What Is Fish Collagen?

Type I collagen in fish is a major extracellular matrix component widely found in skin, bone, scales and muscle, and has an amino acid sequence similar to that of land vertebrates.

Because collagen is hard to dissolve, it must be processed to extract it. Most collagen in use today is dissolved and extracted by alkali or enzyme treatment.

For fish scale collagen, differences have been reported between collagen extracted with acid and collagen extracted with an enzyme (pepsin).

Dr.JAPAN uses collagen extracted by enzymatic processing from the skin of wild cod caught in the North Atlantic. Its characteristics as a raw material, based on published figures:

Extraction, thermal properties and religious acceptability by collagen source, from published data. Values vary with species and measurement method.

Lower denaturation and melting temperatures mean easier dissolving in cold water and less gelling; mammalian gelatins form stronger gels than cold-water fish gelatin.

Fish collagen comes from many kinds of fish. Here is how the wild cod skin we use compares with other common fish.

Allergen labeling shows only whether the fish is on the recommended list; it does not mean no allergy can occur. People with fish allergy should take care with fish collagen too.

Fish scales are made of hydroxyapatite (the calcium mineral also found in bone) and type I collagen fibers. To extract collagen from scales, this calcium must first be dissolved and removed; this step is called demineralization.

Hydrochloric acid is commonly used. In a study of carp scales, soaking in 1.0 M HCl for 95 minutes removed about 93% of the minerals. EDTA can be used instead; it causes little collagen loss but removes minerals less efficiently. At high HCl concentrations fish collagen can dissolve.

The wild cod skin we use has no calcium layer like scales, so collagen can be extracted without this demineralization step.

Native collagen molecules are very large, with a molecular weight of about 300,000. In cod, the α1 and α2 chains are about 120,000 and 110,000, slightly smaller than in mammals (about 130,000 and 115,000).

Collagen peptides used in foods are made by enzymatically breaking down gelatin, with molecular weights of a few thousand. Peptide size is determined by how far it is broken down (the process), not by the source; a study comparing sources prepared fish, pig and cattle peptides at the same average molecular weight (about 2,000).

Some studies have compared the amount and type of peptides appearing in the blood after taking collagen peptides from different sources.

The peptides appearing in the blood differ by source, but both studies were small and their results differ. They do not show that any source is better for the body.

In a study where fish-skin collagen peptides were taken at 12.5 g a day (five times the usual amount) for eight weeks, no changes were seen in blood test values.