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Randomized trial · measured lab tests or safety

12-week trial in 82 teenage swimmers: vitamin D left immune gland activity unchanged

Mayan and colleagues · The Israel Medical Association journal : IMAJ · 2015

Original title: Thymus Activity, Vitamin D, and Respiratory Infections in Adolescent Swimmers.

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

No difference

Thymus activity marker did not differ by vitamin D status and was not changed by supplements. No significant links were found between this marker and how severe or long colds were.

The study at a glance

Type of study
Randomized trial
Who or what was studied
82 people · Teenage competitive swimmers, 55 of 82 with low vitamin D
What was tested
Vitamin D3 vs placebo for 12 winter weeks, then looked at thymus (immune gland) activity and cold symptoms
What it measured
Lab tests or markers
How long
12 weeks
Who has a stake
No disclosure in PubMed
No disclosure in PubMed.
Journal
The Israel Medical Association journal : IMAJ, 2015
Source
PubMed record 26625549. 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: 82 people.
  • •Lasted 12 weeks.
  • –Measured lab tests or markers, which stand in for colds, flu and other respiratory infections. A better marker does not always mean better health.
  • •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

  3. Trials in people: lab tests or safety

    1

    1 no difference

    ↑ This study is the ringed dot

  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

Few other papers sit on the same step, so there is little to compare it with.

Other papers on the same step

None among the papers we read.

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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