Influence of vitamin D supplementation on muscle strength and exercise capacity in Mongolian schoolchildren: a randomised controlled trial

• Published in: medRxiv : the preprint server for health sciences
• Main Authors: Ganmaa, Davaasambuu, Hemmings, Stephanie, Jolliffe, David A, Buyanjargal, Uyanga, Garmaa, Gantsetseg, Adiya, Unaganshagai, Tumurbaatar, Tumenulzii, Dorjnamjil, Khulan, Tserenkhuu, Enkhtsetseg, Erdenenbaatar, Sumiya, Tsendjav, Enkhjargal, Enkhamgalan, Nomin, Achtai, Chuluun-Erdene, Talhaasuren, Yagaantsetseg, Byambasuren, Tuya, Ganbaatar, Erdenetuya, Purevdorj, Erkhembulgan, Martineau, Adrian R
• Format: Journal Article
• Language: English
• Published: United States 28.03.2024

To determine whether weekly oral vitamin D supplementation influences grip strength, explosive leg power, cardiorespiratory fitness or spirometric lung volumes in Mongolian schoolchildren. Multicentre, randomised, double-blind, placebo-controlled clinical trial conducted in children aged 6-13 years at baseline attending 18 schools in Ulaanbaatar. The intervention was weekly oral doses of 14,000 IU vitamin D (n=4418) or placebo (n=4433) for 3 years. Outcome measures were grip strength, standing long jump distance and serum 25-hydroxyvitamin D (25[OH]D) concentrations (determined in all participants), peak oxygen uptake (VO , determined in a subset of 632 participants using 20-metre multi-stage shuttle run tests) and spirometric outcomes (determined in a subset of 1,343 participants). 99.8% of participants had serum 25(OH)D concentrations <75 nmol/L at baseline, and mean end-study 25(OH)D concentrations in children randomised to vitamin D vs. placebo were 77.4 vs. 26.7 nmol/L (mean difference 50.7 nmol/L, 95% CI, 49.7 to 51.4). However, vitamin D supplementation did not influence mean grip strength, standing long jump distance, VO , spirometric lung volumes or peak expiratory flow rate, either overall or within sub-groups defined by sex, baseline 25(OH)D concentration <25 vs. ≥25 nmol/L or calcium intake <500 vs. ≥500 mg/day. A 3-year course of weekly oral supplementation with 14,000 IU vitamin D elevated serum 25(OH)D concentrations in Mongolian schoolchildren with a high baseline prevalence of vitamin D deficiency. However, this intervention did not influence grip strength, explosive leg power, peak oxygen uptake or spirometric lung volumes, either overall or in sub-group analyses.