(15-03-11) Estimation of the dietary requirement for vitamin D in healthy adolescent white girls1,2,3

1. Kevin D Cashman,
2. Anthony P FitzGerald,
3. Heli T Viljakainen,
4. Jette Jakobsen,
5. Kim F Michaelsen,
6. Christel Lamberg-Allardt, and
7. Christian M??lgaard
+ Author Affiliations
1. 1From the School of Food and Nutritional Sciences and Departments of Medicine (KDC) and Epidemiology and Public Health, and Statistics (APF), University College Cork, Cork, Ireland; the National Food Institute, Technical University of Denmark, Copenhagen, Denmark (JJ); the Department of Human Nutrition, Faculty of Life Sciences, University of Copenhagen, Copenhagen, Denmark (CM and KFM); the Hospital for Children and Adolescents, Helsinki University Central Hospital, Helsinki, Finland (HTV); and the Calcium Research Unit, Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland (CL-A).
?? ↵2 This research was enabled by financial support from the OPTIFORD project (QLK1-CT-2000-00623) under the European Commission's Framework V Programme.
?? ↵3 Address correspondence to KD Cashman, School of Food and Nutritional Sciences, Department of Medicine, University College Cork, Cork, Ireland. E-mail: [email protected].
Abstract
Background: Knowledge gaps have contributed to considerable variation (between 0 and 15 ??g/d) in international dietary recommendations for vitamin D in adolescents.
Objective: We aimed to establish the distribution of dietary vitamin D required to maintain serum 25-hydroxyvitamin D [25(OH)D] concentrations above several proposed cutoffs (25, 37.5, 40, and 50 nmol/L) during wintertime in adolescent white girls.
Design: Data (baseline and 6 mo) from 2 randomized, placebo-controlled, double-blind, 12-mo intervention studies in Danish (55??N) and Finnish (60??N) girls (n = 144; mean age: 11.3 y; mean vitamin D intake: 3.7 ??g/d) at vitamin D3 supplementation amounts of 0, 5, and 10 ??g/d were used. Serum 25(OH)D was measured with an HPLC assay in a centralized laboratory.
Results: Clear dose-related increments (P < 0.0001) in serum 25(OH)D with increasing supplemental vitamin D3 were observed. The slope of the relation between vitamin D intake and serum 25(OH)D at the end of winter was 2.43 nmol ⋅ L−1 ⋅ ??g intake−1, and no difference in the slopes between Finnish and Danish girls was observed. The vitamin D intakes that maintained serum 25(OH)D concentrations at >25, >37.5, and >50 nmol/L in 97.5% of the sample were 8.3, 13.5, and 18.6 ??g/d, respectively, whereas an intake of 6.3 ??g/d maintained a serum 25(OH)D concentration >40 nmol/L in 50% of the sample.
Conclusion: The vitamin D intakes required to ensure that adequate vitamin D status [defined variably as serum 25(OH)D >25 and >50 nmol/L] is maintained during winter in the vast majority (>97.5%) of adolescent girls (mean age: 11.3 y) at northern latitudes (>55??N) are 8.3 and 18.6 ??g/d, respectively. This trial was registered at clinicaltrials.gov as NCT00267540.

Source: Am J Clin Nutr March 2011 vol. 93 no. 3 549-555

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