Collagen Types I, II and III: What the Numbers on the Package Mean

On the banks of collagen there are Roman numerals: I, II, III, sometimes “I + III” together. It looks like a classification by quality, as if a higher number means something more perfect or specialized. In fact, the number means something completely different - it indicates which tissue the protein comes from and in which tissue it performs its role in the body. It is worth understanding this before choosing a product, because this is where the most expensive mistake of the buyer occurs: hydrolysate type II and undenatured collagen type II are different supplements with different doses and mechanisms, although the number on them is the same.

Why are there twenty-eight types, but only three on the packages?

Collagen is not a single substance, but a family of proteins. According to a review by Ricard-Blum (2011), there are 28 types in mammals, each containing at least one triple-helical domain. The common feature is the characteristic coiled structure of three chains; differences concern the length of the helix, the structure of the terminal regions, and the supramolecular structures into which the protein assembles in tissue.

Of these twenty-eight, three actually occur in supplements. The reason is purely production-related: on an industrial scale, collagen is extracted from food raw materials, which are skin, bones, scales, and cartilage. What is in these tissues ends up in the product. The remaining twenty-five types are either present in negligible quantities or are contained in tissues that are not processed into food raw materials.

The question of whether all this has a practical effect is a separate one, and it is discussed in the material on whether collagen works and what the studies show. This is only about what is there.

Type I: skin, bone, tendon

The most common type in the body, it accounts for the vast majority of all collagen in the body. It is fibrillar: the molecules assemble into elongated fibers that are able to withstand tensile loads. That is why type I predominates where the tissue works under tension - in the dermis, tendons, ligaments and the organic part of the bone.

The raw materials for it are the skin and bones of pigs and cattle, as well as the skin and scales of fish. Virtually all hydrolyzed collagen in powders and capsules is type I collagen, regardless of whether it is indicated on the label or not.

This type is also associated with most of the marketing arguments on the packaging - about molecular weight, depth of hydrolysis and peptide size. To what extent these numbers mean anything, we will analyze the material on the comparison of 2000 and 5000 daltons.

Type II: hyaline cartilage

Type II is arranged differently. It does not form thick parallel bundles, but a thin three-dimensional network, the cells of which contain proteoglycans - molecules capable of binding large amounts of water. It is this structure that gives cartilage the ability to elastically compress under load and restore its shape.

Therefore, type II is concentrated in hyaline cartilage: articular surfaces, intervertebral discs, cartilage of the nose and trachea. In the production of supplements, the source is almost always the same - chicken pectoral cartilage, a tissue with a high content of this type and available as a by-product of the food industry.

Type III: the one that is almost never sold separately

Type III is also fibrillar, but forms thinner and more flexible fibers. It predominates where the tissue must be elastic and able to change shape: blood vessel walls, intestines, uterus, lungs. In the skin it is always present and works in tandem with type I, and their ratio changes with age.

This brings up a detail that is useful when reading labels. The inscription “collagen type I + III” is neither an advantage of the product nor the result of a complex formulation – it is simply a consequence of the fact that the raw material was leather, where both types are naturally present. A manufacturer who extracts collagen from leather automatically obtains a mixture of I and III; one who works with bone obtains mainly I. There is no additional technological effort behind this inscription.

Type indicates fabric, not quality

This is the most important point of the entire article, and it is the one most often turned upside down in advertising. The type number is an element of biological classification, not a quality scale. Type II is not a “higher grade” of type I, and type III is not an “improved version” of either. They perform different mechanical tasks in different tissues, and it is impossible to compare them in terms of effectiveness, even theoretically: studies in which different types of collagen would be tested in direct comparison in the same population with the same endpoint have not been conducted.

Therefore, any statement like “type II is more effective” or “I + III works better than just I” is a marketing assumption, not a conclusion from the data. What really distinguishes products from each other lies in another plane: in the raw materials, the depth of processing and the set of short peptides that are formed during digestion. These characteristics are analyzed in the material on the peptide profile of collagen.

