Collagen Types: A Comprehensive Review Sources, structure, and human health applications

Collagen Types: A Comprehensive Review Sources, structure, and human health applications

Collagen Types: Sources, Structure & Health Applications
Scientific Review · Collagen Science · 2026

Collagen Types: A Comprehensive Review
Sources, structure, and human health applications

The full English companion to the peer-reviewed review article published by the Celluragen R&D team in the Journal of Food and Nutrition Research. The location of each collagen type in the body, its biological function, and findings from clinical studies.

J. Food Nutr. Res. · February 2026 28 Collagen Types 79 Academic Sources Collaxir R&D Team
📄 Peer-Reviewed Publication · Indexed in SCI-E (Science Citation Index Expanded) & Scopus
Comprehensive review of collagen types: sources, structure, and human health applications
Doğan H., Aslanhan S., Yaman M. · Journal of Food and Nutrition Research · February 2026 · DOI: 10.64122/NVIW7824
Read the full article →
About the authors

This article is the comprehensive English companion to our peer-reviewed review, authored by Handan Doğan (M.Sc. Food Engineer, founder of Collaxir Biotechnology and Celluragen), academic Prof. Dr. Mustafa Yaman, and Sultan Aslanhan, and published in February 2026 in the Journal of Food and Nutrition Research, indexed in Science Citation Index Expanded (SCI-E) / Clarivate and Scopus.

The Basics

What is collagen, and why does it matter?

Collagen is the body's most fundamental structural protein, making up roughly 30% of total protein mass and 75% of skin protein.

Collagen serves as a core structural component in almost every tissue of the body, not just skin and bone, but also the cornea, blood vessel walls, cartilage, tendons, the intestinal wall, lungs, the kidney basement membrane, and the vitreous body of the eye. This wide distribution is exactly what makes collagen the body's most critical protein: although its different types function in different tissues, no tissue can maintain its mechanical integrity without collagen.

In vertebrates, 28 distinct collagen types built from at least 46 different polypeptide chains have been described. What all of these types share is a repeating (Gly-X-Y) amino acid sequence: glycine sits in every third position, while the X and Y positions are usually occupied by proline and hydroxyproline. Collagen is lost at a rate of roughly 1% per year after the age of 20, and by age 80 production may have fallen by 75% compared with young adults.

28Defined collagen types
80–90%Share of Type I, II, III in the body
1%/yrCollagen loss after age 20
All 28 Collagen Types

Each type's location and clinical evidence

Our article examines all 28 types, classified into fibril-forming, network-forming, FACIT, transmembrane, anchoring, basement membrane, and multiplexin groups.

🔹 Fibril-Forming Collagens
I
Type I Collagen
Skin, tendon, connective tissue, bone structure
Skin · Bone

The most abundant collagen type in the body. Collagen makes up 75% of skin dry weight, and Type I accounts for 80–90% of that (the rest being 8–12% Type III and under 5% Type V). As the main structural component of the dermis, it is responsible for the skin's strength and durability. In hydrolyzed peptide form it has shown strong antioxidant properties in in vitro studies, an effect thought to arise from specific amino acid sequences and hydrophobic residues within the peptide.

Clinical finding: In a randomized controlled trial giving women aged 45–60 a daily 10 g of marine collagen hydrolysate for 12 weeks, significant improvements were seen in wrinkle scores, skin hydration, and elasticity measures compared with the control group.
II
Type II Collagen
Cartilage structure, nucleus pulposus, vitreous body
Joint · Cartilage

The most studied type in joint health research. As a core component of the vitreous body, it supports the transmission of light to the retina. In an adjuvant-induced arthritis model in rats, Type II collagen was reported to raise glutathione (GSH) levels in the spleen and thymus, supporting antioxidant defense mechanisms.

Clinical finding: Studies have examined whether Type II collagen may increase tear volume and reduce ocular inflammation.
III
Type III Collagen
Skin, reticular fibers, vascular connective tissue
Skin · Vascular

Alongside Type I, a core type studied in skin health. It is abundant in the intestinal wall and is critical for elasticity and tensile strength. In a Col3a1 transgenic mouse model, mutations in Type III collagen were shown to impair vascular collagen fibrillogenesis and tissue integrity.

