Tier 1 — highest

Effects of Hydrolyzed Collagen Supplementation on Skin Aging: A Systematic Review and Meta-Analysis

Roseane B. de Miranda, Patrícia Weimer, Rochele C. Rossi
International Journal of Dermatology 2021 60(12):1449-1461

Bibliography

PubMed
PMID 33742704
DOI
10.1111/ijd.15518
Funding
Funding source: None, as declared in the published article.
Competing interests
Conflict of interest: None, as declared in the published article.

Study snapshot

DesignSystematic review and meta-analysis of randomised, double-blind, controlled trials
ModelHealthy adults aged 20-70 years (95% women) pooled across 19 included RCTs
Sample19 RCTs, 1,125 total participants
InterventionOral hydrolysed collagen (HC) supplementation vs placebo; doses across pooled trials ranged from 372 mg to 10 g/day
Duration4 to 16 weeks across pooled trials; benefits reported as evident from around 60-90 days of supplementation and maintained for roughly 30 days after stopping
EndpointsSkin hydration (corneometry); Skin elasticity (cutometry); Skin roughness; Wrinkle depth/area

What the study showed, in plain terms

This review pools 19 randomised, placebo-controlled trials of oral hydrolysed collagen for skin ageing, covering 1,125 participants. Combining the results statistically, hydrolysed collagen significantly improved skin hydration and skin elasticity compared with placebo, and the grouped analysis also showed a reduction in wrinkles and an increase in skin density.

The authors' practical read is that around 90 days of daily supplementation is the point by which benefits become clearly evident, and that gains persisted for about 30 days after supplementation stopped in the trials that tracked this.

The main caveat is heterogeneity — the studies pooled used different collagen sources, doses, formulations (some combined with vitamins or coenzyme Q10) and measurement units, which the authors themselves flag as the review's central limitation.

Key findings

  • Pooled analysis of 9 studies: hydrolysed collagen significantly improved skin hydration versus placebo (overall effect size 1.01, 95% CI 0.24-1.78, Z=2.58, p=0.010).
  • Pooled analysis of 14 studies: hydrolysed collagen significantly improved skin elasticity versus placebo (overall effect size 1.27, 95% CI 0.19-2.35, Z=2.31, p=0.02).
  • Grouped analysis showed a significant decrease in skin wrinkles (SMD -1.11, 95% CI -1.94 to -0.28, p=0.009) and a significant increase in cutaneous density (SMD 0.48, 95% CI 0.09-0.88, p=0.02).
  • No significant grouped differences were found for transepidermal water loss (TEWL), skin rash, dermal collagen levels, or melatonin pattern as secondary outcomes.
  • Subgroup analysis by hydration measurement unit (micrometres) showed a significant, more homogeneous favourable effect (0.73, 95% CI 0.19-1.27, p=0.008) after excluding one study using a different measurement technique.
  • Funnel plot inspection showed no strong evidence of publication bias; asymmetry appeared attributable to sample-size variation rather than selective reporting.

What this study can and cannot tell us

  • Substantial statistical heterogeneity across the pooled analyses (I² up to 93-98% in the main hydration and elasticity pooled estimates), driven by differing collagen sources, doses, formulations and outcome-measurement units across the 19 included trials.
  • Several included commercial products combined collagen with vitamins, minerals, coenzyme Q10 or hyaluronic acid, making it difficult to attribute the pooled benefit to collagen peptides alone in every trial.
  • Participant lifestyle factors (diet quality, hydration habits, sun exposure) were not accounted for in the analysis and may have influenced individual trial results.
  • The longest individual included trial ran only 90 days plus a 30-day follow-up, so the review cannot speak to longer-term (multi-year) use.
  • As the authors note, further large-scale, long-duration RCTs with standardised measurement units are needed to confirm the pooled effect sizes.

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Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology