Impact of three different daily doses of vitamin D3 supplementation in healthy schoolchildren and adolescents from North India: a single-blind prospective randomised clinical trial

In India, there is a lack of information about the adequate daily dose of vitamin D-3 supplementation in school children. Hence, we undertook this study to evaluate the adequacy and efficacy of different doses of vitamin D-3 in schoolchildren. A total of 1008 vitamin D-deficient (VDD) children, aged 6-16 years with serum 25-hydroxyvitamin D (25(OH)D) levels <50nmol/l, were cluster randomised into three groups (A-344, B-341 and C-232) for supplementation (600, 1000 and 2000 IU daily) of vitamin D-3 under supervision for 6 months. Of the 1008 subjects who completed the study, 938 (93 %) were compliant. Baseline and post-supplementation fasting blood and urine samples were evaluated for Ca, phosphates, alkaline phosphatase, 25(OH)D and parathormone and urine Ca:creatinine ratio. The mean age of the subjects was 11 center dot 7 (sd 2 center dot 4) years, and the overall mean baseline serum 25(OH)D level was 24 center dot 3 (SD 9 center dot 5)nmol/l. Post-supplementation rise in serum 25(OH)D in compliant group was maximum with 2000 IU (70 center dot 0 (SD 30 center dot 0)nmol/l), followed by 1000 IU (46 center dot 8 (SD 22 center dot 5)nmol/l) and 600 IU (36 center dot 5 (SD 18 center dot 5)nmol/l), and serum 25(OH)D levels of >= 50nmol/l were achieved in 71 center dot 5, 81 center dot 8 and 92 center dot 9 % by groups A, B and C, respectively. Secondary hyperparathyroidism decreased from 31 center dot 7 to 8 center dot 4 % post-supplementation. Two participants developed hypercalciuria, but none developed hypercalcaemia. Children with VDD benefit maximum with the daily supplementation of 2000 IU of vitamin D-3. Whether recommendations of 400 IU/d by Indian Council of Medical Research or 600 IU by Indian Academy of Pediatrics or Institute of Medicine would suffice to achieve vitamin D sufficiency in children with VDD remains debatable.