Lean Mass Accretion Associates With Vitamin D Intake: A 6 Month Randomized Controlled Trial in 2–8 y Olds Using Fortified Foods

Canadian children do not meet the recommended dietary intake for vitamin D. Vitamin D is well established as a fundamental nutrient for bone health, but the effect of vitamin D intake on lean mass accretion in children is not well understood. The objective was to determine whether increasing vitamin D intake by 300IU/d, compared to normal intakes (~200 IU/d), would be beneficial for lean mass accretion in young children. Healthy children 2 to 8 y (n=51) from the Greater Montreal area, randomized by family, consumed vitamin D intakes of ~200 IU/day in the control group with an additional 300 IU/d in cheese or yogurt beverage in the fortified group for 6 months starting in October 2014 (clinicaltrials.gov: NCT02387892). Whole body and regional lean mass and fat mass were measured at baseline and 6 months using DXA (Hologic Discovery APEX software version 13.3). Fasted venous blood was sampled at baseline, 3 and 6 mo for measurement of vitamin D status (total serum 25(OH)D: Liaison, Diasorin and LC‐MS/MS) as well as ionized calcium (ABL80 Flex, Radiometer) followed by standardized anthropometry, demographics plus activity and dietary questionnaires. A mixed model ANOVA with post‐hoc Bonferroni adjustment was used to test for differences between groups. Data are mean ± SE unless otherwise stated. At baseline participants (5.64 ± 0.27 y) were 61% male (31/51), had BMI z‐score of 0.65 ± 0.12 with 4% (2/51) having serum 25(OH)D concentration below 50 nmol/L and there were no children who were deficient (< 30 nmol/L). Forty nine (96%) children completed the study with no differences between groups in baseline vitamin D intakes ( Table 1). There were no differences between groups for macronutrient intakes, except at baseline where fat intake was significantly higher in the control group (p = 0.01). Serum 25(OH)D stayed above 50 nmol/L in 80% (39/49) of children across the study, no children became deficient and there were no changes in ionized calcium. There was a significant difference between groups (p = 0.02) for percent change in total lean mass (control: 6.2% ± 1.2%, fortified: 9.2% ± 1.0%) ( Figure 1A) but not appendicular lean mass (control: 7.8% ± 1.9%, fortified: 13.2% ± 1.9%) over 6 months. There was no difference between groups for percent change in total fat mass (control: −4.3% ± 4.2%, fortified: −7.1% ± 3.7%) ( Figure 1B) over 6 months. Change in android and gynoid fat, along with fat mass and lean mass indices (trunk/limb fat mass ratio, lean mass + bone mineral content/height 2 ) were not different between groups. These data in healthy young children suggests that a vitamin D intake meeting the estimated average requirement (400 IU/d), compared to normal intakes, may have a positive impact on lean mass accretion without significantly influencing fat mass during winter months. Support or Funding Information This work was supported by funding from Dairy Farmers of Canada, the Canadian Foundation for Innovation and Canada Research Chairs and in‐kind support from Agropur and Ultima Foods for the study products. Dairy Farmers of Canada did not have a role in design, implementation, analysis or interpretation. 1 Vitamin D intake assessed by a validated 30 d food frequency questionnaire (FFQ) in 2–8 y old children.Time point Control group Fortified groupBaseline 202 ± 76 a (n=25) 248 ± 73 a (n=26) 3 month 239 ± 117 a (n=24) 466 ± 95 b (n=26) 6 month 241 ± 124 a (n=23) 486 ± 90 b(n=26)a,b Boxes with different superscripts are significantly different, using a repeated measures mixed model ANOVA. Data are unadjusted mean ± SD.