Collagen Type I and III: What They Are and Why They Are Often Paired
Type I and Type III are two of the most widely discussed collagen types. They are separate members of the collagen protein family, but they frequently occur together within skin and other connective tissues. They are also the main collagen types commonly associated with bovine-derived collagen ingredients.
Understanding the relationship between Type I and Type III can help explain why these collagen types are often listed together on bovine collagen products. This guide focuses specifically on where Type I and Type III collagen are found, how their structures differ and why bovine collagen is commonly associated with both types.
For a broader introduction to Types I, II, III, IV and V, read our complete guide to collagen types explained.
1. What is Type I collagen?
Type I is the most abundant collagen type in the human body. It forms strong, densely packed fibres that provide structure within tissues exposed to pulling forces and physical strain. Type I collagen is commonly found in:
- Skin
- Bones
- Tendons
- Ligaments
- Teeth
- Other connective tissues
Its strong fibre-forming structure distinguishes it from collagen types that create finer networks or sheet-like structures. Type I is also commonly found in animal-derived collagen sources. Bovine collagen and marine collagen are both generally associated with Type I collagen.
2. What is Type III collagen?
Type III collagen is a separate collagen type that forms thinner fibres than Type I. It is often found in softer and more flexible connective tissues, where it helps form a supportive structural network. Type III collagen is commonly present in:
- Skin
- Blood vessels
- Muscles
- Internal organs
- Other connective tissues
Type III frequently occurs alongside Type I, particularly within tissues that require a combination of strength and flexibility. Bovine collagen is commonly associated with Type III as well as Type I.
3. Are Type I and Type III collagen the same?
No. Type I and Type III are different collagen proteins. They have different molecular structures and form different types of fibres. Type I forms thicker and more densely packed fibres. Type III forms finer fibres, sometimes described as reticular fibres, that help create a more flexible structural framework.
Although they are distinct, they often occur in the same tissues and work as part of the wider connective-tissue structure. This is why they are frequently discussed together rather than treated as completely unrelated collagen types.
4. Why are Type I and Type III often paired?
Type I and Type III are often paired because they naturally coexist in several tissues. Type I contributes strong structural fibres, while Type III forms a finer supporting network around cells and tissues.
Their relative amounts can differ depending on the tissue, age and stage of tissue development. For example, developing or healing tissues may contain a different balance of Type I and Type III than mature tissue. The fact that the two types occur together also explains why bovine collagen products commonly identify both Types I and III on their labels.
5. Where are Type I and Type III found together?
Type I and Type III collagen can both be found in several connective tissues.
Skin
Both types occur within the skin’s connective-tissue structure. Type I is generally the dominant type, while Type III contributes a finer supporting network.
Blood vessels
Type III collagen is commonly present within blood-vessel walls alongside other structural proteins, including Type I collagen.
Muscles and surrounding tissues
Type I and Type III can occur in the connective tissues that surround and organise muscles.
Internal organs
Type III is found within the supporting frameworks of several organs, often alongside Type I and other collagen types. Their presence together does not mean they perform exactly the same function. Each type contributes a different fibre structure.
6. Type I vs Type III collagen
The main differences between Type I and Type III relate to their fibre structure and tissue distribution.
| Feature | Type I collagen | Type III collagen |
|---|---|---|
| Relative abundance | Most abundant collagen type | Less abundant than Type I |
| Fibre structure | Thick, strong fibres | Thinner, finer fibres |
| Common locations | Skin, bones, tendons and ligaments | Skin, blood vessels, muscles and organs |
| Relationship | Often occurs alongside Type III | Often occurs alongside Type I |
| Common supplement source | Bovine and marine collagen | Primarily associated with bovine collagen |
This is a general comparison. Collagen types exist as part of complex tissue structures rather than acting independently.
7. Which collagen sources contain Type I?
Type I is found in several animal collagen sources.
Bovine collagen
Bovine collagen is derived from cattle and is commonly associated with both Type I and Type III collagen. Bovine hide is one of the most frequently used source materials.
Marine collagen
Marine collagen is derived from fish materials, commonly skin or scales. It is generally associated primarily with Type I collagen. The presence of Type I in both sources does not mean marine and bovine collagen are identical. Their animal origin and wider collagen-type profiles differ.
8. Which collagen sources contain Type III?
Type III is most commonly discussed in relation to bovine collagen. Cattle-derived connective tissues such as bovine hide commonly contain Type I and Type III collagen together. Marine collagen is generally promoted for its Type I profile and is not normally described as a major Type III source. This is one of the clearest collagen-type distinctions between common bovine and marine ingredients.
9. Does bovine collagen contain Type I and Type III?
Bovine collagen is commonly derived from source tissues containing both Type I and Type III collagen. This is why bovine collagen peptide products frequently state that they are associated with Types I and III.
However, collagen-type wording should be presented accurately. When bovine collagen is hydrolysed, its original protein structures are divided into smaller peptide fragments. The finished powder is therefore derived from Type I and Type III collagen sources rather than containing unchanged native collagen fibres. The source profile remains relevant, but the processing should also be understood.
10. Does marine collagen contain Type III?
Marine collagen is generally associated primarily with Type I collagen. The exact collagen profile may vary depending on the fish species and tissue used, but standard marine collagen products are not normally promoted as significant sources of Type III.
This differs from bovine collagen, which is commonly associated with both Types I and III. The distinction relates to the original animal tissue rather than one source being universally better than the other.
11. Is Type I collagen better than Type III?
No. Type I is not inherently better than Type III. Collagen type numbers are scientific classifications rather than quality rankings. Type I and Type III have different fibre structures and occur in different proportions across tissues.
Type I is more abundant and forms thicker fibres. Type III forms a finer network and is often present alongside Type I. Because they perform different structural roles, comparing them as though one must be superior is misleading.
12. Beauvyn Type I and Type III collagen
Beauvyn uses hydrolysed bovine collagen peptides. The bovine source material is commonly associated with Type I and Type III collagen. Beauvyn clearly identifies the product as bovine-derived and explains its collagen-type profile so customers can understand where the ingredient comes from.
The finished product contains one ingredient: hydrolysed bovine collagen peptides. This information is presented as part of Beauvyn’s commitment to clear and transparent product labelling.
The Final Say
Type I and Type III are two distinct collagen types that commonly occur together within connective tissues. Type I is the most abundant collagen type and forms strong, densely packed fibres. Type III forms thinner fibres and contributes to a more flexible structural network.
Their natural association explains why bovine collagen is commonly described as a Type I and Type III source. However, the presence of two collagen types should not be treated as a guarantee of overall product quality. Collagen-type claims should be supported by clear information about the animal source and how the ingredient has been processed.
For a wider explanation of Type I, II, III, IV and V collagen, read our main pillar guide to collagen types explained.
