Winter Cholecalciferol Supplementation at 55°N Has No Effect on Markers of Cardiometabolic Risk in Healthy Children Aged 4–8 Years

Abstract

Low serum 25-hydroxyvitamin D [25(OH)D] has been associated with unfavorable cardiometabolic risk profiles in many observational studies in children, but very few randomized controlled trials have investigated this. We explored the effect of winter-time cholecalciferol (vitamin D3) supplementation on cardiometabolic risk markers in young, white, 4- to 8-y-old healthy Danish children (55°N) as part of the pan-European ODIN project. In the ODIN Junior double-blind, placebo-controlled, dose-response trial, 119 children (mean ± SD age: 6.7±1.5 y; 36% male; 82% normal weight) were randomly allocated to 0, 10 or 20 µg/d of vitamin D3 for 20 wk (October-March). Cardiometabolic risk markers including BMI-for-age z score (BMIz), waist circumference, systolic and diastolic blood pressure, serum triglycerides and cholesterol (total, LDL, HDL, and total:HDL), plasma glucose and insulin, and whole-blood glycated hemoglobin were measured at baseline and endpoint as secondary outcomes together with serum 25(OH)D. Intervention effects were evaluated in linear regression models as between-group differences at endpoint adjusted for baseline value of the outcome, and additionally for age, sex, baseline serum 25(OH)D, BMIz, time since breakfast, and breakfast content. Mean±SD serum 25(OH)D was 56.7±12.3 nmol/L at baseline and differed between groups at endpoint with concentrations of 31.1±7.5, 61.8±10.6, and 75.8±11.5 nmol/L in the 0-, 10-, and 20 µg/d groups, respectively (P<0.0001). Vitamin D3 supplementation had no effect on any of the cardiometabolic risk markers in analyses adjusted for baseline value of the outcome (all P≥0.05), and additional covariate adjustment did not change the results notably. Preventing the winter decline in serum 25(OH)D with daily vitamin D3 supplementation of 10 or 20 µg had no cardiometabolic effects in healthy 4- to 8-y-old Danish children. This trial was registered at www.clinicaltrials.gov as NCT02145195.