Fish, pork and bovine collagen: how do they differ?

Collagen from pigs, cattle and fish is taken from different raw materials (pig skin; cattle hides, bones and tendons; fish skin, scales and swim bladders), but most of it is the same kind of protein: type I collagen, built from three chains wound into a triple helix. The raw materials differ mainly in two measurable ways. The first is the amino acids: earlier studies cited in a 2019 study report about 215 to 220 imino acids (proline plus hydroxyproline) per 1,000 amino acids for collagen from calf and pig skin, while collagen from fish skins has been measured at 157 to 199. The second is heat stability: in these studies, collagen from most fish skins unfolded, or denatured, at lower temperatures than calf collagen, and collagen from cold-water fish skins at the lowest.

In short:

• Same type: skin, hides, scales, bones and tendons give mainly type I collagen
• Amino acids: imino acids 215–220 per 1,000 for calf and pig skin (earlier studies cited by Wang et al. 2019); 185–199 for the other fish skins and scales in these studies; 157–165 for cold-water fish skins (also cited)
• Heat stability: measured with one method in one study, calf tendon collagen unfolded at 38.2 °C, silver carp skin at 32.6 °C and salmon skin at 15.6 °C; other studies use other methods
• Yield: depends on the raw material, from under 2% for fish scales to about 16–29% for fish skin and swim bladder in Thai studies
• Daily amount: no Thai RDI for collagen; the Thai RDI for protein is 50 g

This article compares collagen by raw material, using laboratory studies, including several from Prince of Songkla University in Thailand. It looks at composition and physical properties only and does not discuss effects in the body. For how gelatin and collagen peptides are made from these raw materials, see Collagen peptides and gelatin: how do they differ?

Which raw materials is collagen taken from?

Collagen is found only in animals. The Nutrition Source at the Harvard T.H. Chan School of Public Health says that, in food, collagen is found in the connective tissue of meat and in the bones and skin of freshwater and saltwater fish.

Raw materials and collagen type

A 2019 review in Molecules by León-López and colleagues reports that skin, bones and tendons contain mainly type I collagen, and cartilage mainly type II. For fish scales, a 2011 study from Prince of Songkla University found type I collagen.

The same chain make-up

Type I collagen is made of three chains. Studies of Nile tilapia skin (2019) and puffer fish skin (2019) found the form (α1)2α2: two alpha-1 chains and one alpha-2 chain. Studies from Prince of Songkla University found the same alpha chains in seabass skin and goatfish scales, together with beta chains and, in the scales, gamma chains. The León-López review gives about 300 kDa for the whole collagen molecule.

How do the amino acids differ between pig, cattle and fish collagen?

The tilapia study describes the repeating Gly-X-Y pattern shared by all collagens, with glycine as the most common amino acid. The main difference between raw materials is in proline and hydroxyproline, the two imino acids.

Imino acids (proline plus hydroxyproline) per 1,000 amino acids

For tilapia, the 2019 study gives proline and hydroxyproline separately for two extraction methods; the combined figure here is the sum for each method.

Glycine

The tilapia study measured glycine at 322 to 343 per 1,000 and cites 320 and 334 for bovine skin and 326 for porcine skin. The goatfish scale study measured 336 to 340 per 1,000. Glycine is therefore similar across sources; the larger differences are in the imino acids.

Why imino acids matter for structure

The 2019 puffer fish study by Wang and colleagues explains that the ring structures of proline and hydroxyproline restrict how the chains can move, and that hydroxyproline forms hydrogen bonds inside the molecule. Both help hold the triple helix together, so collagen with more imino acids tends to stay folded at higher temperatures.

At what temperature does each collagen unfold?

The denaturation temperature (Td) is the temperature at which the triple helix comes apart into loose chains. In the puffer fish study, for example, it was measured from the change in viscosity of collagen dissolved in dilute acetic acid. Other studies use other methods, so results from different laboratories are not directly comparable.

One method, four sources

A 2021 study from Jiangsu Ocean University in China measured four collagens with the same dye-based method and found no significant difference from the viscosity method.

Results from other studies

The goatfish scale collagen in the 2011 study had a maximum transition temperature (Tmax) of 41.58 °C (acid-soluble) and 41.01 °C (pepsin-soluble). Tmax is measured differently from the denaturation temperatures above, so it is shown separately.

What the numbers show

The puffer fish study found lower temperatures for puffer skin than for calf skin and higher temperatures than for cold-water fish, and notes that this was consistent with the amino acid composition. Collagen from fish that live in cold water unfolds at the lowest temperatures. In the tables above, collagen from fish common in Thailand, such as seabass, tilapia and bigeye snapper, mostly falls between the cold-water fish and the calf and cattle collagen, though tilapia skin overlapped with the cited calf skin value, and the studies used different methods.

How much collagen can be extracted from each raw material?

The share of collagen recovered depends on the raw material and the extraction method, so the figures below are examples rather than fixed values.

Two ways of extracting collagen

Studies usually report two kinds of collagen. Acid-soluble collagen (ASC) is dissolved from the tissue with a weak acid. Pepsin-soluble collagen (PSC) is extracted with the help of the protein-cutting enzyme pepsin; the 2010 bigeye snapper study explains that pepsin is used because acid extraction alone gives a low yield. In that study, the same bigeye snapper skin was extracted with pepsin from two sources: pepsin from pig stomach and pepsin from tongol tuna stomach. The collagen extracted with pig pepsin had more beta chains and fewer alpha chains than the collagen extracted with tuna pepsin, although the triple helix was intact in both. Only the enzyme differed; the collagen came from the same fish skin.

Yields reported in studies

The studies used different bases for their percentages, so the table shows the range rather than a ranking. The 2010 bigeye snapper study notes that fish skin is a by-product of fish processing and that bigeye snapper is widely used for surimi in Thailand. All of these were laboratory studies of the collagen itself.

Does the raw material matter in food?

Collagen is a protein

Collagen from any animal is a protein. There is no Thai Reference Daily Intake (Thai RDI) for collagen; the Thai RDI covers total protein from all foods, at 50 g a day. For which amino acids the body needs from food, see What are essential amino acids?

Collagen in everyday food

The Harvard Nutrition Source lists tough cuts of meat rich in connective tissue and the bones and skin of fish as foods that contain collagen, and describes bone broth, made by simmering animal bones, as promoted as rich in collagen. Examples of such foods in Thai cooking include pork skin, beef tendon, chicken feet and fish skin.

What should people keep in mind?

Fish allergy

Collagen may be made from fish skin and scales. The US Food and Drug Administration lists fish among the major food allergens. People with a fish allergy should talk to a doctor or pharmacist.

Pregnancy and regular medication

If you are pregnant or breastfeeding, or take medication regularly, talk to a doctor or pharmacist before taking dietary supplements.

Dietary supplements are not intended to prevent, treat or cure any disease.