Built in steps
A 1976 review lists the steps collagen needs: hydroxylation of proline and lysine, glycosylation, folding into a triple helix and conversion of procollagen to collagen. A fault at any step can produce abnormal fibres.5
Research · Collagen and skin
Types of collagen: what each does, and what studies show.
“Collagen” is a family, not a single protein. This guide reads the reviews on which types matter in skin, how collagen is made and lost, what happens to collagen peptides when they are swallowed, and why two 2025 meta-analyses of collagen supplements reach opposite conclusions. Every claim cites its source.
28
Types of collagen are found in the human body, according to a 2024 review. Five are most often used in supplements: I, II, III, V and X.2
26 trials
Pooled in a 2023 meta-analysis of 1,721 people. Oral hydrolyzed collagen beat placebo for skin hydration and elasticity, with several biases noted.9
19.3% vs 4.4%
Absolute oral bioavailability of the dipeptide Pro-Hyp and the tripeptide Gly-Pro-Hyp in rats. This is animal data.7
No effect
Found in a 2025 meta-analysis for trials not funded by pharmaceutical companies, and for high-quality trials.12
The short answer
- A big family, a short skin list. Around 28 types exist,2 and a 2025 review singles out types I, III, IV, VII and XVII as the ones that play key roles in skin aging.1
- Collagen is lost, not just slowed. With age, dermal collagen becomes fragmented and its total amount decreases, driven by more matrix metalloproteinase activity and impaired TGF-β signalling.3
- Eating collagen is not the same as adding it. The only absorption study we read was in rats, and it reports oral bioavailability of 19.3% for one collagen peptide and 4.4% for another.7
- The trials disagree. Several meta-analyses found better hydration and elasticity,891011 while a 2025 one found no effect in trials without pharmaceutical funding and in high-quality trials.12
01 · The family
One word, about twenty-eight proteins.
A 2024 review states that collagen is the most abundant protein in mammals and that around 28 different types are found in the human body.2 They fall into two broad groups. Fibrillar collagens are types I, II, III, V, XI, XXIV and XXVII; non-fibrillar collagens include types IV, VI, VII and XVII, among many others.2
Five types, I, II, III, V and X, are the ones most generally used in supplements.2 The review places type I in skin, bone, tendon, cornea and vascular tissue, type II in cartilage and the vitreous body, and type III alongside type I in skin, uterus, intestine and vessels.2
02 · Types in skin
Five collagens, five jobs.
A 2025 review of collagen in skin aging describes the roles of five types. It is a Chinese-language review with an English abstract, and the roles below are those the abstract gives.1
Type I: Mechanical support to the dermis
The structural collagen of the dermis. Reported in skin, bone, tendon and cornea.12
Type I collagen in depth
Type III: Elasticity, and a helper in barrier repair
Found alongside type I and a main component of reticular fibres. Reported in skin, uterus, intestine and vessels.12
Type III collagen in depth
Type IV: Stability of the basement membrane
Non-fibrillar. Forms the basal lamina and is reported in capillaries and the epithelium-secreted layer of the basement membrane.12
Type IV collagen in depth
Type VII: Anchoring epidermis to dermis
Non-fibrillar. Mediates the epidermal-dermal anchoring. Reported in skin and mucous membranes.12
Type VII collagen in depth
Type XVII: Epidermal stem-cell homeostasis
Non-fibrillar. Regulates the homeostasis of epidermal stem cells, according to the 2025 review.1
Type XVII collagen in depth
What genetics shows. Rare inherited disorders show what happens when a type is missing or faulty. Ehlers-Danlos syndrome type IV is caused by a mutation in the collagen III gene, and a mutation in the collagen I gene underlies another form (type VII).4 Decreased type I collagen synthesis is described in osteogenesis imperfecta.5 These are medical conditions, not skincare findings.
03 · Making and losing it
How collagen is built, and how it frays.
