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VITAMINS & SUPPLEMENTS · GUIDE

UC-II Undenatured Type II vs Hydrolyzed Collagen for Joints: How the Evidence Differs

UC-II undenatured type II collagen and hydrolyzed collagen are separate products with separate trials; this page compares what reviews and trials report and where evidence is missing.

Content last updated . This page has not been medically reviewed.

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Quick answer
UC-II (undenatured type II collagen) and hydrolyzed collagen are different interventions. Trials of one cannot be used to judge the other. We found no trial that compared them directly with each other for joints (Proper evidence not found). What exists is separate meta-analyses for each, one trial of both given together, and several comparisons of UC-II with glucosamine.

How the evidence is labeled

Undenatured means the collagen has not been broken down by heat and chemicals as hydrolyzed collagen has. Meta-analysis pools trials. WOMAC and VAS are symptom questionnaires and pain scales. Heterogeneity means trials differ a lot from each other.

What each one is

  • UC-II is described as derived from chicken sternum cartilage. [1] A 2025 review says it is proposed to act through an immune-mediated mechanism known as oral tolerance. [2] Details on the product type are at UC-II and undenatured type II collagen.
  • Hydrolyzed collagen is protein broken into smaller peptides; see what the terms mean.

What the evidence found

5 findings · 5 limited or unclearThe colour follows the evidence label on each card.

  1. UC-II vs placebo, knee OA

    Review with limited meta-analysis; small trials

    A review of 8 randomized trials with follow-up of 3 to 6 months reported better WOMAC and VAS scores with UC-II; the authors say further large studies are needed. [3]

  2. UC-II daily amount in trials

    Review; study amount, not advice

    A 2025 review describes UC-II 40 mg daily as safe and efficacious short and mid-term, and calls for larger trials. [2]

  3. Hydrolyzed and other collagen vs placebo, knee OA

    Meta-analysis; high heterogeneity

    A meta-analysis of 11 trials (870 people) reported improved function and pain, with high variation between trials. [4]

  4. UC-II and hydrolyzed collagen given together

    Single small trial

    In a 68-person randomized trial over 12 weeks, the combination was not superior to placebo; both groups improved. [5]

  5. Many supplements vs placebo

    Systematic review; very low quality evidence

    A 2018 review found collagen hydrolysate and UC-II among supplements with notable short-term pain effects; only green-lipped mussel extract and UC-II had clinically important effects at medium term; overall quality was very low. [6]

No universal winner

Each has promising but limited trial evidence in its own product type. For the overall joint picture see collagen for joint pain and osteoarthritis.

Frequently asked questions

Is UC-II the same as collagen peptides?

No. UC-II is undenatured; hydrolyzed collagen peptides are broken down. They are studied as different products. [2]

Which has more evidence for knee osteoarthritis?

Proper evidence not found for a direct comparison. Both have separate reviews with limits. [3] [4]

How much is used in trials?

The UC-II trials above used 40 mg a day. [1] Those are study amounts for one product type, not advice; other collagen types use different amounts, listed on collagen amounts in studies.

Does combining them help?

In one small 12-week trial the combination was not better than placebo. [5]

Should I ask my clinician first?

Yes, especially with a chicken or egg allergy, pregnancy or regular medicines. Proper evidence not found for many of these groups in the sources we read.

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

Limits and uncertainty
  • Different comparators. The UC-II trials above include comparisons with glucosamine and chondroitin. [1] [7] The hydrolyzed collagen meta-analysis pools placebo trials. [4] Comparing across them is not like-for-like.
  • Small, short trials. Follow-up in the UC-II review was 3 to 6 months. [3]
  • Funding. The 2025 combined-collagen trial noted earlier collagen studies were mostly industry-sponsored. [5] We did not establish funding for every trial.
  • Biomarker versus outcome. Symptom scores are what these trials measured; structure on imaging was not established in what we read.
Safety and who should ask first
In the UC-II trial with 191 people, safety outcomes did not differ among the groups. [1] Neither source reports long-term safety data. UC-II comes from chicken; people with chicken or egg allergy should ask a clinician first (see collagen allergy). Medicines, pregnancy, breastfeeding, children, kidney or liver conditions: Proper evidence not found in the sources we read. Talk to a clinician or pharmacist and see medication interactions. Do not stop prescribed arthritis medicines on the basis of a supplement.
References
  1. Lugo JP, Saiyed ZM, Lane NE. Efficacy and tolerability of an undenatured type II collagen supplement in modulating knee osteoarthritis symptoms: a multicenter randomized, double-blind, placebo-controlled study. Nutr J 2016 (abstract read). Read 2026-10-23.
  2. Gupta A, Maffulli N. Undenatured type II collagen for knee osteoarthritis. Ann Med 2025 (abstract read). Read 2026-10-23.
  3. Kumar P, Bansal P, Rajnish RK, et al. Efficacy of undenatured collagen in knee osteoarthritis: review of the literature with limited meta-analysis. Am J Transl Res 2023 (abstract read). Read 2026-10-23.
  4. Simental-Mendía M, Ortega-Mata D, Acosta-Olivo CA, et al. Effect of collagen supplementation on knee osteoarthritis: an updated systematic review and meta-analysis of randomised controlled trials. Clin Exp Rheumatol 2025 (abstract read). Read 2026-10-23.
  5. Yuenyongviwat V, Anusitviwat C, Tuntarattanapong P, et al. Efficacy of combined undenatured type II collagen and hydrolysed collagen supplementation in knee osteoarthritis: a randomised controlled trial. Sci Rep 2025 (abstract read). Read 2026-10-23.
  6. Liu X, Machado GC, Eyles JP, Ravi V, Hunter DJ. Dietary supplements for treating osteoarthritis: a systematic review and meta-analysis. Br J Sports Med 2018 (abstract read). Read 2026-10-23.
  7. Crowley DC, Lau FC, Sharma P, et al. Safety and efficacy of undenatured type II collagen in the treatment of osteoarthritis of the knee: a clinical trial. Int J Med Sci 2009 (abstract read). Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.