Identification of food-derived collagen peptides in human blood after oral ingestion of gelatin hydrolysates
Small-sample open-label human bioavailability study without a placebo control — mechanistic, not efficacy.
Extracellular matrix synthesis and tissue elasticity research
Hydrolysed Collagen Peptides Evidence: 85 Verified Research Papers
Hydrolysed collagen contains enzymatically fragmented collagen proteins. Digestion releases amino acids and a subset of hydroxyproline-containing peptides detectable in human blood. Clinical effects depend on peptide preparation, dose, comparator and outcome; skin trials conflict when funding and trial quality are considered, while joint and tendon studies mix distinct collagen forms or training protocols.
Evidence at a glance
17
Tier 1
42
Tier 2
20
Tier 3
6
Tier 4
Bioavailability
Comparison of quantity and structures of hydroxyproline-containing peptides in human blood after oral ingestion of gelatin hydrolysates from different sources
Very small single-blind human crossover comparing peptide profiles across three collagen sources — mechanistic, hypothesis-generating for source-specific effects.
Oral ingestion of collagen hydrolysate leads to the transportation of highly concentrated Gly-Pro-Hyp and its hydrolyzed form of Pro-Hyp into the bloodstream and skin
Small human single-blind crossover for plasma kinetics plus supportive murine tissue-distribution arm — mechanistic, industry-authored on a proprietary product.
Assessment of bioavailability after in vitro digestion and first pass metabolism of bioactive peptides from collagen hydrolysates
Preclinical in-vitro digestion, intestinal-transport and hepatic first-pass model using HIEC-6 human intestinal epithelial cells and HepG2 hepatocytes. It measures peptide recovery and simulated bioavailability, not clinical efficacy or in-vivo human absorption.
Bone Broth Unlikely to Provide Reliable Concentrations of Collagen Precursors Compared With Supplemental Sources of Collagen Used in Collagen Research
Analytical laboratory study measuring amino acid content of bone broth vs commercial collagen supplements — comparative composition analysis, not a clinical outcome study.
Significant Amounts of Functional Collagen Peptides Can Be Incorporated in the Diet While Maintaining Indispensable Amino Acid Balance
Theoretical dietary modelling exercise using PDCAAS calculations — no human intervention, no biological outcomes, purely regulatory/reformulation reference.
Unravelling the bioavailability of amino acids and bioactive peptides from collagen hydrolysate in coffee in healthy volunteers
Randomized human crossover pharmacokinetic study measuring absorption biomarkers rather than clinical outcomes.
Bioavailability; intact-peptide exposure
Absorption of bioactive peptides following collagen hydrolysate intake: a randomized, double-blind crossover study in healthy individuals
Randomized double-blind four-treatment crossover pharmacokinetic pilot; N=6, only acute exposure and manufacturer-supplied hydrolysates, no functional clinical outcome or direct test of DoNotAge powder; absorption is not equivalent to clinical effect
Biology and biochemistry
Current insights into collagen type I
Peer-reviewed narrative review of type I collagen structure, sources, extraction, physicochemical properties and applications. Useful as foundational biology and biomaterials background, but not a systematic review or clinical supplementation efficacy study.
Bone
A calcium-collagen chelate dietary supplement attenuates bone loss in postmenopausal women with osteopenia: a randomized controlled trial
12-month randomised controlled trial with DXA-verified BMD endpoints in postmenopausal osteopenic women — solid design but small sample (n = 39) and industry-funded/supplied.
Assessment of effectiveness of oral administration of collagen peptide on bone metabolism in growing and mature rats
Controlled in-vivo rat evidence directly measures bone mineral outcomes and identifies a high-dose renal safety signal, but provides no human efficacy evidence.
Bone and muscle; confounded combinations
Efficacy of collagen peptide supplementation on bone and muscle health: a meta-analysis
Meta-analysis of randomized trials of collagen alone or combined with calcium/vitamin D; High bone-outcome heterogeneity and mixing isolated collagen with calcium/vitamin D combinations. Trials do not prove fracture prevention, replace osteoporosis m
Bone health
Specific Bioactive Collagen Peptides in Osteopenia and Osteoporosis: Long-Term Observation in Postmenopausal Women
Non-controlled open-label follow-up observation with small sample and no placebo group — cannot isolate the collagen effect from natural history over the 4-year window.
