Vitamin D supplementation during infancy is associated with higher bone mineral mass in prepubertal girls

The objective of this study was to determine whether vitamin D supplementat ion of breast-fed infants during the first year of Life is associated with greater bone mineral content and/or areal bone mineral density (aBMD) in la ter childhood. The design was a retrospective cohort study. One hundred and six healthy prepubertal Caucasian girls (median age, 8 yr; range, 7-9 yr) were classified as vitamin D supplemented or unsupplemented during the firs t year of life on the basis of a questionnaire sent to participating famili es and their pediatricians. Bone area (square centimeters) and bone mineral content (grams) were determined by dual energy x-ray absorptiometry at six skeletal sites. Vitamin D receptor (VDR) 3'-gene polymorphisms (BsmI) were also determined. The supplemented (n = 91) and unsupplemented (n = 15) gro ups were similar in terms of season of birth, growth in the first year of l ife, age, anthropometric parameters, and calcium intake at time of dual ene rgy x-ray absorptiometry. The supplemented group had higher aBMD at the lev el of radial metaphysis (mean +/- SEM, 0.301 +/- 0.003 vs. 0.283 +/- 0.008; P = 0.03), femoral neck (0.638 +/- 0.007 us. 0.584 +/- 0.021; P = 0.01), a nd femoral trochanter (0.508 +/- 0.006 vs. 0.474 +/- 0.016; P = 0.04). At t he lumbar spine level aBMD values were similar (0.626 +/- 0.006 vs. 0.598 /- 0.019; P = 0.1). In a multiple regression model taking into account the effects of vitamin D supplementation, height, and VDR genotype on aBMD (dep endent variable), femoral neck aBMD remained higher by 0.045 g/cm(2) in the supplemented group (P = 0.02). Vitamin D supplementation in infancy was fo und to be associated with increased aBMD at specific skeletal sites later i n childhood in prepubertal Caucasian girls.