Quick answer
Collagen peptides are collagen cut by enzymes into pieces of about 3 to 6 kDa, against about 300 kDa for whole collagen, so they dissolve easily in water. Gelatin is collagen that has not been cut into small peptides. Undenatured type II collagen is a different product, taken at 40 mg a day.1,2,3
Key facts
- Collagen peptides are also sold as hydrolyzed collagen or collagen hydrolysate.1
- Whole collagen is thick in water; collagen peptides are thin and mix easily.1
- About 28 types of collagen are known.1
- Collagen counts as an incomplete protein because it lacks tryptophan.4
What collagen peptides are
Collagen peptides, also sold as hydrolyzed collagen or collagen hydrolysate, are collagen cut by enzymes into small pieces of about 3 to 6 kDa, against about 300 kDa for whole collagen. That makes them dissolve easily in water.1
Heat unwinds collagen's triple helix into separate chains, and enzymes then cut the chains into peptides. The review describes these peptides as highly digestible and easily absorbed.1
Collagen peptides vs gelatin
Gelatin is a non-hydrolyzed form of collagen, not cut down into small peptides. In a direct comparison, glycine from gelatin peaked in the blood later than glycine from collagen peptides.2
Both supply the same amino acids. Gelatin was the form used in the vitamin C and exercise study, at 15 g an hour before activity.2,5
Undenatured type II collagen
Undenatured type II collagen, made from chicken sternum cartilage, is a different product taken in milligrams, not grams: its trial used 40 mg a day.3
In 55 healthy adults who felt knee discomfort only during exertion, 40 mg a day of undenatured type II collagen for 120 days gave greater knee extension than placebo. It is a single trial of a patented ingredient.3
Because the amount is so small, it is not a protein source at all, and its results do not carry over to collagen peptides taken by the scoop.3
Bovine, marine, porcine and chicken
Collagen for supplements comes mainly from cattle (bovine) and pigs (porcine), and also from fish skin, scales and bones (marine) and from chicken. In a 2023 analysis of skin trials, 14 of 26 used fish collagen and only one used bovine.1,6
No source has been shown to work best. The 2023 analysis found no significant difference between sources for skin elasticity, and most trials used branded peptides whose results may not carry over to other products.6
Types I, II and III
About 28 types of collagen are known. Type I is the most common in skin, bone and tendon, type II is found in cartilage, and type III in skin, muscle and blood vessels.1
Is collagen a complete protein?
Collagen lacks tryptophan, one of the nine essential amino acids, so it counts as an incomplete protein and scores zero on the standard protein-quality scale. In head-to-head tests, whey raised muscle protein building more than collagen.4,7
What's in ours
What’s in ours
- Collagen Peptides: Hydrolyzed Collagen Peptides, 20 g per serving, from the label
- Collagen Peptides: Hydrolyzed Collagen Peptides, 20 g per serving, from the label
Ours is hydrolyzed collagen peptides from bovine hide, the form described at the top of this page.
Allergies
Fish collagen is a concern for people allergic to fish, a major food allergen that labels must name. Some people with alpha-gal syndrome, a red meat allergy usually caused by tick bites, also react to gelatin and other products made from mammals.8,9
Questions people ask
Are collagen peptides better than plain collagen?
For a supplement, peptides are the practical form: they dissolve easily, and the review describes them as highly digestible and easily absorbed. They are also the form most skin and joint trials tested.1,6
Is collagen peptides powder the same as collagen protein?
It is collagen protein in a cut-down form. As protein it counts only in part, because collagen lacks tryptophan.4
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Sources
- León-López A, Morales-Peñaloza A, Martínez-Juárez VM, Vargas-Torres A, Zeugolis DI, Aguirre-Álvarez G. Hydrolyzed Collagen: Sources and Applications. Molecules. 2019;24(22):4031. Opened 2026-10-07.
- Alcock RD, Shaw GC, Tee N, Burke LM. Plasma Amino Acid Concentrations After the Ingestion of Dairy and Collagen Proteins, in Healthy Active Males. Front Nutr. 2019;6:163. Opened 2026-10-07.
- Lugo JP, Saiyed ZM, Lau FC, et al. Undenatured type II collagen (UC-II®) for joint support: a randomized, double-blind, placebo-controlled study in healthy volunteers. J Int Soc Sports Nutr. 2013;10(1):48. Opened 2026-10-07.
- Paul C, Leser S, Oesser S. Significant Amounts of Functional Collagen Peptides Can Be Incorporated in the Diet While Maintaining Indispensable Amino Acid Balance. Nutrients. 2019;11(5):1079. Opened 2026-10-07.
- Shaw G, Lee-Barthel A, Ross ML, Wang B, Baar K. Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis. Am J Clin Nutr. 2017;105(1):136-143. Opened 2026-10-07.
- Pu SY, Huang YL, Pu CM, Kang YN, Hoang KD, Chen KH, Chen C. Effects of Oral Collagen for Skin Anti-Aging: A Systematic Review and Meta-Analysis. Nutrients. 2023;15(9):2080. Opened 2026-10-01.
- Khatri M, Naughton RJ, Clifford T, Harper LD, Corr L. The effects of collagen peptide supplementation on body composition, collagen synthesis, and recovery from joint injury and exercise: a systematic review. Amino Acids. 2021;53(10):1493-1506. Opened 2026-10-01.
- U.S. Food and Drug Administration. Food Allergies. Content current as of March 11, 2026. Opened 2026-10-07.
- Platts-Mills TAE, Li RC, Keshavarz B, Smith AR, Wilson JM. Diagnosis and Management of Patients with the α-Gal Syndrome. J Allergy Clin Immunol Pract. 2020;8(1):15-23.e1. Opened 2026-10-07.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.