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

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 558N.
Design: In a double-blind, randomized, controlled trial 119 children
(mean age: 6.7 y) were assigned to 0 (placebo), 10, or 20 mg
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: Themean6 SD baseline serum25(OH)D was 56.76 12.3 nmol/L
(range: 28.7–101.4 nmol/L). Serum 25(OH)D increased by a mean 6
SE of 4.9 6 1.3 and 17.7 6 1.8 nmol/L in the groups receiving
10 and 20 mg vitamin D3/d, respectively, and decreased by 24.1 6
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 mg/d, respectively, and 4.4 mg/d was required to maintain
serum 25(OH)D .40 nmol/L in 50% of participants.
Conclusions: Vitamin D intakes between 8 and 20 mg/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.