FAQ · Collagen
What is the difference between Type I and Type II collagen?
Type I and Type II are different molecules taken at different doses for different goals. Type I is the dominant collagen in skin, hair, nails, tendons, and bone; taken hydrolysed at 5 to 15 grams per day. Type II is the dominant collagen in cartilage; taken undenatured (UC-II) at 40 milligrams per day via the oral-tolerance immune pathway. They are not substitutes. A combined routine for skin plus joints typically uses 10 g hydrolysed Type I plus 40 mg UC-II Type II.
Type I collagen
- · Dominant in skin, hair, nails, tendons, bone.
- · Hydrolysed (broken into small peptides) for gut absorption.
- · Dose: 5 to 15 grams per day. Shaw 2017 used 15 g pre-exercise for tendon.
- · Sources: marine (almost pure Type I), bovine (Type I + III), porcine.
- · Mechanism: nutritional absorption; amino acid pool plus signal peptides upregulate fibroblast collagen synthesis.
Type II collagen
- · Dominant in cartilage.
- · Taken undenatured (UC-II) at 40 mg/day. Not hydrolysed.
- · Sources: chicken sternum cartilage (the standard UC-II source).
- · Mechanism: oral tolerance immune pathway, not nutritional absorption. Small daily exposure trains the immune system to dampen inflammation in joint cartilage.
- · Evidence: Crowley 2009, Lugo 2016 in osteoarthritis and active-adult knee discomfort.
Why dose units differ so much
Type I works as a substrate: you need to put grams of amino acids into the body to support new collagen synthesis. Type II UC-II works as a signal: small daily antigen exposure trains the immune system. Higher doses of UC-II do not improve outcomes and may overwhelm the tolerance pathway.
Type III collagen
Type III is the third major collagen type, present in skin elasticity, gut lining, and blood vessels. Almost always supplied alongside Type I in bovine collagen products. Not commonly sold as a standalone supplement because bovine Type I + III is the standard form.
Type I vs Type II collagen at a glance
| Feature | Type I | Type II (UC-II) |
|---|---|---|
| Dominant tissue | Skin, hair, nails, tendons, bone | Cartilage |
| Form | Hydrolysed peptides | Undenatured (UC-II), not hydrolysed |
| Typical intake in studies | 5 to 15 g per day | 40 mg per day |
| How it works | Nutritional substrate; amino acids and signal peptides support collagen synthesis | Oral-tolerance immune pathway, not nutritional absorption |
| Common sources | Marine, bovine (with Type III), porcine | Chicken sternum cartilage |
| Cited human studies | Shaw 2017 (tendon) | Crowley 2009, Lugo 2016 (joint) |
Collagen is a food supplement, not a medicine. The intake figures reflect the cited studies, not personal advice. Check product labels and your own circumstances.
Frequently asked questions
Are Type I and Type II collagen interchangeable?
No. They are different molecules used for different goals. Type I is the dominant collagen in skin, hair, nails, tendons, and bone, taken as hydrolysed peptides. Type II is the dominant collagen in cartilage, taken undenatured (UC-II) through the oral-tolerance immune pathway. They are not substitutes for one another.
Why is Type II taken in milligrams when Type I is taken in grams?
Type I works as a substrate, so grams of amino acids are needed to support collagen synthesis. Type II UC-II works as a signal: a small daily exposure trains the immune tolerance pathway, which is why studies use around 40 mg. Higher UC-II doses do not improve outcomes.
Can I take Type I and Type II together?
They are often combined for skin plus joint goals, for example hydrolysed Type I alongside UC-II Type II, because they act through different pathways. Collagen is a food supplement, so check product labels and consider your own circumstances rather than treating this as personal advice.
Related: Type I vs II deep-dive · Oral tolerance and UC-II · Types I, II, III hub.