Specific Collagen Peptides Improve Bone Mineral Density and Bone Markers in Postmenopausal Women — A Randomized Controlled Study
Adequately powered 12-month randomised, double-blind, placebo-controlled phase III trial with objective DXA endpoints and supporting bone turnover biomarkers.
Effects of Collagen Peptide Supplementation on Bone Turnover, Cytokine, and Inflammatory Markers in Female Distance Runners: A Randomized Pilot Study
Small, short-duration pilot RCT (n=22, 4 weeks) explicitly designed to establish preliminary signal and feasibility rather than confirm clinical efficacy; surrogate blood biomarkers only, with no bone density or structural imaging outcomes.
Collagen biochemistry & mechanism
Hydrolyzed Collagen—Sources and Applications
Narrative (non-systematic) review of hydrolysed collagen extraction sources, molecular properties, and industrial/nutraceutical applications; provides mechanistic and background context rather than primary clinical outcome data, and summarises other primary studies without independent meta-analytic pooling.
Vitamin C–Enriched Gelatin Supplementation before Intermittent Activity Augments Collagen Synthesis
Randomised, double-blinded, crossover trial with independent academic (non-industry) funding and no disclosed conflicts of interest, but the human cohort is very small (n=8) and the primary endpoints are mechanistic/surrogate (circulating amino acids, serum PINP, and an engineered-ligament tissue culture bioassay) rather than a clinical outcome. Tests gelatin plus vitamin C timed around exercise, not a standardised hydrolysed collagen peptide product, so it is included as a mechanism reference rather than direct clinical evidence.
Digestive symptoms; uncontrolled pilot
Effect of a Daily Collagen Peptide Supplement on Digestive Symptoms in Healthy Women: 2-Phase Mixed Methods Study
Prospective open-label single-arm digital feasibility pilot following exploratory qualitative phase; No placebo/control group, high attrition (26/40), self-report outcomes, limited to women with BMI >25, tested Peptan 20 g not DoNotAge 10 g. Insuffic
Sourcedoi:10.2196/36339PMID 35639457PMC9198822 Trial registry
Gut microbiome; severe burn patients
Effects of hydrolyzed collagen alone or in combination with fish oil on the gut microbiome in patients with major burns
Randomized double-blind three-arm controlled clinical trial; Critically ill burn population, very high 40-g dose, short intervention, microbiome surrogates only. Not directly representative of healthy adults taking 10-g bovine collagen; cannot claim
Sourcedoi:10.1016/j.burns.2023.08.017PMID 38114377 Trial registry
Joint
24-Week study on the use of collagen hydrolysate as a dietary supplement in athletes with activity-related joint pain
Randomized, double-blind, placebo-controlled human trial in physically active adults with 24-week follow-up; evidence is clinically relevant but limited by substantial attrition/completer analysis and manufacturer funding.
A randomized controlled trial on the efficacy and safety of a food ingredient, collagen hydrolysate, for improving joint comfort
Multicentre double-blind placebo-controlled 6-month RCT with n=250 in diagnosed knee OA — one of the largest and longest collagen-for-OA trials, though industry involvement present.
Collagen hydrolysate for the treatment of osteoarthritis and other joint disorders: a review of the literature
Peer-reviewed narrative review of preclinical and early clinical collagen-hydrolysate literature. It searched PubMed through May 2006 but also included congress abstracts and German-language literature based on author judgment, with no meta-analysis or formal risk-of-bias framework; therefore it is background synthesis rather than tier-1 efficacy evidence.
Joint health
Effect of collagen supplementation on osteoarthritis symptoms: a meta-analysis of randomized placebo-controlled trials
Meta-analysis of randomised placebo-controlled trials in humans — the top of the evidence hierarchy for the joint-comfort question, though limited by the small number of primary trials available.
Effect of Collagen Hydrolysate in Articular Pain: A 6-Month Randomized, Double-Blind, Placebo Controlled Study
Single, adequately powered (n=200) double-blind, placebo-controlled RCT with a statistically significant primary endpoint at 6 months but a non-significant result at 3 months, manufacturer funding tied to the tested product, and no benefit shown on validated joint-specific questionnaires.
