Collagen: What it does in the body, why you lose it, and how to get it back

Collagen is a protein that the body produces itself and is found in skin, connective tissue, tendons, joints, and bones. It is a central part of the body's structure and helps tissues maintain their shape, strength, and elasticity. In the skin, collagen contributes to firmness and density. In joints and tendons, it allows the body to withstand stress without tissue breakdown.

Collagen is not a cosmetic substance. It is a structural protein that affects the entire body.

What collagen is actually made of

Collagen primarily consists of three amino acids:

• glycine
• proline
• hydroxyproline

These are assembled into long fibers that form an internal framework in tissues. The body cannot produce collagen without access to these building blocks.

Collagen works together with other structural components in the body:

• elastin, which gives tissues the ability to stretch and contract
• hyaluronic acid, which contributes to moisture balance in the tissues
• vitamin A (retinol), which is involved in the skin's normal cell renewal
• vitamin C, which is necessary for the body to be able to form collagen

Why you lose collagen

The body renews collagen constantly, but production gradually decreases with age. At the same time, existing collagen breaks down faster. This happens to everyone, but the pace is affected by lifestyle and strain.

Factors that increase collagen loss:

• aging
• hormonal changes
• sun and UV radiation
• sleep deprivation
• high stress levels
• low protein intake
• lack of movement

How this develops with age

In your 20s, collagen production is high and stable. Building and breakdown are in balance, and net loss is usually very low.

From the late 20s and through the 30s, collagen production begins to decline, often estimated at around 1% per year. The changes are small, but recovery is slower than before.

In your 40s and 50s, the loss becomes more noticeable. Overall, the skin may have lost around 20–30% of its collagen compared to young adulthood. In women, hormonal changes can lead to faster loss during certain periods.

After age 60, collagen turnover is significantly lower. Total collagen loss in the skin can then be 40–50% or more compared to levels in the 20s. The body's focus is more on maintaining existing structure.

How the body actually gets collagen back

The body cannot absorb ready-made collagen and place it directly in the skin or joints. All collagen supplied through food or supplements is first broken down during digestion.

During digestion, collagen is broken down into:

• free amino acids
• short peptides

These are absorbed into the bloodstream and used by the body to produce its own collagen where needed. The actual production takes place in cells called fibroblasts.

For this process to work, three things must be in place.

1. Correct amino acids – what you actually need to eat

Regular lean meat contains little glycine. For collagen, the body needs proteins that also contain connective tissue.

Foods that provide good collagen building blocks:

• meat with connective tissue (beef, lamb)
• fish with skin
• eggs
• gelatin
• bone broth

This is why traditional diets used the whole animal, not just fillets.

2. Vitamin C must be present

Without vitamin C, the body cannot form collagen fibers correctly. The process stops, regardless of how much protein is available.

3. Load – collagen is built where it is used

Collagen is only produced in tissues that are loaded.

This means:

• strength training
• walking
• carrying
• movement in joints
• daily activity

Without load, the body does not receive a signal to build new collagen.

4. Sleep – the numbers are clear

Most tissue repair occurs during sleep.

For collagen maintenance, the body needs:

• 7–9 hours of sleep per night
• a consistent sleep schedule

Prolonged sleep deprivation leads to lower collagen synthesis and faster breakdown.

Where dietary supplements fit in

Collagen supplements provide a concentrated source of glycine and proline. They do not replace:

• sleep
• food
• movement

They are often used as a supplement when:

• food intake is lower
• protein mainly comes from lean meat
• age increases
• recovery takes longer

When collagen is part of diet, exercise, and sleep, it becomes part of how the body maintains its structure over time.