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Randomized trial · measured other health measures

Trial in 185 pregnant women in New Zealand: no clear difference in colds

Grant and colleagues · Allergy · 2016

Original title: Vitamin D supplementation during pregnancy and infancy reduces aeroallergen sensitization: a randomized controlled trial.

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What the study found

No difference

Mite allergy sensitization was lower with vitamin D. Doctor visits for asthma: 11%, 0%, 4% (placebo, lower, higher dose; P = 0.002). No group differences for other respiratory diagnoses such as colds.

The study at a glance

Type of study
Randomized trial
Who or what was studied
185 people · Pregnant women in New Zealand and then their babies, checked at 18 months
What was tested
Vitamin D in pregnancy and infancy (1000/400 IU or 2000/800 IU a day) vs placebo, to age 6 months
What it measured
Several kinds of outcomes
Daily amount
2000 IU a day
Who has a stake
No disclosure in PubMed
No disclosure in PubMed.
Journal
Allergy, 2016
Source
PubMed record 27060679. 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.
  • •Medium size: 185 people.
  • •Measured several kinds of outcomes.
  • •The PubMed record has no conflict-of-interest statement.
  • •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

  2. Trials in people: other measures

    5

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

    ↑ This study is the ringed dot

  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 4 papers on the same step: 1 benefit, 1 mixed, 1 no difference, 1 harm. This one found no difference.

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 reviewer corrected 1 field after reading the abstract. 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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