Calcium-vitamin D-fortified milk is as effective on circulating bone biomarkers as fortified juice and supplement but has less acceptance: a randomised controlled school-based trial

Background: Hypovitaminosis D, especially during cold seasons, is quite prevalent among primary school children in Tehran. The present study aimed to compare the efficacy of calcium-vitamin D-fortified-milk, -orange juice and supplement in primary school children. Methods: Children aged 9-12 years from both sexes were randomly assigned to one of six groups to receive plain milk, fortified milk, plain orange juice, fortified orange juice, supplement or placebo. Both fortified-milk and -juice contained 100 IU of vitamin D and 500 mg of calcium per 200 mL package, whereas supplement contained 200 IU of vitamin D and 500 mg of calcium. The duration of intervention was 12 weeks, from November 2008 to March 2009. Results: A total of 410 children completed the study. Regression analysis with adjustment for both sex and initial values of 25(OH) D revealed that consumption of either supplement, fortified orange juice or fortified milk resulted in a 20.8 nM [confidence interval (CI) = 17.4-23.9], 9.9 nM (CI = 7.4-12.3) or 6.9 nM (CI = 3.3-10.5) increase in circulating 25(OH) D compared to the related control groups. However, changes in serum osteocalcin and intact parathyroid hormone in the supplement group did not differ from those of fortified milk or plain milk. The increment of osteocalcin in both plain milk and fortified milk was more than in fortified orange juice, although the difference was statistically insignificant. Conclusions: Despite having double amount of vitamin D and being more effective in raising serum 25(OH) D, supplementation did not confer additional benefit in terms of osteocalcin and intact parathyroid hormone compared to either fortified or plain milk.