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Pooled review (meta-analysis)

Pooled review of 19 trials, 1,125 people: collagen improved skin hydration, elasticity and wrinkles

de Miranda and colleagues · International journal of dermatology · 2021

Original title: Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and 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

Pooled results from 19 studies and 1,125 people favored collagen over placebo for skin hydration, elasticity and wrinkles. The authors say 90 days of use reduced wrinkles.

The study at a glance

Type of study
Pooled review (meta-analysis)
Who or what was studied
19 studies, 1,125 people · People aged 20 to 70 (95% women) in 19 trials
What was tested
Collagen taken by mouth, compared with placebo; the abstract says benefits were seen with 90 days of use
What it measured
The question itself: skin wrinkles, elasticity and hydration
Who has a stake
No disclosure in PubMed
No disclosure in PubMed.
Journal
International journal of dermatology, 2021
Source
PubMed record 33742704. This page is based on the abstract only.

How much this study counts

  • ✓Pools the results of 19 studies with 1,125 people.
  • •A pooled review is only as strong as the studies it pools.
  • ✓Measured the question itself: skin wrinkles, elasticity and hydration.
  • •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

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: wrinkles, skin elasticity and moisture

    15

    13 benefit, 2 mixed

  2. Trials in people: other measures

    1

    1 benefit

  3. Trials in people: lab tests or safety

    0

    None among the papers we read.

  4. Population studies

    0

    None among the papers we read.

  5. Blood levels and genes

    0

    None among the papers we read.

↓ 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 collagen reduce skin aging?”

Unclear; higher-quality trials found no effect.

Confidence: low. Based on 22 on-topic papers.

Read the full answer
  • Part of the finding “Reviews find better hydration and elasticity”.
  • Summed up in “What reviews found”: Pooled 19 trials with 1,125 people aged between 20 and 70, 95% women. Collagen beat placebo on hydration, elasticity and wrinkles. The authors concluded that 90 days of use reduces skin aging.

Other reviews on this question

See all 22 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 agreed on every checked field. 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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