Cited by 2,040Vitamin D Research StudiesRespiratory viral infections researchNutrition and Health Studies

The DOI matches its Crossref record; 59 of the 60 references it cites were found in a registry or an index; none of the 19 sources its claims cite is checked for support yet.

Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data

Open access

Abstract

Objectives To assess the overall effect of vitamin D supplementation on risk of acute respiratory tract infection, and to identify factors modifying this effect. Design Systematic review and meta-analysis of individual participant data (IPD) from randomised controlled trials. Data sources Medline, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, ClinicalTrials.gov, and the International Standard Randomised Controlled Trials Number registry from inception to December 2015. Eligibility criteria for study selection Randomised, double blind, placebo controlled trials of supplementation with vitamin D3 or vitamin D2 of any duration were eligible for inclusion if they had been approved by a research ethics committee and if data on incidence of acute respiratory tract infection were collected prospectively and prespecified as an efficacy outcome. Results 25 eligible randomised controlled trials (total 11 321 participants, aged 0 to 95 years) were identified. IPD were obtained for 10 933 (96.6%) participants. Vitamin D supplementation reduced the risk of acute respiratory tract infection among all participants (adjusted odds ratio 0.88, 95% confidence interval 0.81 to 0.96; P for heterogeneity <0.001). In subgroup analysis, protective effects were seen in those receiving daily or weekly vitamin D without additional bolus doses (adjusted odds ratio 0.81, 0.72 to 0.91) but not in those receiving one or more bolus doses (adjusted odds ratio 0.97, 0.86 to 1.10; P for interaction=0.05). Among those receiving daily or weekly vitamin D, protective effects were stronger in those with baseline 25-hydroxyvitamin D levels <25 nmol/L (adjusted odds ratio 0.30, 0.17 to 0.53) than in those with baseline 25-hydroxyvitamin D levels ≥25 nmol/L (adjusted odds ratio 0.75, 0.60 to 0.95; P for interaction=0.006). Vitamin D did not influence the proportion of participants experiencing at least one serious adverse event (adjusted odds ratio 0.98, 0.80 to 1.20, P=0.83). The body of evidence contributing to these analyses was assessed as being of high quality. Conclusions Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit. Systematic review registration PROSPERO CRD42014013953.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This individual participant data meta-analysis of 25 randomised controlled trials found that vitamin D supplementation reduced the risk of acute respiratory tract infection overall (adjusted odds ratio 0.88, 95% confidence interval 0.81 to 0.96). Benefit was strongest in participants receiving daily or weekly vitamin D without bolus doses and in those with baseline 25-hydroxyvitamin D <25 nmol/L.

Key findings

  • Overall, vitamin D supplementation reduced the proportion of participants experiencing at least one acute respiratory tract infection: adjusted odds ratio 0.88 (0.81 to 0.96), P=0.003, NNT=33 (20 to 101); P for heterogeneity <0.001.
  • Daily or weekly vitamin D without additional bolus doses was protective (adjusted odds ratio 0.81, 0.72 to 0.91; NNT=20), whereas regimens including at least one bolus dose were not (adjusted odds ratio 0.97, 0.86 to 1.10; P for interaction=0.05).
  • Among those receiving daily or weekly vitamin D, protection was greater with baseline 25-hydroxyvitamin D <25 nmol/L (adjusted odds ratio 0.30, 0.17 to 0.53; NNT=4) than with baseline ≥25 nmol/L (adjusted odds ratio 0.75, 0.60 to 0.95; P for interaction=0.006).
  • Vitamin D did not increase serious adverse events of any cause (adjusted odds ratio 0.98, 0.80 to 1.20, P=0.83); hypercalcaemia occurred in 21/3850 (0.5%) and renal stones in 6/3841 (0.2%), evenly represented between arms.

Methods

  • Systematic review and individual participant data meta-analysis of randomised, double-blind, placebo-controlled trials of vitamin D3 or vitamin D2; searches of Medline, Embase, CENTRAL, Web of Science, ClinicalTrials.gov, and ISRCTN to December 2015 identified 25 eligible trials with 11,321 randomised participants aged 0 to 95 years.
  • Primary outcome was incidence of acute respiratory tract infection; one-step and two-step random-effects IPD meta-analyses were adjusted for age, sex, and study duration, with prespecified subgroup analyses by baseline 25-hydroxyvitamin D, dosing regimen, dose size, age, body mass index, asthma, COPD, and influenza vaccination.
  • IPD were obtained for 10,933 (96.6%) participants for the primary analysis; risk of bias was assessed with the Cochrane tool, and GRADE was used to assess quality of evidence.

Limitations

  • Stated: funnel plot asymmetry raised the possibility that small trials showing adverse effects of vitamin D were missed; power was limited for some subgroups and secondary outcomes, so null or borderline results may reflect type 2 error; adherence data were not available for all participants; acute respiratory tract infection definitions were diverse and few events had virological, microbiological, or radiological confirmation.
  • Stated: residual confounding by other effect modifiers cannot be excluded, especially in stratified analyses with few trials represented, so the authors advise caution interpreting the dosing-frequency-stratified subgroup results.
  • Evident from the text: race or ethnicity was not investigated as an effect modifier because data were missing for 3680/10,933 (34%) participants and power was limited; two trials were at unclear risk of bias due to high loss to follow-up (Dubnov-Raz: 52% did not complete all symptom questionnaires; Laaksi: 37% lost to follow-up).

