Vitamin D-fortified foods improve wintertime vitamin D status in women of Danish and Pakistani origin living in Denmark: a randomized controlled trial

  • Ida M. GrønborgEmail author
  • Inge Tetens
  • Tue Christensen
  • Elisabeth W. Andersen
  • Jette Jakobsen
  • Mairead Kiely
  • Kevin D. Cashman
  • Rikke Andersen
Original Contribution



Low vitamin D status is prevalent worldwide. We aim to investigate the effect of vitamin D fortification on serum 25-hydroxyvitamin D (25(OH)D) concentration in women of Danish and Pakistani origin at risk of vitamin D deficiency.


A 12-week randomized, double-blinded, placebo-controlled intervention trial during winter time, designed to provide 20 µg vitamin D3/day through fortified yoghurt, cheese, eggs and crisp bread, and assess the change in serum 25(OH)D. Participants were 143 women of Danish and Pakistani origin, living in Denmark, randomized into four groups, stratified by ethnicity.


Mean (SD) baseline 25(OH)D concentrations among women of Danish and Pakistani origin were 49.6 (18) and 46.9 (22) nmol/L, respectively (P = 0.4). While 9% of Danish women had 25(OH)D < 30 nmol/L, the prevalence among women of Pakistani origin was 24%. Median (IQR) vitamin D intake among Danish and Pakistani women at endpoint was 32.0 (27.0, 34.4) µg/day and 24.2 (19.2, 30.8) µg/day, respectively. Endpoint serum 25(OH)D increased in fortified groups to 77.8 (14) nmol/L among Danish women and 54.7 (18) nmol/L among women of Pakistani origin (P < 0.01). At endpoint, 0% in the Danish-fortified group and 3% in the Pakistani-fortified group had 25(OH)D < 30 nmol/L, compared with 23 % and 34% in their respective control groups.


Vitamin D fortification of four different foods for 12 weeks during winter was effective in increasing serum 25(OH)D and reducing the prevalence of very low vitamin D status among women of Danish and Pakistani origin. with identifier



Vitamin D Food-based RCT ODIN Women of Pakistani origin Women of Danish origin Fortified foods 



Serum 25-hydroxyvitamin D


Parathyroid hormone


Randomized controlled trial


Food-based solutions for optimal vitamin D nutrition and health through the life cycle


Standard deviation


Coefficient of variance ((SD/mean) × 100)


Tolerable upper intake level


Food frequency questionnaire


Towards a strategy for optimal vitamin D fortification


University College Cork


Liquid chromatography–tandem mass spectrometry


Vitamin D standardization program


Analysis of variance


Analysis of covariance


Confidence Interval



We thank the following individuals for their help and assistance with this trial: Majken Ege, Karin Hess Ygil, Dorte L Korsbech, Erika Baig for assisting with the measurements, dietary intake calculations and FFQ work, Bashy Quraishy, Raza Mustafa, Saima Raza, Shahnaz Qureshi and Shais Anais for introducing us to the Pakistani societies in Copenhagen, Denmark. We would also like to thank Dr. George Hull and Ms. Kirsten Dowling at University College Cork for their contribution to the analysis of serum 25(OH)D within the ODIN project. We thank our industrial partners FrieslandCampina, Hedegaard, Lantmännen Cerealia and DSM nutritional products for delivering the foods used in the trial.

Author contributors

IMG and RA collected the data, TC managed intake data, JJ analyzed the vitamin D content of the food, KC oversaw the analysis of serum 25(OH)D, IMG undertook the statistical analyses and wrote this paper. EWA assisted with the statistical analyses. RA, IT, KC and MK designed the study. All contributed to the manuscript.


This research was undertaken by the National Food Institute, Technical University of Denmark (DTU) and the study is a part of the European collaborative project “Food-based solutions for eradication of vitamin D deficiency and health promotion throughout the life cycle - ODIN”, which was funded by the European Commission (FP7/2007-2013) under grant agreement no. 613977 (ODIN) and by the National Food Institute, Technical University of Denmark. The cheese and yoghurt products were produced and provided free of charge by FrieslandCampina. The eggs were produced and provided free of cost by Hedegaard Agro, including chicken feed produced by Dava Foods, the crisp bread was produced by Smørum konditori (confectionary) with ingredients provided free of cost by Lantmännen cerialia and vitamin D3 supplied by DSM Nutritional Products.

Compliance with ethical standards

Ethical standards

Written informed consent was obtained from all participants on enrolment. The study protocol was approved by the local ethical committee (protocol no. H-15008276) and registered at with identifier: NCT02631629. The study was carried out in accordance with the Declaration of Helsinki.

Conflict of interest

None of the authors had conflicts of interest. The industry partners had no influence on the design of the study, the interpretation of the results or the writing of this manuscript.


