Collagen Peptides
Hydrolyzed Collagen · Type I, II, III · Bioactive Peptides
Evidence grade 3 of 5, Mixed. Read how the Atlas grades evidence.
The skin evidence is large but soft. Pooled meta-analyses look impressive on paper (Pu 2023 in Nutrients: 26 RCTs, 1,721 participants, elasticity effect size ~0.72; a separate 14-RCT/967-participant review found hydration effect ~0.58), yet the effect largely evaporates under scrutiny. A 2025 systematic review in The American Journal of Medicine reported that in subgroup analysis, studies NOT funded by supplement or pharmaceutical companies showed no significant benefit for hydration, elasticity, or wrinkles, while industry-funded studies did, and high-quality trials alone showed no significant effect. Nearly all positive trials also used specific branded, low-molecular-weight peptides rather than generic collagen. For knee osteoarthritis, a 2023 meta-analysis (4 RCTs, 507 participants) found a moderate pain reduction (SMD around -0.58) but rated all four trials at high risk of bias; a broader 2024 trial-sequential meta-analysis in Osteoarthritis and Cartilage found small-to-moderate pain and function benefits at moderate certainty. Net: mixed/moderate RCT support that is real but funding-tilted and modest. grade 3.
- FDA
- Legal supplement; GRAS food
- WADA
- Not prohibited
Reference only. Not medical advice.
What can go wrong
Generally well tolerated, but heavy-metal contamination is documented in marine and lower-tier sources, and it is an incomplete protein that should not replace whole dietary protein.
Collagen is one of the largest supplement categories on the market, and the marketing has run well ahead of the evidence. The honest headline is a modest but real signal for skin hydration and elasticity, plus some knee osteoarthritis pain relief, seen mostly with specific branded peptides rather than generic powder. The catch is funding: when you separate out the studies paid for by supplement makers, much of the skin benefit fades, and the joint trials carry a high risk of bias. Mechanism is genuinely interesting, because collagen is not simply digested into loose amino acids, and small peptides like Pro-Hyp do reach the blood and appear to signal skin cells. Read it as a plausible, low-stakes bet with soft evidence, not a settled one.
A massive market with a real branded-peptide story underneath the marketing.
What people take it for
These are the reasons people give for taking it. They are not effects it has been shown to have.
How it is supposed to work
Hydrolyzed collagen contains short peptides (mostly dipeptides and tripeptides) produced by enzymatic cleavage of native collagen protein. These peptides survive digestive proteolysis at higher rates than intact proteins, particularly the proline-hydroxyproline dipeptides that show up in plasma within hours of oral dosing. The marketing claim has historically been that ingested collagen rebuilds tissue collagen, but the actual mechanism is more interesting: bioactive peptides act as signaling molecules, stimulating fibroblasts in skin and joint tissue to upregulate their own collagen synthesis. This is why peptide identity matters more than total collagen dose, and why certain branded hydrolysates (Verisol, Fortigel, BioCell, Tendoforte) outperform generic collagen in head-to-head trials at lower total doses. Vitamin C is genuinely required, not optional. Collagen synthesis depends on two ascorbate-dependent enzymes (prolyl hydroxylase, lysyl hydroxylase) that hydroxylate proline and lysine residues to lock the triple helix structure. Without adequate vitamin C status, supplemental collagen peptides cannot be assembled into stable connective tissue. This is the biochemical basis for scurvy, historically a connective-tissue collapse, and the reason collagen co-supplementation with vitamin C is mechanistically defensible rather than a marketing add-on. The amino acid profile is also distinctive: collagen is unusually rich in glycine, proline, and hydroxyproline (rare in other food proteins) but deficient in tryptophan and low in methionine and several other essentials. This makes collagen a useful complement to whole-protein intake, not a substitute for it.
How it is taken
Branded bioactive collagen peptides are studied at 2.5g/day (Verisol, skin) or 5g/day (Fortigel, joints), meaningfully lower than typical generic dosing because peptide identity, not total grams, drives the mechanism. Undenatured type-II forms (UC-II, BioCell) work at 40mg/day through oral immune tolerance, a completely different mechanism that does not require gram-scale doses. Generic hydrolyzed collagen for general use is typically dosed 10-20g/day, primarily delivering amino acid substrate. Most users do not need timing precision. Vitamin C co-supplementation (or vitamin C-rich foods at the same meal) is mechanistically meaningful, not marketing. Effects on skin and joint endpoints accumulate over 8-16 weeks; expect to commit to a full quarter before evaluating.
