All about Collagen

Major Collagen Types: Sources, Uses, and Evidence

Obviously, with 28 different kinds of collagen identified so far, I could write pages and pages on this network of protein structures.

I’ll keep it high-level and tell you where the best sources of these collagens are and what they can do for you.

Below is a breakdown of the best-known collagen types, their functions, sources, and the findings of relevant studies on their use.

1 - Type I Collagen: 

This is the most abundant type of collagen in the human body and is found in skin, tendons, ligaments, bones, corneas, and many connective tissues.

What it's used for / Functions:

• Provides tensile strength to tissues
  

• In skin gives structure and firmness
  

• In bone, forms much of the organic matrix to anchor mineral crystals
  

• Also used in biomaterials, tissue engineering, and wound repair
  
  

Supplement / clinical use & studies

• Most “collagen peptide” supplements are derived from Type I (often bovine, porcine, or marine)
  

• A meta-analysis of 26 randomized controlled trials shows that oral hydrolyzed collagen improves skin hydration and elasticity compared to a placebo.

• In a randomized, triple-blind, placebo-controlled trial, fish-derived collagen peptides were shown to improve skin wrinkles and elasticity over 12 weeks.

• And a large review of collagen treatments reports benefits in skin regeneration, wound healing, bone defects, osteoarthritis, sarcopenia, and etc.
  

Caveats / Limitations

• Absorption and distribution may vary depending on the collagen source and hydrolysis (achemical reaction where water is used to break apart a larger molecule)
  

• Many supportive studies are industry-funded; long-term safety data are limited
  

2 - Type II Collagen:

This collagen is the predominant collagen in cartilage, especially articular (joint) cartilage.

What it's used for / Functions

• Provides resistance to compressive forces in cartilage
  

• Helps maintain cartilage integrity and function
  

• In clinical settings, a form called undernatured type II collagen (UC-II) is used to modulate immune response and support joint health
  

Supplement / clinical use & studies

• In osteoarthritis and rheumatoid arthritis, some trials have shown that undenatured type II collagen (e.g., from chicken sternum) helps reduce joint pain and improve function compared to a control.

• One trial demonstrated that taking native type II collagen in combination with paracetamol (acetaminophen) improved symptoms of knee osteoarthritis compared to paracetamol alone. 

Caveats / Limitations

• Efficacy appears strain- and dose-dependent. Meaning you have to get the right kind in the right amount.
  

• Not all type II supplements are the “undenatured” form; denatured / hydrolyzed (broken down) type II may not have the same effects
  

3 - Type III Collagen: 

This kind of collagen is often found alongside type I in skin, blood vessels, internal organs, and musculature.

It’s known to provide structural support to hollow organs and vasculature as well as help maintain skin elasticity in combination with Type I, and this is why it’s sometimes included in multi-collagen supplements

Supplement / clinical use & studies

• Many collagen supplements label “Types I & III” together, especially bovine collagen blends
  

• The meta-analysis mentioned earlier (26 RCTs) showed that skin benefits generally include collagen sources containing combinations of Type I and Type III.
  

• A study on skin radiance collagen found increased collagen (types I & III) with good absorption and safety.
  

Caveats / Limitations

• Hard to isolate the effects of Type III alone
  

• Effects are often studied in combination with Type I

4 - Type IV Collagen:

This network-forming collagen is found in basement membranes (e.g., kidney basement membrane, glomeruli, alveoli, in epithelium). It’s not like other types, which help to form external networks or supportive ligament and joint structures.

What it's used for / Functions

• Provides scaffolding and filtration barrier in tissues
  

• Important in kidney function, epithelial tissue integrity
  

Supplement / clinical use & studies

• Rarely used in supplements
  

• Mostly studied in pathology (kidney disease, tumor biology) as a basement membrane component
  

5 - Type V Collagen:

Another form of collagen that you will frequently find alongside Types I and III. It’s typically distributed to the corneas, hair, placenta, and some connective tissues.

Its primary function is to assist with fibril assembly (nucleator role) in the formation of Type I/III collagen. So it depends on those two collagens to do its job in creating ocular tissues, placenta, and hair structure.

