Collagen Types I II III: What Are the Differences and Which Collagen to Choose
Collagen types I, II, and III: what studies say about peptide absorption, how UC-II differs from collagen hydrolysate, and how to read a supplement label.
On supplement labels, the type of collagen is sometimes indicated as if it designates the target location in the body: type I for skin, type II for joints, type III for blood vessels. In vertebrates, 28 types of collagen have been described (Ricard-Blum, Cold Spring Harbor Perspectives in Biology, 2011) and three of them actually build the tissues mentioned in advertisements. The problem lies elsewhere. Protein consumed orally does not return to the tissue from which it originated, as the digestive tract breaks it down beforehand. Below you will find how collagen types differ in the body, what studies on their supplementation have really shown, who funded these studies, and how to make use of this when reading a label.
KEY INFORMATION
• In vertebrates, 28 types of collagen have been described, and the fibers of the dermis together form types I and III (Ricard-Blum, 2011).
• Hydrolysate breaks down into amino acids and short peptides, mainly prolyl-hydroxyproline (Iwai et al., 2005).
• Collagen peptides and undenatured type II are two different mechanisms, not two doses of the same.
• Most collagen research is funded by the raw material producer.
How many types of collagen are there and how do they differ from each other?
In vertebrates, 28 types of collagen have been described, but in supplements, you will encounter three. Type I builds the dermis, bone, and tendon. Type II is the main collagen in articular cartilage. Type III co-forms skin fibers together with type I, and outside the skin, it builds the walls of blood vessels and hollow organs (Ricard-Blum, 2011).
| Type | Where it is found in the body | Surowiec w suplemencie |
|---|---|---|
| I | Dermis, bone, tendon, cornea | Fish skins, pork skin, cattle hides |
| II | Articular cartilage, vitreous body of the eye | Sternal cartilage of chicken |
| III | Skin along with type I, vessels, intestine | Always paired with type I in bovine hydrolysate |
The division has anatomical significance and promises nothing beyond that. Type II differs from type I in the arrangement of fibers. In cartilage, it forms a thin mesh that transmits pressures. Type I in skin and tendon is arranged in thick strands that work on tension. This difference pertains to the tissue you already have, not the powder you pour into a cup. Collagen constitutes about 30 percent of the mass of all mammalian proteins, so we are talking about a structural material of the body, not a niche supplement.
Does type II collagen go straight to the joints, and type I to the skin?
No. The body does not direct the ingested type of collagen to the corresponding tissue. The hydrolysate breaks down in the digestive tract into free amino acids and short peptides. In the blood of volunteers after drinking the hydrolysate, primarily the dipeptide prolyl-hydroxyproline was detected, at a concentration of 20-60 nmol per milliliter of plasma after 1-2 hours (Iwai i in., Journal of Agricultural and Food Chemistry, 2005).
The most interesting aspect of this study is what is not visible in advertisements. Volunteers received hydrolysates from three different sources: from pork skin, from chicken feet, and from cartilage. The same small peptides with hydroxyproline entered the bloodstream. Thus, the type name describes the starting material, not the target address in the body.
What does this mean practically? The label "type II collagen for joints" on the hydrolysate package indicates only that the raw material was cartilage. It does not say that the amino acids from this cartilage will specifically return to your knee. This is confirmed by a comparison of sources: a meta-analysis of 26 studies involving 1721 people found no significant difference between types of collagen in terms of skin elasticity (p = 0.21; Pu i in., Nutrients, 2023). We have noticed that this particular fragment of product descriptions often diverges from the literature, regardless of the brand.
What did studies on collagen peptides for skin and bones show?
The effects are measurable, but more modest than advertising suggests. In the study by Proksch and colleagues, 69 women aged 35-55 took 2.5 g or 5 g of hydrolysate daily for 8 weeks. The average improvement in skin elasticity compared to placebo was 7 percent (Skin Pharmacology and Physiology, 2014).
The effect lasted for 4 weeks after discontinuation, but only in a subgroup of women over 50 years old, consisting of nine individuals per group. Skin hydration and water loss through the epidermis did not reach statistical significance in the entire studied population. The preparation was provided by GELITA AG, the producer of the raw material sold under the name VERISOL, and two authors work at the CRI Collagen Research Institute.
In terms of bones, the picture is similar. König and colleagues administered 5 g of collagen peptides or placebo to 131 postmenopausal women for 12 months. The mineral density of the spine and femoral neck increased in the study group, the bone formation marker P1NP also increased, while the bone resorption marker CTX-1 rose in the control group (König i in., Nutrients, 2018). The study was partially funded by GELITA AG, and the producer provided the preparation. The aforementioned meta-analysis from 2023 confirmed improvements in skin hydration and elasticity, but reported a risk of error in thirteen of the 26 included studies, mainly due to missing outcome data.
