, area during January to March 2012, analysis of covariance was used to determine associations between health beliefs about vitamin D, parental vitamin D-containing supplement use, and the individual responsible for pill administration with supplement adherence measured by pill counts. Mean and median supplement pill count adherence over 3 months were 84% and 89%, respectively. Adherence was positively associated with parents' use of vitamin D-containing supplements (7% higher, P=0.008) and with combined child and parent responsibility for administration of the supplement compared with child only (9% higher, P=0.03). Parents' beliefs about vitamin D neither predicted their children's beliefs nor positively influenced children's adherence. Adherence was higher when parents took vitamin D-containing supplements and when parents and children shared responsibility for administering the supplement. Promoting child supplement use through parent involvement and role modeling may be a practical solution for registered dietitians who are aiming to improve vitamin D adherence in at-risk youth.