Effects of Oral Administration of Type II Collagen on Rheumatoid Arthritis
Single randomised, double-blind, placebo-controlled phase II trial (n=60) with statistically significant but small-sample results and disclosed sponsor-linked financial interests. Tests native, undenatured chicken type II collagen via an oral-tolerance immune mechanism — a different ingredient and mechanism from the hydrolysed collagen peptides this site otherwise reviews.
Efficacy and Tolerability of an Undenatured Type II Collagen Supplement in Modulating Knee Osteoarthritis Symptoms: A Multicenter Randomized, Double-Blind, Placebo-Controlled Study
Multicenter, randomised, double-blind, placebo- and active-comparator-controlled trial (n=191) with a 180-day intervention and pre-specified primary/secondary endpoints, but two of three authors are employees of the product's manufacturer and sponsor, a direct financial conflict of interest warranting tier-2 rather than tier-1. Tests undenatured type II collagen (UC-II) — a different ingredient, mechanism and dose scale (milligrams) from the hydrolysed collagen peptides (gram-scale) this site otherwise reviews.
Improvement of Activity-Related Knee Joint Discomfort Following Supplementation of Specific Collagen Peptides
Monocentric, prospective, randomised, double-blind, placebo-controlled phase III trial (n=139 completers of 160 randomised), fully funded by the tested product's manufacturer (GELITA Health GmbH), with pre-specified co-primary endpoints and Bonferroni-Holm correction for multiplicity.
Impact of Specific Bioactive Collagen Peptides on Joint Discomforts in the Lower Extremity during Daily Activities: A Randomized Controlled Trial
Monocentric, prospective, randomised, double-blind, placebo-controlled trial (n=182 randomised, n=154 per-protocol analysed) in a general adult population — not restricted to physically active young adults — with hip and knee joint pain during ordinary daily activities, using Bonferroni-Holm-corrected co-primary endpoints assessed independently by both physician and participant.
The Influence of Specific Bioactive Collagen Peptides on Knee Joint Discomfort in Young Physically Active Adults: A Randomized Controlled Trial
Large randomised, double-blind, placebo-controlled trial (n=218 randomised; n=180 per-protocol) with pre-specified co-primary endpoints assessed by both participant and blinded physician, but the product was manufacturer-supplied and manufacturer-funded, one author has received GELITA-supported lecture fees, and another author joined the manufacturer-linked Collagen Research Institute after the study concluded.
Therapeutic Efficacy and Safety of Undenatured Type II Collagen Singly or in Combination with Glucosamine and Chondroitin in Arthritic Dogs
This is a small (n=5/group), double-blinded, placebo-controlled animal (canine) study, not a human trial, using subjective owner/veterinarian pain-scoring rather than validated clinical instruments. Two co-authors are employees of the funding manufacturer. It tests undenatured type II collagen (UC-II) at a microgram dose via a proposed oral-tolerance mechanism in dogs — a fundamentally different ingredient, species, dose scale and mechanism from the hydrolysed collagen peptides this site otherwise reviews — and is included purely as a differentiation reference.
Joints and meniscus
The effect of supplementation with type I and type III collagen peptide and type II hydrolyzed collagen on pain, quality of life and physical function in patients with meniscopathy: a randomized, double-blind, placebo-controlled study
Randomized double-blind placebo-controlled trial, but very small and uses a multi-ingredient formula that prevents collagen-specific attribution.
Sourcedoi:10.1186/s12891-024-08244-wPMID 39755603PMC11699701 Trial registry
Joints and osteoarthritis
Effect of supplementation with type 1 and type 3 collagen peptide and type 2 hydrolyzed collagen on osteoarthritis-related pain, quality of life, and physical function: A double-blind, randomized, placebo-controlled study
Double-blind randomized placebo-controlled trial, but very small and tests a multi-ingredient finished product, so effects cannot be attributed to hydrolysed collagen alone.
