Collagen primarily comes from animal sources, as it is a structural protein found in the connective tissues of many animals. It is naturally present in animal flesh such as meat and fish that contain connective tissue

. The main animal sources for collagen used in supplements and products include:

• Bovine collagen : Derived from cows' bones, tendons, and hides. It mainly contains type I and III collagen

• Porcine collagen : Sourced from pigs' skin, also rich in type I and III collagen

• Marine collagen : Extracted from fish skin and scales, and sometimes from marine invertebrates like jellyfish. It is rich in type I collagen and noted for higher bioavailability and easier absorption by the body

• Poultry collagen : From chicken bones, cartilage, and tissues, containing type II collagen

• Ovine collagen : From sheep skin, bones, and by-products, rich in type I and III collagen

Collagen is synthesized naturally in the human body by fibroblast cells, primarily from amino acids such as glycine, proline, and hydroxyproline, with vitamin C playing a crucial role in its formation

. While collagen itself is only found in animal tissues, plant foods can provide nutrients that support the body's collagen production

. In summary, collagen comes from animal connective tissues, with common commercial sources being cows, pigs, fish, chickens, and sheep. The body also produces collagen internally using amino acids derived from dietary protein