Collagen

Which type of collagen is best?

Updated 9 Nov 2026

Short answer

The two main forms were tested for different aims and at very different doses. Collagen peptides were tested at 2.5 to 15 g a day for skin, joints, bone and muscle.[1][2][3][4][5] Undenatured type II collagen was tested at 40 mg a day for knee osteoarthritis.[6]

Collagen peptides

Collagen peptides, also called hydrolyzed collagen, are short chains cut from collagen with enzymes. They weigh 3 to 6 kDa. Makers take them from cattle and pigs, or from the skin, scales and bones of fish.[7]

Trials of collagen peptides gave 2.5 to 15 g a day.[1] They were tested for skin, osteoarthritis, bone density and muscle.[2][3][4][5]

Undenatured type II collagen

Undenatured type II collagen, often sold as UC-II, comes from chicken breastbone cartilage.[6] Type II collagen is found mostly in cartilage.[8] Trials gave only 40 mg a day.[6][9] A 2025 review says it acts through oral tolerance, a response of the immune system to a protein taken by mouth.[9]

In a trial of 191 people with knee osteoarthritis, 40 mg a day for 180 days lowered the WOMAC score, a measure of pain, stiffness and function, more than placebo. It also lowered it more than 1,500 mg of glucosamine with 1,200 mg of chondroitin.[6] In a 90-day trial, the WOMAC score fell by 33% with UC-II and by 14% with glucosamine and chondroitin.[10] A 2018 review found that its short-term effect on pain was of unclear clinical importance, and its medium-term effect was clinically important.[11]

Gelatin and bone broth

Gelatin hydrolysates from pig skin, chicken feet and cartilage also put collagen peptides into the blood.[12] In a small trial, 15 g of gelatin with vitamin C doubled a blood marker of new collagen after exercise.[13]

Bone broth made to a standard recipe had less hydroxyproline, glycine and proline than a 20 g dose of a collagen supplement. Broths made to other recipes differed a lot.[14]

Fish, cattle or pigs

In a 2023 review of skin trials, the source of the collagen changed the effect on skin hydration, but not the effect on elasticity.[15] People with a fish allergy may react to fish collagen.[16]

Reading the label

The two forms are dosed in different units. UC-II is taken in milligrams and collagen peptides in grams: 40 mg against 2,500 to 15,000 mg a day in trials.[6][1]

Sources (16)

  1. Significant Amounts of Functional Collagen Peptides Can Be Incorporated in the Diet While Maintaining Indispensable Amino Acid Balance. Paul C, Leser S, Oesser S Nutrients, 2019. PMID 31096622
  2. Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis. de Miranda RB, Weimer P, Rossi RC Int J Dermatol, 2021. PMID 33742704
  3. Efficacy and safety of collagen derivatives for osteoarthritis: A trial sequential meta-analysis. Liang CW, Cheng HY, Lee YH, Liao CD, Huang SW Osteoarthritis Cartilage, 2024. PMID 38218227
  4. Specific Collagen Peptides Improve Bone Mineral Density and Bone Markers in Postmenopausal Women-A Randomized Controlled Study. König D, Oesser S, Scharla S, Zdzieblik D, Gollhofer A Nutrients, 2018. PMID 29337906
  5. Impact of Collagen Peptide Supplementation in Combination with Long-Term Physical Training on Strength, Musculotendinous Remodeling, Functional Recovery, and Body Composition in Healthy Adults: A Systematic Review with Meta-analysis. Bischof K, Moitzi AM, Stafilidis S, König D Sports Med, 2024. PMID 39060741
  6. Efficacy and tolerability of an undenatured type II collagen supplement in modulating knee osteoarthritis symptoms: a multicenter randomized, double-blind, placebo-controlled study. Lugo JP, Saiyed ZM, Lane NE Nutr J, 2016. PMID 26822714
  7. Hydrolyzed Collagen-Sources and Applications. León-López A, Morales-Peñaloza A, Martínez-Juárez VM, Vargas-Torres A, Zeugolis DI, Aguirre-Álvarez G Molecules, 2019. PMID 31703345
  8. COL2A1 gene: MedlinePlus Genetics. MedlinePlus, US National Library of Medicine, 2024. medlineplus.gov
  9. Undenatured type II collagen for knee osteoarthritis. Gupta A, Maffulli N Ann Med, 2025. PMID 40253594
  10. Safety and efficacy of undenatured type II collagen in the treatment of osteoarthritis of the knee: a clinical trial. Crowley DC, Lau FC, Sharma P, Evans M, Guthrie N, Bagchi M, et al. Int J Med Sci, 2009. PMID 19847319
  11. Dietary supplements for treating osteoarthritis: a systematic review and meta-analysis. Liu X, Machado GC, Eyles JP, Ravi V, Hunter DJ Br J Sports Med, 2018. PMID 29018060
  12. Identification of food-derived collagen peptides in human blood after oral ingestion of gelatin hydrolysates. Iwai K, Hasegawa T, Taguchi Y, Morimatsu F, Sato K, Nakamura Y, et al. J Agric Food Chem, 2005. PMID 16076145
  13. Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis. Shaw G, Lee-Barthel A, Ross ML, Wang B, Baar K Am J Clin Nutr, 2017. PMID 27852613
  14. Bone Broth Unlikely to Provide Reliable Concentrations of Collagen Precursors Compared With Supplemental Sources of Collagen Used in Collagen Research. Alcock RD, Shaw GC, Burke LM Int J Sport Nutr Exerc Metab, 2019. PMID 29893587
  15. Effects of Oral Collagen for Skin Anti-Aging: A Systematic Review and Meta-Analysis. Pu SY, Huang YL, Pu CM, Kang YN, Hoang KD, Chen KH, et al. Nutrients, 2023. PMID 37432180
  16. Collagen-An Important Fish Allergen for Improved Diagnosis. Kalic T, Kamath SD, Ruethers T, Taki AC, Nugraha R, Le TTK, et al. J Allergy Clin Immunol Pract, 2020. PMID 32389794

More about collagen

What is collagen?Can you get collagen from food?What is collagen used for?How long does collagen take to work?Is collagen safe?Does collagen help joint pain?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.