Menopause; skin, hair and bone mixed endpoints
Calcium and Vitamin D Supplementation with and Without Collagen on Bone Density and Skin Elasticity in Menopausal Women-A Randomized Controlled Study
Four-arm randomized controlled study comparing collagen, calcium/vitamin D, their combination and placebo; Marine fish formulation, not bovine DoNotAge product. Multi-arm within-group findings should not be mistaken for placebo-adjusted effects; samp
Muscle
Collagen peptide supplementation in combination with resistance training improves body composition and increases muscle strength in elderly sarcopenic men: a randomised controlled trial
Randomised double-blind placebo-controlled trial with DXA-measured body composition and objective muscle-strength testing in a clinically relevant sarcopenic population. Strong human design, but the 2025 corrigendum documents industry support: Gelita supplied the study product and covered participant-compensation and sample-analysis costs; a co-author was also a patent co-inventor.
Muscle & body composition
Effects of 12 Weeks of Hypertrophy Resistance Exercise Training Combined with Collagen Peptide Supplementation on the Skeletal Muscle Proteome in Recreationally Active Men
Single double-blind, randomised, placebo-controlled RCT (n=25) with funding tied to the tested product's manufacturer via a closely affiliated research institute; the proteomic outcomes are exploratory/mechanistic rather than confirmatory clinical efficacy data.
Prolonged Collagen Peptide Supplementation and Resistance Exercise Training Affects Body Composition in Recreationally Active Men
Randomised, double-blinded, placebo-controlled trial (n=57 analysed) with a 12-week intervention, muscle biopsies and multiple objective outcome measures, but funded by an industry-affiliated research institute (Collagen Research Institute), a limiting factor for tier-1 status.
Specific Collagen Peptides in Combination with Resistance Training Improve Body Composition and Regional Muscle Strength in Premenopausal Women: A Randomized Controlled Trial
Randomised, double-blind, placebo-controlled trial (n=77 per-protocol) with a 12-week intervention and both per-protocol and intention-to-treat analyses, but the tested product is manufactured by Gelita AG and the paper's own funding disclosure is internally inconsistent (see funding field), which together limit this to tier-2.
Muscle and body composition
The Influence of Specific Bioactive Collagen Peptides on Body Composition and Muscle Strength in Middle-Aged, Untrained Men: A Randomized Controlled Trial
Randomised, placebo-controlled, double-blind trial with objective DXA body composition and isometric strength endpoints; adequate sample per group with pre-specified power calculation.
Whey protein but not collagen peptides stimulate acute and longer-term muscle protein synthesis with and without resistance exercise in healthy older women: a randomized controlled trial
Randomised, double-blind, parallel-group trial with gold-standard stable isotope tracer measurement of muscle protein synthesis (the direct mechanistic endpoint) in the target population.
Muscle and exercise
Specific collagen peptides supplementation increases collagen type I content in skeletal muscle after 12 weeks of high-load resistance training: a randomized controlled trial
Randomized placebo-controlled human trial with tissue biopsy outcomes, but small sample and partial industry funding.
Sourcedoi:10.3389/fphys.2026.1839695PMID 42376607PMC13310693
Muscle; direct protein-quality comparator
The effects of whey, pea, and collagen protein supplementation beyond the recommended dietary allowance on integrated myofibrillar protein synthetic rates in older males: a randomized controlled trial
Double-blind randomized controlled feeding trial with deuterated water and muscle biopsies; Short mechanistic trial in older men and not a long-term strength outcome; does not exclude collagen's connective-tissue benefits. Research proteins were not
Sourcedoi:10.1016/j.ajcnut.2024.05.009PMID 38762187PMC11291473
Muscle; indirect collagen versus whey comparisons
Which Protein-Based Dietary Supplements Most Effectively Enhance Fat-Free Mass and Strength Gains in Healthy Adults Undergoing Resistance Training? A Network Meta-Analysis
Network meta-analysis of protein interventions plus resistance training; searched through May 2024; Indirect rankings and transitivity assumptions, very different population/training/supplement designs, small collagen nodes and no proof of direct bio
Muscle; mixed whey-collagen acute synthesis
Ingestion of a Whey Plus Collagen Protein Blend Increases Myofibrillar and Muscle Connective Protein Synthesis Rates
Randomized double-blind placebo-controlled tracer infusion and muscle biopsy study; Acute study, men only, no whey-only arm; product 83% whey. Public–private funded with GELITA involvement, and not a trial of collagen-alone efficacy.
