MANCHESTER, United Kingdom—A community-based, double blind, randomized controlled trial in secondary schoolgirls revealed vitamin D supplementation may need to begin at earlier ages to better capitalize on a period of increased bone mineralization and muscle building in early adolescence. Published in the Journal of Clinical Endocrinology and Metabolism, the study involved 73 postemenarchal girls, 12 to 14 years old, who received either four doses of 150,000 IU of vitamin D2 (ergocalciferol) or a control supplement over the period of a year. Researchers tested hydroxyvitamin D [25(OH)D] levels and several activity parameters, as well as bone composition and strength.
Vitamin D supplementation did not appear to affect bone health, although some benefit was seen to muscle function in the vitamin D group. Hydroxyvitamin D [25(OH)D] levels increased in the intervention group, however there were no accompanying increases in increase mineral accretion, bone geometry or strength, muscle force, or power. The researchers concluded the “lack of effect of intervention after the period of peak mineral and muscle mass accretion suggests that earlier action is required.”