What is elastin, and which foods contain it?

Elastin is a protein of the body's connective tissue. It is made when many molecules of a smaller protein, tropoelastin, are tied together by cross-links, and some of those cross-links, such as desmosine and isodesmosine, are found in elastin. Because the finished protein is so heavily cross-linked, it does not dissolve in water. In food, elastin comes with animal connective tissue: the sheets around beef muscles, ligaments, and in fish the bulbus arteriosus, a part of the heart outflow. Elastin is not a nutrient with a Thai Reference Daily Intake (Thai RDI).

In short:

• What it is: a protein of connective tissue, built from tropoelastin
• What it is made of: water-repelling stretches rich in glycine, proline, leucine and valine, alternating with stretches that form cross-links
• Its own cross-links: desmosine and isodesmosine, formed from the amino acid lysine
• Compared with collagen: a different protein, with a different amino acid pattern and different cross-links
• In food: beef muscle and ligaments; in fish, the bulbus arteriosus
• When eaten: digested like other proteins
• Thai RDI: none

This article explains what elastin is, how it differs from collagen and where it is found in food. For what happens to collagen you eat, see What happens to collagen you eat?

What is elastin?

A protein of connective tissue

A 2005 review by Mithieux and Weiss at the University of Sydney lists large arteries, the lungs, ligaments, tendons, skin and elastic cartilage among the vertebrate tissues that contain elastin. Elastin sits outside the cells, in the extracellular matrix, usually together with very fine fibres called microfibrils.

Built from tropoelastin

The body does not make elastin in one piece. It first makes tropoelastin, a single protein chain, and many tropoelastin molecules then line up and are joined by cross-links. The review describes this lining up as directed by an alternating pattern of water-repelling and water-attracting sequences.

Keeley and colleagues at the Hospital for Sick Children in Toronto describe elastin as made of about 36 domains, which alternate between two kinds:

The same paper describes native elastin as insoluble, and its experiments used small, lab-made pieces based on the sequence of human elastin. Halabi and Mecham at Washington University in St. Louis describe the working form of elastin as a highly cross-linked polymer arranged as sheets or fibres. Because it does not dissolve, it cannot be isolated with standard laboratory chemistry; instead, harsh treatments remove everything that is not elastin and leave an insoluble product with the amino acid make-up expected of elastin.

How is elastin different from collagen?

Elastin and collagen are both proteins of connective tissue and often lie side by side, but they are different molecules.

The collagen figures come from a 2019 review in Molecules by León-López and colleagues, which describes each alpha chain as about 1,014 amino acids long with a molecular weight of around 100 kDa. The elastin figures come from Keeley and colleagues. Because both are proteins, the Thai RDI for protein, 50 g a day, covers them together with all other proteins in the diet.

Desmosine: an amino acid found in elastin

The US National Library of Medicine's MeSH vocabulary describes desmosine as a rare amino acid found in elastin, formed when four molecules of lysine condense into a ring. Isodesmosine is a closely related form. Researchers at Boston University describe desmosine and isodesmosine as specific to elastin and hydroxylysyl pyridinoline as specific to collagen, so these cross-links are used in laboratory work to tell the two proteins apart.

Which foods contain elastin?

Elastin comes with connective tissue, so it is found in animal foods that contain sinew, ligament or vessel walls, not in plant foods. Elastin is rarely measured in foods in grams, so the table shows what individual studies found.

Beef muscle and ligaments

A 1986 study at the CSIRO Meat Research Laboratory in Queensland looked at elastin in two beef muscles under the microscope. Both had the same two kinds of elastin fibres. The semitendinosus, a muscle of the hind leg, had very heavy deposits of the coarse fibres, while the longissimus dorsi, the loin muscle, had less, and the finer fibres were common in both. The study describes the structure; it did not measure elastin in grams.

The Boston University study measured desmosine directly. Its authors note that calf neck ligament is not a usual part of human diets, so they also tested a more typical food, lean ground beef. A 454 g portion contained 4 mg of desmosine and 2 mg of isodesmosine, far less than the ligament meal.

The bulbus arteriosus of fish

The bulbus arteriosus is a part of the heart outflow in fish such as tuna. A 2003 study of yellowfin tuna, bigeye tuna and blue marlin found that the wall of the bulbus has a large ratio of elastin to collagen, a limited amount of collagen, no elastin layers (lamellae), and elastin of low water-repelling character.

Fish maw in Thailand

Fish maw (กระเพาะปลา) is the dried and puffed swim bladder of fish, another animal tissue eaten in Thailand. No measured figures for elastin in fish maw were found for this article. A 2015 study from Prince of Songkla University in Hat Yai studied how fish maw is made from the swim bladder of seabass (ปลากะพงขาว), a by-product of gutting fish. The swim bladder is dried, pre-fried and then fried, and the drying temperature, moisture content and frying temperatures set how much it expands and how much oil it takes up. At frying temperatures of 180 and 200 °C, the fish maw took up 451.06 to 578.06 g of oil per kg. The study measured texture, colour and oil, not elastin.

What happens to elastin when you eat it?

Elastin is a protein, so it goes through the same digestion as other proteins. The NIDDK, part of the US National Institutes of Health, explains that stomach acid and digestive enzymes break down proteins, the pancreas makes a digestive juice with enzymes that break down proteins, and the small intestine completes the breakdown. Elastin peptides are shorter pieces of elastin made during manufacturing; like other proteins, they are digested into smaller pieces and amino acids.

Is there a recommended daily amount?

No. Elastin is not a nutrient with a Thai Reference Daily Intake (Thai RDI), so there is no recommended daily amount in Thailand. The Thai RDI covers protein from all foods together, at 50 g a day. For the amino acids the body needs from food, see What are essential amino acids?

What the studies in this article measured

The studies here describe the structure of elastin and where it sits in animal tissue. They used beef, calf ligament, tuna, marlin and seabass, and different methods and units, so their figures cannot be compared with each other directly.

Who should talk to a doctor or pharmacist?

People with a fish allergy

Elastin ingredients can come from fish tissue. The US Food and Drug Administration lists fish among the nine major food allergens and explains that food allergies happen when the body reacts to certain proteins in food. People with a fish allergy should ask a doctor or pharmacist before eating products made from fish.

People who avoid certain animal foods

Elastin can come from cattle or fish. People who avoid some of these for religious or personal reasons can check which animal an ingredient comes from.

Pregnant or breastfeeding women and people who take regular medication

If you are pregnant or breastfeeding, or take medication regularly, check with a doctor or pharmacist before taking supplements.

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