Lost with age
In aging dermis, collagen becomes fragmented and coarsely distributed and its total amount falls. The review ties this to higher matrix metalloproteinase activity and impaired TGF-β signalling caused by reactive oxygen species.3
A loop that feeds itself
Less collagen hinders the mechanical interaction between fibroblasts and their matrix, which worsens fibroblast function and lowers collagen further.3
A note on vitamin C. A 2014 laboratory study calls vitamin C a known enhancer of collagen deposition, and found that sodium ascorbate at 50 to 200 micromolar stimulated both collagen and elastic fibres in cultures of skin cells.6 It was done on cells and skin samples, so it does not show what a cream or a supplement does on a person.
04 · What happens when you eat it
Collagen peptides, after the swallow.
The skin trials pooled below tested hydrolyzed collagen, which is collagen broken into peptide fragments.89 A 2023 study in rats gave three collagen peptides, the tripeptide Gly-Pro-Hyp and the dipeptides Pro-Hyp and Gly-Pro, by mouth and into a vein and followed what reached the blood.7
- Absolute oral bioavailability was 19.3% for Pro-Hyp and 4.4% for Gly-Pro-Hyp. Gly-Pro was very low in the circulation.7
- Gly-Pro-Hyp tended to undergo more first-pass metabolism than Pro-Hyp, and the Pro-Hyp formed from it behaved like Pro-Hyp given on its own.7
- The authors describe absorption as slow, probably reflecting transporter-mediated uptake.7
The study shows that these peptides can reach the blood in rats. It does not follow them into skin, and it does not show what they do there. One author works for a health-food company.7
05 · The trials
Five meta-analyses, two stories.
Five systematic reviews and meta-analyses pooled randomized trials of oral collagen and skin. The bars show how many people each included, from fewest to most.
- 646 peopleDanessa and colleagues, 2025
- 967 peopleDewi and colleagues, 2023
- 1,125 peoplede Miranda and colleagues, 2021
- 1,474 peopleMyung and Park, 2025
- 1,721 peoplePu and colleagues, 2023
| Review | Trials | People | What it reported |
|---|---|---|---|
| Danessa and colleagues, 2025 | 10 RCTs | 646 | Hydration SMD 1.25 and elasticity SMD 0.61 favoured collagen. Doses of 1 to 10 g a day; most common 4 g. Risk of bias generally unclear and results more applicable to females.11 |
| Dewi and colleagues, 2023 | 14 studies | 967 | Moisture and elasticity improved compared with placebo, which the authors tie to a 12-week regimen.10 |
| de Miranda and colleagues, 2021 | 19 studies | 1,125 | Favourable hydration, elasticity and wrinkle results. Participants were aged 20 to 70 and 95% were women. The authors say 90 days is effective.8 |
| Myung and Park, 2025 | 23 RCTs | 1,474 | Pooled, all trials favoured collagen. Without pharmaceutical-company funding, and among high-quality trials, no significant effect. The authors conclude there is currently no clinical evidence to support collagen supplements for skin aging.12 |
| Pu and colleagues, 2023 | 26 RCTs | 1,721 | Hydration and elasticity improved against placebo. Hydration results varied with collagen source and duration. Several biases were found in the included trials.9 |
The case for
The case for caution
- In trials not funded by pharmaceutical companies, the 2025 analysis found no effect on hydration, elasticity or wrinkles. Funded trials did show effects.12
- High-quality trials showed no significant effect in any category; low-quality trials showed an improvement in elasticity.12
- Other reviews flag bias in the included trials, unclear risk of bias, moderate heterogeneity and mostly female participants.9118
How to read this. The reviews pooled different sets of trials and differ in what they weigh. The 2025 analysis is the only one of the five that split trials by funding source and quality, and it says the benefit seen in the pooled data did not hold up in either subgroup.12 We do not pick a winner; the honest summary is that the effect is unsettled.
06 · Beyond skin
Type II collagen is a different story.
