Marine collagen: the types, the sources and the difference that matters

Marine collagen: the types, the sources and the difference that matters

Pick up six tubs of marine collagen in a Swedish health shop and read the backs. Five will say marine collagen or fish collagen and stop there. One might say type I. None will tell you which part of the fish it came from, and none will state the molecular weight of the peptides, even though the powder inside was engineered around exactly that number.

That is not a scandal. Nothing in EU food law requires a supplement to declare the collagen type, the source tissue or the peptide size. It does mean that the most useful distinction in this whole category, the one between collagen taken from fish skin and collagen taken from fish cartilage, is invisible at the point of sale.

This piece is about that distinction. Not whether collagen works, which is a separate and messier question, but what the words on the label actually describe.

The short version

• Marine collagen is almost always type I from fish skin and scales, because that is the cheapest and most abundant raw material stream. Type II comes from cartilage and is a different material, carrying glycosaminoglycans such as chondroitin sulphate because they were never separate to begin with.

• The nuance that matters most: nothing in EU law requires a label to state the collagen type, the source tissue or the peptide size. The only direct human comparison also found closely comparable blood concentrations for hydrolysates at 2000 and at 5000 Da, in six people after one dose, so a lower number on a specification sheet buys less than the marketing suggests.

• Beauty Complete contains Cartidyss, hydrolysed fish cartilage at more than 65 per cent collagen peptides and at least 25 per cent chondroitin sulphate, at 500 mg per daily dose. That is the dose used in the ingredient's published trial. No collagen health claim is authorised in the EU, so we make none, but vitamin C contributes to normal collagen formation for the normal function of skin.

Health Royals Beauty Complete, supplement with Cartidyss marine collagen, Hyabest hyaluronic acid, Ceramosides and vitamin C as PureWay-C

Which raw material, at which dose

Beauty Complete contains Cartidyss, a hydrolysed marine type II collagen complex from fish cartilage: more than 65 per cent collagen peptides, at least 95 per cent of those under 3000 Da, and at least 25 per cent chondroitin sulphate. The dose is 500 mg per daily dose, the same as in the ingredient's published trial, in which skin structure was measured by imaging. It also carries vitamin C as PureWay-C, and vitamin C contributes to normal collagen formation for the normal function of skin. The raw material is named so that it can be looked up and argued with.

See Beauty Complete

What is marine collagen, and what is it actually made from?

Marine collagen is collagen extracted from fish, almost always from skin, scales or bones, and almost always type I.

EU hygiene law is unusually blunt about the raw material. Regulation 853/2004 defines collagen as the protein based product derived from animal bones, hides, skins and tendons. Every collagen supplement sold, marine or bovine, is made from the parts of an animal the food industry does not sell as meat.

A 2024 review in Collagen and Leather puts the scale of that stream at roughly 7.3 million tonnes of fish by-product discarded worldwide each year, with scales, bones, cartilage and skin routinely thrown away during processing. Skin and scales dominate the collagen supply because they are the cheapest and most abundant part of it.

Fish cartilage is a far smaller stream, and it yields something structurally different.

What is the difference between collagen type 1, 2 and 3?

Type I is the structural rope of skin, bone and tendon, type II is the framework of cartilage, and type III sits alongside type I in skin and in blood vessel walls.

Twenty eight collagen types have been described, and type I accounts for more than 90 percent of the collagen in the human body. It is not an exotic ingredient. It is the default material of connective tissue.

In skin specifically, a 2022 review in Biomedicines puts type I at roughly 80 to 85 percent of the dermal matrix and type III at roughly 8 to 11 percent.

This is why so many products are sold as type 1 and 3 together. The pairing reflects real anatomy, but it is usually not two ingredients. Hide and skin contain both, so one extract carries both, and the label reports what came out of the tank. Type 1 and 3 describes the raw material rather than a formulation decision.

Type II is the exception, because it comes from a tissue nobody else is processing.

Why is collagen type 2 not the same thing as type I?

Because cartilage matrix is not made of collagen alone, so a cartilage extract is not made of collagen alone either.

Collagen makes up around two thirds of the dry mass of adult articular cartilage, and type II dominates that fraction, according to a review in Protein and Cell. Most of the rest is proteoglycan. Aggrecan carries chains of chondroitin sulphate and keratan sulphate, and as an NCBI Bookshelf chapter on aggrecan and hyaluronan explains, the high negative charge density of those glycosaminoglycans is what gives cartilage its water holding and its resistance to compression.