Clinical finding: In systemic sclerosis, Type III collagen accumulation has been reported to feed the fibrotic process.
IV (fibril)
Type IV Collagen (Fibril group)
Hair, lung, cornea, placenta
Cornea

The Type IV listed here is the form placed in the fibril-forming classification. It plays a structural role in the health of hair and lung tissue.

XI
Type XI Collagen
Articular cartilage, vitreous body
Cartilage

By regulating the organization and arrangement of collagen fibrils in tendon and cartilage, it contributes to the biomechanical properties of these tissues.

🔹 Network-Forming Collagens
VIII
Type VIII Collagen
Endothelial cells, atherosclerotic lesions
Vascular

A collagen type mainly expressed in arterial remodeling and atherosclerotic plaques. While direct antioxidant effects have not been shown, it is associated more with extracellular matrix remodeling and plaque structure than with the regulation of oxidative stress.

X
Type X Collagen
Cartilage structure (hypertrophic zone)
Cartilage

Known as a type specific to the hypertrophic cartilage zone, playing a role in cartilage calcification and ossification processes.

🔹 FACIT Collagens (Fibril-Associated Collagens with Interrupted Triple helices)
IX
Type IX Collagen
Cornea, cartilage structure, vitreous body
Cornea · Cartilage

It is thought to help preserve moisture and elasticity in skin and cartilage health. However, its specific role in reducing wrinkles and visible signs of aging has not yet been clearly established; the available evidence comes mainly from studies using mixed collagen preparations.

XII
Type XII Collagen
Tendons, perichondrium, ligaments
Tendon · Ligament

It supports the extracellular matrix by interacting with Type I collagen fibers. Altered Type XII collagen expression has been reported to be associated with disruptions in tissue repair and matrix organization; however, its direct role in skin hydration and wound healing in humans has not yet been clarified.

XIV
Type XIV Collagen
Skin, tendon, placenta, lung
Skin · Tendon

By interacting with fibril-forming collagens (Types I–III), it can regulate matrix organization during adipose tissue expansion.

XIX
Type XIX Collagen
Rhabdomyosarcoma cells, various tissues
Basement Membrane Associated

A collagen associated with the basement membrane, with structural and biological roles in various tissues. Its specific role in skin structure, aging, or clinical skin outcomes has not been clearly demonstrated to date.

XX
Type XX Collagen
Embryonic skin, sternal cartilage, tendons
Embryonic Tissue

A FACIT collagen prominent during embryonic development and the subject of limited research in adult tissues.

XXI
Type XXI Collagen
Blood vessel wall
Vascular

A FACIT type localized in the blood vessel wall and studied in vascular tissue organization.

🔹 Transmembrane Collagens
XIII
Type XIII Collagen
Skin, hair, endomysium; optic nerve and neural retina
Skin · Neural

Concentrating in skin fibroblasts and focal adhesions, it may enhance cell adhesion and support the extracellular matrix. It has also been shown to be widely expressed in the optic nerve and neural retina. While oral collagen supplementation has been reported to broadly support skin elasticity and appearance, Type XIII's specific contribution to these effects has not yet been isolated in clinical studies.

XVII
Type XVII Collagen
Dermal-epidermal junction
Epidermal Integrity

It plays a critical role in regulating stem cell behavior, a property that matters for skin regeneration and wound healing. It is associated with conditions such as bullous pemphigoid and junctional epidermolysis bullosa.

Clinical finding: Translational research has shown that it supports keratinocyte adhesion and maintains the stability of the epidermal-stromal junction.
🔹 Anchoring Fibrils
VII
Type VII Collagen
Oral mucosa, skin
Skin Repair

It forms the anchoring fibrils that bind the epidermis to the dermis, making it vital for wound healing and skin repair. It is associated with recessive dystrophic epidermolysis bullosa (RDEB).

Clinical finding: Therapies targeting recombinant Type VII collagen have been reported to show potential for supporting wound healing in affected patients.
🔹 Basement Membrane Collagens
IV
Type IV Collagen (Basement Membrane)
Basement membrane: kidney, skin, intestine
Basement Membrane

One of the most important components of the basement membrane. It provides structural support to intestinal epithelial cells and contributes to nutrient absorption. In diabetic nephropathy, Type IV collagen synthesis has been reported to increase, thickening the kidney basement membrane and potentially advancing the nephropathy.

