Types of collagen explained: I, II, III and beyond

The main collagen types and which supplements deliver them

Collagen type matters because different tissues use different types and different supplements deliver different type mixes. Here is the picture by tissue and by source.

1. Type I: the workhorse

Type I collagen makes up around 90 percent of all body collagen. It forms the dense fibrous bundles of tendon and ligament. It is the primary collagen in bone (combined with calcium phosphate crystals). It is the dominant collagen in skin (dermis), the cornea, blood vessel walls and internal organ capsules. Bovine, porcine, marine and most general collagen supplements are predominantly Type I. For skin, bone and tendon support this is the type you want.

2. Type II: cartilage and joint specific

Type II collagen is the primary structural protein in articular cartilage and the vitreous of the eye. It is structurally different from Type I with shorter fibrils and a different cross-linking pattern that allows cartilage to resist compression. Type II supplements are usually sourced from chicken sternum cartilage. Two distinct supplement formats exist: hydrolysed Type II (similar dose to Type I) and undenatured Type II (UC-II at a much smaller 40 mg/day dose). Both have evidence for joint outcomes.

3. Type III: skin and vascular elasticity

Type III collagen sits alongside Type I in skin, blood vessels and internal organs. It is more elastic and forms finer fibrils than Type I. Skin Type III content declines faster with age than Type I which is part of why skin loses elasticity with ageing. Most bovine and porcine collagen supplements deliver Type I plus Type III in a natural ratio. This is sometimes marketed as the more complete skin collagen profile.

4. Types IV through XXVIII: specialised roles

Type IV forms the basement membrane between tissue layers. Type V supports cell surfaces and is found in cornea and placenta. Type VI is involved in microfibril formation around cells. Type X is found in calcifying cartilage during growth and bone healing. The remaining types serve specialised roles. Supplement marketing rarely focuses on these because the dietary supplementation evidence is concentrated on Types I, II and III.

5. Matching the type to the goal

For skin support: Type I and III in combination (bovine or porcine source) or Type I alone (marine source). For joint and cartilage support: Type II specifically, either hydrolysed or undenatured (UC-II) format. For bone support: Type I (bovine, porcine or marine). For tendon support in athletes: Type I (any source). For general health and the broadest type coverage: bovine collagen typically provides Type I plus III with small amounts of other types.

How to choose the right collagen type in five steps

Type choice is one of the bigger decisions in collagen supplementation. Match it to your goal using this framework.

Step 1. Identify your specific goal

Skin appearance and hydration. Joint discomfort. Bone density. Tendon support during training. Hair and nail strength. Each goal aligns with specific collagen types. Vague general goals produce vague results. Pick one or two specific outcomes to target.

Step 2. Match goal to type

Skin: Type I plus III (bovine or porcine) or Type I (marine). Joint cartilage: Type II (specifically). Bone: Type I. Tendon and ligament for athletes: Type I. Hair and nails: Type I (the evidence is general not type-specific). Mixed goals: Type I plus III bovine is the broadest baseline.

Step 3. Match type to source

Marine collagen: Type I dominant. Good for skin. Often lower molecular weight peptides for better absorption. Bovine collagen: Type I plus III. Good for skin and broader uses. Porcine collagen: Type I plus III. Similar to bovine. Chicken cartilage: Type II. Specific to joint use. Eggshell membrane: contains some Type I and unique compounds. Mixed marketing claims.

Step 4. Match source to your dietary requirements

Halal: marine collagen or bovine certified halal. Kosher: marine or specially certified bovine. Vegetarian or vegan: no animal collagen suits. Use plant-based collagen builders instead. Fish allergy: avoid marine. Beef allergy: avoid bovine. Pork allergy: avoid porcine.

Step 5. Check for specific bioactive forms in joint use

For joint pain specifically, undenatured Type II collagen (UC-II at 40 mg daily) works through a different mechanism than hydrolysed Type II (5 to 10 g daily). UC-II induces oral tolerance reducing autoimmune cartilage attack. Hydrolysed Type II provides building blocks plus signalling peptides. Both have evidence. Trial the format with more evidence for your specific condition.

For anyone targeting skin support specifically, our Collagen Gummies deliver hydrolysed marine Type I collagen with vitamin C. Same type that dominates the dermis. Bioactive peptide profile from cold-water fish source.

When collagen is a problem

All collagen types at standard doses are generally well tolerated. Type-specific cautions apply. Stop and see your GP if any of the following apply.

• Allergic reaction to the source. Each type comes from different source animals with their own allergy risks.
• Severe kidney disease. Applies across all collagen types because all are protein.
• Autoimmune joint disease worsening with hydrolysed Type II. Some people respond differently to hydrolysed versus undenatured Type II. Consult your rheumatologist.
• Persistent gastrointestinal symptoms not resolving with dose reduction.
• Pregnancy. Standard collagen sources are generally fine. Discuss specific products with your midwife.

Type II collagen supplements are particularly relevant for people with osteoarthritis or other cartilage conditions. People with rheumatoid arthritis or other autoimmune joint conditions should discuss collagen supplementation with their specialist before starting because of complex immune effects.

More on collagen sources and applications

Type connects to source. Marine collagen vs bovine collagen covers source comparison in depth. Is bovine collagen better than marine covers the choice directly. And Collagen and joint health covers Type II evidence specifically.