Hydrolyse fish skin and you get peptides. Hydrolyse fish cartilage and the glycosaminoglycans come with them, because they were never separate to begin with.

That shows up in a specification. Cartidyss, the fish cartilage hydrolysate in our own skin formula, is described in its published trial as more than 65 percent collagen peptides, at least 95 percent of those under 3000 Da, a minimum of 25 percent chondroitin sulphate and 9 percent minerals. A fish skin type I hydrolysate is close to pure peptide by comparison. Our ingredient page on Cartidyss goes through the material in more detail.

One warning about the words type II on a front label. Type II is sold in two incompatible ways: hydrolysed, in hundreds of milligrams to grams, as a source of peptides and glycosaminoglycans, or undenatured, at around 40 mg, where the proposed mechanism is immune tolerance in the gut rather than supply of raw material, as set out in a 2020 review in Animals. A pack that says only type II collagen could be either. The dose tells you which.

What do hydrolysed and peptide mean on a collagen label?

Both mean the collagen has been cut into fragments, and in practice they are the same word written two ways.

Intact collagen is around 300 kDa, built from alpha chains of about 100 kDa, according to a 2019 review in Molecules. Nothing that size is absorbed as a peptide. Heat alone denatures it into gelatin. Enzymes, alcalase, papain or pepsin, in acid or alkaline conditions, cut it further into hydrolysed collagen with a typical weight of 3 to 6 kDa, and some marine hydrolysates come in below 600 Da.

Collagen peptides, hydrolysed collagen and collagen hydrolysate all name the same class of material, and none of the three is a legally defined quality grade. A label that says peptides tells you the protein was hydrolysed, which is true of essentially every collagen supplement sold, and nothing more.

Does molecular weight matter for absorption?

It matters up to a point, and the point sits lower than the marketing suggests.

The absorption itself is well described. In a 2024 crossover study in Frontiers in Nutrition, healthy volunteers given 10 g of collagen hydrolysate showed prolyl hydroxyproline as the most abundant peptide in blood, along with Hyp-Gly, Gly-Pro-Hyp and Pro-Gly, and total hydroxyproline ran 36 to 47 percent above the free form, meaning real di- and tripeptides crossed the gut intact rather than being broken all the way down to amino acids.

The same study is the awkward part. It compared bovine hydrolysates at 2000 Da and at 5000 Da and found highly comparable peptide and amino acid concentrations in blood, with fish skin, porcine skin and bovine hide following similar overall patterns. Six people, a single dose, one author employed by a collagen manufacturer, so it settles nothing alone. It is also close to the only direct human comparison there is, and it does not support the idea that a smaller number on a specification sheet buys much extra absorption in that range.

The number is almost never printed because no rule requires it, and because molecular weight is a manufacturing specification rather than a nutrient, so it drifts between batches unless the supplier controls it deliberately. Suppliers who do control it tend to be the ones selling a named, documented ingredient, which is the practical case for branded raw materials over generic ones.

Fish collagen or bovine collagen, what really separates them?

The raw material stream and who is willing to eat it, rather than any demonstrated difference in absorption.

  • Source. Bovine collagen comes from hides and bones and delivers types I and III. Marine collagen comes from fish skin and scales, delivering type I, or from fish cartilage, delivering type II. Both are by-products of food production.
  • Diet and belief. Marine collagen is acceptable to people who avoid bovine material for religious or personal reasons. Neither is vegetarian and neither is vegan, whatever the packaging design implies.
  • Allergen. Fish is a declared allergen under Annex II of Regulation 1169/2011 and must be labelled. The two exemptions there cover fish gelatine as a vitamin carrier and as a fining agent in beer and wine, and neither applies to a supplement.
  • Sustainability. Marine collagen genuinely uses a discarded stream. So does bovine collagen. Marine is not automatically the lower impact option, because that depends on the fishery, the transport and the processing, none of which a label discloses.
  • Absorption. On the evidence above, source species is a minor variable. Choose on tissue and type, not on the animal.

What does the evidence not show?

It does not show that swallowing collagen does what the category implies, and European regulators have said so in writing.