Supplement / clinical use & studies

• Included in “multi-collagen” supplements (I, II, III, V, X)
  

• Not much direct clinical evidence for Type V alone
  

Caveats / Limitations

• Effects are subtle; mostly structural/regulatory within fibril architecture

6 - Type VI Collagen:

Type VI is a microfibrillar collagen that you can find in many tissues, especially around muscle, in the extracellular matrix of mesenchyme (ECM).

Its main job is to connect cells to their extracellular matrix as it supports the structural integrity and mechanical stability of tissues.

Supplement / clinical use & studies

• Less common in supplements
  

• Studied in muscle disorders, fibrosis, matrix biology
  

• Mutations in collagen VI genes are implicated in certain muscular dystrophies
  

7 - Type VII Collagen:

Anchoring fibrils connecting the basement membrane to underlying connective tissue (e.g., dermal-epidermal junction. Essentially, it helps pull tissue together and keep it in place by anchoring skin layers, preventing excessive sliding and blistering.

Supplement / clinical use & studies

• Rare in supplements
  

• Studied in skin blistering disorders like epidermolysis bullosa
  

8 - Type X Collagen:

Type X is found in growth plate cartilage during endochondral bone formation (in developing bones and is a marker of chondrocyte hypertrophy and bone growth, as well as being involved in cartilage-to-bone transition.

Supplement / clinical use & studies

• Occasionally included in multi-collagen blends
  

• Clinically studied as a biomarker in osteoarthritis (elevated Type X correlates with disease progression) Arthritis Foundation

The Big Takeaways?

While there are over 28 types of collagen, most supplements and therapeutic interest center on Types I, II, III, V, and sometimes X.

Types I and III are abundant in skin, bone, tendons, and are the backbone of many collagen supplements for skin health, whereas type II is specialized for cartilage and joints; the “undenatured type II” form is used in joint support protocols.

The less common types (IV, V, VI, VII, X) often play structural roles in tissues (basement membranes, fibril regulation, anchoring) rather than being direct supplement targets.

The good news is that the research base for collagen supplementation is growing — meta-analyses support benefits in skin hydration and elasticity.

That being said, many studies don’t distinguish among collagen types, and effects depend heavily on the form (hydrolyzed peptides, undenatured forms).

Also, long-term human safety and comparative studies are still limited, so there’s not a ton to go off of for conclusive results.

If you want a small “supplement guide,” I made the following:

With so many collagen options available, it helps to know what you’re actually getting. Each collagen type supports different parts of the body, and some forms are better suited to specific health goals. 

Here’s a quick guide to help you choose wisely:

Collagen Supplement Guide:

1. For skin, hair, and nails:

Look for Type I and Type III collagen — often sourced from bovine or marine collagen peptides. These types help promote skin elasticity, hydration, and firmness. Many people notice smoother skin, stronger hair, and nails after consistent use.

2. For joint comfort and mobility:

Choose supplements containing Type II collagen, preferably in the undenatured form (UC-II®). This type is derived from chicken sternum and supports cartilage repair and flexibility by helping the body maintain healthy joint tissue.

3. For bone strength:

Type I collagen forms the foundation of bone tissue, so supplements that contain Type I or multi-collagen blends (I, II, III, V, X) can be supportive for bone density and recovery.

4. For overall support:

If you’re looking for an all-in-one approach, multi-collagen supplements combine several types (usually I, II, III, V, and X). These target skin, joints, bones, and connective tissue together — great for general wellness or as an anti-aging support.

5. For digestive and connective tissue repair:

Marine collagen (mainly Type I) and bovine collagen blends (Types I & III) are popular for maintaining gut lining integrity and promoting tissue recovery, especially after injury or stress.

Tips for Getting the Most Out of Collagen

• Look for “hydrolyzed” collagen peptides. These are broken down for better absorption.
  

• Consistency matters. Collagen builds gradually — most studies show results after 8–12 weeks of daily use.
  

• Pair it with vitamin C. Your body needs vitamin C to form new collagen fibers.
  

• Check for clean sourcing. Choose collagen that’s third-party tested, grass-fed (for bovine), or sustainably sourced (for marine).