Clinical finding: A clinical study reported that collagen supplementation may protect the intestinal barrier by supporting tight junctions between epithelial cells and reducing the absorption of toxins from the gut.
🔹 Microfibrillar Collagens
VI
Type VI Collagen
Skin, intervertebral disc, cartilage, placenta
Skin · Muscle

It regulates dermal matrix organization and fibroblast motility. It has been reported to confer resistance to apoptosis and oxidative damage in various tissues and cells, including myofibrils, neurons, and fibroblasts. In obesity studies, increased Type VI collagen accumulation has been reported in the subcutaneous adipose tissue of obese individuals.

Clinical finding: It has been shown to potentially minimize oxidative stress by maintaining cellular homeostasis and promoting autophagy.
🔹 Multiplexin Collagens
XV
Type XV Collagen
Kidney, fibroblasts, muscle cells
Multiplexin

It contributes to collagen fibril organization and the preservation of tissue integrity in many tissues. Its specific role in skin aging and any potential anti-aging effects have not yet been shown in clinical studies.

XVI
Type XVI Collagen
Fibroblasts, amniotic fluid, keratinocytes
Skin

Acting like an adaptor protein, it links and organizes fibrillar networks, enhancing the integrity and stability of the extracellular matrix, which is critical for skin elasticity and overall skin structure. Hydrolyzed collagen supplementation has been reported to show promising effects in reducing signs of aging.

XVIII
Type XVIII Collagen
Lung, liver
Basement Membrane

Owing to its presence in the basement membrane and its role in tissue regeneration, it is considered potentially effective in improving hydration and reducing wrinkles, though the findings are not clear. It may contribute to tissue integrity.

🔹 Lesser-Known Types (Type V, XXII, XXIII, XXVI–XXVIII)
V
Type V Collagen
Cornea and skin dermis (heterotypic fibrils)
Cornea · Skin

By interacting with matrix collagens and structural proteins, it provides structural integrity to tissue scaffolds. It acts as a regulator of collagen fibrillogenesis. Type V collagen deficiency is associated with loss of corneal transparency and classic Ehlers-Danlos syndrome. In in vitro studies, Type V collagen peptides derived from pearl oyster mantle collagen hydrolysates have shown antioxidant activity.

XXII
Type XXII Collagen
Tissue junction sites, skin
Skin

It serves as a cell adhesion ligand for skin epithelial cells and fibroblasts, contributing to the preservation of tissue junctions, elasticity, and hydration. It plays an important role in the structure of the extracellular matrix. It has been reported to potentially offer benefits by easing skin aging and related skin conditions.

XXIII
Type XXIII Collagen
Various tissues (shared structural features with Type XXII)
Transmembrane

Recent genetic and functional studies have shown that collagen XXIII variants and overexpression (COL23A1) are associated with increased susceptibility to eczema herpeticum in patients with atopic dermatitis. However, its direct role in more common skin conditions such as wrinkles and intrinsic skin aging has not yet been clarified in clinical studies.

XXVI–XXVIII
Type XXVI, XXVII, XXVIII Collagens
Various tissues
Under-Researched

These types share similar functions, such as preserving skin structure, elasticity, and hydration. However, their specific role in slowing age-related skin changes has not yet been clearly defined in clinical studies. This represents an important research gap in the literature.

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Frequently Asked Questions
How many types of collagen are there?
In vertebrates, 28 distinct collagen types built from at least 46 different polypeptide chains have been described. Of these, 80–90% are Type I, II, and III collagen. The other types are found in smaller amounts in specific organs such as the cornea, lung, heart muscle, basement membrane, and intestinal mucosa.
Why is Type I collagen important? Is it found throughout the body?
Type I collagen is one of the most critical structural proteins, being the dominant collagen type in almost every tissue of the body. It makes up roughly 80% of the bone's organic matrix, over 90% of tendon dry weight, 80–90% of corneal stromal fibrils, and the collagen that forms 75% of skin dry weight, of which 80–90% is Type I.

However, in most tissues collagens coexist as more than one type:

Skin: 75% of dry weight is collagen; of that, 80–90% is Type I, 8–12% Type III, and under 5% Type V. With aging, Type I synthesis is reported to decline while the proportion of Type III relatively increases.

Bone: Although Type I is the dominant type, Type V also forms heterotypic fibrils with Type I in bone. Research has shown that the Type I α1/α2 chain ratio plays a regulatory role in the osteoblast phenotype.