EFSA assessed a claim for collagen hydrolysate and maintenance of joints and concluded that a cause and effect relationship has not been established. No health claim for collagen of any type is authorised in the EU. The only authorised wording that mentions the word at all belongs to a vitamin: under Regulation 432/2012, vitamin C contributes to normal collagen formation for the normal function of skin. That claim is about the collagen your own cells build, not about collagen you eat.

The skin literature is real but thin. A 2025 systematic review and meta-analysis in the Indian Journal of Dermatology, Venereology and Leprology pooled 10 randomised trials and 646 participants, reporting a standardised mean difference of 1.25 for hydration and 0.61 for elasticity, with moderate heterogeneity, generally unclear risk of bias, mostly female participants and too few studies to test for publication bias. That is a signal inside an imperfect literature, not a settled result. The biology underneath is covered in our piece on the biology of radiant skin.

The trial behind our own ingredient is not exempt. The 2021 study in Molecules randomised 46 women aged 45 to 59, of whom 43 completed, taking 500 mg of the fish cartilage hydrolysate daily for 90 days, with skin structure measured by imaging. One author was employed by the ingredient manufacturer, and the confocal microscopy sub-analysis rested on six participants per group. It is one trial of ordinary size. We use the ingredient at the dose that trial used, and we build no claim on it, because EU law does not permit one and the evidence does not yet earn one.

The supplier deserves the same candour. Abyss Ingredients, which makes Cartidyss in Caudan in Brittany, is not an old ingredient house. The French company register lists it with a workforce band of ten to nineteen employees for 2023. Small suppliers can run good science. They simply have less of it than a house with a century of files.

How do you read a collagen label in practice?

Ask four questions in order, and most of the category answers them badly.

  • Which tissue? Skin and scales mean type I. Cartilage means type II with its own glycosaminoglycans. If the label is silent, assume skin, because skin is what the industry has most of.
  • Which type, in which form? Type II at 40 mg and type II at 500 mg are different propositions with different proposed mechanisms.
  • What dose, and does it match a study? A named ingredient with a published trial at a stated dose can be checked. An unnamed collagen at an unnamed molecular weight cannot.
  • What is the ingredient called? Named raw materials can be looked up, argued with and criticised in public. That is the point of naming them.

None of this makes collagen a treatment for anything. It makes a label legible, which is a smaller and more honest goal. Our skin page sets out the reasoning behind our own formula, and Beauty Complete is where the Cartidyss sits at 500 mg.

Further reading

Frequently asked questions

What is the difference between collagen type 1, 2 and 3?
Type I is the load-bearing material of skin, bone and tendon, and accounts for more than 90 per cent of the collagen in the body. Type II is the framework of cartilage. Type III sits alongside type I in skin and in blood vessel walls, which is why so many products are sold as type 1 and 3: one extract from hide or skin carries both, so the label describes the raw material rather than a formulation decision.

Is marine collagen better than bovine collagen?
The difference lies in the raw material stream and in who is willing to eat it, not in any demonstrated advantage in absorption. Marine works for people who avoid bovine material for religious or personal reasons. Neither is vegetarian or vegan, and it is more useful to choose on tissue and type than on species.

Does molecular weight matter?
Up to a point, and the point sits lower than the marketing suggests. In the 2024 crossover study, hydrolysates at 2000 Da and at 5000 Da produced highly comparable peptide and amino acid concentrations in blood. Six people, a single dose, and one author employed by a collagen manufacturer, so it settles nothing alone, but it is close to the only direct human comparison there is.

Can I take marine collagen if I am allergic to fish?
No. Fish is a declared allergen under Annex II of Regulation 1169/2011 and must always appear on the label. The two exemptions in that annex cover fish gelatine as a vitamin carrier and as a fining agent in beer and wine, and neither applies to a supplement.

Is marine collagen more sustainable?
Not automatically. Marine collagen genuinely uses a discarded stream, roughly 7.3 million tonnes of fish by-product a year, but so does bovine collagen. The impact depends on the fishery, the transport and the processing, none of which a label discloses.

Is marine collagen worth the money?
That depends on what you expect from it. EFSA concluded that a cause and effect relationship between collagen hydrolysate and maintenance of joints has not been established, and no collagen health claim of any type is authorised in the EU. What you can actually check before buying is whether the ingredient is named and whether the dose matches a published trial. An unnamed collagen at an unnamed molecular weight cannot be checked at all.

Sources