800 IU of vitamin D got most white Danish children to 20 nanograms – RCT Oct 2016

Estimation of the dietary requirement for vitamin D in white children aged 4–8 y: a randomized, controlled, dose-response trial

Am J Clin Nutr, First published October 12, 2016, doi: 10.3945/ajcn.116.136697
Charlotte Mortensen3,4,9, cmo at nexs.ku.dk, Camilla T Damsgaard3,9, Hanne Hauger3, Christian Ritz3, Susan A Lanham-New5, Taryn J Smith5, Áine Hennessy6, Kirsten Dowling6, Kevin D Cashman6,7, Mairead Kiely6,8, and Christian Mølgaard3
3Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark;
4Department of Nutrition and Midwifery, Faculty of Health and Technology, Metropolitan University College, Copenhagen, Denmark;
5Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Surrey, United Kingdom;
6Cork Centre for Vitamin D and Nutrition Research, School of Food and Nutritional Sciences,
7Department of Medicine, and
8Irish Centre for Fetal and Neonatal Translational Research, University College Cork, Cork, Ireland

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Background: Children in northern latitudes are at high risk of vitamin D deficiency during winter because of negligible dermal vitamin D3 production. However, to our knowledge, the dietary requirement for maintaining the nutritional adequacy of vitamin D in young children has not been investigated.

Objective: We aimed to establish the distribution of vitamin D intakes required to maintain winter serum 25-hydroxyvitamin D [25(OH)D] concentrations above the proposed cutoffs (25, 30, 40, and 50 nmol/L) in white Danish children aged 4–8 y living at 55°N.

Design: In a double-blind, randomized, controlled trial 119 children (mean age: 6.7 y) were assigned to 0 (placebo), 10, or 20 µg vitamin D3/d supplementation for 20 wk. We measured anthropometry, dietary vitamin D, and serum 25(OH)D with liquid chromatography–tandem mass spectrometry at baseline and endpoint.

Results: The mean ± SD baseline serum 25(OH)D was 56.7 ± 12.3 nmol/L (range: 28.7–101.4 nmol/L). Serum 25(OH)D increased by a mean ± SE of 4.9 ± 1.3 and 17.7 ± 1.8 nmol/L in the groups receiving 10 and 20 µg vitamin D3/d, respectively, and decreased by 24.1 ± 1.2 nmol/L in the placebo group (P < 0.001). A nonlinear model of serum 25(OH)D as a function of total vitamin D intake (diet and supplements) was fit to the data. The estimated vitamin D intakes required to maintain winter serum 25(OH)D >30 (avoiding deficiency) and >50 nmol/L (ensuring adequacy) in 97.5% of participants were 8.3 and 19.5 µg/d, respectively, and 4.4 µg/d was required to maintain serum 25(OH)D >40 nmol/L in 50% of participants.

Conclusions: Vitamin D intakes between 8 and 20 µg/d are required by white 4–8-y-olds during winter in northern latitudes to maintain serum 25(OH)D >30–50 nmol/L depending on chosen serum 25(OH)D threshold. This trial was registered at clinicaltrials.gov as NCT02145195.