title: Vitamin D-enhanced eggs are protective of wintertime serum 25-hydroxyvitamin D in a randomized controlled trial of adults.
abstract: BACKGROUND
  Despite numerous animal studies that have illustrated the impact of additional vitamin D in the diet of hens on the resulting egg vitamin D content, the effect of the consumption of such eggs on vitamin D status of healthy individuals has not, to our knowledge, been tested.
  
  
  OBJECTIVE
  We performed a randomized controlled trial (RCT) to investigate the effect of the consumption of vitamin D-enhanced eggs (produced by feeding hens at the maximum concentration of vitamin D3 or serum 25-hydroxyvitamin D [25(OH)D3] lawfully allowed in feed) on winter serum 25(OH)D in healthy adults.
  
  
  METHODS
  We conducted an 8-wk winter RCT in adults aged 45-70 y (n = 55) who were stratified into 3 groups and were requested to consume ≤2 eggs/wk (control group, in which status was expected to decline), 7 vitamin D3-enhanced eggs/wk, or seven 25(OH)D3-enhanced eggs/wk. Serum 25(OH)D was the primary outcome.
  
  
  RESULTS
  Although there was no significant difference (P > 0.1; ANOVA) in the mean preintervention serum 25(OH)D in the 3 groups, it was ∼7-8 nmol/L lower in the control group than in the 2 groups who consumed vitamin D-enhanced eggs. With the use of an ANCOVA, in which baseline 25(OH)D was accounted for, vitamin D3-egg and 25(OH)D3-egg groups were shown to have had significantly higher (P ≤ 0.005) postintervention serum 25(OH)D than in the control group. With the use of a within-group analysis, it was shown that, although serum 25(OH)D in the control group significantly decreased over winter (mean ± SD: -6.4 ± 6.7 nmol/L; P = 0.001), there was no change in the 2 groups who consumed vitamin D-enhanced eggs (P > 0.1 for both).
  
  
  CONCLUSIONS
  Weekly consumption of 7 vitamin D-enhanced eggs has an important impact on winter vitamin D status in adults. This trial was registered at clinicaltrials.gov as NCT02678364.
authors.affiliation: Cork Centre Center for Vitamin D and Nutrition Research.
authors.forename: Aoife
authors.initials: A
authors.lastname: Hayes
authors.affiliation: School of Agriculture and Food Science, University College Dublin, Dublin, Ireland; and.
authors.forename: Sarah
authors.initials: S
authors.lastname: Duffy
authors.affiliation: Muscle Foods Research Group, School of Food and Nutritional Sciences, and.
authors.forename: Michael
authors.initials: M
authors.lastname: O'Grady
authors.affiliation: National Food Institute, Technical University of Denmark, Søborg, Denmark.
authors.forename: Jette
authors.initials: J
authors.lastname: Jakobsen
authors.affiliation: Cork Centre Center for Vitamin D and Nutrition Research.
authors.forename: Karen
authors.initials: K
authors.lastname: Galvin
authors.affiliation: Cork Centre Center for Vitamin D and Nutrition Research.
authors.forename: Joanna
authors.initials: J
authors.lastname: Teahan-Dillon
authors.affiliation: Muscle Foods Research Group, School of Food and Nutritional Sciences, and.
authors.forename: Joseph
authors.initials: J
authors.lastname: Kerry
authors.affiliation: School of Agriculture and Food Science, University College Dublin, Dublin, Ireland; and.
authors.forename: Alan
authors.initials: A
authors.lastname: Kelly
authors.affiliation: School of Agriculture and Food Science, University College Dublin, Dublin, Ireland; and.
authors.forename: John
authors.initials: J
authors.lastname: O'Doherty
authors.affiliation: Cork Centre Center for Vitamin D and Nutrition Research.
authors.forename: Siobhan
authors.initials: S
authors.lastname: Higgins
authors.affiliation: Cork Centre Center for Vitamin D and Nutrition Research.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Seamans
authors.affiliation: Cork Centre Center for Vitamin D and Nutrition Research, Department of Medicine, University College Cork, Cork, Ireland; k.cashman@ucc.ie.
authors.forename: Kevin D
authors.identifier: http://orcid.org/0000-0002-8185-1039
authors.initials: KD
authors.lastname: Cashman
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood*; D000368:Aged; D000818:Animals; D002112:Calcifediol / Q000032:analysis / Q000097:blood*; D002645:Chickens; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000032:analysis / Q000378:metabolism; D003258:Consumer Behavior; D003296:Cooking; D004032:Diet / Q000662:veterinary*; D004531:Eggs / Q000032:analysis; D005260:Female; D005518:Food Preferences; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009753:Nutritive Value; D015995:Prevalence; D012306:Risk; D012621:Seasons; D012677:Sensation; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology / Q000517:prevention & control*
chemical_list: D002762:Cholecalciferol; D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol
keywords: 25(OH)D; RCT; bioaddition; vitamin D deficiency; vitamin D–enhanced eggs