Sourcedoi:10.1249/MSS.0000000000003596PMID 39501478PMC11801439
Musculoskeletal evidence
The Effects of Type I Collagen Hydrolysate Supplementation on Bones, Muscles, and Joints: A Systematic Review
Systematic review focused on randomized evidence for Type I collagen hydrolysate, with useful formulation specificity but heterogeneous protocols and commercial ties.
Nails
Oral supplementation with specific bioactive collagen peptides improves nail growth and reduces symptoms of brittle nails
Open-label, single-arm, single-centre trial with no placebo control — cannot separate treatment effect from natural history and behavioural change.
Osteoarthritis; direct hydrolysed-collagen RCT
Evaluation of the Efficacy and Safety of CollaSel PRO Type I and Type III Hydrolyzed Collagen Peptides in the Treatment of Osteoarthritis: A Double-Blind, Placebo-Controlled, Randomized Clinical Trial
Double-blind randomized parallel placebo-controlled clinical trial in two university physical-medicine centers; Industry-linked authors associated with product supply; proprietary CollaSel PRO not the DoNotAge formulation; 8-week symptom outcomes wit
Sourcedoi:10.3390/jcm14113655PMID 40507417PMC12156922 Trial registry
Osteoarthritis; mixed collagen interventions
Efficacy and safety of collagen derivatives for osteoarthritis: A trial sequential meta-analysis
Systematic review of RCTs through June 2023, RoB 2 and GRADE plus trial-sequential analysis; Combines mechanistically distinct hydrolysed collagen and undenatured type II collagen; results cannot be attributed wholly to DoNotAge's bovine hydrolysate.
Osteoarthritis; null combination-product RCT
Efficacy of combined undenatured type II collagen and hydrolysed collagen supplementation in knee osteoarthritis: a randomised controlled trial
Double-blind randomized placebo-controlled OA trial; Combination supplement, not isolated hydrolysed collagen; 68 people over 12 weeks. Does not disprove outcomes from other preparations or long-term trials.
Sourcedoi:10.1038/s41598-025-17505-0PMID 40897777PMC12405528
Safety
Dietary Influences on Urinary Oxalate and Risk of Kidney Stones
Narrative literature review of pooled human and epidemiological data on dietary oxalate; not itself a controlled trial and does not test collagen or collagen peptide intake directly.
Relationship of Protein Intake to Urinary Oxalate and Glycolate Excretion
Well-controlled academic study combining a large observational cohort (n=101) with a smaller controlled-diet crossover (n=11), with no industry funding or apparent conflicts of interest. Rated tier-3 rather than tier-1/2 because it studies general dietary protein intake — not hydrolysed collagen peptides specifically — and its endpoint (urinary oxalate/glycolate excretion) is a biochemical surrogate for kidney stone risk, not a clinical stone-formation outcome. Included as a background safety reference for readers considering higher-dose collagen peptide (i.e., concentrated protein) intake, alongside massey-2003-urinary-oxalate-kidney-stones.
Safety of Egg Membrane Collagen Peptides as a Novel Food Pursuant to Regulation (EU) 2015/2283
This is an official EU regulatory scientific opinion by an independent expert panel, based on a manufacturer-submitted compositional and production-process dossier; the Panel concluded no toxicological studies were required given the nature of the novel food. It is not a primary clinical or preclinical research study, so it is rated below tier-1/2 despite its regulatory authority. It concerns egg membrane collagen peptides — a distinct raw material and product category (450–500 mg/day proposed dose) from the gram-scale hydrolysed bovine, porcine, marine or fish collagen peptides this site otherwise reviews — and is included as a differentiation and safety reference.
Safety; free hydroxyproline and urinary oxalate
A single-blind, parallel trial of l-hydroxyproline in healthy adult subjects
Single-blind four-arm parallel dose-ranging human trial; Free hydroxyproline is not equivalent to peptide-bound hydroxyproline in collagen powder; small study of healthy people with no stone-former cohort; manufacturer-funded.