- Branded skin
- 2.5g/day Verisol, the only dose with controlled trial evidence at that scale.
- Branded joints
- 5g/day Fortigel or Tendoforte, the studied dose; not 10g, not 20g.
- UC-II / BioCell
- 40mg/day, yes, milligrams. Different mechanism (oral tolerance), different dose scale.
- Generic
- 10-20g/day for general use; effect mostly amino acid substrate plus general collagen exposure.
- Vitamin C
- At least 100-200mg with the dose. Mechanism, not marketing.
- Time to effect
- 8-16 weeks. Faster claims are marketing.
- Coffee / hot liquids
- Fine. Collagen peptides are heat-stable in normal consumption ranges.
- Timing
- Anytime. Pre/post-workout has minimal evidence as more effective than other timing.
Which form to buy
Not all preparations of the same ingredient are the same thing, and the trials were run on particular ones.
Verisol® Bioactive Collagen Peptides
Branded specific peptides (BCP) from Gelita, optimized for skin endpoints. The most-evidenced collagen formulation for skin elasticity and wrinkle reduction. Studied at 2.5g/day in multiple RCTs, meaningfully lower than typical generic dosing because peptide identity matters more than total grams.
Fortigel® Bioactive Collagen Peptides
Gelita's joint-targeted bioactive collagen peptide. Studied at 5g/day for joint comfort, cartilage proteoglycan content, and athletic recovery. The branded peptide profile is genuinely different from generic hydrolysate.
Tendoforte® Specific Collagen Peptides
Tendon and ligament-targeted Gelita variant. Trial evidence for ankle instability and tendon recovery. Smaller evidence base than Verisol/Fortigel but the most-evidenced formulation for tendon-specific use.
BioCell Collagen® (Undenatured Type II)
Native (not hydrolyzed) type-II collagen plus chondroitin and hyaluronic acid. Mechanistically distinct: works through oral immune-tolerance pathways at very low doses (40mg/day) rather than through peptide signaling. Multiple joint-pain trials.
UC-II® Undenatured Type II Collagen
Lonza's native type-II collagen product. Same low-dose oral tolerance mechanism as BioCell. Head-to-head with glucosamine + chondroitin showed superior pain reduction in some trials. The 40mg dose is real, not a typo.
Generic Hydrolyzed Bovine Collagen
Most consumer products. Provides protein and amino acids but lacks the specific bioactive peptide profile of branded forms. Reasonable if used at higher doses (10-20g/day) and the primary value is amino acid intake plus general collagen exposure. Cost-effective.
Marine Collagen (Fish)
Fish-skin-derived hydrolysate, typically type-I dominant with smaller peptide profile than bovine. Sometimes marketed for "better absorption", modest evidence. Real concern with heavy-metal and PCB contamination from poor sourcing.
Bone Broth
Traditional dietary source. Contains gelatin (partially hydrolyzed collagen) plus minerals and amino acids. Variable peptide content. Pleasant culinary use; not a substitute for specific bioactive peptides when targeting clinical endpoints.
Vegan "Collagen Boosters"
Vitamin C plus glycine, proline, lysine, and silica. Provides substrates the body uses to build its own collagen but does not contain peptide signaling molecules. Mechanistically defensible for collagen synthesis support; not equivalent to bioactive collagen peptides.
Who it works for, and who it does not
Postmenopausal women, skin focus
The strongest cohort case for collagen peptides. Verisol-style branded peptides at 2.5g/day produce measurable elasticity improvements in this population over 8-12 weeks. The effect is modest but reproducible and the cohort biology (declining endogenous collagen synthesis with estrogen drop) is sound.
Postmenopausal women, bone density
The König 2018 trial in osteopenic women is the clearest case: 5g Specific Collagen Peptides daily for 12 months improved DEXA-measured BMD. Should be paired with vitamin D3, calcium, and resistance training. Not a substitute for bisphosphonates in established osteoporosis.
Athletes with joint or tendon issues
Fortigel and Tendoforte trial evidence for cartilage and ligament support is genuine. Effects accumulate over 12-16 weeks, not days. Pair with appropriate sports-medicine guidance for injury management.
