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Even with 400 IU of vitamin D in winter, 1 in 6 were still vitamin D deficient – RCT Aug 2013

Randomized controlled trial of the effects of vitamin D–fortified milk and bread on serum 25-hydroxyvitamin D concentrations in families in Denmark during winter: the VitmaD study

Am J Clin Nutr August 2013 ajcn.059469
Katja H Madsen kjma at food.dtu.dk , Lone B Rasmussen, Rikke Andersen, Christian Mølgaard, Jette Jakobsen, Poul J Bjerrum, Elisabeth W Andersen, Heddie Mejborn, and Inge Tetens
From the Divisions of Nutrition (KHM, LBR, RA, HM, and IT) and Food Chemistry (JJ), National Food Institute, Technical University of Denmark, Søborg, Denmark; the Department of Applied Mathematics and Computer Science, Technical University of Denmark, Lyngby, Denmark (EWA); the Clinical Biochemical Department, Holbæk Hospital, Holbæk, Denmark (PJB); the Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Frederiksberg C, Denmark (CM); and the Hans Christian Andersen Children's Hospital Odense University Hospital, Odense C, Denmark (CM).
Supported by grants from the Danish Dairy Research Fund, Centre for Advanced Food Studies, and The European Regional Development Fund. Arla Foods A/S, Lantmännen Cerealia A/S, and The Association of Danish Trade Mills partially sponsored the study foods.

Background: Vitamin D intakes are lower than dietary recommendations in most populations, and thus, a low vitamin D status is widespread, especially during winter.

Objective: We investigated the effects of increasing vitamin D intake to the recommended amount by fortification of milk and bread on serum 25-hydroxyvitamin D [25(OH)D] concentrations in families during winter in Denmark.

Design: The study was a randomized controlled trial in 782 children and adults (4–60 y old) recruited as 201 families. Families were randomly assigned to vitamin D–fortified or nonfortified milk and bread for 6 mo starting in September. The milk and bread replaced the participants’ usual consumptions of products.

Results: Median (IQR) vitamin D intakes (habitual diet plus fortified products) were 9.4 μg/d (6.5, 12.3 μg/d) and 2.2 μg/d (1.5, 3.0 μg/d) in fortification and control groups, respectively. Geometric mean (IQR) serum 25(OH)D concentrations decreased from 73.1 nmol/L (61.9, 88.5 nmol/L) to 67.6 nmol/L (56.2, 79.4 nmol/L) in the fortification group and from 71.1 nmol/L (61.2, 85.9 nmol/L) to 41.7 nmol/L (29.5, 58.9 nmol/L) in the control group (both P < 0.001). The final 25(OH)D concentration was significantly higher in the fortification group than in the control group (P < 0.001).
By the end of the study,

  • <1% of subjects in the fortification group and 25% of subjects in the control group had 25(OH)D concentrations <30 nmol/L and
  • 16% and 65% of subjects, respectively, had 25(OH)D concentrations <50 nmol/L.

Conclusion: Vitamin D fortification of milk and bread reduces the decrease in serum 25(OH)D concentrations during winter and ensures 25(OH)D concentrations >50 nmol/L in children and adults in Denmark. This trial was registered at clinicaltrials.gov as NCT01184716.

See also VitaminDWiki