Safety; hydroxyproline metabolism and urinary oxalate
Hydroxyproline ingestion and urinary oxalate and glycolate excretion
Controlled-diet human feeding comparison of gelatin versus whey and gelatin dose challenges; Gelatin rather than a defined modern hydrolysed-collagen brand; high 30-g comparison; only 10 participants; urinary surrogate, not prospective ston
Skin
Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology: a double-blind, placebo-controlled study
Individual randomised double-blind placebo-controlled trial with objective skin biomechanical endpoints, though single-centre, female-only, and industry-supplied product with Gelita-linked co-authors.
Oral intake of specific bioactive collagen peptides reduces skin wrinkles and increases dermal matrix synthesis
Individual randomised double-blind placebo-controlled trial with objective 3D wrinkle imaging plus suction-blister biomarker subgroup, though single-centre, female-only, and industry-supplied product with Gelita-linked co-authors.
A collagen supplement improves skin hydration, elasticity, roughness, and density: results of a randomized, placebo-controlled, blind study
Controlled, placebo-comparator, single-blind human trial in 72 women with objective skin endpoints. The Methods describe allocation by alternation rather than a concealed random sequence, so the study is better regarded as quasi-randomized/systematically allocated; the tested ELASTEN product was also a multi-ingredient formulation, limiting collagen-specific attribution.
Sourcedoi:10.3390/nu11102494PMID 31627309PMC6835901 Trial registry
An insight into the changes in skin texture and properties following dietary intervention with a nutricosmeceutical containing a blend of collagen bioactive peptides and antioxidants
Randomised double-blind placebo-controlled trial with objective skin elasticity + histological analysis in a substantial female sample — solid design but industry-funded and multi-ingredient product prevents isolating collagen effect.
Collagen supplementation for skin health: a mechanistic systematic review
Peer-reviewed systematic review that screened 9,057 records and included 10 publications, with a mechanistic focus on oral collagen and skin health. It did not perform a quantitative meta-analysis, and the small, heterogeneous, uniformly favorable evidence base limits certainty compared with pooled high-quality clinical evidence.
Oral Intake of Low-Molecular-Weight Collagen Peptide Improves Hydration, Elasticity, and Wrinkling in Human Skin: A Randomized, Double-Blind, Placebo-Controlled Study
Randomised, double-blind, placebo-controlled trial with instrumental skin measurements in a modest but adequate sample of the target demographic.
Safety and Efficacy of a Hydrolyzed Collagen Formulation (HYCOS) for Facial Skin Elasticity and Wrinkles: A Randomized, Double-Blind, Placebo-Controlled Trial
Randomized double-blind placebo-controlled human trial with objective skin measurements, but the intervention combined collagen with glutathione and vitamin E, preventing collagen-specific attribution.
The Sustained Effects of Bioactive Collagen Peptides on Skin Health: A Randomized, Double-Blind, Placebo-Controlled Clinical Study
Randomized double-blind placebo-controlled human skin trial with objective outcomes, but small sample and substantial manufacturer-employee involvement.
Sourcedoi:10.1111/jocd.70565PMID 41311286PMC12661388 Trial registry
The Effects of Dietary Supplementation with Collagen and Vitamin C and Their Combination with Hyaluronic Acid on Skin Density, Texture and Other Parameters: A Randomised, Double-Blind, Placebo-Controlled Trial
Three-arm randomized, double-blind, placebo-controlled human trial with objective skin measurements; industry co-funding and a combination formula limit ingredient-specific interpretation.
Sourcedoi:10.3390/nu16121908PMID 38931263PMC11206740 Trial registry
Skin and nails
Influence of collagen peptide supplementation on visible signs of skin and nail health and -aging in an East Asian population: A double blind, randomized, placebo-controlled trial
Double-blind randomized placebo-controlled human trial with instrumental skin outcomes, but manufacturer-funded and conducted by manufacturer employees.
Skin health
Effect of Vitamin C and Its Derivatives on Collagen Synthesis and Cross-Linking by Normal Human Fibroblasts
In vitro cell-culture and three-dimensional lattice model using normal human fibroblasts; no human subjects, no oral supplementation, and no hydrolysed collagen peptides tested. Included as mechanistic background on vitamin C's cofactor role in collagen cross-linking, not as clinical evidence for any collagen peptide product.
