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Pooled review (meta-analysis)

Pooled review of 26 trials, 1,721 people: collagen improved skin hydration and elasticity

Pu and colleagues · Nutrients · 2023

Original title: Effects of Oral Collagen for Skin Anti-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 26 trials showed better skin hydration (Z = 4.94, p < 0.00001) and elasticity (Z = 4.49, p < 0.00001) than placebo. The authors found several biases in the trials.

The study at a glance

Type of study
Pooled review (meta-analysis)
Who or what was studied
26 studies, 1,721 people · 1721 people in 26 randomized trials
What was tested
Hydrolyzed collagen by mouth, compared with placebo
What it measured
The question itself: skin wrinkles, elasticity and hydration
Who has a stake
No stake declared
No competing interests declared.
Journal
Nutrients, 2023
Source
PubMed record 37432180. This page is based on the abstract only.

How much this study counts

  • ✓Pools the results of 26 studies with 1,721 people.
  • •A pooled review is only as strong as the studies it pools.
  • ✓Measured the question itself: skin wrinkles, elasticity and hydration.
  • ✓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

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
  • Quoted in “What we found”: The largest review here pooled 26 trials with 1721 people. Collagen gave better skin hydration and elasticity than placebo, but the authors found several biases in the trials.
  • Part of the finding “Reviews find better hydration and elasticity”.
  • Summed up in “What reviews found”: Pooled 26 randomized trials with 1721 people. Hydrolyzed collagen improved skin hydration and elasticity compared with placebo. The authors found several biases in the trials and called for larger trials to confirm the findings.
  • Marked as a key paper in the research timeline: Biggest pooled review: 26 trials, 1721 people.

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 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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