Oral Collagen Peptides and Skin Rejuvenation

BACKGROUNDCutaneous aging is characterized by progressive degradation of the extracellular matrix, manifesting as diminished hydration, loss of elasticity, and increased wrinkle depth. While oral hydrolyzed collagen peptides (HCPs) are increasingly utilized as systemic nutricosmetics, previous evidence syntheses have been limited by severe methodological heterogeneity and the inability to account for highly influential statistical outliers. This updated systematic review and meta-analysis evaluated the clinical efficacy of oral collagen peptides for skin rejuvenation using an advanced statistical framework.

METHODSA comprehensive literature search was conducted on PubMed (MEDLINE), Cochrane Library, and Google Scholar from inception to November 2025. Randomized controlled trials evaluating oral collagen supplementation in healthy adults were included. Data were synthesized using random effect models. To differentiate true clinical signals from statistical artifacts, analyses were reinforced with multilevel meta-analysis, leave-one-out sensitivity testing, and dose–response spline regressions.

RESULTSThirty-five randomized controlled trials comprising 2534 participants were included. Primary analysis revealed that oral collagen supplementation yielded statistically significant improvements in instrumental measures of skin hydration (SMD = 0.44; 95% CI: 0.15–0.73), skin elasticity (SMD = 0.62; 95% CI: 0.15–1.10), and barrier function via reduced transepidermal water loss (SMD = −0.39; 95% CI: −0.62 to −0.16). Efficacy appeared predominantly time-dependent rather than dose-dependent, with elasticity and barrier improvements requiring at least 12 weeks of supplementation. Conversely, rigorous sensitivity and multilevel analyses demonstrated that apparent improvements in structural parameters, specifically skin wrinkles, roughness, and dermal density, were statistical artifacts driven by high-leverage outliers and severe inter-study heterogeneity.

CONCLUSIONOral collagen peptide supplementation is an effective functional systemic moisturizer that produces significant time-dependent improvements in cutaneous hydration, elasticity, and barrier retention. However, current evidence from trials of standard duration remains limited and inconsistent regarding structural anti-aging effects, including macroscopic wrinkle reduction and dermal densification, and the existing data are simply not robust enough to support definitive conclusions in these domains.

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