Effects of Oral Collagen for Skin Anti-Aging: A Systematic Review and Meta-Analysis
Important 2023 synthesis of 26 skin RCTs (n=1,721) with risk-of-bias, source and duration analyses. Newer 2025–2026 syntheses and funding-sensitive subgroup results conflict, so this favorable pooled result is not definitive clinical proof.
Effects of Hydrolyzed Collagen Supplementation on Skin Aging: A Systematic Review and Meta-Analysis
Systematic review and random-effects meta-analysis of 19 RCTs (n=1,125) pooling skin hydration and elasticity outcomes for hydrolysed collagen supplementation, with formal risk-of-bias grading, sensitivity analysis, and a symmetrical funnel plot arguing against publication bias.
Exploring the Impact of Hydrolyzed Collagen Oral Supplementation on Skin Rejuvenation: A Systematic Review and Meta-Analysis
Systematic review and meta-analysis of 14 randomised, double-blind, placebo-controlled trials (n=967) following PRISMA and Cochrane Handbook methodology, with formal RoB-2 risk-of-bias assessment, funnel-plot publication-bias check, and pre-specified subgroup analyses by collagen source and supplementation duration.
Ingested Hyaluronan Moisturizes Dry Skin
Peer-reviewed narrative review summarising six clinical trials of oral hyaluronan for dry skin. Useful for historical context and dose mapping, but it is not a systematic review or meta-analysis and several primary studies involved Kewpie-affiliated investigators or products.
Ingestion of Bioactive Collagen Hydrolysates Enhance Facial Skin Moisture and Elasticity and Reduce Facial Ageing Signs in a Randomised Double-Blind Placebo-Controlled Clinical Study
Randomised, double-blind, placebo-controlled trial (n=85) comparing two collagen hydrolysates of differing bioactive dipeptide content against placebo, with objective corneometry/cutometry/VisioFace SSA instrumentation and blood safety testing, but two of three authors are employees of the product manufacturer and the trial was conducted at a single site.
Hydrolyzed Marine Collagen: Emerging Evidence of Benefits via the Oral Route – Review and Insights for Medical Aesthetics Practitioners
Narrative review (explicitly not a full systematic review; authors describe a rigid but non-exhaustive PubMed search restricted to indexed, high-impact journals) of preclinical studies and a small number of methodologically screened human RCTs on hydrolysed marine collagen and skin regeneration, published with funding from a company whose medical director is a co-author and markets a hydrolysed marine collagen supplement — a disclosed, direct commercial conflict of interest.
Oral Hyaluronan Relieves Wrinkles and Improves Dry Skin: A 12-Week Double-Blinded, Placebo-Controlled Study
Randomised, double-blind, placebo-controlled human trial (n=40) with 12 weeks of oral hyaluronan and instrumental skin endpoints. Directly relevant to oral HA efficacy, but small and manufacturer-funded with three authors employed by Kewpie Corporation.
The Effect of Oral Collagen Peptide Supplementation on Skin Moisture and the Dermal Collagen Network: Evidence from an Ex Vivo Model and Randomized, Placebo-Controlled Clinical Trials
Two randomised, placebo-controlled clinical trials (pilot n=33; confirmatory n=101) plus ex vivo mechanistic work, with multiple objective instrumental endpoints (corneometry, high-resolution ultrasound, reflectance confocal microscopy), but two of four authors are employed by commercial entities with a direct interest in the tested collagen peptides and no formal funding/COI disclosure is provided in the article.
