Background: There are few longitudinal studies of vitamin D status from childhood to early adulthood, and it is uncertain whether this predicts peak bone mass in young adults.
Objective: To evaluate tracking of vitamin D status occurs from age 6 to 20 in healthy study individuals, and to study associations between serum 25-hydroxyvitamin D (25OHD) at different developmental stages and peak bone mass measured at age 20.
Design: Participants are offspring of the Western Australian Pregnancy Cohort (Raine) study. Serum 25OHD was assessed at 6, 14, 17 and 20 years, and whole body bone mineral density (BMD) measured at 20 years using DXA. This analysis included 821 participants (385 females) who had ≥ 3 serum 25OHD measures and BMD data.
Result: There were significant correlations between serum 25OHD levels measured at different time points in both males (r=0.360-0.560, P<0.001) and females (r=0.346-0.537, P<0.001), and the associations were stronger at adjacent time points. In males, but not females, 25OHD level at each time point was positively associated with total body BMD at 20 years (r=0.102-0.183, P < 0.05). Further analysis in males using multiple linear regression models included all 25OHD measures as predictor variables, and adjusted for covariates including age, body weight, smoking, alcohol intake, physical activity level and calcium intake at 20 years, only 25OHD level at 20 years remained as a significant predictor and uniquely associated with 3.1% of the variance of total body BMD. The results are similar when deseasonalised 25OHD values were used.
Conclusion: We found that there were moderate associations between vitamin D status measured at pre-puberty, adolescence and early adulthood in both genders. Vitamin D status appears to be a significant determinant of peak bone mass in males but not females.