  1. 1.
    Ross AC, Taylor CL, Yaktine AL, Del Valle HB (2011) Calcium and Vitamin D. Institute of Medicine, the National Academic Press, Washington, DCGoogle Scholar
  2. 2.
    EFSA Panel on Dietetic Products Nutrition and Allergies (NDA) (2016) Scientific opinion on dietary reference values for vitamin D. EFSA J. CrossRefGoogle Scholar
  3. 3.
    Cashman KD, Dowling KG, Skrabakova Z et al (2016) Vitamin D deficiency in Europe: pandemic? Am J Clin Nutr 103:1033–1044. CrossRefPubMedPubMedCentralGoogle Scholar
  4. 4.
    Holick M, Chen T (2008) Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr 87:1080–1086CrossRefGoogle Scholar
  5. 5.
    Andersen R, Mølgaard C, Skovgaard LT et al (2008) Pakistani immigrant children and adults in Denmark have severely low vitamin D status. Eur J Clin Nutr 62:625–634. CrossRefPubMedGoogle Scholar
  6. 6.
    Andersson Å, Björk A, Kristiansson P, Johansson G (2013) Vitamin D intake and status in immigrant and native Swedish women: a study at a primary health care centre located at 60 oN in Sweden. Food Nutr Res 1:1–8Google Scholar
  7. 7.
    Meyer HE, Falch JA, Søgaard AJ, Haug E (2004) Vitamin D deficiency and secondary hyperparathyroidism and the association with bone mineral density in persons with Pakistani and Norwegian background living in Oslo, Norway, The Oslo Health Study. Bone 35:412–417. CrossRefPubMedGoogle Scholar
  8. 8.
    Cashman KD, Dowling KG, Škrabáková Z et al (2015) Standardizing serum 25-hydroxyVitamin D data from four Nordic population samples using the Vitamin D Standardization Program protocols: Shedding new light on Vitamin D status in Nordic individuals. Scand J Clin Lab Invest 75:549–561. CrossRefGoogle Scholar
  9. 9.
    Holick MF (2006) Resurrection of vitamin D deficiency and rickets. J Clin Invest 116:2062–2072. CrossRefPubMedPubMedCentralGoogle Scholar
  10. 10.
    Nordic council of Ministers (2014) Nordic nutrition recommendations 2012-Integrating nutrition and physical activity, 5th ed.Google Scholar
  11. 11.
    The Scientific Advisory Committee on Nutrition (SACN) (2016) SACN vitamin D and health reportGoogle Scholar
  12. 12.
    Brot C, Vestergaard P, Kolthoff N et al (2001) Vitamin D status and its adequacy in healthy Danish perimenopausal women: relationships to dietary intake, sun exposure and serum parathyroid hormone. Br J Nutr 86:97–103. CrossRefGoogle Scholar
  13. 13.
    Pedersen AN, Christensen T, Matthiessen J et al (2015) Danskernes kostvaner 2011–2013. Hovedresultater. p 210Google Scholar
  14. 14.
    The Danish health Authority (2010) Prevention of Vitamin D deficiency [Public health information at, May 2010]Google Scholar
  15. 15.
    Knudsen VK (2014) Danskernes forbrug af kosttilskud (The use of dietary supplements in Denmark). e-paper Natl. Food Institute, DTUGoogle Scholar
  16. 16.
    Tetens I, Biltoft-Jensen A, Spagner C et al (2011) Intake of micronutrients among Danish adult users and non-users of dietary supplements. Food Nutr Res 55:1–8. CrossRefGoogle Scholar
  17. 17.
    Cashman KD, Kiely M (2016) Tackling inadequate vitamin D intakes within the population: fortification of dairy products with vitamin D may not be enough. Endocrine 51:38–46. CrossRefGoogle Scholar
  18. 18.
    Kiely M, Black LJ (2012) Dietary strategies to maintain adequacy of circulating 25-hydroxyvitamin D concentrations. Scand J Clin Lab Invest Suppl 243:14–23. CrossRefGoogle Scholar
  19. 19.
    Grønborg IM, Tetens I, Ege M et al (2018) Modelling of adequate and safe vitamin D intake in Danish women using different fortification and supplementation scenarios to inform fortification policies. Eur J Nutr 2018:1–6. CrossRefGoogle Scholar
  20. 20.
    Jääskeläinen T, Itkonen ST, Lundqvist A et al (2017) The positive impact of general Vitamin D food fortification policy on Vitamin D status in a representative adult Finnish population: evidence from an 11-y follow-up based on standardized 25-hydroxyVitamin D data. Am J Clin Nutr 105:1512–1520. CrossRefGoogle Scholar
  21. 21.
    Calvo MS, Whiting SJ, Barton CN (2004) Vitamin D fortification in the United States and Canada: current status and data needs 1–4 lawful addition of vitamin D to foods in. Am J Clin Nutr 80:1710–1716. CrossRefGoogle Scholar
  22. 22.
    Ritu G, Gupta A, Gupta A (2014) Fortification of foods with vitamin D in India. Nutrients 6:3601–3623. CrossRefGoogle Scholar