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1136/bmj.i6583

Cites

59 of 59 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 19 cited sources checked · 0 supported · 0 flagged

Show all 76 claims

  • Probably not a substantial claim. 25
  • It may state two separate claims as one. 17
  • The quote only partly states this claim. 1
34 of 34
  • The paper relies on this without support.

    The acute respiratory tract infection case definitions used across the included trials are sufficiently comparable to be pooled in the meta-analysis.

    “Data relating to study characteristics were extracted for the following variables: setting, eligibility criteria, details of intervention and control regimens, study duration, and case definitions for acute respiratory tract infection.”
  • The paper relies on this without support.

    The 25-hydroxyvitamin D measurements from different assays and laboratories are comparable enough to classify participants by baseline vitamin D status.

    “Baseline serum 25-hydroxyvitamin D concentrations were determined in 19/25 trials: mean baseline concentration ranged from 18.9 to 88.9 nmol/L.”
  • The paper relies on this without support.

    Outcome data missing for 3.4% of participants are missing at random.

    “Outcome data for the primary analysis of proportion of participants experiencing at least one acute respiratory tract infection were obtained for 10 933 (96.6%) of the randomised participants.”
  • The authors state this as an assumption.

    Use of bolus doses of vitamin D was ineffective.

    “under the assumption that use of bolus doses was ineffective”
4 of 4

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • The higher-baseline-vitamin-D subgroup has six or 11 trials

    Minor

    The text says 1603 participants with higher baseline vitamin D concentrations came from six daily-or-weekly-dosing studies, but the corresponding Table 3 row lists 11 trials. The row's denominators, 729 and 874, sum to the stated 1603 participants.

1 of 1

Citations

Cites

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Show all 60 references

1 of the 60 references couldn’t be matched to a known paper.

Research works printed but not linked: 1

  1. [29]Department of Health. Department of Health Report on Health and Social Subjects, No. 49. Nutrition and bone health with particular reference to calcium and vitamin D. London; 1998. 9932291

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Metadata

Authors
Martineau, A. R., Jolliffe, D. A., Hooper, R. L., Greenberg, L., Aloia, J. F., Bergman, P., Dubnov-Raz, G., Esposito, S., Ganmaa, D., Ginde, A. A., Goodall, E. C., Grant, C. C., Griffiths, C. J., Janssens, W., Laaksi, I., Manaseki-Holland, S., Mauger, D., Murdoch, D. R., Neale, R., Rees, J. R., Simpson, S., Stelmach, I., Kumar, G. T., Urashima, M., & Camargo, C. A.
Affiliations
  • Queen Mary University of London (GB)
  • Winthrop-University Hospital (US)
  • Karolinska Institutet (SE)
  • University of Milan (IT)
  • Harvard University (US)
  • University of Colorado Anschutz (US)
  • McMaster University (CA)
  • University of Auckland (NZ)
  • Universitair Ziekenhuis Leuven (BE)
  • University of Tampere (FI)
  • Pennsylvania State University (US)
  • University of Otago (NZ)
  • QIMR Berghofer Medical Research Institute (AU)
  • Dartmouth College (US)
  • University of Tasmania (AU)
  • Medical University of Lodz (PL)
  • University of Delhi (IN)
  • Jikei University School of Medicine (JP)
Corresponding author
Martineau, Adrian R
Venue
BMJ
Publisher
BMJ
Published
2017-02-15
Volume
356
Pages
i6583
ISSN
  • 1756-1833 (ISSN-L)
  • 0959-8138
OpenAlex
W2588906490
Cited by
2,040
References
60
Citations by year
2026: 76 · 2025: 96 · 2024: 126 · 2023: 241 · 2022: 305 · 2021: 459 · 2020: 454 · 2019: 113 · 2018: 107 · 2017: 61
FWCI
32.11
Type
journal article
Language
en
Open access
Locations
  • BMJ (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • University of Birmingham Research Portal (University of Birmingham) (publishedVersion, cc-by)
  • Tampere University Institutional Repository (Tampere University) (publishedVersion, other-oa)
  • UTAS Research Repository (acceptedVersion)
  • Lirias (submittedVersion, other-oa)
  • eCite Digital Repository (University of Tasmania) (submittedVersion, cc-by)
  • Figshare (submittedVersion, cc-by)
  • HighWire Press Open Archive (submittedVersion)
  • Queen Mary Research Online (Queen Mary University of London) (submittedVersion, cc-by)
  • Tampere University Institutional Repository (Tampere University) (submittedVersion, cc-by)
  • Greater South Information System
Funders
  • National Institute for Health and Care Research (RP-PG-0407-10398, 13/03/25, HTA/13/03/25)
  • Health Technology Assessment Programme (13/03/25)
  • National Heart, Lung, and Blood Institute (U10HL098115, U10HL064313)
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Vitamin D Research Studies
  • Health Sciences › Medicine › Epidemiology › Respiratory viral infections research
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Nutrition and Health Studies
Keywords
vitamin D supplementation, acute respiratory infections, vitamin D3, vitamin D2, 25-hydroxyvitamin D, bolus dosing, dose-response relationship, baseline vitamin D status, infection control, adverse events, children, adults, older adults, pregnant women, lactating women, postpartum women, preterm infants, preterm birth, preterm birth prevention, preterm birth risk
MeSH terms
Humans, Respiratory Tract Infections, Vitamin D, Randomized Controlled Trials as Topic, Dietary Supplements

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