Older adults with osteoarthritis
UC-II and BioCell undenatured type-II have the cleanest joint-pain evidence at very low doses. Lin meta-analysis suggests modest pain reduction comparable across approaches, with better safety than NSAIDs.
General "wellness" adults
The bulk of consumer collagen use. Real value for skin and joints is concentrated in branded peptides and specific cohorts. Generic hydrolysate use as a "wellness ritual" in healthy young adults is a marketing-driven category with thinner evidence per dollar than the branded-peptide use cases.
Vegans and vegetarians
No animal-source collagen available. "Vegan collagen boosters" provide amino acid substrates and vitamin C cofactor but do not deliver the bioactive peptide signaling that distinguishes branded products. Mechanism difference is real, not just marketing.
Trained adults seeking muscle gain
Whey protein, casein, and standard whole-protein sources substantially outperform collagen for muscle protein synthesis due to collagen's incomplete amino acid profile (low tryptophan and methionine, no leucine relative to whey). Collagen is not a primary muscle-building protein.
Taken with other things
Combinations people actually use. Evidence for one ingredient is not evidence for a pair.
Vitamin C
Required cofactor for prolyl and lysyl hydroxylase, the enzymes that hydroxylate collagen residues to form the stable triple helix. Without adequate vitamin C status, supplemental collagen peptides cannot be assembled into stable connective tissue. 100-200mg co-supplementation is mechanistically appropriate.
Vitamin D3 and Calcium (bone focus)
For the König-style bone density use case in postmenopausal women, vitamin D3 and calcium co-supplementation is part of the supported protocol. Collagen alone is unlikely to produce comparable bone outcomes without these.
Hyaluronic acid (joint focus)
Some trials have used combinations (often within BioCell formulations) of type-II collagen plus hyaluronic acid for joint endpoints. Mechanistically complementary; the standalone marginal benefit of HA alongside type-II collagen is modest.
Whey protein (muscle goals)
Collagen's incomplete amino acid profile (low tryptophan, methionine; no meaningful leucine) makes it a poor muscle-building protein alone. Pairing with whey or another complete protein source addresses the amino acid gap.
Resistance training
For tendon, ligament, and muscle endpoints, collagen peptides taken ~30-60 minutes before training combined with vitamin C have preliminary evidence for enhanced collagen synthesis in connective tissue.
Hot brewed coffee
Heat-stable in normal consumption ranges. The "collagen in coffee" trend is fine, neither destroys the peptides nor amplifies them.
Marine-source allergens (fish, shellfish)
Marine collagen is fish-derived. Users with fish or shellfish allergy should choose bovine or porcine sources.
Phenylketonuria
Collagen is high in phenylalanine. Not appropriate for users with PKU.
What to look for on the label
The single most important quality marker is whether a branded bioactive peptide (Verisol, Fortigel, Tendoforte, BioCell, UC-II) is explicitly disclosed on the label. Generic "hydrolyzed collagen" can be anything. Third-party heavy-metal testing (NSF, USP, ConsumerLab, Lead Safe Mama findings) is a non-negotiable for marine collagen and a reasonable filter for bovine. "Type I, II, III" marketing is mostly meaningless, bovine collagen is naturally ~90% type I and III with some type II; the type-II joint claims belong to specific products (UC-II, BioCell), not to general bovine hydrolysate.
Safety in detail
- Heavy-metal contamination has been documented in lower-tier sources, particularly some marine collagens. Bone-derived products carry slightly elevated lead and cadmium accumulation risk; reputable manufacturers test and disclose.
- Mercury and PCB contamination is a real concern in marine collagen from poorly-sourced fish; molecular distillation and third-party testing matter.
- Allergic reactions in users with fish, shellfish, or egg sensitivities depending on collagen source. Bovine and porcine collagens carry their own (much lower) allergenicity profiles.
- Incomplete amino acid profile: collagen lacks tryptophan and is low in methionine and several other essentials. Not appropriate as a sole or primary protein source. Cancer-associated cachexia and bodybuilding contexts should use whole-protein sources, not collagen, as primary.
- BSE/TSE concerns with bovine sources are theoretical and well-controlled by modern regulatory frameworks; products from countries with established BSE surveillance carry minimal practical risk.
