Collagen is the most abundant protein in the human body, serving as the primary structural component of connective tissues. It provides the framework that gives tissues their form, strength, and resilience. While there are at least 28 different types, research and supplementation primarily focus on five specific types: I, II, III, V, and X. These types are differentiated by their unique molecular structures, tissue distribution, and biological functions.
The Primary Structural Collagens: Types I, II, and III
Collagen Type I is the most prevalent, accounting for approximately 90% of the body’s total collagen content. It is composed of dense, rope-like fibers that provide high tensile strength. Type I is the main component of bone, tendons, ligaments, and the skin’s dermis layer. Its primary function is to resist stretching and maintain the integrity of structures subject to significant pulling forces, including teeth and scar tissue.
Type III collagen is the second most abundant form and often works in close association with Type I. It assembles into finer, more flexible reticular fibers important in soft, pliable tissues. This type is a major structural component of hollow organs such as the uterus, bowel, and large blood vessels, where elasticity is necessary. In the skin, Type III is concentrated during the early stages of wound healing, and its ratio to Type I is important for maintaining skin elasticity.
Type II collagen is almost exclusively found in cartilage, the connective tissue that cushions the joints. Its unique structure allows it to resist compressive forces, acting like a shock absorber to protect bones during movement. Type II makes up about 90 to 95% of the collagen within articular cartilage, providing the tissue with firm yet elastic properties. This type is also a component of the vitreous humor in the eye and the nucleus pulposus of intervertebral discs.
Specialized Roles of Types V and X
Collagen Type V is a minor fibrillar collagen that plays a regulatory role in connective tissue architecture. Instead of forming large structural fibers on its own, it co-assembles with Type I and Type III collagen. Type V molecules are located at the core of these larger fibers, effectively regulating their diameter and organization. This function is particularly important in tissues like the cornea and the dermis, where the precise arrangement of fibers is necessary for clarity and strength.
Type X collagen has a highly specific, non-structural function related to bone development and repair. It is a transient short-chain collagen produced by hypertrophic chondrocytes in the growth plates of long bones. Its presence is a biochemical marker for endochondral ossification, the process by which cartilage is converted into bone. Type X facilitates the mineralization of the cartilage matrix, which is necessary for new bone tissue formation. This specialized type is highly concentrated during skeletal growth and is often included in supplements aimed at supporting bone health.
Sourcing, Processing, and Bioavailability
Collagen supplements are sourced from various animal byproducts, with the source dictating the natural blend of collagen types.
Bovine Collagen
Derived from cow hides and bones, bovine collagen is rich in both Type I and Type III collagen. This combination makes it a popular choice for supporting skin, bone, and gut health.
Marine Collagen
Extracted from the skin and scales of fish, marine collagen consists almost entirely of Type I collagen. It is favored by those with dietary restrictions against land animals and is often marketed for its skin and beauty benefits.
Chicken Collagen
Derived from cartilage, chicken collagen is the primary source for supplements focused on Type II collagen. This type is often used specifically to support joint cartilage and mobility.
Regardless of the source, raw collagen molecules are too large for efficient absorption due to their triple-helix structure. Therefore, nearly all commercial supplements undergo hydrolyzation, a process using heat or enzymes to break the large protein into smaller fragments known as collagen peptides. These hydrolyzed peptides are significantly smaller, typically ranging from 2,000 to 6,000 Daltons. This reduced size increases the product’s bioavailability, allowing the peptides to pass through the intestinal wall and enter the bloodstream more rapidly.
Once absorbed, the body breaks these peptides down further into their constituent amino acids, which are then distributed throughout the body. The body uses these amino acids as building blocks to synthesize new collagen wherever the need is greatest. This process is not directly dictated by the specific type of collagen originally consumed. For instance, consuming Type I peptides provides the raw materials, but the body’s own biochemical signals determine where those materials are used.