Effect of Vitamin D3 Supplementation in Black and in White Children: A Randomized, Placebo-Controlled Trial.

Randomized, double-blind, placebo-controlled trial in healthy Black and White children aged 8 to 14 years from the Pittsburgh area who were not taking vitamin supplements. Active intervention arms were analyzed separately for Black and White participants over a 6-month period.

Children received oral vitamin D3, 1000 IU once daily as a tablet for 6 months, compared with placebo in race-stratified randomized arms. The active regimen was the same in Black and White children.

Vitamin D3 1000 IU/day safely increased serum 25(OH)D, but it did not produce an overall improvement in PTH or bone-turnover markers. In Black children, 25(OH)D rose from 16.6 Ϯ 7.4 to 24.2 Ϯ 7.4 ng/mL at 6 months; in White children, it rose from 23.5 Ϯ 6.0 to 29.2 Ϯ 7.0 ng/mL. PTH changed little in either group, and osteocalcin and C-telopeptide showed no consistent overall benefit, although race-specific changes were observed. No hypercalcemia occurred. The 25(OH)D-PTH relationship was linear without a clear plateau, and mean 25(OH)D still did not reach 30 ng/mL.

The intervention was short term and involved a modest number of healthy children from one geographic region, which limits generalizability. Follow-up was only 6 months, and skeletal outcomes were limited to biochemical markers rather than clinical bone endpoints. Race-specific findings and seasonal enrollment may complicate interpretation of subgroup effects.