Klotho is a protein named after the Greek Fate who spun the thread of life — and the name fits. Mice bred to lack it age prematurely; mice engineered to make more of it live longer. In humans, a common genetic variant that raises klotho levels is linked to sharper cognition and better ageing, and a single injection has improved memory in ageing monkeys. The science of klotho and longevity is among the most intriguing in the field, but it is still early — here is what is genuinely established and what remains unproven.
What klotho is
Klotho was discovered in the 1990s when researchers noticed that mice with a disrupted version of a particular gene aged rapidly — developing atherosclerosis, bone loss, skin thinning and a short lifespan — while mice that overexpressed the same gene lived meaningfully longer. The gene was named klotho, and the protein it encodes has been studied as an ageing regulator ever since.
The gene is expressed most strongly in the kidneys and in parts of the brain. It exists in two main forms: a membrane-bound version that acts as a co-receptor regulating phosphate and vitamin D metabolism, and a soluble form (often called alpha-klotho) that circulates in the blood and cerebrospinal fluid and appears to act as a signalling molecule with broad effects. It is this circulating soluble klotho that most longevity research focuses on, and its levels tend to decline with age.
The ageing and cognition associations
Soluble klotho has been linked in laboratory and observational work to several of the recognised hallmarks of ageing — it appears to counter processes including cellular senescence, telomere attrition and mitochondrial dysfunction. That places it upstream of the same pathways targeted by other longevity approaches, such as senolytics that clear senescent “zombie” cells.
The cognitive angle is what has drawn the most attention. In mice, systemic overexpression of klotho improved performance on learning and memory tasks, strengthened a form of synaptic plasticity called long-term potentiation, and enriched a key NMDA-receptor subunit involved in memory. Intriguingly, the cognitive benefit appeared even in young mice and did not track with age — suggesting klotho may enhance brain function somewhat independently of the ageing process itself, rather than simply slowing decline.
The human genetics: the KL-VS variant
The most robust human evidence comes from a common variant of the KLOTHO gene known as KL-VS. People who carry a single copy (heterozygous carriers) tend to have more soluble klotho in their blood than non-carriers, and the variant is reasonably common — present in roughly 15–20% of some populations.
Research linking KL-VS to better cognition tested the association across several separate studies involving several hundred people spanning middle to older age, and found that single-copy carriers performed better on cognitive measures than non-carriers. The relationship is nuanced: carrying one copy appears beneficial, while carrying two copies does not confer the same advantage, pointing to a dose-dependent effect rather than “more is always better.” Separate lines of work have explored whether KL-VS carriage buffers some of the cognitive risk associated with Alzheimer’s-related genetics, though that remains an active and unsettled research question.
The caveat is important: these are genetic associations, not interventions. Carrying KL-VS is correlated with better outcomes, but that does not by itself prove that raising klotho in a non-carrier would reproduce the benefit.
Exercise raises klotho — the actionable part
For most readers, the practical question is whether anything can raise klotho without a gene you do not have. Exercise appears to do exactly that, and this is the most actionable finding in the whole area.
Studies have shown that physical activity increases circulating soluble klotho. A single bout of higher-intensity exercise produces an acute, transient rise in serum klotho, and — more usefully — reviews of training studies find that aerobic exercise sustained over weeks raises soluble klotho levels across a range of populations and health conditions. Aerobic and combined (concurrent) training show the clearest effect; resistance training alone has shown a weaker klotho response in the shorter studies to date, though strength work retains its own well-established longevity benefits.
This dovetails with the broader evidence that exercise is the closest thing we have to a longevity drug. If a simple, free intervention nudges up a protein associated with better brain ageing, that is one more mechanistic reason to protect your aerobic training — alongside the muscular and metabolic benefits captured by markers like grip strength and longevity.
Therapeutic research: promising but early
Could klotho become a treatment? The research is genuinely promising and genuinely early — both at once.
The most striking result to date came from a study, published in Nature Aging with UCSF neurologist Dena Dubal as senior author, in which ageing monkeys given a single injection of klotho showed modest improvements in working memory lasting around two weeks. Notably, a low dose worked where a high dose did not — the effective dose raised klotho to roughly the level seen in early life — underscoring that klotho biology is dose-sensitive and not simply “more is better.” The mechanism is not fully understood: circulating klotho does not appear to cross the blood-brain barrier easily, so researchers suspect it acts indirectly, perhaps by improving signalling between neurons.
That is a long way from a human therapy. There is no approved klotho treatment, the human trial landscape is at an early stage, and questions of delivery, dosing, durability and safety remain open. Anyone marketing a “klotho supplement” or injection as a proven anti-ageing or cognitive therapy is getting well ahead of the evidence. The responsible summary is that klotho is one of the more exciting targets in longevity biology, with a credible mechanistic and genetic rationale, awaiting the human trials that would tell us whether it translates. Tracking whether such interventions actually move validated ageing markers — the kind measured by epigenetic clocks — will be the real test.
Frequently asked questions
What does the klotho protein do?
Klotho is an ageing-regulating protein made mainly in the kidneys and brain. A membrane-bound form helps regulate phosphate and vitamin D metabolism, while a soluble circulating form acts as a signalling molecule linked to better cognition and to countering hallmarks of ageing such as cellular senescence. Its levels generally decline with age.
What is the KL-VS klotho variant?
KL-VS is a common variant of the KLOTHO gene. People who carry a single copy tend to have higher soluble klotho and have shown better cognitive performance in multiple studies. Carrying two copies does not confer the same benefit, suggesting a dose-dependent rather than linear effect. It is an association, not a proven intervention.
Can you increase klotho naturally?
Exercise is the best-supported way. Aerobic and combined training sustained over weeks raises circulating soluble klotho across varied populations, and a single harder session causes an acute, temporary rise. No supplement has been proven to raise klotho and deliver the associated benefits.
Is there a klotho treatment for ageing?
Not yet. A single klotho injection modestly improved memory in ageing monkeys at a low dose, which is encouraging, but there is no approved klotho therapy and human trials are at an early stage. Products marketed as proven klotho anti-ageing treatments are ahead of the evidence.
The takeaway
Klotho sits at an unusual intersection: strong basic biology, suggestive human genetics, an eye-catching primate result, and almost no proven human therapy. The honest reading is that it is a legitimate longevity target still awaiting its translational evidence — exciting, but not yet something you can buy. What you can act on today is the part that is already supported: aerobic exercise raises your own klotho, which is one more reason that the least glamorous longevity intervention remains the most reliable one while the therapeutic science catches up.