- Religious dietary restrictions matter: most collagen is bovine or porcine, with marine being the practical alternative for kosher/halal/pescatarian consumers.
- Phenylketonuria contraindication: collagen is high in phenylalanine and not appropriate for PKU patients.
- Generally very well tolerated. Mild GI upset and a sense of "fullness" at high doses (>20g) are the most common reports.
What people get wrong
Often saidCollagen supplements rebuild your skin and joints by becoming new collagen.
ActuallyThe mechanism is peptide signaling to fibroblasts, not direct collagen replacement. Ingested collagen is broken down to peptides and amino acids; some peptides reach plasma intact and act as signaling molecules, but they do not become tissue collagen directly.
Often saidAll collagen products work the same way.
ActuallyVerisol, Fortigel, Tendoforte, BioCell, and UC-II each have specific peptide profiles or mechanisms with named clinical trials at specific doses. Generic "hydrolyzed collagen" can be any of these or none of them.
Often saidYou need 20-30g of collagen per day for benefit.
ActuallyBranded bioactive peptides are studied at 2.5-5g/day. Undenatured type-II works at 40mg/day. The "more grams equals more benefit" framing is generic-product marketing, not mechanism.
Often saidCollagen is a great protein source.
ActuallyCollagen has an incomplete amino acid profile, no tryptophan, low methionine, no leucine relative to whey. It is not appropriate as a primary protein source.
Often saidType I, II, III on the label means it works for everything.
ActuallyBovine collagen is naturally a mix of types. "Type II for joints" claims belong to specific undenatured type-II products (UC-II, BioCell), not to bovine hydrolysate generally.
Often saidMarine collagen is better than bovine.
ActuallyMarine has smaller peptides and is often marketed for "better absorption", modest evidence. The bigger differentiator is sourcing quality (heavy metals, PCBs) than fish-versus-cow.
Often saidVegan collagen exists.
ActuallyNo animal-source collagen is in vegan products. "Vegan collagen boosters" provide vitamin C plus amino acid substrates, mechanistically defensible for endogenous synthesis support, but not equivalent to bioactive peptide products.
Who profits, and who pushes back
Examine.com analysts
Generic collagen supplementation for general "skin and hair" wellness has substantially less evidence than the consumer marketing suggests. The real cases, branded bioactive peptides for specific endpoints, undenatured type-II for joint pain, vitamin C cofactor support, are narrower and more specific than the broad consumer category implies.
Stuart Phillips
Collagen is an incomplete protein, it lacks tryptophan and is low in several essentials including the leucine that drives muscle protein synthesis. It's not appropriate as a primary protein source. The "high protein" marketing on collagen products is misleading for users seeking muscle or sarcopenia benefit.
Vital Proteins (Nestlé Health Science)
Sells this. Has a commercial interest in a product sold as this compound, as of July 2026.
Among the most aggressive marketers in the consumer collagen space. Owned by Nestlé since 2020. Has shifted toward disclosing branded peptide content in formulations.
Steffen Oesser
Sells this. Has a commercial interest in a product sold as this compound, as of July 2026.
Career at the German collagen peptide manufacturer behind Verisol, Fortigel, Tendoforte. Substantial body of peer-reviewed work; disclosed industry affiliation throughout.
Mark Hyman
Sells this. Has a commercial interest in a product sold as this compound, as of July 2026.
Long-standing collagen advocate in functional medicine. Has his own branded collagen products. Commercial interest disclosed; framing has been on the marketing-positive side.
Jennifer Aniston
Sells this. Has a commercial interest in a product sold as this compound, as of July 2026.
High-visibility celebrity partnership that substantially drove consumer category awareness. Paid relationship clearly disclosed in advertising.
Kara Collier
Has covered both the evidence base and the cohort-specificity nuances. Has independent academic framing despite working in commercial nutrition.
Where the research comes from
| Place | Share of published research |
|---|---|
| United States | 32% |
| Germany | 22% |
| Japan | 16% |
| Other | 16% |
| France | 14% |
Research published from: Germany · France · Japan.
