Collagen Types Explained: Type I, II, and III (and Which You Need)

Your body contains 28 different types of collagen, but only three matter for supplementation. Type I makes up 90% of your body's collagen and provides structure to skin, bones, and tendons. Type II is the primary collagen in joint cartilage. Type III supports blood vessels, intestinal walls, and works alongside Type I in skin. Which one you need depends on your goal — joints, skin, gut, or bones — and understanding the differences prevents you from wasting money on marketing dressed up as science.

That last point is important, because the collagen supplement market has gotten very good at selling confusion. "Multi-collagen" blends, "5 types in one scoop," marine versus bovine debates — most of it has very little to do with what the research actually shows. Let's fix that.

What Does Each Collagen Type Do?

Type I: The Foundation (~90% of Your Collagen)

Type I is the most abundant protein in the human body. It forms dense, tightly packed fibers that give structural strength to nearly everything holding you together.

Found in: Skin (dermis), bones, tendons, ligaments, teeth, corneas, blood vessel walls.

What it does: In skin, Type I collagen creates the mesh-like network in the dermis responsible for firmness. In bone, it's the organic framework — roughly 90% of bone's organic matrix — onto which minerals are deposited. When people talk about "collagen for skin" or "collagen for bones," they're talking about Type I.

Supplemental evidence: The most-studied collagen type for supplementation. RCTs have demonstrated benefits for skin elasticity (Proksch et al., 2014), wrinkle reduction, and bone mineral density in postmenopausal women (Konig et al., 2018). Typical effective dose: 2.5-10g per day of hydrolyzed collagen.

Type II: The Joint Protector

Type II forms thinner, more loosely organized fibers than Type I. It has one specific and critical job.

Found in: Hyaline cartilage (the smooth tissue covering joint surfaces), elastic cartilage, vitreous humor of the eye, and the cushioning discs between vertebrae.

What it does: Type II collagen creates a mesh that traps proteoglycans — molecules that hold water and give cartilage its cushioning properties. When cartilage breaks down in osteoarthritis, it's the Type II collagen network deteriorating.

Supplemental evidence: This is where things get interesting. Type II collagen can be supplemented in two fundamentally different forms — undenatured (UC-II) and hydrolyzed — and they work by completely different mechanisms. A landmark trial found that 40mg of UC-II per day outperformed glucosamine + chondroitin for knee osteoarthritis after 180 days (Lugo et al., 2016). We'll explain the mechanism below.

Type III: The Flexible Partner

Type III collagen forms thinner, more flexible reticular fibers. It's almost always found alongside Type I but plays distinct roles in organs that need to stretch and expand.

Found in: Blood vessel walls (especially arteries), intestinal walls, uterus, skin (alongside Type I), muscles, and lymphoid organs.

What it does: Type III provides structural support to organs that expand and contract — your gut, your blood vessels, your uterus during pregnancy. The clinical significance of Type III is dramatically illustrated by vascular Ehlers-Danlos syndrome, a genetic condition where Type III collagen is defective. Patients face serious risks of arterial rupture and intestinal perforation because these tissues depend on Type III for their integrity.

For gut health specifically, Type III is the collagen that structures your intestinal walls. This is part of why bone broth collagen — which naturally contains Type III — has been traditionally associated with digestive health.

Types V and X: Supporting Cast

Type V helps regulate the diameter and assembly of Type I and Type III fibers. It's found in cell surfaces, hair, and the cornea. Think of it as the project manager — it doesn't do the structural work, but it helps organize it.

Type X is involved in bone growth and development, specifically in the growth plates where cartilage converts to bone. It's primarily relevant during growth and in cartilage repair.

Neither Type V nor Type X has been studied as a standalone supplement in human clinical trials. Their inclusion in "multi-collagen" products is based on the fact that they exist in the body, not on evidence that supplementing them does anything measurable.

How Does Supplemental Collagen Actually Work?

This is the question nobody selling collagen wants to answer honestly, because the real answer is more nuanced than "eat collagen, get collagen."

What does NOT happen: You don't swallow collagen and deposit it directly into your skin or joints. Collagen is a massive protein — far too large to cross the intestinal barrier intact. Your digestive system breaks it down first.

What DOES happen (two mechanisms):

1. Building blocks. Digestive enzymes break collagen into free amino acids (glycine, proline, hydroxyproline) and small peptides. Your body uses these amino acids as raw material to synthesize its own collagen wherever it's needed.

