What is collagen made of and what does it do?
Scarlett Gray
BNutrDiet (Hons), APD, SDA
Accredited Practising Dietitian with Dietitians Australia (APD200526). Accredited Sports Dietitian and Credentialled Eating Disorder Clinician. First Class Honours in Nutrition and Dietetics from the University of Newcastle.
What is collagen made of and what does it do?
You have probably heard of collagen by now. You might even be aware of some of its benefits. What was once the preserve of the elite end of the beauty industry is becoming increasingly popular with ordinary people. But do you actually know what collagen is, what it does in the body, and why levels start to drop as we age?
What is collagen made of?
Collagen is a protein made up of amino acids — primarily glycine, proline and hydroxyproline. These are described as "non-essential" amino acids because the body can produce them itself, rather than having to obtain them entirely from food. That said, collagen itself is hard to get in meaningful amounts from a typical diet — we don't generally eat large quantities of skin, bone and connective tissue — which is part of the reason hydrolysed collagen supplements have become so popular.
Collagen is a building block of a healthy body. It is found in the flesh and connective tissue of mammals, helping to maintain firmness and suppleness of the skin. It also helps support skin elasticity. Collagen fibres support the structure of tissues throughout the body, which is why declining collagen contributes to visible signs of ageing such as fine lines and reduced skin firmness.
Ligaments hold joints together and tendons attach bone to muscle. Bones, muscles, tendons and ligaments are all made up of proteins, and one of the most abundant of these is collagen. A good way of thinking about collagen is as a kind of biological scaffolding — it provides the body with both strength and structure.
The different types of collagen
There are 28 known types of collagen in the human body — older sources sometimes cite 16, but current research recognises 28. Despite that variety, around 80 to 90 per cent of the collagen in the body belongs to Types I, II and III.
Type I
The most abundant type. Found in skin, bones, tendons and ligaments. Type I is the dominant collagen type in human skin.
Type II
The primary collagen in cartilage. Most relevant when the conversation is about joint health and connective tissue.
Type III
Works alongside Type I in skin, blood vessels and internal organs. Associated with softer, more flexible tissue structures.
By weight, Type I collagen fibres are remarkably strong — pound for pound, comparable to some structural materials, which is part of why collagen has been called the body's natural scaffolding.
What does collagen do?
Collagen proteins help to strengthen the different structures throughout the body. But it's not just about strength and structure — collagen also plays a part in overall skin health and contributes to the resilience of connective tissues.
Beyond skin and joints, collagen is found throughout the body — in blood vessels, the digestive tract, the heart, the gallbladder and the kidneys. Wherever the body needs structural support and elasticity, collagen is part of the design.
Why do we lose collagen as we age?
We all lose collagen over time. From around the age of 25, the body's natural collagen production gradually declines — at approximately 1% per year. Over a few decades that accumulates into a meaningful drop, which is when most people start to notice the visible and physical signs.
Beyond age, the other well-established factor is sun exposure. Research shows that ultraviolet radiation increases the rate at which existing collagen breaks down, damages collagen fibres and contributes to the build-up of abnormal elastin in the skin. This is one of the main reasons sun protection consistently shows up in dermatologist advice — skin damage from UV is, in large part, collagen damage.
What happens when collagen levels drop?
As collagen declines, skin can become thinner and less elastic, and hair and nails can show changes in strength and texture. Joints may also feel stiffer over time. Multiple systematic reviews now link collagen supplementation with measurable changes in skin outcomes — elasticity, hydration and the appearance of fine lines — and emerging research is looking at hair, nail and joint outcomes as well.
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Collagen peptide supplements are typically made from one of two sources:
- Marine collagen — derived from the skin and scales of fish. Predominantly Type I collagen, the dominant type in human skin. Marine collagen is well-researched, sustainable (using parts of the fish that would otherwise be discarded) and suitable for pescatarians.
- Bovine collagen — derived from cattle hide and bones. Contains Types I and III collagen, and is often used in joint-focused supplementation.
In both cases, the collagen is hydrolysed — broken down into smaller peptides — so the body can absorb it through the digestive tract. You can read more in our marine collagen vs bovine collagen guide.
Does drinking collagen actually work?
If you're already eating a balanced diet and being sensible about sun exposure, you might be wondering what else can support your collagen levels. This is where collagen supplements come in.
Collagen drinks and supplements don't add directly to the collagen in your skin. Instead, they provide the amino acid building blocks the body uses to support its own collagen synthesis. The published clinical evidence is clearest for skin outcomes — a 2024 review of the research reports that consistent daily supplementation at around 10g (10,000mg) per day improves skin elasticity, hydration and the appearance of fine lines over 8 to 12 weeks. More research is emerging on hair, nail and joint outcomes.
Dose is the critical factor. Most clinical studies have used 5,000–10,000mg per day. Many collagen products on the market contain a fraction of this — which is part of why some people see results and others don't.
Frequently Asked Questions
What is collagen made of?
Collagen is a protein made up of amino acids — predominantly glycine, proline and hydroxyproline. These are "non-essential" amino acids, meaning the body can produce them, but collagen itself is hard to get in meaningful amounts from a typical diet.
What does collagen do in the body?
Collagen is the body's main structural protein. It provides strength and elasticity to skin, bones, tendons, ligaments, cartilage, blood vessels and connective tissue throughout the body. It's often described as the body's biological scaffolding.
How many types of collagen are there?
Current research recognises 28 distinct types of collagen in the human body. Older sources often cite 16. Despite the variety, around 80 to 90 per cent of the collagen in the body belongs to Types I, II and III.
Why do we lose collagen?
The body's natural collagen production gradually declines from around the age of 25, at approximately 1% per year. Sun exposure also accelerates collagen breakdown by damaging collagen fibres directly.
Does drinking collagen actually work?
The clinical evidence for hydrolysed collagen peptides is clearest for skin outcomes — elasticity, hydration and the appearance of fine lines — at doses of around 10g (10,000mg) per day over 8 to 12 weeks. More research is emerging on hair, nail and joint outcomes. The dose and consistency matter — many products on the market are underdosed.
Want the full picture? Read our complete guide to liquid marine collagen — covering dose, sources, the research and how to choose the right supplement.
Kollo Health was co-founded by Jenni Falconer — TV presenter, Smooth Radio breakfast host, ten-time London Marathon runner and host of the RunPod podcast. Read her story and why she created Kollo.