  23. 23.
    O’Neill CM, Kazantzidis A, Kiely M et al (2017) A predictive model of serum 25-hydroxyvitamin D in UK white as well as black and Asian minority ethnic population groups for application in food fortification strategy development towards vitamin D deficiency prevention. J Steroid Biochem Mol Biol 173:245–252. CrossRefPubMedGoogle Scholar
  24. 24.
    Madsen K, Rasmussen L, Andersen R et al (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 98:374–382. CrossRefGoogle Scholar
  25. 25.
    Hirvonen T, Sinkko H, Valsta L et al (2007) Development of a model for optimal food fortification: vitamin D among adults in Finland. Eur J Nutr 46:264–270. CrossRefPubMedGoogle Scholar
  26. 26.
    Thuesen B, Husemoen L, Fenger M et al (2012) Determinants of vitamin D status in a general population of Danish adults. Bone 50:605–610. CrossRefPubMedGoogle Scholar
  27. 27.
    Cashman KD, Ritz C, Kiely M (2017) Improved dietary guidelines for vitamin D: application of individual participant data (IPD)-level meta-regression analyses. Nutrients 9:1–17CrossRefGoogle Scholar
  28. 28.
    EFSA Panel on Dietetic Products Nutrition and Allergies (NDA) (2012) Scientific opinion on the tolerable upper intake level of vitamin D. EFSA J 10:1–45. CrossRefGoogle Scholar
  29. 29.
    Burild A, Frandsen HL, Poulsen M, Jakobsen J (2014) Quantification of physiological levels of vitamin D3 and 25-hydroxyvitamin D3 in porcine fat and liver in subgram sample sizes. J Sep Sci 37:2659–2663. CrossRefGoogle Scholar
  30. 30.
    National Food Institute DTU (2015) Fooddata. Accessed 8 Jan 2018
  31. 31.
    Jakobsen J, Wreford Andersen EA, Christensen T et al (2018) Vitamin D vitamers affect vitamin D status differently in young healthy males. Nutrients 10(1):12CrossRefGoogle Scholar
  32. 32.
    National Food Institute DTU (2009) The Danish food composition database (version 7). Accessed 4 Mar 2018
  33. 33.
    Cashman KD, Kiely M, Kinsella M et al (2013) Evaluation of vitamin D standardization program protocols for standardizing serum 25-hydroxyvitamin D data: a case study of the program’s potential for national nutrition and health surveys. Am J Clin Nutr 97:1235–1242. CrossRefPubMedPubMedCentralGoogle Scholar
  34. 34.
    Bischof MG, Heinze G, Vierhapper H (2006) Vitamin D status and its relation to age and body mass index. Horm Res 66:211–215. CrossRefPubMedGoogle Scholar
  35. 35.
    R Core Team (2017) R: a language and environment for statistical computing. R Foundation for Statistical Computing,Vienna, Austria.
  36. 36.
    Tripkovic L, Wilson LR, Hart K et al (2017) Daily supplementation with 15 µg vitamin D 2 compared with vitamin D 3 to increase wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial. Am J Clin Nutr 106:481–490. CrossRefPubMedGoogle Scholar
  37. 37.
    Ahmad M, Flatzb G (1984) Prevalence of primary adult lactose malabsorption in Pakistan. Hum Hered 34:69–75. CrossRefPubMedGoogle Scholar
  38. 38.
    Kolars JC, Levitt MD, Aouji M, Savaiano DA (1984) Yogurt—an autodigesting source of lactose. N Engl J Med 5:1–3. CrossRefGoogle Scholar
  39. 39.
    Danish Health Authority AND the Danish Veterinary and Food Administration (2005) Do you get enough vitamin D? Important if you have dark skin or wears covered clothing, vol 1Google Scholar
  40. 40.
    Danish National Health Authority (2009) Health information in English on vitamin D and health, provided for ethnic minorities.
  41. 41.
    Pilz S, März W, Cashman KD et al (2018) Rationale and plan for vitamin D food fortification: a review and guidance paper. Front Endocrinol (Lausanne) 9:1–16. CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Division of Nutrition, National Food InstituteTechnical University of DenmarkLyngbyDenmark
  2. 2.Department of Nutrition, Exercise and Sports, Vitality-Centre for good older livesUniversity of CopenhagenCopenhagenDenmark
  3. 3.Section for Statistics and PharmacoepidemiologyDanish Cancer SocietyCopenhagenDenmark
  4. 4.Institute of Applied Mathematics and Computer ScienceTechnical University of DenmarkLyngbyDenmark
  5. 5.Cork Centre for Vitamin D and Nutrition Research, School of Food and Nutritional SciencesUniversity College CorkCorkIreland
  6. 6.Department of MedicineUniversity College CorkCorkIreland

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