High-dose vitamin D₃ supplementation shows no beneficial effects on white blood cell counts, acute phase reactants, or frequency of respiratory infections.

"Declarations Ethics approval and consent to participateWritten informed consent was obtained from all participants before enrolment. The Copenhagen Bone-Gonadal Study (NCT01304927) was approved by the Danish Health and Medicines authority, the local committee of Danish National Center for Ethics, and the data protection agency (approval no. 2010-024588-42, H-4-2010-138, and 2010124801). Consent for publicationNot applicable. Competing interestsThe authors declare no competing interests. Competing interests The authors declare no competing interests."

"Funding Open access funding provided by Copenhagen University. No influence from any sponsor on the study design, interpretation of results, or the decision to submit the manuscript for publication. This study was supported by FSS, Beckett foundation and Novo Nordisk foundation. Open access funding provided by Copenhagen University"

"Trial registration NCT01304927 (ClinicalTrials.gov). Registered February 20, 2011."