Article Text

Vitamin D3 supplementation in patients with frequent respiratory tract infections: a randomised and double-blind intervention study
  1. Peter Bergman1,2,3,
  2. Anna-Carin Norlin2,4,
  3. Susanne Hansen2,
  4. Rokeya Sultana Rekha5,
  5. Birgitta Agerberth5,
  6. Linda Björkhem-Bergman6,
  7. Lena Ekström6,
  8. Jonatan D Lindh6,
  9. Jan Andersson3
  1. 1Department of Laboratory Medicine, Clinical Microbiology, Karolinska Institutet, Stockholm, Sweden
  2. 2Clinical Immunology, Immunodeficiency Unit, Karolinska University Hospital, Stockholm, Sweden
  3. 3Department of Medicine, Center for Infectious Medicine (CIM), Karolinska Institutet, Stockholm, Sweden
  4. 4Department of Laboratory Medicine, Clinical Immunology, Karolinska Institutet, Stockholm, Sweden
  5. 5Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
  6. 6Department of Laboratory Medicine, Clinical Pharmacology, Karolinska Institutet, Stockholm, Sweden
  1. Correspondence to Dr Peter Bergman; peter.bergman{at}


Background Low serum levels of 25-hydroxyvitamin D3 are associated with an increased risk of respiratory tract infections (RTIs). Clinical trials with vitamin D3 against various infections have been carried out but data are so far not conclusive. Thus, there is a need for additional randomised controlled trials of effects of vitamin D3 on infections.

Objective To investigate if supplementation with vitamin D3 could reduce infectious symptoms and antibiotic consumption among patients with antibody deficiency or frequent RTIs.

Design A double-blind randomised controlled trial.

Setting Karolinska University Hospital, Huddinge.

Participants 140 patients with antibody deficiency (selective IgA subclass deficiency, IgG subclass deficiency, common variable immune disorder) and patients with increased susceptibility to RTIs (>4 bacterial RTIs/year) but without immunological diagnosis.

Intervention Vitamin D3 (4000 IU) or placebo was given daily for 1 year.

Primary and secondary outcome measures The primary endpoint was an infectious score based on five parameters: symptoms from respiratory tract, ears and sinuses, malaise and antibiotic consumption. Secondary endpoints were serum levels of 25-hydroxyvitamin D3, microbiological findings and levels of antimicrobial peptides (LL-37, HNP1–3) in nasal fluid.

Results The overall infectious score was significantly reduced for patients allocated to the vitamin D group (202 points) compared with the placebo group (249 points; adjusted relative score 0.771, 95% CI 0.604 to 0.985, p=0.04).

Limitations A single study centre, small sample size and a selected group of patients. The sample size calculation was performed using p=0.02 as the significance level whereas the primary and secondary endpoints were analysed using the conventional p=0.05 as the significance level.

Conclusions Supplementation with vitamin D3 may reduce disease burden in patients with frequent RTIs.

  • Infectious Diseases
  • Bacteriology
  • Respiratory Medicine (see Thoracic Medicine)

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: and

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Supplementary materials

  • Supplementary Data

    This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

    Files in this Data Supplement: