Comparison
Collagen types explained: I, II and III
Type I collagen is the most abundant in the body and is found in skin, bone and tendons; type II is the main collagen in cartilage; type III sits alongside type I in skin and organs. Skin-focused supplements are usually type I, often with type III, while joint products tend to be type II. Collagen carries no authorised EFSA health claim, so treat firm skin or joint promises with caution. This is information, not medical advice.
At a glance
| Collagen type | What it is | In supplements | Most relevant to |
|---|---|---|---|
| Type I | The most abundant collagen in the body, found in skin, tendons, bone and ligaments. | Most marine and many bovine peptide supplements are predominantly type I. | Those interested in skin and bone-related products (note collagen carries no authorised EFSA claim). |
| Type II | The main collagen in cartilage. | Usually sold as a separate cartilage-derived product rather than in skin powders. | Those looking specifically at joint-focused products. |
| Type III | Found alongside type I in skin, blood vessels and internal organs. | Often present together with type I in bovine peptide products. | Those choosing a bovine peptide blend covering types I and III. |
Type and source are not the same
A common mix-up is treating the collagen type (I, II or III) and the source (marine or bovine) as the same thing. The type describes the protein's structure and where it occurs in the body; the source describes where the collagen was obtained. Marine collagen, from fish, is usually predominantly type I, while bovine peptide blends often cover types I and III. Neither suits vegans.
How we compared
Our methodology is disclosed and factual. We describe each collagen type by where it is found in the body and which kinds of supplement tend to contain it, without claiming any type treats a condition, because collagen has no authorised EFSA health claim. We do not rank by commission, and any buying link is marked pending until it is live.
Named UK collagen brands
For the wider picture see our guide to collagen for women, the best collagen UK roundup, or whether you really need collagen after 40. It is most discussed through perimenopause and menopause.
Frequently asked questions
What is the difference between collagen type I, II and III?
Type I is the most abundant collagen in the body and is found in skin, bone and tendons. Type II is the main collagen in cartilage. Type III sits alongside type I in skin, blood vessels and organs. Skin powders tend to be type I, often with type III; joint products tend to be type II.
Which collagen type is best for skin?
Skin is predominantly type I collagen, so skin-focused powders are usually type I, sometimes with type III. That said, collagen itself carries no authorised EFSA health claim, so be cautious of firm promises about skin. Vitamin C, which contributes to normal collagen formation, is sometimes paired with it on the label.
Does the collagen type matter when buying?
It can help you match a product to your interest, for example a type II product for joint-focused use. More useful in practice is the source (marine or bovine), the amount per serving and whether vitamin C is included, since those are what you can actually verify on a UK label.
Is marine collagen a different type?
Source and type are separate things. Marine (from fish) and bovine (from cattle) describe where the collagen comes from; type I, II or III describes its structure. Marine collagen is usually predominantly type I. Neither marine nor bovine collagen suits vegans.
This is information, not medical advice, and is not a substitute for a registered clinician. Always read product labels and speak to your GP or pharmacist before starting a supplement.
Editor, Her Vitals
Oliver leads Her Vitals's editorial coverage of women's life-stage health and supplements. He curates and reviews existing branded products across trying to conceive, pregnancy, postnatal, perimenopause, menopause and the senior years, weighing what the evidence supports against guidance from bodies such as EFSA, the NHS and NICE, and is clear that the content is information rather than medical advice.
Last reviewed: 8 June 2026