2. Bioactive signaling — the more interesting part. Certain collagen-derived peptides, particularly Pro-Hyp (prolyl-hydroxyproline) and Hyp-Gly, resist complete digestion and enter your bloodstream intact (Iwai et al., 2005). These peptides travel to skin and cartilage tissue where they act as signaling molecules — they tell your fibroblasts and chondrocytes to produce more collagen, hyaluronic acid, and elastin. One study found Pro-Hyp increased hyaluronic acid synthesis nearly 4-fold in human skin cells (Ohara et al., 2010).

So collagen supplements work by both providing raw materials AND sending biological signals that stimulate your body's own collagen production. The signaling effect may actually be the more important mechanism.

Undenatured vs. Hydrolyzed: Two Completely Different Things

This is the distinction most collagen articles miss, and it matters enormously.

Hydrolyzed Collagen (Collagen Peptides)

This is what most collagen powders are. The collagen has been enzymatically broken into small peptides (2,000-5,000 daltons) for easy absorption. It works through the building-block and signaling mechanisms described above.

• Source: Usually bovine hide (Types I/III), marine fish skin (Type I), or chicken
• Dose: 2.5-15g per day
• Mechanism: Provides amino acids + bioactive peptide signals

Undenatured Type II Collagen (UC-II)

This is native, intact Type II collagen from chicken cartilage. It has NOT been broken down — and that's the whole point. UC-II works through an entirely different mechanism called oral tolerance.

Small amounts of intact Type II collagen are recognized by immune cells in your gut. This triggers the production of regulatory T cells that produce anti-inflammatory signals (IL-10, TGF-beta). These regulatory cells then suppress the immune system's attack on your own joint cartilage. It was first demonstrated in a Science study on rheumatoid arthritis patients (Trentham et al., 1993).

• Source: Chicken sternal cartilage
• Dose: 40mg per day (milligrams, not grams)
• Mechanism: Immune modulation via oral tolerance

The dose difference tells the story. Hydrolyzed collagen requires grams because you need enough material to raise blood levels of signaling peptides. UC-II requires milligrams because you only need enough intact protein for immune recognition. More is not better — a multicenter RA trial found that the lowest dose (20 mcg) actually outperformed higher doses, consistent with how oral tolerance works (Barnett et al., 1998).

Why this matters for shopping: If a collagen product claims to contain "Type II collagen" but is hydrolyzed, it won't deliver the oral tolerance mechanism. The hydrolysis process destroys the intact structure that the immune system needs to recognize. Most multi-collagen blends use hydrolyzed chicken collagen — which provides amino acids like any other protein, but doesn't act as an immune modulator.

Which Supplement Sources Provide Which Types?

PaleoPro Bone Broth Collagen is derived from grass-fed bovine bones and connective tissue, naturally providing Types I, II, and III in the ratios found in real bone broth. For those wanting broader collagen type coverage, PaleoPro Protein+ Multi-Collagen combines multiple collagen sources.

The Multi-Collagen Question: Is Combining Types Better?

The honest answer: there are zero published clinical trials comparing a multi-type collagen supplement to a single-type collagen supplement head-to-head.

Every positive clinical trial on collagen — every skin study, every joint study, every bone density study — used a single-source, single-type supplement at a studied dose. No RCT has demonstrated that combining Types I, II, III, V, and X in one product outperforms any single-type supplement for any outcome.

There's also a practical problem. UC-II (the immune-modulating form of Type II) requires its intact native structure — and the hydrolysis process that makes Types I/III absorbable as peptides destroys that structure. Combining them in one product means the Type II is just amino acids, not an immune modulator.

This doesn't mean multi-collagen products are worthless. They provide a broad amino acid profile and may offer convenience. But "5 types in one scoop" is a marketing claim, not a research-backed advantage. If you have a specific goal, a targeted approach with studied doses will serve you better than a little bit of everything at potentially sub-clinical amounts.

How Much Collagen Decline Happens With Age?

Collagen production drops approximately 1% per year starting in your mid-20s (Varani et al., 2006). Fibroblasts from older adults produce significantly less Type I procollagen than those from young adults. As collagen degrades, it fragments — and the fragmented matrix no longer provides the mechanical signals that tell fibroblasts to make more collagen. It's a declining spiral.

For women, menopause accelerates this dramatically. Research shows women lose approximately 30% of their skin collagen in the first five years after menopause, after which the rate slows to about 2% per year (Brincat et al., 1987). The same study found that skin collagen loss parallels bone density loss — suggesting a common mechanism driven by declining estrogen.

This is why collagen supplementation is particularly relevant for women over 40, a topic we cover in depth in our protein for women over 40 guide.

Which Type Do You Need? A Quick Guide

For most people, a bovine bone broth collagen like PaleoPro Bone Broth Collagen covers the broadest range of goals because it naturally contains all three major types from a single, whole-food source. If your primary concern is severe joint pain, a dedicated UC-II supplement at 40mg is the most targeted approach.