How we got here
Collagen has been part of human diet and medicine since antiquity through bone broth, gelatin, and connective-tissue food traditions. Modern collagen industry traces to the 19th-century gelatin manufacturing of Charles and Hartson Knox (Knox Gelatine, 1894 in the US) and the German Gelita-Werke founding in 1875. For most of the 20th century, gelatin was a food ingredient with no significant clinical-trial profile. The modern bioactive collagen peptide era began in the 1990s when Gelita researchers (and competitors) developed enzymatic hydrolysis processes producing specific peptide profiles. Steffen Oesser at Gelita is associated with the foundational mechanism work showing that hydrolyzed collagen peptides reach plasma intact, stimulate fibroblast collagen synthesis in vitro, and have measurable effects on cartilage proteoglycan content in animal models. The Proksch 2014 skin trials with Verisol established the modern consumer category, followed by Fortigel joint trials and the rapid commercial expansion of the late 2010s. The BioCell and UC-II undenatured type-II collagen line represents a different mechanism (oral tolerance) and a different commercial lineage (InterHealth Nutraceuticals, now Lonza). Both threads, bioactive hydrolyzed peptides and undenatured oral-tolerance type-II, have legitimate clinical evidence at very different doses. Consumer marketing has frequently conflated them, contributing to the widespread misunderstanding that "more collagen" equals "more benefit." Nestlé's 2020 acquisition of Vital Proteins for ~$1.2 billion was the largest collagen-category transaction to date, marking the category's arrival as mainstream consumer wellness.
- AntiquityBone broth, gelatin, and connective-tissue food traditions across cultures
- 1875Gelita-Werke founded in Germany, modern industrial gelatin manufacturing
- 1894Knox Gelatine launches in the US, consumer gelatin category begins
- 1990sGelita develops enzymatic hydrolysis for specific bioactive peptide profiles
- 2002Clark BioCell undenatured type-II joint trial, distinct mechanism established
- 2014Proksch Verisol skin trials, foundational modern consumer evidence
- 2017Schunck Fortigel cartilage MRI trial
- 2018König Specific Collagen Peptides postmenopausal bone trial
- 2020Nestlé acquires Vital Proteins for ~$1.2B
- 2023EFSA reviews several branded collagen peptide health claim applications
What we do not know
- Whether the bioactive peptide signaling mechanism extends to dietary collagen from bone broth and traditional preparation methods, or is specific to enzymatic hydrolysate processing.
- Optimal dose-response for postmenopausal bone density, the König trial used 5g but dose-response above and below is thin.
- Whether the apparent skin elasticity effects of Verisol persist with chronic use or diminish over time.
- Whether collagen peptides plus resistance training in trained athletes produce meaningful tendon-injury prevention versus standard nutrition.
- Whether vegan amino acid + vitamin C combinations can approach the clinical effects of bioactive peptides for cohorts that need this.
- How much of the consumer "skin/hair/nails" wellness market's perceived benefit is real versus placebo plus selection effect.
Legal status
Universally available as a dietary supplement and food ingredient. GRAS status in the US. No regulatory restrictions in any major market. The branded bioactive peptide market is dominated by Gelita (Germany, manufacturer of Verisol, Fortigel, Tendoforte) and a small number of competitors (Rousselot, Nitta Gelatin). Consumer brands license these branded peptides, the relevant label question is whether a product discloses Verisol or Fortigel content versus generic "hydrolyzed collagen." Vital Proteins (Nestlé Health Science since 2020) and Ancient Nutrition (Garden of Life adjacent) dominate the US consumer market; both increasingly disclose branded peptide content.
Status current as of July 2026. Regulatory positions change, sometimes quickly.
The market for this
What follows describes how this is bought and sold. It is not a buying guide and it is not an endorsement of any seller.
For branded bioactive peptide products, look for Verisol, Fortigel, Tendoforte, BioCell, or UC-II disclosed on the label, these are licensed ingredient brands with named clinical trials. For generic hydrolyzed collagen, third-party testing for heavy metals is important; published Certificate of Analysis disclosure separates the responsible brands from the rest. Bovine sources from grass-fed cattle in countries with strong BSE surveillance (Brazil, Argentina, US, EU) are the dominant practical choice. Marine collagen sourcing matters more than most consumers realize, wild fish from clean waters with documented sourcing is meaningfully different from generic fish-skin extract.