Articular cartilage: Roughly 60% of its dry weight is collagen, of which 90–95% is Type II. Meanwhile, the minor collagens Type I, IX, XI, III, VI, and X also coexist in cartilage, contributing to the stability of the Type II fibril network. Interestingly, Type I collagen has been reported to be more highly expressed in the superficial zone of articular cartilage.

Cornea: 80–90% of stromal fibrils are Type I; Type V coexists with Type I within the same fibril and, by regulating fibril diameter, may contribute to preserving corneal transparency.

This multiple coexistence shows that tissue specificity arises not from a single type but from the architecture that the types build together.
Which collagen type is most important for skin?
Type I, II, III, and IV collagens are the most studied types in skin health. Type I, as the main structural component of the dermis, is directly linked to skin strength and elasticity.
What proportion of the skin's collagen is Type I?
Roughly 75% of skin dry weight is collagen. The distribution of the types that make up this collagen is as follows: 80–90% Type I, 8–12% Type III, and under 5% Type V. As the dominant structural component of the dermis, Type I provides the skin's tensile strength and elasticity. With aging, Type I collagen synthesis declines first, while the proportion of Type III is reported to relatively increase.
How does fish collagen differ from other sources?
As summarized in our research, marine collagen hydrolysate can be biologically detected in connective tissue 4 hours after consumption, and more than 90% of it is digested. It is also known to carry no risk of animal diseases such as BSE or FMD, and to stand out for its high Type I collagen content.
At what age does collagen loss begin?
Research shows that collagen loss in the body begins between ages 18 and 29 and continues at roughly 1% per year after age 40. By age 80, collagen production may have fallen by 75% compared with young adults.
Scientific sources: clickable links
  • Doğan H., Aslanhan S., Yaman M. Comprehensive review of collagen types: sources, structure, and human health applications. J Food Nutr Res, 2026. DOI: 10.64122/NVIW7824 →
  • Rahman A. et al. Unlocking the therapeutic potential of marine collagen. Marine Drugs, 22, 2024. DOI →
  • Bruyère O. et al. Effect of collagen hydrolysate in articular pain: A 6-month RCT. Complement Ther Med, 20, 2012. DOI →
  • Evans M. et al. Freshwater marine collagen on skin wrinkles and elasticity: RCT. J Cosmet Dermatol, 20, 2021. DOI →
  • Pu S.Y. et al. Effects of oral collagen for skin anti-aging: Systematic review and meta-analysis. Nutrients, 15, 2023. PMC →
  • Choi F.D. et al. Oral collagen supplementation: Systematic review of dermatological applications. J Drugs Dermatol, 18, 2019. JDD →
  • Barati M. et al. Collagen supplementation for skin health: A mechanistic systematic review. J Cosmet Dermatol, 19, 2020. DOI →
  • Wang X. et al. Recombinant Type VII collagen promotes wound closure. Mol Ther, 21, 2013. DOI →
  • Watanabe M. et al. Type XVII collagen coordinates proliferation in the interfollicular epidermis. eLife, 6, 2017. DOI →
  • Nishie W. Collagen XVII processing and blistering skin diseases. Acta Derm Venereol, 100, 2020. DOI →
  • Theocharidis G. et al. Type VI collagen regulates dermal matrix assembly. J Invest Dermatol, 136, 2016. DOI →
  • Cescon M. et al. Collagen VI at a glance. J Cell Sci, 128, 2015. DOI →
  • D'hondt S. et al. Type III collagen affects dermal and vascular collagen fibrillogenesis. Matrix Biol, 70, 2018. DOI →
  • Abreu-Velez A.M., Howard M.S. Collagen IV in normal skin and pathological processes. N Am J Med Sci, 4, 2012. DOI →
  • Mak K.M. et al. Type V collagen in health, disease, and fibrosis. Anat Rec, 299, 2016. DOI →
  • Martin P. et al. Abnormal collagen V deposition in dermis correlates with skin thickening in systemic sclerosis. Autoimmun Rev, 11, 2012. DOI →
  • Hägg P. et al. Type XIII collagen: a novel cell adhesion component. Matrix Biol, 19, 2001. DOI →