Frequently Asked Questions

What is the difference between Type I and Type III collagen?

Type I collagen forms dense, strong fibers that provide structure to skin, bones, tendons, and ligaments — it's 90% of your body's collagen. Type III forms thinner, more flexible fibers found in blood vessels, intestinal walls, and organs that expand and contract. They're almost always found together in skin and connective tissue, and both decline with age. Bovine collagen supplements typically provide both Types I and III.

Is Type II collagen better for joints than Type I?

It depends on the form. Undenatured Type II collagen (UC-II) at 40mg per day has strong evidence for joint pain relief through immune modulation — it outperformed glucosamine + chondroitin in clinical trials. However, hydrolyzed Type I/III collagen at 10-15g per day also supports joints by providing building blocks for cartilage repair. They work through different mechanisms, and both have evidence supporting them.

Do I need all 5 types of collagen?

No clinical trial has shown that supplementing all 5 types together is superior to supplementing a single type at an effective dose. Types V and X have never been studied as standalone supplements in humans. Focus on the type that matches your specific health goal rather than trying to cover all types. Bone broth collagen naturally provides the three types that matter most (I, II, and III).

What type of collagen is best for skin?

Type I, which makes up 75-80% of your skin's dry weight. Hydrolyzed bovine collagen (primarily Type I with some Type III) at 2.5-10g per day has the most clinical evidence for improving skin hydration, elasticity, and wrinkle reduction. Results typically require 8-12 weeks of consistent supplementation.

Does marine collagen absorb better than bovine collagen?

Marine collagen peptides are often marketed as "more bioavailable," but this is primarily because they're typically processed to a smaller molecular weight (2,000-3,000 daltons) than bovine peptides (3,000-8,000 daltons). When both are hydrolyzed to the same molecular weight, absorption rates are comparable. Marine collagen provides primarily Type I only, while bovine sources can provide Types I and III (from hide) or Types I, II, and III (from bone broth).

How much collagen should I take per day?

It depends on your goal and the type. For skin health: 2.5-10g of hydrolyzed collagen per day. For joints (UC-II): 40mg per day. For bones: 5g per day with calcium and vitamin D. For general wellness and broad support: 10-15g per day. Studies have used up to 20g per day with no serious adverse effects. Consistency matters more than hitting an exact number — daily use over months produces better results than occasional high doses.

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Your body makes 28 types of collagen, but it makes less every year. Supplementing the right type at the right dose gives your body the building blocks and biological signals it needs to keep producing. PaleoPro Bone Broth Collagen delivers Types I, II, and III from grass-fed cattle — the broadest natural coverage from a single source. For complete protein alongside your collagen, pair it with PaleoPro Paleo Protein. Browse our full protein collection.

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Sources:

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2. Konig, D., et al. (2018). "Specific Collagen Peptides Improve Bone Mineral Density and Bone Markers in Postmenopausal Women." Nutrients, 10(1), 97. PubMed
3. Lugo, J.P., et al. (2016). "Efficacy and tolerability of an undenatured type II collagen supplement in modulating knee osteoarthritis symptoms." Nutrition Journal, 15, 14. PubMed
4. Trentham, D.E., et al. (1993). "Effects of oral administration of type II collagen on rheumatoid arthritis." Science, 261(5129), 1727-1730. PubMed
5. Barnett, M.L., et al. (1998). "Treatment of rheumatoid arthritis with oral type II collagen." Arthritis & Rheumatism, 41(2), 290-297. PubMed
6. Iwai, K., et al. (2005). "Identification of food-derived collagen peptides in human blood after oral ingestion of gelatin hydrolysates." Journal of Agricultural and Food Chemistry, 53(16), 6531-6536. PubMed
7. Ohara, H., et al. (2010). "Collagen-derived dipeptide, proline-hydroxyproline, stimulates cell proliferation and hyaluronic acid synthesis in cultured human dermal fibroblasts." Journal of Dermatology, 37(4), 330-338. PubMed
8. Oesser, S. & Seifert, J. (2003). "Stimulation of type II collagen biosynthesis and secretion in bovine chondrocytes cultured with degraded collagen." Cell and Tissue Research, 311(3), 393-399. PubMed
9. Varani, J., et al. (2006). "Decreased collagen production in chronologically aged skin." American Journal of Pathology, 168(6), 1861-1868. PubMed
10. Brincat, M., et al. (1987). "A study of the decrease of skin collagen content, skin thickness, and bone mass in the postmenopausal woman." Obstetrics & Gynecology, 70(6), 840-845. PubMed
11. de Miranda, R.B., et al. (2021). "Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis." International Journal of Dermatology. PubMed