Collagen is often called the "glue" that holds our bodies together. It’s a vital protein that keeps our skin youthful, joints flexible, and organs strong. But did you know there are many types of collagen, each with unique roles? In this guide, we dive into the history of collagen discovery, explain why Roman numerals are used, and explore the 5 most common types found in supplements and your body.

A Brief History: Collagen Discovery and the Roman Numeral Tradition

Nearly 100 years ago, histologists—scientists who study tissues—first identified Type I collagen. The early researchers, working in dimly lit basement labs, chose to label collagen types using Roman numerals—a tradition that continues today. Why Roman numerals? According to Dr. Cate, a collagen expert, it’s simply the style preferred by these pioneering scientists.

How Many Types of Collagen Are There?

The exact number of collagen types in the human body is still debated. Some studies suggest 16 types, others 28, and some claim there could be as many as 183 different forms. Mark Moyad, MD from the University of Michigan Medical Center, calls the science “in its infancy.”

Despite the uncertainty, we know collagen is critical to many bodily functions. In nutrition and supplements, five types stand out as most important—and these are the focus of our discussion.

The 5 Most Common Types of Collagen in Your Body and Supplements

Collagen supplements often highlight these types using Roman numerals:

• Type I

• Type II

• Type III

• Type V

• Type X
  
  

Let’s explore each type’s unique role, sources, and benefits.

Type I Collagen: The Superstar of Collagens

Type I collagen accounts for approximately 90% of the collagen in your body. It is found throughout your skin, hair, nails, bones, tendons, ligaments, blood vessels, organs, and even your eyes.

Think of Type I as the “Homecoming Queen” of collagen types, the most abundant and most sought after in supplements. Its primary function is to provide strength and structure, keeping tissues firm and resilient.

Best sources: Beef, bone broth, eggs.

Type II Collagen: The Joint Protector

Type II collagen is primarily found in cartilage, joints, and the gut lining. It plays a vital role in cushioning joints and supporting digestive health.

Studies, though small, have shown promising effects of Type II collagen supplements in alleviating rheumatoid arthritis symptoms. Whether or not you believe anecdotal evidence, many users report relief and improved joint function.

Best sources: Chicken, bone broth.

Type III Collagen: The Structural Sidekick

Type III collagen often works alongside Type I and is a key component in organs, blood vessels, and muscle structure. It’s essential for maintaining the flexibility and integrity of blood vessels and organs.

A small study found that lack of Type III collagen was linked to vascular diseases, highlighting its importance in arterial health.

Best sources: Beef, bone broth, fish.

Type V Collagen: The Placenta and Cornea Contributor

Less known but incredibly important, Type V collagen is found in the placenta and the cornea of the eyes. It supports fetal development during pregnancy and contributes to eye health.

Pregnant women can safely take collagen supplements containing Type V, offering nutritional support for their growing baby.

Best sources: Eggs, multi-collagen supplements.

Type X Collagen: The Bone and Joint Builder

Type X collagen plays a critical role in the health of bones and joints, working behind the scenes to support cartilage and bone development.

Because Type X collagen is often sourced from eggshells and chicken cartilage, getting sufficient amounts from diet alone can be challenging.

Best sources: Eggs (especially eggshell membranes), chicken.

Lesser-Known Collagen Types

Other types, such as Type IV collagen, exist and serve specialized roles. For instance, Type IV supports the skin’s basement membrane and helps filter blood in kidneys. However, these are rarely included in supplements.

Collagen vs. Hydrolyzed Collagen Peptides

When shopping for supplements, be aware that most products contain hydrolyzed collagen peptides—broken-down forms that are easier for your body to absorb. Not all collagen types are equally represented in these products, so choosing a multi-collagen blend ensures you get a broad spectrum.

Final Thoughts: Why Collagen Matters

Whether for skin elasticity, joint comfort, or organ support, collagen is fundamental to our health. While science continues to uncover more about its many types, current research and customer testimonials affirm the benefits of collagen supplementation.

If you want the convenience of all five key types, look for multi-collagen products sourced from diverse animal origins like beef, chicken, fish, and eggs.