Tracking of vitamin D status from childhood to early adulthood and its association with peak bone mass.

To our knowledge, there are few longitudinal studies of vitamin D status from childhood to early adulthood, and it is uncertain whether vitamin D predicts peak bone mass in young adults. The purpose of this longitudinal study was to evaluate the long-term stability of vitamin D status from ages 6 to 20 y in healthy individuals and to study associations between serum 25-hydroxyvitamin D [25(OH)D] at different developmental stages and bone mass measured at age 20 y. Participants were offspring of the Western Australian Pregnancy Cohort (Raine) study. Serum 25(OH)D was assessed at ages 6, 14, 17, and 20 y, and whole-body bone mineral content (BMC) and bone mineral density (BMD) were measured at age 20 y through the use of dual-energy X-ray absorptiometry (DXA). Our analysis included 821 participants (385 females) who had ≥3 serum 25(OH)D measures and DXA data. We used latent class growth analysis and identified 4 vitamin D status trajectories: consistently lower ( = 259), decreasing ( = 125), increasing ( = 138), and consistently higher ( = 299). There were significant correlations between serum 25(OH)D concentrations at different time points in both sexes ( = 0.346-0.560, < 0.001), with stronger correlations at adjacent time points. In males, but not in females, serum 25(OH)D at ages 6, 17, and 20 y was positively associated with total-body BMC and BMD at age 20 y [covariate-adjusted increments of 40.7-53.9 g and 14.7-18.6 mg/cm, respectively, per 25 nmol/L 25(OH)D]; when 25(OH)D at all 4 ages was included in the same model, the concentration at age 6 y remained significant. Males in the "consistently higher" trajectory had 3.2-3.4% higher total body BMC and BMD than those who were in the "consistently lower" trajectory, accounting for age and anthropometric and lifestyle factors. Within both sexes, there are moderate associations between vitamin D status measured in prepuberty, adolescence, and early adulthood. Vitamin D status in childhood is a significant predictor of peak bone mass in male but not female subjects.