There are 28 known types of collagen in the human body, each serving specific structural roles in different tissues. For supplement purposes, understanding the main types — and what each one supports — helps you choose the right product for your health goals. Here is a comprehensive breakdown of the most important collagen types, the tissues they support, and the research on supplementation.
Type I Collagen: The Foundation of Skin, Bone, and Tendon
Type I is the most abundant collagen in the human body, accounting for approximately 90% of total body collagen. It forms the thick, tightly packed fibers that give skin, bone, tendons, ligaments, teeth, and corneas their structural strength.
Where Type I Collagen Is Found
- Skin: Approximately 80% of the dermal collagen is Type I. It provides tensile strength and supports the elastic network that maintains skin firmness and prevents sagging.
- Bone: Bone is ~1/3 collagen by weight, and the vast majority is Type I. The Type I collagen matrix is the scaffold onto which calcium and other minerals are deposited to create bone mineral density.
- Tendons and ligaments: These connective tissues are nearly entirely Type I collagen, organized in parallel fibers to withstand high tensile forces.
- Teeth: The dentin and cementum of teeth contain Type I collagen as structural support.
What Happens When Type I Declines
Type I collagen production peaks in the early 20s and declines approximately 1% per year thereafter. By age 40, most people have lost 15–20% of their peak dermal collagen density — visible as increased wrinkle depth, reduced skin elasticity, and thinner skin. Bone collagen also declines, contributing to decreased bone mineral density with age.
Supplementation Research for Type I
- Proksch et al. (2014, Skin Pharmacology and Physiology): 69 women, 2.5–10g collagen peptides daily for 8 weeks showed significant improvement in skin elasticity and eye wrinkle reduction
- Clark et al. (2008, Current Medical Research and Opinion): 147 athletes, 10g daily for 24 weeks showed significant reduction in joint pain (most joint connective tissue is Type I)
- König et al. (2018, Nutrients): 5g collagen daily for 12 months in postmenopausal women increased bone mineral density versus decline in placebo
Both bovine collagen (Types I and III) and marine/fish collagen (primarily Type I) are rich in Type I collagen and highly effective for skin, tendon, ligament, and bone support.
Type II Collagen: The Cartilage Collagen
Type II collagen is the primary structural protein in articular cartilage — the smooth, slippery tissue that covers the surfaces of bones at joints, allowing them to move without friction. Unlike Type I, Type II collagen fibers are more loosely organized in a mesh-like network that allows cartilage to withstand compressive forces rather than tensile forces.
Where Type II Collagen Is Found
- Articular cartilage: The cushioning at all major joint surfaces (knee, hip, shoulder, spine) is primarily Type II collagen
- Intervertebral discs: The nucleus pulposus of spinal discs contains Type II collagen
- The nose and ear cartilage
- Vitreous humor: The gel-like fluid inside the eye contains Type II collagen
Supplementation and Joints
Type II collagen supplements come in two forms:
- Hydrolyzed Type II (broken into peptides) — similar mechanism to hydrolyzed Type I, providing amino acids for cartilage synthesis
- Undenatured Type II (UC-II) — native, intact Type II collagen taken at low doses (10–40mg). Proposed mechanism: oral tolerance, where the immune system "learns" from small amounts of intact collagen to reduce inflammatory attacks on joint cartilage. Used in much lower doses than hydrolyzed collagen.
Research: multiple clinical trials in both athletes and osteoarthritis patients show Type II collagen supplementation reduces WOMAC pain scores and improves joint function. A 2009 study found UC-II superior to glucosamine + chondroitin for knee osteoarthritis outcomes.
Note: bovine cartilage-derived collagen supplements specifically targeting Type II are a separate category from the Type I/III hydrolyzed bovine collagen peptides — though hydrolyzed bovine collagen peptides also show significant clinical joint benefits.
Type III Collagen: Skin Firmness and Gut Health
Type III collagen is the second most abundant collagen in the body and is often found alongside Type I, contributing to the mechanical properties of skin, blood vessels, intestinal walls, and organs. It forms reticular fibers — thinner and more flexible than Type I fibers.
Where Type III Collagen Is Found
- Skin dermis: Works alongside Type I to provide elasticity and structural support. Fetal skin is very high in Type III (giving fetal skin its distinctive softness and elasticity). Type III ratio decreases as we age.
- Blood vessel walls: Type III is essential for the integrity of arteries and veins
- Intestinal walls: The gut lining contains significant Type III collagen
- Uterus and hollow organs
Type III in Supplements
Bovine collagen peptides contain both Type I and Type III collagen (bovine hides are a rich source of both). Marine (fish) collagen is primarily Type I with minimal Type III. If Type III-specific support (skin elasticity, gut wall, blood vessel integrity) is a goal, bovine collagen has an advantage over marine collagen in amino acid profile diversity.
Type V Collagen: Hair and Cell Surface
Type V collagen is a minor but important collagen type found in:
- Hair and skin (where it helps regulate Type I fiber diameter)
- Placental tissue
- Cell membranes and interstitial matrix
Type V collagen is not specifically targeted by most collagen supplements, but both bovine and marine collagen contain small amounts as part of their natural collagen composition from source tissues.
Type X Collagen: Bone Formation and Growth
Type X collagen is found specifically in growth plate cartilage (the hypertrophic zone) and plays a role in endochondral ossification — the process by which cartilage is converted to bone during growth. It is less relevant for adult supplementation than Types I, II, and III, but is present in cartilage-derived collagen supplements.
Which Type of Collagen Do You Need?
| Health Goal | Most Relevant Type | Best Supplement Source |
|---|---|---|
| Skin elasticity, hydration, wrinkles | Type I (+ III) | Bovine or marine collagen peptides |
| Joint pain, osteoarthritis | Type II | Hydrolyzed or undenatured bovine/chicken collagen |
| Skin firmness (elasticity-focused) | Type III | Bovine collagen peptides (contains I + III) |
| Tendons and ligaments | Type I | Bovine or marine collagen peptides |
| Bone density | Type I | Bovine or marine collagen peptides |
| Gut lining integrity | Types I and III | Bovine collagen peptides |
| Hair and nails | Types I, III, V | Bovine collagen peptides |
Shop AletaCollagen's OU Kosher certified options:
- Bovine Collagen Peptides — Types I and III from kosher-certified bovine sources, independently 3rd party tested
- Marine Collagen from tilapia — Type I focused, OU Kosher Pareve, independently tested
Not sure which to choose? Our bovine vs marine collagen comparison covers the full breakdown. For dosage, timing, and how to get the best results: The Complete Guide to Kosher Collagen. For testing and certification documentation: AletaCollagen 3rd Party Testing and OU Kosher.