The Science of Skin Ageing: What's Actually Happening Under the Surface A

Ageing is inevitable. But understanding the biology of how and why it happens gives you a far more targeted and effective approach than chasing whichever serum is trending.

Here's what's actually going on beneath the surface, and what the evidence says you can do about it.

Collagen loss: the structural story

From your mid-20s onward, collagen production declines at roughly 1% per year. Collagen is the main structural protein in your dermis; it's what gives skin its firmness and resilience. As levels fall and the collagen fibres that remain become disorganised and cross-linked, you get the gradual loss of elasticity and the formation of lines and wrinkles.

Compounding this is a parallel loss of elastin (which allows skin to snap back) and hyaluronic acid (which binds water in the dermis, giving skin its plump, hydrated appearance).

Intrinsic vs extrinsic ageing

It helps to distinguish between these two processes.

Intrinsic ageing is chronological, driven by genetics and the passage of time. Cell turnover slows, the epidermis thins, and melanocytes (pigment-producing cells) become less evenly distributed.

Extrinsic ageing is environmental, primarily UV radiation, but also air pollution, smoking, and repeated muscle contractions. UV exposure alone accounts for an estimated 80–90% of visible facial ageing. This is the category where your choices make an enormous difference.

What the evidence actually supports

Retinoids remain the most thoroughly studied anti-ageing topical ingredient in dermatology. Prescription tretinoin has decades of randomised controlled trial data showing it increases collagen synthesis, speeds cell turnover, and reduces the appearance of fine lines, uneven pigmentation, and rough texture. Over-the-counter retinol converts to retinoic acid on the skin and works via the same mechanism, though more gradually and with less irritation.

Start with a low concentration (0.025–0.05% retinol, or 0.025% tretinoin if prescribed), apply at night, and introduce it slowly: two to three nights a week before building up.

SPF is genuinely the most impactful anti-ageing product you can use. A landmark split-face study demonstrated measurably reduced photoageing on the SPF-protected side over just a few years. A broad-spectrum SPF 30–50, used daily (including on overcast days) is non-negotiable.

Vitamin C (L-ascorbic acid) acts as an antioxidant, neutralising the free radicals generated by UV exposure that degrade collagen. At concentrations of 10–20%, it also has direct evidence for stimulating collagen synthesis. It's notoriously unstable, so look for formulas with a low pH and opaque or airless packaging, and use it in the morning under SPF.

Peptides send signalling messages to fibroblast cells, encouraging collagen production. The evidence is less robust than for retinoids, but specific peptides (particularly Matrixyl, or palmitoyl pentapeptide-4) have peer-reviewed data supporting their activity. They're a good supporting ingredient, particularly for those who can't tolerate retinoids.

The honest bottom line

No topical product reverses ageing. What they can do, with good evidence, is slow the rate of visible change and improve skin quality. The best regimen is the one you'll actually use consistently: daily SPF, a retinoid three to five nights a week, and adequate hydration.