How does undenatured type II collagen differ from peptides?
By mechanism, not dosage. UC-II is chicken sternal cartilage processed to preserve the intact triple helix. It does not serve as a building block but interacts with the immune system of the gut. The daily dose in studies was 40 mg of the preparation, which corresponds to 1.2 mg of undenatured type II collagen.
In comparison, hydrolysate is dosed in grams, which is a thousand times larger. These are not two powers of the same product, but two different substances with different modes of action. Mixing them in one product description is a common mistake and leads the reader to conclude that 10 g of hydrolysate from cartilage will replace 40 mg of UC-II.
In the study by Lugo and colleagues, 191 individuals with knee osteoarthritis took UC-II, glucosamine with chondroitin at a dose of 1500 mg plus 1200 mg, or placebo for 180 days. The WOMAC score improved in the UC-II group compared to placebo (p = 0.002) and compared to glucosamine with chondroitin (p = 0.04) (Lugo i in., Nutrition Journal, 2016). The study was sponsored by InterHealth Nutraceuticals, the producer of UC-II, two authors were its employees, and the third provided consulting services for it. The authors themselves state that the mechanism of action of the preparation requires further research, so the explanation through food tolerance remains a working hypothesis.
How to choose a preparation and what to look for on the label?
Start with the goal. Then check the raw material and dosage used in studies. For skin, the hydrolysate was studied at doses of 2.5-5 g daily for 8 weeks, for bones at a dose of 5 g for 12 months, and for the knee joint, 40 mg of UC-II was administered for 180 days. This is a description of the studies, not a recommendation for you.
You do not need to look for type III separately, as it is not sold separately. The fibers of the dermis are a hybrid of type I and type III, so hydrolysate from cattle hides contains both. The structural importance of type III is shown by genetics: mutations in the COL3A1 gene cause the vascular form of Ehlers-Danlos syndrome, with a risk of rupture of arteries and hollow organs (Omar i in., Matrix Biology Plus, 2021). This is an argument for not omitting type III in the description of physiology, rather than for a separate supplement.
A noteworthy label provides three things: the raw material, the mass of peptides per serving, and the form of type II, if the product contains it. When the producer writes only "marine collagen" without the weight, you cannot compare it with any study. Our observations from browsing offers are that the lack of weight on the front label almost always goes hand in hand with a serving below the doses studied. We break down the difference between hydrolysate and unprocessed collagen in the text. Peptydy kolagenowe vs kolagen.
Frequently Asked Questions
What is the difference between type I and type II collagen?
They differ in their location in the body and the structure of the fibers. Type I forms thick strands that work on tension in the dermis, bones, and tendons. Type II arranges itself in a thin mesh that transmits pressures and is the main collagen in articular cartilage (Ricard-Blum, 2011). The difference pertains to the tissue, not the powder in the cup.
Does type II collagen really reach the joints?
There is no mechanism that directs the ingested type of collagen to the corresponding tissue. After drinking the hydrolysate, free amino acids and short peptides with hydroxyproline appear in the blood, regardless of whether the raw material was pork skin, chicken feet, or cartilage (Iwai et al., 2005).
What dose of UC-II was used in joint studies?
Participants took 40 mg of UC-II preparation daily for 180 days, which corresponds to 1.2 mg of undenatured type II collagen. The WOMAC score improved compared to placebo (p = 0.002) and compared to glucosamine with chondroitin (p = 0.04). The study was sponsored by the raw material producer (Lugo et al., Nutrition Journal, 2016).
Does marine collagen work better than bovine?
A meta-analysis of 26 studies involving 1721 people found no significant difference between sources of collagen in terms of skin elasticity (p = 0.21; Pu et al., Nutrients, 2023). While skin hydration varied among subgroups, the authors reported a risk of error in several of the included studies.
Do you need to buy type III collagen separately?
It is not possible and there is no need. The fibers of the dermis are a hybrid of type I and type III, and the hydrolysate from bovine hides contains both (Ricard-Blum, 2011). Separate type III preparations are not available for sale, so the declaration type I plus III describes the raw material, not an additional ingredient.
You will find collagen preparations and other products supporting the skin and joints in the section supplements.
This article is for informational and educational purposes and does not constitute medical advice. Before starting supplementation, consult your doctor, especially if you are taking medications regularly, are pregnant or breastfeeding, or have a chronic illness.
Author: Michał Waluk · Opublikowano: 2026-06-22 · Aktualizacja: 2026-08-08
