A randomised controlled trial of two vitamin D dosage regimens for correcting deficiency in adolescents

Background Vitamin D deficiency is common in adolescents yet the optimal dosage regimen for correcting such deficiency is unknown.

Aims To test safety and efficacy of two different vitamin D dosage regimens for correcting vitamin D deficiency in adolescents.

Methods In this 12-month, double-blind, placebo-controlled randomised controlled trial, 28 adolescents (serum 25 hydroxyvitamin D (25OHD) of 21 to 50 nmol/L) were recruited through general practice and advertising and randomly assigned to receive 50,000 IU vitamin D3 orally monthly (n=9),  150,000 IU vitamin D3 orally 3-monthly (n=9) or placebo (n=10). Serum 25-hydroxy vitamin D was measured at baseline, 3, 6 and 12 months.

Results Two participants withdrew after baseline measurement from the 3-monthly group. At 12 months, the average vitamin D levels for the monthly, 3-monthly and placebo groups were 76.4, 64.7 and 49.7 nmol/L, respectively (P<0.001 for difference between monthly group  and placebo after adjustment for age, sex and seasonal variation; p=0.04 for 3-monthly and placebo and 0.07 for monthly and 3-monthly) (Figure 1). At 12 months, one participant was mildly deficient in both monthly (25OHD=46 nmol/l) and 3-monthly (50 nmol/L) groups, whereas six out of ten in the placebo remained deficient. No adverse events related to the interventions were observed.

Conclusion Both 50,000IU monthly and 150,000 3-monthly vitamin D3 safely and effectively correct vitamin D deficiency in adolescents.  A monthly dose may be marginally more effective.  These data provide treatment options which can be tailored to patient preference.

Acknowledgements: This study was funded by the RACGP Research Foundation

 Figure 1: