What actually causes ageing? (beyond wrinkles)

Most people think of ageing as the visible stuff - the lines, the grey hair, the gradual slowing down. These are real, but they're symptoms of something happening at a level you can't see. The actual mechanisms of ageing are cellular and molecular, and understanding them changes how you think about what's worth doing to slow the process.

This matters beyond aesthetics. The same processes that produce wrinkles and grey hair also drive the diseases most likely to limit your health and lifespan - cardiovascular disease, cognitive decline, cancer, and metabolic dysfunction. Ageing and disease aren't separate things. They share the same root mechanisms.

Ageing isn't a single process. It's the cumulative effect of several interlocking mechanisms - most of which are at least partially influenced by how you live.

Cellular senescence

Cells can only divide a limited number of times before they stop replicating - a limit determined partly by the length of telomeres, the protective caps on chromosomes that shorten with each division. When a cell reaches this limit, it becomes senescent: it stops dividing but doesn't die. It continues to exist in a dysfunctional state, secreting inflammatory signals that damage the surrounding tissue.

Senescent cells accumulate with age, and their pro-inflammatory secretions - sometimes called the senescence-associated secretory phenotype - are now understood to be a significant driver of chronic inflammation, tissue dysfunction, and many age-related diseases. Telomere length is partly genetic but is also significantly influenced by lifestyle: chronic stress, poor diet, sleep deprivation, smoking, and inactivity all accelerate shortening. Regular exercise, conversely, is one of the most consistently supported interventions for slowing it.

Oxidative stress and free radical damage

Normal cellular metabolism produces free radicals - unstable molecules that damage DNA, proteins, and cell membranes in a process called oxidative stress. Under healthy conditions, the body neutralises these with antioxidants, particularly glutathione, which is produced internally. As we age, both free radical production tends to increase and antioxidant capacity declines, tipping the balance toward cumulative damage.

This oxidative damage accumulates in DNA over time, contributing to the mutations that underlie both ageing and cancer. It damages mitochondria, reducing their efficiency and energy output. It affects proteins throughout the body, impairing their function. Environmental factors dramatically increase oxidative load: pollution, cigarette smoke, excessive alcohol, and a diet high in processed food all generate free radicals far beyond what normal metabolism produces.

Supporting glutathione production - the body's master antioxidant - is one of the more evidence-backed approaches to reducing oxidative burden. NAC (N-acetyl-cysteine) provides cysteine, the rate-limiting precursor to glutathione, making it more effective at raising levels than supplementing glutathione directly.

Mitochondrial decline

Mitochondria are the energy-producing structures within cells, and their function declines progressively with age. This decline reduces the efficiency of energy production, increases oxidative stress (mitochondria are both producers and targets of free radicals), and impairs the cellular repair processes that depend on adequate energy supply.

Mitochondrial decline is one of the reasons physical and cognitive performance tends to fall with age even in people who remain active. The cells are simply producing energy less efficiently than they used to. Coenzyme Q10, which plays a central role in the mitochondrial energy production chain, declines with age and its supplementation has reasonable evidence for supporting mitochondrial function. NAD+ - also central to mitochondrial metabolism - declines significantly from the 30s onward, and its restoration via NMN is an active area of longevity research.

Chronic inflammation - "inflammaging"

One of the most well-supported theories of ageing centres on the role of chronic, low-grade inflammation - a state that researchers have termed "inflammaging." Unlike acute inflammation, which resolves after an injury or infection, chronic inflammation persists at a low level over years and decades, gradually damaging tissues and organs.

Inflammaging drives cardiovascular disease by promoting atherosclerosis. It contributes to insulin resistance and type 2 diabetes. It accelerates cognitive decline and is associated with increased Alzheimer's risk. It promotes cancer by creating an environment in which abnormal cells are more likely to survive and proliferate. The common thread through most major age-related diseases is this background inflammatory state.

Diet is the most powerful lever. Ultra-processed food, refined carbohydrates, and seed oils promote inflammation; whole foods, omega-3 fatty acids, and a diverse plant-based diet reduce it. Curcumin - the active compound in turmeric - has among the strongest evidence of any food-derived compound for modulating inflammatory pathways, and at the 95% curcuminoid extract dose with enhanced absorption, it reaches therapeutic concentrations in the bloodstream.

What you can actually do about it

The lifestyle interventions with the strongest evidence for slowing biological ageing are not complicated: regular exercise (particularly resistance training), consistent high-quality sleep, a whole-food diet low in sugar and ultra-processed food, not smoking, and limiting alcohol. These aren't small effects - people who consistently do these things show measurably younger biological markers than those who don't, regardless of chronological age.

Caloric restriction and intermittent fasting have strong evidence in animal models and growing evidence in humans for activating longevity pathways - particularly AMPK and sirtuins - that improve cellular maintenance. Time-restricted eating is the most accessible version for most people.

For supplementation, the most credible interventions map directly onto the mechanisms above. NAC for glutathione and oxidative stress. Curcumin for chronic inflammation. Coenzyme Q10 and NMN for mitochondrial function and NAD+ restoration. Omega-3 fatty acids for anti-inflammatory signalling. None of these reverse ageing, but each addresses one of its core mechanisms with meaningful evidence behind it.