Type II Hydrolysate and Undenatured Type II are Different Supplements

Undenatured type II collagen is the opposite by design. It is obtained at low temperatures so that the triple helix remains intact, and is taken in tens of milligrams: in the work of Lugo et al. (2016) the daily amount was 40 mg. The difference with the hydrolysate reaches about two and a half orders of magnitude, and this is the most reliable sign that the mechanism is fundamentally different - it is assumed to be immune, associated with the recognition of the intact molecule by the lymphoid tissue of the intestine. Hence the main vulnerability of this form: it is worth destroying the helix, and the substance loses precisely what the assumed mechanism is based on.

The practical conclusion is simple. When you see “type II collagen” on the label, look not at the number, but at the dose. Grams mean hydrolysate, tens of milligrams mean the undenatured form. What the depth of processing means is explained in the material on hydrolyzed collagen and gelatin, and what clinical studies show in the joint context is explained in the article on collagen for joints.

How to read the label

Let's put it all together. The chain works in one direction: the raw material determines the type, the type together with processing determines the format and dosage.

Three things to look at when choosing, in order of importance: dosage, because it immediately distinguishes the undenatured form from the hydrolysate; the source of the raw material, because it determines both the type and allergenicity; and only then the type, which mostly follows from the first two.

A few words about precautions, and they directly follow from the topic of the article. Since the type is set by the raw material, it also entails an allergenic profile: type II - chicken, marine - fish, regular hydrolysate - pork or beef. That is, the choice of type automatically means the choice of allergen, and for people with food allergies or religious restrictions, it is this, not the number on the can, that is decisive. The remaining precautions do not depend on the type at all: kidney pathology, pregnancy, lactation and constant drug therapy - situations when the appropriateness of any protein powder is determined by a doctor.

Frequently asked questions

How many types of collagen are there?
According to survey data, there are 28 types in mammals. In fact, three types are found in supplements, because the rest are absent in tissues that are processed into food raw materials.

What type of collagen is best?
There is no such distinction. The type indicates the tissue in which the protein performs a role, not the quality of the product; no direct comparisons of efficacy between types have been made.

What does the inscription "collagen type I + III" mean?
That the raw material was leather, where both types are present naturally. This is a consequence of the origin of the raw material, and not the result of a separate formulation.

How is type II hydrolysate different from undenatured?
Processing and dosage. The hydrolysate is split and taken in grams, the undenatured one retains the entire helix and is taken in tens of milligrams.

How do I understand from the label which type II form it is?
By dose. Grams mean hydrolysate, tens of milligrams mean undenatured form, the effect of which depends on the preserved structure of the molecule.

Is marine collagen a separate type?
No, it is the same type I, obtained from fish skin or scales. The difference is the source of the raw material, not the type of protein.

Do I need to select a type for a specific purpose?
Data for such a selection are lacking: no studies have been conducted that compare types with each other for the same endpoint.

Sources

• Ohara H. and others. (2007). Comparison of quantity and structures of hydroxyproline-containing peptides in human blood after oral ingestion of gelatin hydrolysates from different sources. Journal of Agricultural and Food Chemistry. https://pubmed.ncbi.nlm.nih.gov/17253720/
• Ricard-Blum S. (2011). The collagen family. Cold Spring Harbor Perspectives in Biology. https://pmc.ncbi.nlm.nih.gov/articles/PMC3003457/
• Lugo JP, Saiyed ZM, Lane NE (2016). Efficacy and tolerability of an undenatured type II collagen supplement in modulating knee osteoarthritis symptoms: a multicenter randomized, double-blind, placebo-controlled study. Nutrition Journal. https://pmc.ncbi.nlm.nih.gov/articles/PMC4731911/
• Virgilio N. and others. (2024). Absorption of bioactive peptides following collagen hydrolysate intake: a randomized, double-blind crossover study in healthy individuals. Frontiers in Nutrition. https://pmc.ncbi.nlm.nih.gov/articles/PMC11325589/

Dietary supplement. Not a medicine. Consult a doctor before use.