Type II collagen is found in cartilage and the vitreous body.2 A 2025 randomized trial in 68 people with knee osteoarthritis gave tablets with undenatured type II collagen (UC-II) and hydrolysed collagen, or placebo, for 12 weeks. Both groups improved on pain and function scores over time, with no significant difference between them, and no adverse effects.13
The authors note that most earlier collagen studies in this area were industry-sponsored.13 This is a joint trial. It says nothing about skin, and we include it only to show why “collagen” on a label is not one claim.
07 · Reading a claim
Five questions to ask of any collagen claim.
Which type, and where?
Types I and III live in the dermis, IV and VII at the junction beneath the epidermis, and type II in cartilage.12 A label that names a type should say what it is for.
Peptides or intact protein?
The skin trials tested hydrolyzed collagen,89 and the absorption data we have are for small peptides in rats.7
Who paid for the study?
In the 2025 meta-analysis, the funding source changed the result.12 Check the disclosures.
What was measured, for how long?
The pooled outcomes were hydration, elasticity, wrinkles and firmness over about 12 weeks.810
Is it your skin?
Participants were mostly women,811 and the reviews cover adults from 20 to 70.8 Results in one group do not carry over automatically.
08 · What we could not confirm
The gaps, stated plainly.
- A yearly percentage of collagen lost with age. The review we read says the amount decreases, with no yearly rate, so we state none.3
- The proportion of type I to type III in young versus aged skin. Our searches did not return a study we could read, so we make no claim.
- Whether any topical collagen reaches the dermis. We found no study we could read and make no claim about creams or masks.
- Whether collagen peptides reach human skin, or stimulate fibroblasts there. The absorption study we read was in rats.7
- That bovine, marine, chicken or eggshell sources differ in effect on skin. One meta-analysis found collagen source changed hydration results but not elasticity results, and we did not verify which sources.9
- Which collagen type a supplement should contain to help skin. We found no trial that tests this.
- Long-term safety and results beyond about 12 weeks. The trials we read were short.10
- Product comparison tables and delivery-method rankings. We did not use them, because we could not trace their figures to sources we could read.
Vanu Health’s DermaGlass® masks are hydrating skincare. This page makes no collagen, firming or anti-aging claim about them or any other Vanu Health product.
09 · Questions
Frequently asked questions.
How many types of collagen are there?
A 2024 review says around 28 different types are found in the human body. Five of them (types I, II, III, V and X) are the ones most generally applied in supplements. Types I, II, III and V are fibrillar; types IV, VI, VII and XVII are among the non-fibrillar ones. 2
Which collagen types matter most in skin?
A 2025 review of skin aging describes five: type I gives the dermis mechanical support, type III enhances elasticity and assists barrier repair, type IV keeps the basement membrane stable, type VII anchors the epidermis to the dermis, and type XVII regulates the homeostasis of epidermal stem cells. 1
Does eating collagen put collagen in my skin?
We found no human study that tracks swallowed collagen into the skin. The one pharmacokinetic study we read was in rats: collagen peptides were detected in the circulation, with an absolute oral bioavailability of 19.3% for Pro-Hyp and 4.4% for Gly-Pro-Hyp. Whether that carries over to people, and what it does in skin, is not shown there. 7
Do collagen supplements work for skin?
The meta-analyses disagree. Four meta-analyses pooled randomized trials and reported better skin hydration and elasticity than placebo. A 2025 meta-analysis of 23 trials found the same when all trials were pooled, but found no significant effect in trials not funded by pharmaceutical companies, or in high-quality trials, and concluded there is currently no clinical evidence to support collagen supplements for skin aging. 89101112
Does the type of collagen in a supplement decide where it works?
We found no trial that shows that. The skin trials pooled in the meta-analyses used hydrolyzed collagen, and one meta-analysis found no significant difference between collagen sources for elasticity. A trial of undenatured type II collagen in knee osteoarthritis found no difference from placebo. 913
What does vitamin C have to do with collagen?
