Collagen is derived from animal tissues, primarily the skin, bones, tendons, and connective tissue of cattle, pigs, fish, and poultry. There is no plant that naturally produces collagen. Every collagen supplement on the market starts with animal byproducts from the meat or fishing industry, then undergoes chemical or enzymatic processing to break it down into a form your body can absorb.
The Main Animal Sources
Most commercial collagen comes from one of four animal groups, each offering slightly different collagen types and properties.
Bovine (cattle): Cow hides and bones are the most widely used source. Bovine collagen is rich in type I and type III collagen, which are the same types that make up most of your skin, bones, and blood vessels. Bone collagen from cattle contains roughly twice the hydroxyproline (a key amino acid for collagen’s structure) compared to fish skin collagen, which partly explains why bovine sources dominate the supplement market.
Porcine (pig): Pig skin is another major source, yielding about 3.3 grams of collagen per 100 grams of skin. That’s a high extraction rate compared to other animals, making pork skin an efficient raw material. Porcine collagen is structurally very similar to human collagen, which is why it has a long history of use in medical products like wound dressings.
Marine (fish): Fish skin and scales provide type I collagen that’s gained popularity as an alternative to mammalian sources. Marine collagen tends to have smaller peptide chains, which some manufacturers claim improves absorption. Fish skin collagen contains about 21.8 grams of glycine per 100 grams of protein, similar to land animal sources, but has lower hydroxyproline levels than bovine bone collagen.
Poultry (chicken): Chicken skin and sternal cartilage are used, though less commonly than bovine or porcine sources. Chicken skin yields considerably less collagen per gram of tissue. Eggshell membranes are a more novel poultry source, containing types I, V, and X collagen. Eggshell membrane collagen is richer in hydroxyproline and more heavily cross-linked than mammalian collagen, making it more heat-resistant but harder to dissolve.
Where the Raw Material Actually Comes From
Collagen production is largely a byproduct industry. The bones, skin, fatty tissue, hooves, and tendons left over from meat processing are the primary raw materials. The global meat industry produces roughly 330 million tons of animal products annually, and Europe alone generates more than 20 million tons of byproducts each year. Rather than going to waste, a significant portion of this material gets directed toward collagen and gelatin extraction.
This matters if sustainability is part of your purchasing decision. Collagen supplements are essentially upcycled waste from an industry that would produce these byproducts regardless. The alternative is disposal, which contributes to the estimated $2.5 trillion in global food waste costs.
How Raw Tissue Becomes a Supplement
Getting collagen out of a cowhide or fish scale and into a powder you can stir into coffee takes several processing steps. There are four main extraction methods: alkaline, neutral salt, acid, and enzymatic.
The most common approach uses acetic acid to loosen collagen fibers from the surrounding tissue, sometimes combined with an enzyme called pepsin. Pepsin clips away the ends of the collagen molecule while leaving the core triple-helix structure intact. This is what produces “undenatured” or “native” collagen, which retains its original three-dimensional shape.
For hydrolyzed collagen (the type found in most powdered supplements), the process goes further. After extraction, the collagen is broken down into much smaller fragments called peptides. Intact collagen and basic gelatin have a molecular weight around 150,000 daltons. Hydrolyzed collagen peptides clock in around 5,000 daltons, roughly 30 times smaller. That size reduction is what makes collagen peptides dissolve in cold liquids and allows them to pass through the gut wall more efficiently.
Collagen’s Amino Acid Building Blocks
Regardless of the animal source, collagen has a distinctive amino acid fingerprint. About one-third of its amino acids are glycine, with proline and hydroxyproline making up another significant portion. This combination is what gives collagen its unique triple-helix structure and sets it apart from other dietary proteins like whey or soy.
Hydroxyproline is particularly notable because it’s rarely found in other proteins. Your body uses it to stabilize collagen fibers, and its presence in a supplement is essentially proof that the product contains actual collagen rather than generic protein. The exact ratio of these amino acids shifts depending on the source. Bovine bone collagen packs the most hydroxyproline, followed by bovine tendon, with fish skin on the lower end.
What About Plant-Based Collagen?
No plant produces collagen. Collagen is an exclusively animal protein. Products labeled “vegan collagen” or “plant-based collagen” are not collagen at all. They’re blends of plant extracts and fermented amino acids designed to stimulate your body’s own collagen production.
One clinical trial tested a vegan collagen biomimetic containing plant compounds (extracted from gotu kola and ginseng, among others) alongside fermented amino acids against fish collagen supplements and a placebo. The vegan blend was formulated to nudge the body into producing more type I collagen on its own rather than supplying collagen directly. These products can have real effects on skin, but the mechanism is fundamentally different: you’re giving your body building materials and chemical signals rather than pre-formed collagen.
Eggshell Membrane as a Specialty Source
Eggshell membrane collagen deserves its own mention because it behaves differently from other sources. The thin membrane lining the inside of an eggshell contains types I, V, and X collagen bundled with glycoproteins and other bioactive compounds. Each fiber has a collagen-rich core surrounded by a sugar-protein coating.
Research on eggshell membrane has shown it can reduce inflammatory responses and may slow cartilage damage and bone loss in models of arthritis. It also appears to improve calcium uptake in human cells, which has led to interest in using it for bone health applications. The heavy cross-linking that makes eggshell membrane collagen tough and heat-stable also makes it harder to extract and process, which is one reason it remains a niche ingredient compared to bovine or marine collagen.
Choosing a Source That Fits
The “best” collagen source depends on what you’re after. Bovine collagen provides the broadest amino acid profile with the highest hydroxyproline content, making it the default choice for skin and bone support. Marine collagen appeals to people who avoid red meat or pork, and its smaller peptide size may offer a slight absorption advantage. Porcine collagen is common in medical-grade products but less popular in consumer supplements due to dietary restrictions in some religious traditions.
If you follow a vegan diet, collagen supplements are off the table entirely, but plant-based collagen boosters offer an indirect alternative. And if joint health is the priority, eggshell membrane products deliver a unique combination of collagen types alongside anti-inflammatory compounds that standard collagen powders don’t contain.