At a glance
- Body composition
- ~30% of total body protein
- Main tissue location
- Skin, bone, tendon, ligament, cartilage
- Types
- I (skin/bone), II (cartilage), III (skin/vessels) most prevalent
- Skin-targeted dose
- 2.5g/day branded BCP
- Joint-targeted dose (hydrolysate)
- 5g/day branded BCP
- Joint-targeted dose (undenatured)
- 40mg/day UC-II or BioCell
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Collagen Peptides. A short entry is not a safe entry.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
Sources
26-RCT / 1,721-participant meta-analysis found significant improvement in skin hydration and elasticity from hydrolyzed collagen
Pu et al., Nutrients (Effects of Oral Collagen for Skin Anti-Aging)
14-RCT / 967-participant meta-analysis found significant hydration (effect ~0.58) and elasticity (~0.54-0.65) gains
Exploring the Impact of Hydrolyzed Collagen Oral Supplementation on Skin Rejuvenation, PMC
In subgroup analysis, non-industry-funded and high-quality skin trials showed no significant collagen benefit, unlike industry-funded ones
Effects of Collagen Supplements on Skin Aging, The American Journal of Medicine (2025)
4-RCT / 507-participant meta-analysis found moderate knee OA pain reduction (SMD -0.58) but all trials at high risk of bias
Analgesic efficacy of collagen peptide in knee osteoarthritis, PMC (Luo 2023)
Trial-sequential meta-analysis found small-to-moderate collagen benefit on OA pain and function at moderate-to-high certainty, with good safety
Efficacy and safety of collagen derivatives for osteoarthritis, Osteoarthritis and Cartilage (2024)
Intact collagen di/tri-peptides such as Pro-Hyp reach micromolar blood levels after ingestion, higher than most food peptides
Pro-Hyp and Hyp-Gly promote proliferation and migration of skin fibroblasts in culture, supporting a signaling mechanism
Food-Derived Collagen Peptides (Pro-Hyp, Hyp-Gly) Enhance Fibroblast Growth, PMC
A stable bioactive hydroxyproline-containing tripeptide is detectable in human blood after collagen hydrolysate ingestion
Identification of a highly stable bioactive tripeptide in human blood, npj Science of Food (2022)
Clean Label Project testing of 28 top collagen brands found 64% positive for arsenic, 37% lead, 34% mercury, 17% cadmium
Urgent need for collagen codes of conduct after contamination study, NutritionInsight
Collagen peptide supplementation shows mixed musculoskeletal-performance results; not an effective stand-alone ergogenic aid
History of gelatin and hydrolyzed collagen, including Papin's 1682 digester and mid-20th-century industrialization
The studies that matter
Proksch / Verisol skin trial2014
One of the foundational branded-peptide trials: 2.5g Verisol® specific collagen peptides daily for 8 weeks improved skin elasticity (~30%) in women 35-55 in a double-blind RCT.
Proksch wrinkle trial2014
Companion trial: 2.5g Verisol® daily for 8 weeks reduced eye-area wrinkle volume; effects persisted 4 weeks after cessation.
Clark BioCell CII joint trial2002
BioCell undenatured type-II collagen at 40mg/day improved joint comfort and function in osteoarthritis patients, established the much-lower-dose UC-II mechanism distinct from hydrolyzed type-I.
Schunck / Oesser Fortigel cartilage trial2017
Fortigel® specific collagen peptides showed MRI-detectable cartilage proteoglycan content improvements in athletes with knee discomfort, among the few imaging-endpoint collagen trials.
König / Bone-Specific Collagen Peptides trial2018
5g Specific Collagen Peptides daily for 12 months improved bone mineral density in postmenopausal women with osteopenia, a meaningful clinical endpoint at a real time scale.
Choi review of skin RCTs2019
Pooled analysis of 11 RCTs (~800 participants): consistent modest improvements in skin elasticity and hydration; effects strongest with branded specific peptides, not generic collagen.
Praet Tendoforte trial2019
Branded collagen peptide trial in chronic ankle instability: meaningful improvements in subjective stability and dynamic balance versus placebo.
Lin meta-analysis on joint pain2021
Hydrolyzed collagen and UC-II both showed modest joint-pain reduction in osteoarthritis; effect size smaller than NSAIDs but with substantially better safety profile.
Khatri systematic review on muscle/strength2021
Mixed evidence in trained populations; clearer signal in older adults with sarcopenia risk where collagen plus resistance training outperformed training alone.