Supplementation with Three Different Daily Doses of Vitamin D3 in Healthy Pre-pubertal School Girls: A Cluster Randomized Trial.

Objective: To compare the adequacy and efficacy of different doses of vitamin D3 in pre-pubertal girls.

Design: Cluster Randomized controlled trial.

Setting: Public school in Delhi, India, between August 2015 and February 2016.

Participants: 216 healthy pre-pubertal girls, aged 6.1-11.8 years.

Intervention: Daily supplementation with 600 IU (n=74), 1000 IU (n=67) or 2000 IU (n=75) of vitamin D3 under supervision for 6 months.

Outcome Measures: Primary: Rise in serum 25 hydroxy Vitamin D (25(OH)D); Secondary: Change in bone formation and resorption markers.

Results: Following 6 months of supplementation, the mean (SD) rise in serum 25(OH)D was maximum with 2000 IU (24.09 (8.28) ng/mL), followed by with 1000 IU (17.96 (6.55) ng/mL) and 600 IU (15.48 (7.00) ng/mL). Serum 25(OH)D levels of ≥20 ng/mL were seen in 91% in 600 IU group , 97% in 1000 IU group and 100% in 2000 IU group. The overall mean (SD) rise in urinary calcium creatinine ratio (0.05 (0.28) to 0.13 (0.12) mg/mg), and serum procollagen type I N-terminal propeptide (538.9 (199.78) to 655.5 (218.24) ng/mL), and reduction in serum carboxy-terminal telopeptide (0.745 (0.23) to 0.382 (0.23) ng/mL) was significant (P<0.01). The change in the above parameters was comparable among the three groups after adjustment for age.

Conclusions: Daily vitamin D supplementation with 600 IU to 2000 IU for 6 months results in Vitamin D sufficiency in >90% of pre-pubertal girls.