Endocrine Abstracts

Previous observational studies suggest that low 25(OH)D concentrations in childhoodmight have deleterious effects on vasculature. The present study addresses this key knowledge gap with the use of a dose-response randomized clinical trial (RCT) aimed to determine the effect ofone-year vitamin D supplementationon carotid intima media thickness (cIMT) in overweight and obese school children. The current study was a single-blind RCT. A total of 378 children and adolescents, 6–13 y of age, with age- and sex-specific body mass index (BMI) Z-score ≥ 1 (according to the World Health Organizationcriteria)were recruited into the study. Participants were allocated to receive 600, 1000, and 2000 IU/d for 12 months. We measured cIMT at baseline and end of 12 months. In this intention-to-treat analysis, to estimate the effect size of 1000 and 2000 IU/d vitamin D in comparison to 600 IU/d, we fit a linear mixed effect model adjusted for sex, season of recruitment, and baseline cIMT, smoking exposure, physical activity, puberty status, and BMI. Participants’ mean (SD) age was 9.3 (1.7) y; 52.3% wereboys with BMI z scores of 2.55(0.73). The mean (SE) for 25(OH)D were 13.7 (0.79), 14.8 (0.86), 14.8 (0.79) ng/ml at baseline (P = 0.792) and 22.7(0.57), 26.1 (0.70), 30.2 (0.78) ng/ml at the end of 12 months (P < 0.0001) in 600, 1000, and 2000 IU/d, respectively. The standardized mean difference (95% CI) after adjusting covariates was 0.36 (0.07, 0.65) and 0.97 (0.67, 1.28) for 1000 and 2000 IU/d vitamin D, respectively. The mean (SE) for cIMT were 0.396 (0.005), 0.403 (0.005), 0.406 (0.005) mm at baseline (P = 0.389) and 0.400 (0.008), 0.405 (0.009), 0.407 (0.007) mm at the end of 12 months in 600, 1000, and 2000 IU/d, respectively (P = 0.821). The cIMT change during one-year follow-up was not significant between three groups. The standardized mean difference (95% CI) after adjusting covariates was −0.0003 (–0.294, 0.293) and 0.081 (–0.207, 0.370) for 1000 and 2000 IU/d vitamin D, respectively. In conclusion, children with excess weight did not benefit from daily supplementationof 1000 and 2000 IU/d for one year compared with 600 IU/din decreasing subclinical atherosclerosis; although 25(OH)D increased.