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Pooled review (meta-analysis)

2019 pooled review of 25 trials: vitamin D lowered the risk of respiratory infection

Martineau and colleagues · Health technology assessment (Winchester, England) · 2019

Original title: Vitamin D supplementation to prevent acute respiratory infections: individual participant data meta-analysis.

Under review. A person has not yet checked this summary against the paper. It is written from the PubMed abstract. Until a person checks it, search engines are asked not to list this page.

What the study found

Points to benefit

Vitamin D lowered the risk of a respiratory infection (adjusted odds ratio 0.88, 95% CI 0.81 to 0.96). Daily or weekly doses gave 0.81; bolus doses gave 0.97. Starting level <25 nmol/l gave 0.30.

The study at a glance

Type of study
Pooled review (meta-analysis)
Who or what was studied
25 studies, 10,933 people · People aged 0 to 95 years in 25 placebo-controlled trials
What was tested
Vitamin D3 or D2 pills of any dose and length, vs placebo
What it measured
The question itself: colds, flu and other respiratory infections
Who has a stake
Company stake
Some authors report grants or fees from GSK, Pfizer, Sanofi, Vifor and Laboratoires SMB; main funder was the UK NIHR.
Journal
Health technology assessment (Winchester, England), 2019
Source
PubMed record 30675873. This page is based on the abstract only.

How much this study counts

  • ✓Pools the results of 25 studies with 10,933 people.
  • •A pooled review is only as strong as the studies it pools.
  • ✓Measured the question itself: colds, flu and other respiratory infections.
  • –Company stake: Some authors report grants or fees from GSK, Pfizer, Sanofi, Vifor and Laboratoires SMB; main funder was the UK NIHR.
  • •Summarized from the PubMed abstract only. The full paper may hold details the abstract leaves out.

✓ Strength– Limit• Note

These points come from fixed rules about the type of study, its size and length, what it measured, and who has a stake. Every study on Digestery gets the same rules.

Where this study sits

This paper is not on the ladder. It is a pooled review (meta-analysis), and reviews and opinion pieces discuss studies that are already counted on the steps below.

↑ Stronger evidence

  1. Trials in people: colds, flu and chest infections

    10

    2 benefit, 8 no difference

  2. Trials in people: other measures

    5

    1 benefit, 1 mixed, 2 no difference, 1 harm

  3. Trials in people: lab tests or safety

    1

    1 no difference

  4. Population studies

    1

    1 no difference

  5. Blood levels and genes

    4

    3 benefit, 1 no difference

↓ Weaker evidence

  • Points to benefit
  • Mixed
  • No difference
  • No direction
  • Points to harm

How it fits with the other research

The short answer to “Does vitamin D prevent colds and infections?”

Not clearly; any effect looks small.

Confidence: low. Based on 33 on-topic papers.

Read the full answer

Other reviews on this question

See all 33 studies on this question

How this page was made

Label

First read of the abstract
Claude Sonnet
Independent second read
Claude Haiku
Differences settled
The two reads differed. The reviewer checked the abstract and kept the first read. Claude Opus 5.5.
Headline
Claude Sonnet, from the checked study record. A script checked its numbers and wording.
Numbers
Checked against the abstract by a script
“How much this study counts”
Fixed rules, the same for every study
Source check by a person
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