Understanding Collagen Types and Their Importance

Collagen is the most abundant protein in the human body, accounting for approximately 30% of total protein content and up to 80% of the dry weight of the dermis. It provides the structural scaffolding that gives skin its firmness, resilience, and youthful appearance. However, not all collagen is created equal, understanding the different types and their roles is essential for anyone interested in skin health and aesthetic treatments.

What Is Collagen?

Collagen is a family of structural proteins characterised by a distinctive triple-helix molecular structure. At least 28 different types of collagen have been identified in the human body, though five types are particularly relevant to skin health.

The five key collagen types for skin

Type I Collagen

Type I is the most abundant collagen in the body, comprising approximately 80% of dermal collagen. It forms thick, tightly packed fibres that provide the primary structural framework of the skin, giving it tensile strength and resistance to stretching. Type I collagen is the dominant collagen in mature, healed skin.

Research in Matrix Biology (2018) demonstrated that type I collagen fibres become increasingly fragmented and disorganised with age, directly correlating with the visible loss of firmness and the development of wrinkles.

Type III Collagen

Type III collagen comprises approximately 15-20% of dermal collagen. It forms thinner, more flexible fibres that provide elasticity and suppleness. Importantly, type III is the predominant collagen produced during wound healing and tissue repair, it is laid down first and then gradually replaced by the stronger type I collagen during the remodelling phase.

“This is why skin immediately after a wound or treatment feels softer and more pliable,” explains Professor Thornhill. “The initial type III collagen matrix is more flexible. Over the following months, it is gradually remodelled into the denser, stronger type I matrix, which is why the final results of collagen-stimulating treatments continue to improve for 3-6 months.”

Type IV Collagen

Unlike types I and III, type IV collagen does not form fibres. Instead, it forms a sheet-like network that is the primary structural component of the basement membrane, the thin layer separating the epidermis from the dermis. A healthy basement membrane is essential for proper communication between the epidermis and dermis, nutrient transport, and structural integrity.

Type V Collagen

Type V collagen is found on the surface of type I collagen fibres, where it helps regulate fibre diameter and assembly. It also plays a role in tissue development and wound healing. Though less abundant, it is essential for proper collagen fibre organisation.

Type VII Collagen

Type VII collagen forms anchoring fibrils that secure the basement membrane to the underlying dermis. Deficiency or damage to type VII collagen compromises the structural connection between skin layers, which adds to skin fragility and poor wound healing.

How collagen changes with age

Collagen production peaks in the early 20s and begins to decline at approximately 1-1.5% per year from the mid-20s onwards. However, the changes are not simply quantitative, the quality and organisation of collagen also deteriorate.

• Reduced production: Fibroblast activity declines, producing less new collagen
• Increased degradation: Matrix metalloproteinases (MMPs), enzymes that break down collagen, become more active with UV exposure and ageing
• Cross-linking: Advanced glycation end products (AGEs) cause abnormal cross-linking between collagen fibres, reducing flexibility and resilience
• Fragmentation: Existing collagen fibres become broken and disorganised
• Ratio shift: The ratio of type I to type III collagen shifts, affecting overall skin quality

How aesthetic treatments stimulate collagen

Different treatments stimulate collagen through various mechanisms:

Controlled injury (microneedling, laser, peels)

These treatments create controlled damage that activates the wound healing cascade. The initial inflammatory response recruits fibroblasts, which produce type III collagen that is subsequently remodelled into type I. This explains the 3-6 month timeline for optimal results.

Biostimulators (Sculptra, Radiesse)

These products trigger a foreign body response that stimulates fibroblasts to deposit new collagen around the biostimulatory particles. Histological studies have confirmed the production of organised type I collagen fibres in response to PLLA (Sculptra) treatment.

Radiofrequency and Ultrasound

Thermal energy causes immediate collagen contraction (tightening) followed by a healing response that produces new collagen over subsequent months. The heat denatures existing collagen fibres, triggering the body’s repair mechanisms.

Topical Retinoids

Retinoids stimulate collagen production through direct activation of fibroblast gene expression, increasing the production of procollagen (the precursor to mature collagen) and reducing MMP activity that degrades existing collagen.

Collagen supplements: What the evidence says

Oral collagen supplements (typically hydrolysed collagen peptides) have generated significant commercial interest. A systematic review in the Journal of Drugs in Dermatology (2019) analysed 11 randomised controlled trials and found that collagen supplementation (2.5-10g daily for 8-24 weeks) was associated with improvements in skin elasticity, hydration, and wrinkle reduction compared to placebo.

However, the quality of evidence remains moderate, and the mechanisms are debated. Some researchers suggest that ingested collagen peptides act as signalling molecules, stimulating fibroblasts to increase their own collagen production rather than being directly incorporated into the skin.

Frequently asked questions

Can I rebuild lost collagen?

Yes, to a degree. Aesthetic treatments such as microneedling, laser resurfacing, biostimulators, and radiofrequency can stimulate new collagen production. However, the skin will never return to the collagen density of youth. The goal of treatment is to stimulate sufficient new collagen to measurably improve firmness, texture, and appearance. Combining professional treatments with retinoid use and sun protection provides the best outcomes.

Do collagen supplements really work?

Clinical evidence suggests that oral hydrolysed collagen supplements can improve skin hydration, elasticity, and wrinkle depth when taken consistently for at least 8-12 weeks. However, the improvements are modest compared to professional treatments. Collagen supplements are best viewed as a supportive measure alongside a comprehensive skincare and treatment regimen, not a standalone solution.

What destroys collagen the most?

UV radiation is the single greatest extrinsic cause of collagen destruction. It directly damages collagen fibres and dramatically increases MMP activity, the enzymes that break collagen down. Smoking is the second most significant factor. Sugar (through glycation) and chronic inflammation also contribute to collagen degradation. Daily SPF use is the most effective anti-ageing measure precisely because it protects existing collagen from UV-mediated destruction.

Is there a difference between collagen for skin and collagen for joints?

Type I and III collagen are the primary types relevant to skin, whilst type II collagen is the dominant type in cartilage and joints. Supplements marketed for skin typically contain types I and III (often from marine or bovine sources), while joint supplements usually contain type II collagen (often from chicken sternum). Some products combine multiple types for comprehensive support.