A randomized, controlled lower leg growth study of vitamin D supplementation to healthy children during the winter season

Abstract

Background : The deceleration of longitudinal growth in children during winter occurs simultaneously with a decrease in the number of daylight hours and a reduction in vitamin D status. Due to worries about deleterious effects on bone of a relative insufficiency, vitamin D supplementation to healthy children has been suggested. Aim : To see whether supplementation of vitamin D to healthy children during winter affects seasonal growth. Subjects and methods : Twelve girls and eight boys aged 6.2-13.7 (mean 9.8) years, all healthy, were enrolled in a double-blind, randomized, placebo-controlled cross-over study with two 4-week treatment periods and 2-week run-in and wash-out periods. Vitamin D 3 600 IU was given in one tablet ABCDin® daily. Knemometry of the right lower leg was performed on the first and last day of each period. Results : Lower leg growth rates (mean &#45 SEM) during placebo and vitamin D 3 administration were identical: 0.28 &#45 0.04 mm per week ( p = 0.94, t = 0.1, 95% CI: &#109 0.12-0.13 mm per week). Conclusion : Supplementation with vitamin D 3 600 IU day &#109 1 to healthy children during winter may not improve seasonal growth. Therefore, supplementation may not be recommended on the grounds of concerns about growth; however firm conclusions await randomized long-term studies.