Skin, osteoarthritis, bone and muscle
Collagen Supplementation for Skin and Musculoskeletal Health: An Umbrella Review of Meta-Analyses on Elasticity, Hydration, and Structural Outcomes
Umbrella review of published systematic reviews and meta-analyses; literature through March 6, 2025; Double counting of RCTs across included meta-analyses is possible. AMSTAR-2 distribution limits certainty; does not supersede the 2025 funding-sensit
Skin; funding and risk of bias
Effects of Collagen Supplements on Skin Aging: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Meta-analysis of 23 randomized controlled trials; prespecified subgroup analyses by funding and study quality; Subgroup results may have lower power; pooled interventions are heterogeneous and do not specifically test DoNotAge's finished bovine colla
Skin; low-certainty favorable studies
Oral Collagen Supplementation for Skin Hydration and Elasticity: A Systematic Review and Meta-Analysis
PRISMA random-effects review; searched through January 1, 2026; PROSPERO CRD420261285731; Only 5 and 4 trials entered the two quantitative outcomes; risk-of-bias concerns, high heterogeneity, multi-ingredient formulations and frequent industry involv
Skin; robust sensitivity analysis
Oral Collagen Peptides and Skin Rejuvenation: A Systematic Review and an Updated Meta-Analysis of Randomized Controlled Trials
Updated randomized-effects, multilevel and leave-one-out meta-analysis; searched through November 2025; Important heterogeneity and overlap with earlier syntheses. Several citations in the publisher bibliography show apparent incomplete DOI placehold
Sourcedoi:10.1111/jocd.71041
Skin; trial risk of bias and tolerability
Efficacy and safety of hydrolyzed collagen supplementation on skin health outcomes: a systematic literature review of randomized controlled trials
Systematic literature review with Cochrane RoB 2; searched through April 1, 2023; Search ends April 2023 despite 2026 publication, so not the latest primary-trial corpus. Descriptive vote-counting does not substitute for effect estimates. T
Sports nutrition; tendon and strength
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
Systematic review and random-effects meta-analysis of training/supplementation RCTs; Most participants male; doses, training and vitamin C co-interventions varied; several small industry-specific formulation trials; cannot assume gains reflect myofib
Sourcedoi:10.1007/s40279-024-02079-0PMID 39060741PMC11561013
Tendon adaptation; high-dose collagen
Hydrolysed Collagen Supplementation Enhances Patellar Tendon Adaptations to 12 Weeks' Resistance Training in Middle-Aged Men
Double-blind randomized placebo-controlled 12-week resistance-training trial; Only 20 men, 30-g dose and vitamin C plus training. Not evidence that a 10-g generic powder prevents tendon injury or builds more muscle.
Tendon adaptation; strength distinction
Collagen Supplementation on Tendon-Related Structural and Performance Outcomes: A Systematic Review
Systematic review of RCTs incorporating resistance/plyometric loading; Very small total sample and extreme male predominance; review authors' GRADE labels require cautious interpretation; not direct evidence for tendon-injury treatment or generic 10-
Tendon and ligament
Clinical evidence for low-molecular-weight collagen peptides in tendon and ligament tears: a systematic review with narrative synthesis
Systematic review with explicit human clinical eligibility and risk-of-bias discussion, but only six heterogeneous studies were included and overall certainty was judged low.
Tendon and rate-of-force; women athletes
Collagen Supplementation Augments Strength Training-Induced Gains in Tendon Size and Rate of Force Development in Elite Female Master Field Hockey Athletes
Triple-blind randomized training study in elite female Master athletes; Only 22 high-performance women; combined vitamin C and training, high 30-g dose; performance effect does not establish clinical tendon injury prevention.
Tendon morphology; low-dose selected peptides
Specific collagen peptides increase adaptions of patellar tendon morphology following 14-weeks of high-load resistance training: A randomized-controlled trial
Randomized placebo-controlled 14-week high-load knee-extensor training study; Selected branded peptide product, men only and exercise co-intervention; do not generalize low-dose effect to every collagen formulation.
Tendon stiffness; women athletes
High-intensity resistance training and collagen supplementation improve patellar tendon adaptations in professional female soccer athletes
Randomized pair-matched placebo-controlled pre-season training study; N=11 and confounded with concurrent high-intensity training and vitamin C; not evidence for reduced injury rates or a 10-g daily consumer dose.
Tendon; null randomized trial
The Effect of Specific Bioactive Collagen Peptides on Tendon Remodeling during 15 wk of Lower Body Resistance Training
Double-blind placebo-controlled randomized lower-body resistance training study; One selected proprietary peptide preparation, young male sample and specific program; negative result prevents a universal tendon-benefit claim but does not negate all c