Collagen is the most abundant protein in the human body. The many types of collagen form the structural framework that helps keep your skin, bones, cartilage, blood vessels, muscles, and many internal organs strong and functional.
“Although collagen is often discussed as though it were a single substance, there are at least 28 different kinds, each with a specialized role,” says Adam Friedman, MD, FAAD, professor and Chair of Dermatology at George Washington University. We’ll take a look at the top five here.
What Is Collagen?
Collagen is a fibrous protein that acts as the body’s scaffolding. It gives tissues their strength while allowing many of them to remain flexible enough for normal movement and function. Collagen is made primarily from amino acids, including glycine, proline, and hydroxyproline. Its fibers are organized into rope-like bundles that make tissues remarkably strong. Collagen production slows with age, and ultraviolet light, smoking, chronic disease, and other environmental factors accelerate collagen loss.
“Your body is constantly making, breaking down, and remodeling collagen throughout your life, and that process is influenced by your overall health, genetics and age,” Dr. Friedman says.
How Many Types of Collagen Are There?
Researchers have identified at least 28 types of collagen, but only a handful account for nearly all of the collagen in the human body:
- Type I provides strength to skin, bones, tendons, and ligaments.
- Type IIis found primarily in cartilage.
- Type III supports skin, blood vessels, and internal organs.
- Type IV forms specialized support structures known as basement membranes.
- Type V helps regulate how collagen fibers form and supports several tissues.
Because each tissue has unique structural needs, no single collagen type can perform every function. “These tissues have different rates of turnover and respond to different biological signals, so there isn’t one lifestyle intervention that affects every type of collagen equally,” Dr. Friedman explains.
Type I Collagen: The Most Abundant Type
Collagen type I accounts for roughly 80% to 90% of the collagen in the body. It’s found in skin, bones, tendons, ligaments, teeth, and connective tissue. It helps skin remain firm and resilient, allows tendons and ligaments to withstand stretching forces, and gives bones much of their structural integrity. This type is also the collagen most closely associated with visible signs of aging. As type I collagen declines, skin gradually becomes thinner, less elastic, and more prone to wrinkles.
Type II Collagen: Support for Cartilage
Collagen type II is found almost exclusively in cartilage. It helps cartilage absorb shock while allowing joints to move smoothly. Healthy cartilage reduces friction between bones and supports mobility during everyday activities such as walking, climbing stairs, and exercising. As cartilage wears down with age or osteoarthritis, joint pain and stiffness often develop.
Type III Collagen: Support for Skin, Muscles, and Blood Vessels
Collagen type III is commonly found in skin, blood vessels, internal organs, muscles, and hollow organs such as the intestines. It provides flexibility and support to tissues that need to stretch and expand. When wounds heal, type III collagen is produced early in the repair process before gradually being replaced with stronger type I collagen.
Type IV Collagen: A Key Part of Basement Membranes
Unlike types I, II, and III, which form strong, rope-like fibers that provide structure and strength, type IV collagen forms thin, sheet-like networks called basement membranes. These membranes act like a supportive foundation beneath the cells that line the skin, blood vessels, kidneys, lungs, and many other organs. Type IV collagen anchors cells in place, helping tissues maintain their structure, and acts as a selective filter, allowing some substances to pass while blocking others. It also helps organize tissues during growth, wound healing, and normal repair.
Type V Collagen: Important for Skin and Tissue Structure
Collagen type V is found in skin, the cornea, the placenta, hair, and some connective tissues. Although present in much smaller amounts than type I collagen, type V collagen helps regulate how collagen fibers assemble and mature. Abnormalities in this collagen type have been linked to several rare connective tissue disorders.
Other Types of Collagen
These five collagen types account for much of the body’s collagen, but dozens of additional varieties exist. Some support specialized tissues such as cartilage, while others help connect muscle to tendon or contribute to eye structure and nerve function. Researchers continue to identify new functions for these less common collagen types, particularly in the eye, nervous system, and specialized connective tissues.
Supporting Collagen
The best way to support healthy collagen is to focus on habits backed by strong evidence. “The biggest lifestyle factor under your control is protecting the collagen you already have,” Dr. Friedman says. Here’s how:
- Get enough protein and vitamin C. Protein supplies the amino acids needed to build collagen, while vitamin C is essential for proper collagen formation. The recommended dietary allowance of protein for healthy adults is8 grams of protein per kilogram of body weight each day. The European Society for Clinical Nutrition and Metabolism recommends more for older adults:1.0 to 1.2 grams per kilogram of body weight per day. For vitamin C, the National Institutes of Health Office of Dietary Supplements recommends that women get 75 milligrams (mg) per day and men get 90 mg daily. A balanced diet rich in fruits, vegetables, whole grains, and healthy fats provides nutrients needed for tissue repair and may help reduce chronic inflammation.
- Wear sunscreen daily, even on cloudy days. Use a broad-spectrum sunscreen with SPF 30. “Ultraviolet radiation is by far the greatest external driver of collagen breakdown in the skin,” Dr. Friedman says. “Daily sun protection, including sunscreen and sun-protective clothing, is one of the most effective ways to preserve collagen over time.”
- Avoid smoking. If you smoke, ask your healthcare provider about cessation strategies such as nicotine replacement therapy, counseling and medications.
- Get seven to eight hours of sleep each night to reduce oxidative stress that increases collagen breakdown.
- Exercise regularly. Mechanical loading from resistance training stimulates collagen synthesis in muscles, tendons, ligaments, and bone while helping maintain connective tissue strength as you age.
Role of Supplements
Supplements may offer benefits for some people, particularly for skin hydration or joint discomfort, but they should complement these proven lifestyle measures and not replace them.
“Several randomized controlled trials and systematic reviews suggest that oral hydrolyzed collagen supplementation may produce modest improvements in skin hydration and elasticity, and some studies also report reductions in wrinkle depth after several months of daily use,” Dr. Friedman says. However, he cautions that the research varies considerably among products, making it difficult to generalize results to every supplement on the market. There is also evidence supporting certain collagen preparations for improving symptoms of osteoarthritis and joint discomfort.
Most collagen supplements contain type I and type III collagen, typically derived from cows, or type I collagen from fish. Joint health products often contain type II collagen from chicken cartilage.
“The biggest misconception is that collagen is a magic ingredient that automatically runs to the skin after you eat or drink it,” Dr. Friedman says. “That’s simply not how human biology works. When you consume collagen, whether from food or a supplement, your digestive system breaks it down into amino acids and small peptides, just like it does with virtually any other protein. Your body then decides where those building blocks are needed. There is no biological WAZE directing dietary collagen specifically to your face, your wrinkles, or any other single tissue.”
