Loading…
We use essential cookies (authentication, your saved goals/stack) by default. With your permission we'll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Head-to-head evidence comparison — which supplement is right for you?
Collagen wins 3 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
7 of 7 studies with measurable effects showed benefit.
Top outcomes
Verdict
Mostly mechanism / observational
Top outcomes
Shared outcomes (1)
Outcomes where both Collagen and Retinol have evidence — compare verdict strength side-by-side.
10-15g
Any time of day, With vitamin C for enhanced synthesis
Hydrolyzed collagen peptides (powder)
Topical cosmetic only. OTC retinol is formulated roughly 0.1-1% in leave-on serums or creams and applied to clean, dry facial skin at night, starting 2-3 nights per week and building to nightly as tolerated. There is no oral, injectable, or systemic dose — this is not ingested. Higher concentrations work somewhat better but irritate more; pair with a moisturizer and a morning sunscreen. This library does not provide an ingestion protocol.
evening
Leave-on topical serum or cream (0.1-1% retinol)
8-12 weeks
8-12 weeks
12 weeks
First week
Throughout
8-24 weeks
8-24 weeks
Throughout
Effects of Collagen Supplements on Skin Aging: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
The American Journal of Medicine (2025) · Meta analysis · n=1474
A total of 23 RCTs with 1474 participants were analyzed.
Effect of collagen supplementation on knee osteoarthritis: an updated systematic review and meta-analysis of randomised controlled trials
Clinical and experimental rheumatology (2025) · Meta analysis · n=870
The meta-analysis revealed an overall significant improvement of both function [MD, -6.46 (95% CI -9.52, -3.40); I2=75%; p=0.00001] and pain scores [MD, -13.63 (95% CI -20.67, -6.58); I2=88%; p=0.00001], favouring collagen supplementation.
Impact of Collagen Peptide Supplementation in Combination with Long-Term Physical Training on Strength, Musculotendinous Remodeling, Functional Recovery, and Body Composition in Healthy Adults: A Systematic Review with Meta-analysis
Sports medicine (Auckland, N.Z.) (2024) · Meta analysis · n=768
This systematic review and meta-analysis represents the first comprehensive investigation into the effects of long-term CP supplementation combined with regular physical training on various aspects of musculoskeletal health in adults.
Improvement of naturally aged skin with vitamin A (retinol).
Arch Dermatol (2007) · Rct · n=36
Randomized, double-blind, vehicle-controlled left/right-arm study: 0.4% retinol lotion vs vehicle applied up to 3x/week for 24 weeks in 36 elderly subjects (mean age 87)
A stabilized 0.1% retinol facial moisturizer improves the appearance of photodamaged skin in an eight-week, double-blind, vehicle-controlled study.
J Drugs Dermatol (2009) · Rct · n=64
Eight-week, double-blind, split-face, randomized study: stabilized 0.1% retinol moisturizer (36 subjects) vs vehicle (28 subjects) in women with moderate facial photodamage
Comparative efficacy of topical interventions for facial photoaging: a network meta-analysis.
Sci Rep (2025) · Meta analysis
Systematic review and Bayesian network meta-analysis of 23 RCTs (3905 participants) of topical anti-photoaging agents
Meta-analysis of 23 RCTs (n=1474) found collagen significantly improved skin hydration, elasticity, and wrinkles overall, but high-quality and non-industry-funded studies showed no significant effect. Hydrolyzed collagen peptides preferred for bioavailability.
AI-estimated from published studies. Interpret as directional guidance.
Collagen has a higher evidence score (6/10 vs 5/10) and wins in 3 of 3 categories.
For reduce wrinkles & fine lines, Retinol has a higher relevance score (75 vs 65).
No known interactions between Collagen and Retinol have been documented in our database. However, always consult a healthcare provider before combining supplements.