Why does collagen decrease with age?

Your skin makes less and loses more

Collagen is a structural protein that gives skin strength. Type I collagen is the main form in the dermis, the supporting layer beneath the skin's surface. Cells called fibroblasts make collagen, which assembles into fibres that form a supportive network, which is considerably more work than printing collagen on a jar. Collagen is continuously made and broken down, so the skin's support structure comes with ongoing maintenance rather than a lifetime warranty. With age, production and destruction become less balanced. Collagen bundles become thinner, fragmented and disorganised instead of retaining their younger arrangement. The change is therefore about both quantity and quality: less collagen remains, and the network left behind works less effectively.3

Damaged collagen makes replacement harder

Fibroblasts need more than the raw materials for collagen. They attach to surrounding collagen fibres and pull against them, which makes support sound rather less like a desk job. The resistance helps the cells stay spread out and supports the signals involved in collagen production. Enzymes called matrix metalloproteinases gradually cut collagen fibres during ageing. As fragments accumulate, fibroblasts lose attachment points and cannot maintain the same tension. The cells become less spread out, and collagen production falls. This creates a feedback loop: a damaged support network makes the cells responsible for replacing it less productive.4

Changes in chemical signals also contribute. Older skin has higher levels of prostaglandin E2, a signalling molecule that inhibits collagen production in cultured fibroblasts. Reduced cell spreading appears to increase this signal, linking the physical breakdown of the collagen network with a further slowdown in replacement.4

Why does this happen even without sun damage?

Intrinsic ageing means the changes that happen naturally over time, including in skin usually covered by clothing. Genetics influence the pace. Normal cell metabolism produces reactive oxygen species, molecules that can damage cell membranes, enzymes and DNA as they accumulate. Skin cells also age biologically, changing how well the tissue maintains itself. Hormones matter too. Oestrogen helps maintain skin integrity, and its decline around menopause contributes to earlier skin ageing and a significant reduction in collagen production. These processes happen alongside environmental damage rather than instead of it.125

What speeds up collagen loss?

Sun exposure adds damage on top of natural ageing. Ultraviolet light reduces collagen production and speeds up breakdown. Smoking also reduces production, while chemicals in tobacco smoke increase collagen degrading enzymes. Nicotine narrows blood vessels, reducing the oxygen and nutrients reaching skin. Pollution and poor nutrition can accelerate skin ageing too. Too much sugar and refined carbohydrate can contribute through glycation, a process in which sugar attaches to proteins and creates molecules that damage collagen.135

What can you do about it?

You cannot stop intrinsic ageing, but you can reduce avoidable damage. Wear SPF 30 or higher sunscreen every day, use protective clothing and a wide brimmed hat outdoors, and avoid tanning beds and smoking. Eat a balanced diet with enough protein, vitamin C and minerals needed for collagen production. Starting sun protection in adulthood can still slow visible skin ageing.135

Eating collagen does not deliver intact collagen directly to your skin: digestion breaks it into smaller pieces that your body uses where needed, which leaves the skin without a reserved delivery slot. Collagen peptides may improve skin hydration and elasticity, but their benefits remain uncertain. Supporting collagen production is not the same as stopping the ageing processes that reduce it.1