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Randomized trial · measured the question itself

3-year trial in 8,851 Mongolian children: vitamin D, no clear change in tuberculosis tests

Ganmaa and colleagues · The New England journal of medicine · 2020

Original title: Vitamin D Supplements for Prevention of Tuberculosis Infection and Disease.

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What the study found

No difference

A positive tuberculosis test: 3.6% with vitamin D vs 3.3% with placebo (adjusted risk ratio, 1.10; 95% CI, 0.87 to 1.38). Hospital stays for respiratory infection: 29 vs 34 children (adjusted risk ratio, 0.86; 95% CI, 0.52 to 1.40).

The study at a glance

Type of study
Randomized trial
Who or what was studied
8,851 people · Schoolchildren in Mongolia, almost all with low vitamin D, who tested negative for tuberculosis
What was tested
14,000 IU of vitamin D3 a week vs placebo for 3 years
What it measured
The question itself: colds, flu and other respiratory infections
Daily amount
14000 IU/week
How long
156 weeks
Trial registration
NCT02276755
Who has a stake
No stake declared
No potential conflict of interest reported; funded by the National Institutes of Health.
Journal
The New England journal of medicine, 2020
Source
PubMed record 32706534. This page is based on the abstract only.

How much this study counts

  • ✓Randomized: people were put into groups by chance, so the groups start out alike.
  • ✓Compared with a placebo, a dummy treatment.
  • ✓Large: 8,851 people.
  • ✓Long: about 3 years.
  • ✓Measured the question itself: colds, flu and other respiratory infections.
  • ✓No competing interests declared.
  • •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

Each dot is one on-topic paper on this question. Steps near the top answer the question more directly.

↑ Stronger evidence

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

    10

    2 benefit, 8 no difference

    ↑ This study is the ringed dot

  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

Of the other 9 papers on the same step: 2 benefit, 7 no difference. This one found no difference. It agrees with most of them.

Other papers on the same step

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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