VITAMINS & SUPPLEMENTS · GUIDE
Collagen in Skin, Bone, Cartilage, Tendon and Gut: What It Does in Each Tissue
A tissue-by-tissue guide to which collagen types sit in skin, bone, cartilage, tendon and the gut wall, what they do there, and where to read the supplement trials.
Content last updated . This page has not been medically reviewed.
Back to Collagen Supplements: What They Are, Types, Sources and EvidenceQuick answer
Collagen is not one material. Different tissues use different collagen types in different arrangements, and each tissue also contains water, minerals and other proteins. A review of connective tissue says the structure of cartilage, tendons and ligaments, and of organs such as skin, heart, liver, kidney, lungs, blood vessels and bones, depends on collagen. [1] This page maps what the sources say about each tissue. It does not say that a supplement reaches any of them. For that, see how collagen supplements are digested.
Two types, two jobs
Type I collagen is described as a stiff fibrillar protein that gives tensile strength, while type III forms an elastic network that stores energy as elastic rebound. [1] MedlinePlus Genetics calls type I the most abundant form in the human body. [2]The tissue map
| Tissue | What the sources say | Where to read about supplements |
|---|---|---|
| Skin | The dermis is largely a collagen-rich matrix that gives skin mechanical strength, and fibroblasts produce and maintain it. [3] Type I procollagen is described as the major structural protein of human skin. [4] | More about Skin → |
| Bone | Bone has a mineral phase, hydroxyapatite, and an organic phase that consists of type I collagen, other proteins and water. [5] In osteogenesis imperfecta type I, a reduced amount of type I collagen leaves bones brittle. [6] | More about Bone → |
| Cartilage | Fibrils of mainly type II collagen reinforce a highly hydrated gel, and cartilage is about 70% water. [7] Articular cartilage has no or very low ability of self-repair. [7] | More about Cartilage → |
| Tendon | Tendon consists of highly ordered type I collagen molecules grouped into subunits of increasing diameter. [8] | More about Tendon → |
| Gut wall | In normal intestine tissue from one 1988 study, type I made up 68% of the collagen, type III 20% and type V 12%. [9] The thin layer beneath the gut lining, the basement membrane, is built partly from collagenous molecules. [10] | More about Gut wall → |
| Other places | Collagen is also part of the white of the eye (sclera). [2] MedlinePlus lists collagen used to make blood vessels, along with skin, tendons and ligaments, among the things vitamin C helps form. [11] | More about Other places → |
More collagen is not always better
Collagen amounts can rise in a harmful way. In Crohn's disease strictures, both collagen content and the share of type V collagen were higher than in normal intestine, thickening the bowel wall and reducing its flexibility. [9] In the heart, raising type I collagen may increase stiffness. [1] These are disease processes, not reasons to avoid or seek out collagen foods or supplements. They show why "more collagen" is not an automatic goal. If you have bowel symptoms or joint pain that does not settle, talk to a clinician.What the sources do not show
- The 1988 gut figures come from a small study of intestine, including tissue resected from patients with Crohn's disease. A 2005 study of pig small intestine found that collagen arrangement in that segment differed from other gut segments and species, so one set of percentages should not be treated as universal. [9] [12]
- We did not read a human source showing that eating collagen changes the amount of collagen in any one tissue. That is Proper evidence not found here; we searched PubMed for human tissue-level studies after oral collagen and for gut-specific trials, and the trials we found are covered on the evidence pages.
- A summary of the trial evidence is on the collagen overview.
Frequently asked questions
Is the collagen in skin the same as in bone?
Both rely on type I collagen: it is described as the major structural protein of human skin, and as the collagen of bone's organic phase. Bone also has a mineral phase. [4] [5]
What type of collagen is in cartilage?
Mostly type II. Fibrils of mainly type II collagen reinforce a water-rich proteoglycan gel in joint cartilage. [7]
Is there collagen in the gut?
Yes. A 1988 study of normal intestine found mostly type I, with types III and V as well. [9]
Can cartilage repair itself?
One review says articular cartilage has no or very low ability of self-repair. [7] We did not read a source comparing healing across other tissues, so we do not make that comparison.
Do collagen supplements go to the tissue they are named for?
Not shown in the sources we read. See how collagen supplements are digested for what blood-level studies measured.
References
- Singh D, Rai V, Agrawal DK. Regulation of Collagen I and Collagen III in Tissue Injury and Regeneration. Cardiol Cardiovasc Med 2023. Read 2026-10-22.
- MedlinePlus Genetics (US National Library of Medicine). COL1A1 gene. Read 2026-10-22.
- Fisher GJ, Wang B, Cui Y, et al. Skin aging from the perspective of dermal fibroblasts: the interplay between the adaptation to the extracellular matrix microenvironment and cell autonomous processes. J Cell Commun Signal 2023. Read 2026-10-22.
- Quan T, He T, Kang S, et al. Solar ultraviolet irradiation reduces collagen in photoaged human skin by blocking transforming growth factor-beta type II receptor/Smad signaling. Am J Pathol 2004. Read 2026-10-22.
- Boskey AL. Bone composition: relationship to bone fragility and antiosteoporotic drug effects. Bonekey Rep 2013. Read 2026-10-22.
- MedlinePlus Genetics (US National Library of Medicine). Osteogenesis imperfecta. Read 2026-10-22.
- Becerra J, Andrades JA, Guerado E, et al. Articular cartilage: structure and regeneration. Tissue Eng Part B Rev 2010. Read 2026-10-22.
- Thorpe CT, Birch HL, Clegg PD, et al. The role of the non-collagenous matrix in tendon function. Int J Exp Pathol 2013. Read 2026-10-22.
- Graham MF, Diegelmann RF, Elson CO, et al. Collagen content and types in the intestinal strictures of Crohn's disease. Gastroenterology 1988. Read 2026-10-22.
- Hahn U. Facts and problems of the intestinal basement membrane. Digestion 1990. Read 2026-10-22.
- MedlinePlus Medical Encyclopedia, editorial update 08/12/2025. Vitamin C. Read 2026-10-22.
- Prado IMM, Di Dio LJA, Miranda-Neto MH, et al. Three-dimensional distribution of the collagen fibers in the submucosa of the swine terminal ileum. Ital J Anat Embryol 2005. Read 2026-10-22.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.