Collagen types 1 and 3 are the two most abundant collagens in your body, and they work together to maintain the structure of your skin, bones, blood vessels, and organs. Type 1 provides rigid tensile strength to tissues that need to resist pulling forces, while type 3 gives flexibility to organs that need to stretch. They also partner during wound healing, with type 3 forming the initial repair scaffold and type 1 replacing it as the tissue matures.
Type 1 Collagen: Your Body’s Structural Framework
Type 1 collagen is the most abundant protein in the human body. Its primary job is holding tissues together by forming thick, tightly packed fibers that resist stretching and tearing. These fibers assemble into rope-like structures built from a triple-helix molecular shape, roughly 300 nanometers long, that stacks into increasingly complex bundles. The result is a biological cable system with remarkable tensile strength.
You’ll find type 1 collagen concentrated in tissues that bear mechanical load. It makes up 85 to 95% of the organic matrix in bone, where it forms the flexible scaffold that calcium crystals deposit onto, giving bones both strength and slight flexibility. In tendons and ligaments, type 1 collagen fibers align in parallel to handle the directional pulling forces between muscles and bones. It also accounts for 80 to 90% of the collagen in the cornea of your eye, where its precise, uniform arrangement keeps the tissue transparent. Skin, teeth, and the fibrous capsules around organs all depend on it as well.
Beyond providing tensile strength, type 1 collagen acts as a scaffold that cells attach to, migrate along, and use as a guide during tissue growth and repair. It is not just passive structure. It actively supports cell signaling and organization throughout your connective tissues.
Type 3 Collagen: Flexibility for Organs That Stretch
Type 3 collagen forms thinner, more flexible fibers than type 1. It is a major structural component of hollow organs that must withstand repeated stretching: large blood vessels like the aorta, the uterus, and the intestines. These are tissues that expand and contract constantly, and type 3 collagen gives them the compliance to do so without tearing.
It’s also found throughout the skin, muscles, and the walls of smaller blood vessels. In skin, type 3 collagen contributes to softness and pliability, complementing the firmer type 1 fibers. The ratio of type 1 to type 3 collagen in skin stays relatively stable from childhood through young adulthood, though it can shift with aging as the body’s ability to produce type 1 collagen declines.
How They Work Together in Wound Healing
One of the most important interactions between these two collagen types happens when your body repairs damaged tissue. The process follows a predictable sequence. In the early phase of wound healing, your body ramps up production of type 3 collagen. These thinner fibers form quickly and create a temporary, loosely organized mesh at the injury site. Think of it as a first draft of new tissue: fast to produce but not especially durable.
As healing progresses over weeks and months, the balance shifts. Type 1 collagen gradually replaces type 3, forming thicker, more tightly cross-linked fibers. These covalent bonds between fibers restore the mechanical strength of the tissue. The mature scar or healed area ends up with a much higher proportion of type 1 collagen, which is why healed tissue eventually regains significant (though not always complete) tensile strength. This transition from type 3 to type 1 is sometimes described as the shift from “juvenile” collagen to “mature” collagen.
When this remodeling process goes wrong, the consequences can be significant. An imbalance favoring too much type 3 collagen can leave tissue weak, while overproduction of type 1 can contribute to excessive scarring and fibrosis.
Collagen Decline With Age
Your body’s collagen production begins slowing in early adulthood, decreasing by roughly 1% per year. This gradual loss affects both type 1 and type 3 collagen, and it shows up in predictable ways: thinner skin, stiffer blood vessels, weaker bones, and slower wound healing. In aged skin, research suggests the decline is driven partly by impaired synthesis of type 1 collagen specifically, which can shift the ratio between the two types.
This progressive loss is also why joint stiffness, reduced bone density, and slower recovery from injuries become more common with age. The collagen scaffold that supports all of these tissues is simply less abundant and turns over more slowly.
Food and Supplement Sources
Type 1 collagen is most concentrated in bovine (cow) bone and hide, fish skin, scales, and bones, as well as porcine (pig) sources. Chicken, duck, and rabbit skin also provide it. Type 3 collagen comes primarily from animal skin, muscle tissue, and blood vessels, so many animal-derived collagen products naturally contain both types.
Most collagen supplements are hydrolyzed, meaning the proteins have been broken down into smaller peptides. These shorter chains resist further breakdown during digestion and are absorbed into the bloodstream more readily than intact collagen. Once absorbed, collagen-derived peptides circulate in the blood and appear to stimulate the body’s own collagen-producing cells.
In a double-blind, placebo-controlled study, participants with osteoarthritis who took a supplement containing 2,000 mg of type 1 and 3 collagen peptides daily for eight weeks reported significant improvements in pain levels, quality of life scores, and some measures of physical function, including balance and walking distance. These results align with a broader body of research suggesting that hydrolyzed collagen peptides can support joint comfort, though results vary across different functional tests.
Your body does not absorb collagen supplements as intact type 1 or type 3 molecules. The peptides are broken down further and then used as raw materials, so the “type” listed on a supplement label reflects the source tissue rather than a guarantee that your body will rebuild that exact collagen type. Eating collagen-rich foods like bone broth, skin-on fish, and slow-cooked meats provides similar peptides, though in less concentrated amounts.