What Is Collagen? What It Does and Which Benefits Are Real

What is collagen made of? The triple helix explained

Each collagen molecule is made of three long protein chains. Every chain follows a repeating pattern in which every third position is taken by glycine, the tiniest amino acid. Most of the other places are filled by proline and hydroxyproline. Because glycine is so small, the three chains can wind tightly around each other into a rope shaped structure called the collagen triple helix.

Those ropes then line up side by side and link to each other to form fibrils. Fibrils bundle into collagen fibers (spelled fibres in British English), and the fibers weave into a network called the collagen matrix. Think of it like a climbing rope: thin threads, twisted into strands, twisted into a cord that is very hard to snap.

How is collagen made in the body?

Cells called fibroblasts (in skin) and osteoblasts (in bone) build the chains from amino acids. Enzymes then add small chemical groups that lock the helix in place. Those enzymes need vitamin C to work, which is why a severe lack of vitamin C causes scurvy, a disease of weak gums, slow healing and fragile blood vessels. Zinc, copper and manganese also help. Copper is needed for collagen cross linking, the step that ties neighbouring molecules together so the fibers become strong.

So the honest collagen definition is simple: a long, tough, rope like protein that your body builds from food, using amino acids plus a few vitamins and minerals.

Where is collagen found in the body?

About 28 types of collagen are known. Five of them do most of the work you would notice. The table shows where each sits. The full breakdown, including what the numbers on supplement labels mean, is on our page about the different types of collagen.

In the skin, collagen lives in the dermis, the thick middle layer under the surface. It shares that space with elastin, which lets skin snap back, and with hyaluronic acid, which holds water. The top layer you touch, the epidermis, has very little collagen of its own.

What does collagen do to your body?

Collagen's function is mostly mechanical. It is what stops your tissues from tearing, sagging or crumbling. Here is what it does, part by part.

• Skin: keeps it firm and helps it resist stretching. When collagen thins, skin becomes looser and creases more easily. Our collagen for skin guide covers what helps.
• Bones: collagen is the flexible frame that minerals such as calcium stick to. Minerals give hardness; collagen gives a little bend so bones do not shatter.
• Tendons and ligaments: these are packed with type I fibers lined up in one direction, so they can take a huge pull.
• Cartilage: type II collagen forms a mesh that traps water and cushions joints.
• Blood vessels and organs: type III and IV collagen give walls their shape.
• Healing: when you cut yourself, fibroblasts lay down new collagen to close the gap. That is what a scar is made of.

How collagen changes as you age

Your body keeps making and breaking down collagen all your life. In youth, making wins. From early adulthood the balance slowly tips. A figure you will often see is a loss of about 1 percent a year from your mid twenties, but treat that as a rough estimate, not a measured rule. Collagen cannot be measured with a blood test, so nobody can tell you your personal number.

For women, the drop speeds up sharply after menopause as oestrogen falls. A widely repeated dermatology estimate puts the loss at about 30 percent of skin collagen over roughly the first half decade after menopause. Our page on collagen for women looks at that stage in detail, and the collagen for men page covers the slower, steadier male pattern.

If you want to know which changes are normal and which need a doctor, read our guide to signs of low collagen.

Collagen benefits: what the evidence actually shows

Most claims about the health benefits of collagen come from supplement marketing. Here is a calmer view of what research supports, based on reviews such as the Harvard Nutrition Source collagen page. Bear in mind that collagen studies tend to be small, and companies selling collagen paid for a large share of them.

Two things are worth knowing. First, any benefit fades once you stop taking it. Second, collagen is missing tryptophan entirely, which makes it an incomplete protein; keep foods like eggs, beans, yoghurt and fish as the backbone of your protein intake. For the hair question in depth, see collagen for hair; for the weight question, see collagen and weight loss.

Natural collagen in food versus supplements

Animal collagen is found only in foods with connective tissue: skin, bones, tough cuts of meat, the skin of fish, broths made from bones, and gelatin. That is why slow cooked collagen in meat turns soft and sticky. Plants contain no collagen at all, but beans, seeds, citrus and leafy greens supply raw materials like protein, copper, zinc and vitamin C that your body uses to build its own. The collagen rich foods guide sorts foods into those that give collagen itself and those that give the raw materials.

Supplements are usually hydrolyzed collagen, also called collagen peptides: collagen cut into short pieces so it dissolves in a drink. Gelatin is collagen that has been only partly broken down, so it sets when cool.

Whether it comes from a stew or a scoop, eaten collagen is split by digestion into free amino acids and short peptides. Your body does not send it straight to your face. A few of those fragments might signal fibroblasts to get busy, which is the main theory behind the skin trials. To compare forms and doses, start at our collagen supplements guide.

How to keep the collagen you have

Protecting existing collagen is easier than replacing it. This checklist is ordered by strength of evidence.

• Wear sunscreen every day: a broad spectrum product rated SPF 30 plus, on face, neck and hand backs.
• Use a retinoid at night. No other anti-aging cream has as much research behind it as a retinoid. Start slowly; our retinol guide explains how.
• Do not smoke.
• Get enough protein and vitamin C. Aim for the NIH vitamin C intake: 75 mg for women, 90 mg for men, more for smokers.
• Keep sugar moderate to limit glycation.
• Sleep regularly and keep alcohol modest.
• Consider clinic treatments such as microneedling or laser if you want more, done by a qualified practitioner.

For a practical plan aimed at facial skin, read how to boost collagen in your face, and fold the steps into a simple anti-aging skincare routine.

Uses of collagen outside your own body

Animal collagen has many uses beyond supplements. Knowing them helps make sense of some odd search terms.

• Food: gelatin in jellies, sweets and some yoghurts; sausage casings.
• Medicine: wound dressings, some dissolvable stitches and materials that help bone or gum grafts heal.
• Cosmetics: collagen in creams works as a moisturiser and film former. The molecule is too bulky to travel down to the dermis, so it does not add to your own supply.
• Injections: purified bovine collagen fillers were used in the past and are now rare. Most fillers today are hyaluronic acid, and some injectables stimulate your own collagen instead. Our page on collagen injections and treatments compares them.

What is corneal collagen cross linking?

This is an eye procedure, not a beauty treatment. An eye specialist puts riboflavin (vitamin B2) drops on the cornea and shines ultraviolet light on it. This creates new links between collagen fibers, which stiffens a cornea that has become weak and bulging, a condition called keratoconus. It has nothing to do with taking collagen by mouth.

Every collagen topic on this site, in one table

Use this table to jump to the page that answers your question.

Who should be careful with collagen supplements

Collagen is generally well tolerated. When people do have trouble, it tends to be fullness, bloating, heartburn or a lingering taste. Still, some readers should speak to a professional before starting.

Supplements are not checked for safety or effect before sale in the US, so look for an independent seal; USP, NSF and Informed Choice all run testing programmes. You can read more on the Cleveland Clinic collagen page.