Types of Collagen: Type I, II, and III at a Glance

Collagen is the most abundant protein in the human body — and it doesn't come in just one form. Experts now distinguish more than two dozen types, yet in everyday life and on supplement labels, almost always only three show up: Type I, Type II, and Type III. What do these numbers stand for, where does each type sit in the body, and what should you look for when choosing a product? That's exactly what we clarify here.

What Collagen Types Actually Are

Collagen is a structural protein. You can picture it as a scaffold that holds tissue together and gives it tensile strength. It's built from long amino acid chains that twist into a characteristic triple helix — three strands winding around each other like a rope. The building blocks are mainly the amino acids glycine, proline, and hydroxyproline.

The crucial point: not every triple helix is built the same way. Depending on which chains combine and how they're arranged, a different collagen type emerges, with different mechanical properties. These types are numbered with Roman numerals. The numbering roughly follows the order in which they were discovered, not their importance. If you want to dig deeper into the basic mechanics, it's worth checking out our overview Collagen: effects, forms, and peptides.

Type I, II, and III in Detail

These three types account for the bulk of the collagen in the body and are also the ones you'll encounter in powders and capsules. They differ mainly in where they're located and what job the tissue does at that location.

Type I — the All-Rounder Collagen

Type I is by far the most common collagen in the human body. It forms the main component of skin, bone, tendons, ligaments, and the cornea of the eye. Its densely packed fibers are characteristic and provide enormous tensile strength — that's why you find Type I wherever tissue needs to withstand mechanical stress. In dietary supplements, Type I collagen usually comes from bovine hide or from fish (marine collagen). There, it's typically processed as hydrolyzed collagen, or collagen peptides, meaning it's broken down into smaller fragments so it dissolves well in liquid.

Type II — the Cartilage Collagen

Type II is the dominant collagen type in cartilage tissue — the elastic material that covers joint surfaces and sits between the spinal discs. Unlike tensile Type I, Type II is built more for handling compression and elasticity and is embedded in a water-rich ground substance. In products, Type II is often derived from chicken cartilage. One special feature: some preparations use what's called native or undenatured Type II collagen (often labeled UC-II), which is deliberately not hydrolyzed so its three-dimensional structure stays intact. That's a different approach from the classic peptides.

Type III — Type I's Partner

Type III rarely occurs on its own. It's mostly found wherever Type I is also present — in skin, blood vessels, and internal organs. It forms finer, net-like fibers and often appears together with Type I, with the two jointly shaping the structure and elasticity of connective tissue. In bovine collagen products, Type I and Type III are therefore frequently combined, which is then labeled as "Type I & III."

Where the Collagen in a Product Comes From

The source largely determines which type is present. Broadly, the common raw materials break down as follows:

Bovine (cattle): provides predominantly Type I and III. The classic choice for products aimed at skin and general connective tissue.

Fish (marine): predominantly Type I. Marine collagen is considered especially well soluble; its peptides are often small. It's a common alternative for people who don't want to consume beef-derived products.

Chicken: the typical source for Type II, because chicken cartilage is rich in it.

Pork (porcine): likewise rich in Type I and III, but not suitable for everyone due to religious or personal reasons.

A side note: purely plant-based collagen doesn't exist — collagen is an animal protein. Products marketed as "vegan collagen" typically contain nutrients and amino acids that the body uses to build its own collagen, not the finished protein itself.

Which Type Might Interest You?

The distribution in the body suggests an obvious logic that products often follow: Type I and III are used primarily in preparations aimed at skin and connective tissue, Type II in those aimed at cartilage. Whether, and to what extent, ingested collagen actually reaches that specific target tissue is not conclusively established scientifically, though — more on that below.

Important to know: collagen is a protein and, during digestion, is broken down into amino acids and small peptides just like other proteins. The body decides for itself what to use these building blocks for. So the collagen type stated on a product is less an "address" that something gets delivered to, and more an indicator of the raw material's origin and amino acid profile. For how collagen compares to other proteins and active compounds, see our comparisons Collagen and whey protein, Collagen and hyaluronic acid, and, in short form, Collagen and hyaluron.

Another point that's often overlooked: serving size also differs greatly between types. Peptide products made from Type I and III are dosed in the gram range, since they're meant as a protein source. Native Type II works with very small amounts in the milligram range, because what matters here isn't bulk but the preserved molecular structure. If you're comparing both approaches, don't hold the numbers on the label directly against one another — they follow entirely different logic.

Intake and Quality in Practice

For Type I and III in peptide form, powders to stir in are the most common. Typical serving sizes in practice are often in the range of several grams per day; the exact amount is stated on the respective packaging and shouldn't be exceeded without reason. Hydrolyzed peptides dissolve in cold or warm water, in coffee, or in smoothies. Native Type II preparations, by contrast, are usually taken as low-dose capsules, since what matters here is the preserved structure rather than the quantity.

Vitamin C is a sensible companion. The authorized EU health claim states: vitamin C contributes to normal collagen formation for the normal function of the skin. That's why many manufacturers combine collagen with vitamin C, or you can take it alongside a vitamin-C-rich meal.

What you can look for in terms of quality: a clearly stated raw material source (bovine, fish, chicken), information on the type, a traceable degree of processing (hydrolyzed versus native), and ideally information on origin and purity testing. A high-quality product doesn't hide its source.

Honestly Assessed: What's Established and What Isn't

The biology is established: there are different collagen types, they're located in different places in the body, and they perform different mechanical jobs there. It's also clear that collagen is a high-quality protein with a distinctive amino acid profile, and that vitamin C is involved in the body's own collagen formation.

The evidence is less clear-cut on what concrete benefit oral intake of individual collagen types has for skin, joints, or connective tissue. Studies here show mixed results without a final consensus, and many effects aren't authorized as health claims. Collagen is a food, or a dietary supplement, not a medicine. If you have specific complaints — for example with your joints or skin — a supplement is no substitute for medical evaluation. When in doubt, discuss such issues with a doctor.

Frequently Asked Questions (FAQ)

What's the Difference Between Collagen Type I and Type III?

Both frequently occur together, especially in skin and blood vessels. Type I forms thick, highly tensile fibers and also dominates in bone and tendons. Type III forms finer, net-like fibers and complements Type I in connective tissue. In bovine collagen, they're often combined as "Type I & III."

Which Collagen Type Is the Best?

There's no universally "best" type — it depends on your goal. Type I and III are usually associated with skin and connective tissue, Type II with cartilage. Since collagen gets broken down into amino acids in the body anyway, the origin and quality of the product are often more important than the type number alone.

What Is Type II Collagen Derived From?

Type II collagen usually comes from chicken cartilage, because this tissue is especially rich in this type. It's often sold as native or undenatured collagen (UC-II), which is deliberately not hydrolyzed in order to preserve its three-dimensional structure.

Is There Vegan Collagen With Type I, II, or III?

No. Collagen is fundamentally an animal protein and doesn't occur in this form in plants. Products labeled "vegan collagen" usually contain amino acids and nutrients like vitamin C that the body uses to build its own collagen, but not finished collagen itself.

Should I Combine Collagen With Vitamin C?

That's common and well justified: vitamin C contributes to normal collagen formation for the normal function of the skin. Many collagen products already contain vitamin C; otherwise, you can take your collagen alongside a vitamin-C-rich meal. This doesn't replace medical evaluation.