  • Calvo A.C. et al. Type XIX collagen: a promising biomarker from the basement membranes. Neural Regen Res, 15, 2019. DOI →
  • Bretaud S. et al. Collagen XV, a multifaceted multiplexin present across tissues and species. Matrix Biol Plus, 2020. DOI →
  • Grässel S., Bauer R.J. Collagen XVI in health and disease. Matrix Biol, 32, 2013. DOI →
  • Koch M. et al. A novel marker of tissue junctions, collagen XXII. J Biol Chem, 279, 2004. DOI →
  • Chopra S. et al. Collagen XXIII (COL23A1): A novel risk factor for eczema herpeticum. J Allergy Clin Immunol, 156, 2025. DOI →
  • Schönborn K. et al. Role of collagen XII in skin homeostasis and repair. Matrix Biol, 94, 2020. DOI →
  • Sun M. et al. Collagen XI regulates collagen fibril structure in tendon. Matrix Biol, 94, 2020. DOI →
  • Abrahams M. et al. Effect of a daily collagen peptide supplement on digestive symptoms. JMIR Form Res, 6, 2022. DOI →
  • Michelacci Y.M. Collagens and proteoglycans of the corneal extracellular matrix. Braz J Med Biol Res, 36, 2003. DOI →
  • Wang H. A review of the effects of collagen treatment in clinical studies. Polymers, 13, 2021. DOI →
  • Stewart J.A. et al. Nitric oxide-induced collagen IV expression and angiogenesis. AJP Cell Physiol, 300, 2011. DOI →
  • Birk D.E. et al. Collagen type I and type V are present in the same fibril in the avian corneal stroma. J Cell Biol, 106, 1988. PubMed →
  • Nakayasu K. et al. Distribution of types I, II, III, IV and V collagen in normal and keratoconus corneas. Ophthalmic Res, 18, 1986. PubMed →
  • Meek K.M., Fullwood N.J. Corneal collagen: its role in maintaining corneal shape and transparency. PMC, 2017. PMC →
  • Song Y. et al. Application of collagen I and IV in bioengineering transparent ocular tissues. Front Surg, 8, 2021. DOI →
  • Eyre D.R. Articular cartilage and changes in arthritis: collagen of articular cartilage. Arthritis Res, 4, 2002. PMC →
  • Shoulders M.D., Raines R.T. Main and minor types of collagens in articular cartilage. PMC, 2021. PMC →
  • Viggers R. et al. Collagen type I: comprehensive review on biomaterials for tissue engineering. PMC, 2022. Type II ~90–95% in cartilage. PMC →
  • Niyibizi C., Eyre D.R. Structural characteristics of cross-linking sites in type V collagen of bone. Biochem J, 1994. Type I–Type V heterotypic fibrils in bone/tendon/cornea.
FAQ: additional supporting academic sources
  • Birk D.E. et al. Collagen type I and type V are present in the same fibril in the avian corneal stroma. J Cell Biol, 106, 1988. PubMed → (Type I/V in the same fibril, cornea)
  • Nakayasu K. et al. Distribution of types I, II, III, IV and V collagen in normal and keratoconus corneas. Ophthalmic Res, 18, 1986. PubMed → (Corneal collagen distribution)
  • Meek K.M., Fullwood N.J. Corneal collagen: its role in maintaining corneal shape and transparency. PMC, 2017. PMC → (Cornea Type I 80–90%, Type V distribution)
  • Eyre D.R. Articular cartilage and changes in arthritis: collagen of articular cartilage. Arthritis Res, 4, 2002. PMC → (Type II dominant in cartilage; Type I in superficial zone)
  • Viggers R. et al. A comprehensive review on collagen type I: from biosynthesis to biomaterials. PMC, 2022. PMC → (Type II 90–95% in cartilage ECM; bone organic matrix 80% Type I)
  • Eyre D.R., Brickley-Parsons D.M., Glimcher M.J. Predominance of type I collagen at the surface of avian articular cartilage. FEBS Lett, 1978. (Type I predominance at the articular cartilage surface)
  • Niyibizi C., Eyre D.R. Structural characteristics of cross-linking sites in type V collagen of bone. Biochem J, 1994. (Type I–Type V heterotypic fibrils in bone, tendon, and cornea)
  • Rittié L., Fisher G.J. Molecular mechanisms of dermal aging and antiaging approaches. PMC, 2019. PMC → (75% of skin dry weight is collagen; 80–90% Type I, 8–12% Type III, under 5% Type V)

This content is for informational purposes only. Celluragen is a food supplement; it cannot be used to diagnose, treat, or prevent any disease. Findings reported in academic studies do not constitute a guarantee of the product's individual effectiveness.