Collagen needs hydroxylation of proline and lysine to form properly, and a 2014 lab study calls vitamin C a known enhancer of collagen deposition. In cultured skin cells, sodium ascorbate at 50 to 200 micromolar stimulated collagen and elastic fibres. That is a cell study, not a trial of a cream or a supplement. 56
Does Vanu Health make a collagen claim?
No. This page reports what published studies say. It makes no collagen, firming or anti-aging claim about any Vanu Health product.
Keep reading
- The Research Desk: every guide and dataset from the same team.
- The plump effect: hydration versus structure, and what studies show.
- Sunlight and skin health: UV, photoaging and sunscreen amounts.
- Hydrolyzed collagen: the ingredient page.
- Ingredients: what is in a Vanu Health formula, and why.
Related research and reading
- The Plump Effect: hydration versus structure in plump-looking skin.
- Glycation and AGEs: advanced glycation end-products and skin aging.
- Seasonal skincare: how skin changes across spring, summer, autumn and winter.
- Types of light therapy: LED, lasers, IPL, UVB, PDT and cold plasma.
- The Truth About Wrinkles: a book from the Vanu Health library.
- Peeling Away Youth: a book from the Vanu Health library.
- Research Desk sources: every reference, organised by guide.
- The Research Desk: all guides and datasets.
Sources
Where every claim comes from.
Numbers in brackets link to these entries. Each study was read as its PubMed record, with the title, journal, date and abstract, and study details come from PubMed, the US National Library of Medicine. Links open the paper through its DOI. Dates are those shown on the source.
All sources across the Research Desk are collected, by page, in the master source list.
- [1] Chinese Journal of Biotechnology (Li and colleagues; Chinese-language review with an English abstract; some authors are from a health-management company). Roles of different types of collagen in skin aging and their research progress. September 2025.
- [2] Mini Reviews in Medicinal Chemistry (Shahrajabian and Sun). Mechanism of action of collagen and epidermal growth factor: a review on theory and research methods. 2024.
- [3] International Journal of Molecular Sciences (Shin and colleagues). Molecular mechanisms of dermal aging and antiaging approaches. April 2019.
- [4] Der Hautarzt (Brinckmann and colleagues; German-language review with an English abstract). Ehlers-Danlos syndrome. April 1999.
- [5] Journal of Investigative Dermatology (Uitto and Lichtenstein). Defects in the biochemistry of collagen in diseases of connective tissue. February 1976.
- [6] Journal of Dermatological Science (Hinek and colleagues; two authors are from Human Matrix Sciences, LLC). Sodium L-ascorbate enhances elastic fibers deposition by fibroblasts from normal and pathologic human skin. June 2014.
- [7] Journal of Food Science (Won and colleagues; one author is from a health-food company). Pharmacokinetics of collagen dipeptides (Gly-Pro and Pro-Hyp) and tripeptides (Gly-Pro-Hyp) in rats. December 2023.
- [8] International Journal of Dermatology (de Miranda, Weimer and Rossi). Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis. March 2021.
- [9] Nutrients (Pu and colleagues). Effects of oral collagen for skin anti-aging: a systematic review and meta-analysis. April 2023.
- [10] Cureus (Dewi and colleagues). Exploring the impact of hydrolyzed collagen oral supplementation on skin rejuvenation: a systematic review and meta-analysis. December 2023.
- [11] Indian Journal of Dermatology, Venereology and Leprology (Danessa, Notario and Regina). Effects of collagen-based supplements on skin’s hydration and elasticity: a systematic review and meta-analysis. 2025.
- [12] The American Journal of Medicine (Myung and Park). Effects of collagen supplements on skin aging: a systematic review and meta-analysis of randomized controlled trials. May 2025.
- [13] Scientific Reports (Yuenyongviwat and colleagues). Efficacy of combined undenatured type II collagen and hydrolysed collagen supplementation in knee osteoarthritis: a randomised controlled trial. September 2025.
This page is general information from the Vanu Health Research Team. It is not medical advice. The images are AI-generated illustrations, not study images. Last updated October 30, 2026.