Klotho
α-Klotho, s-Klotho, soluble Klotho, KL protein, "longevity protein"; gene KL
1What it is
Klotho was discovered by accident in 1997 when mice with a disrupted KL gene aged rapidly — arteriosclerosis, osteoporosis, skin atrophy, short lifespan — and were named after the Greek fate who spins the thread of life (Kuro-o 1997). Mice that overexpress it live 20–30% longer (Kurosu 2005). In humans, a common variant (KL-VS) and higher circulating Klotho levels are associated with better cognition and lower mortality in some cohorts.
It is a natural protein, not a peptide, and not a synthetic research compound. Its size, glycosylation and instability mean that making a biologically active version is a serious biotechnology undertaking. Anything sold as "Klotho" for self-administration should be assumed, until proven otherwise, not to be active human α-Klotho. Legitimate development is proceeding through gene therapy and engineered proteins in companies and academic labs, not through vials.
2How it's thought to work
3What the research shows
Cognition in mice
Cognition in aged non-human primates
Human genetics and circulating levels
Kidney disease, vascular calcification, fibrosis
Administration to humans
4Reported side effects and interactions
Literature-reported
No human administration data. In mice, high Klotho exposure can cause hypophosphataemia-related effects and has been linked in some studies to impaired bone mineralisation, consistent with its phosphate role. The bell-shaped dose response in monkeys suggests "more" is not better.Community-reported
Reports exist of people injecting products labelled Klotho; given the near-certainty that such products are not active glycosylated α-Klotho, these reports (ranging from "nothing" to "clearer thinking") cannot be attributed to the protein and may reflect placebo or contaminants.Theoretical. Suppressing insulin/IGF-1 signalling could affect glucose handling; FGF23 pathway effects on phosphate, calcium and vitamin D; immunogenicity of any injected foreign protein, especially a poorly characterised one.
Interactions. None established. Phosphate binders, vitamin D analogues and anything acting on the FGF23 axis are the mechanistically relevant classes.
Markers researchers commonly monitor
No markers are established for administration. Markers that follow the physiology, commonly discussed:
| Marker | Why it's watched |
|---|---|
| Serum soluble α-Klotho (ELISA) | available through some specialist labs; assays are variable between manufacturers and poorly standardised, so compare only within one lab. |
| Serum phosphate, calcium, 1,25-dihydroxyvitamin D and intact FGF23 | the core Klotho axis; the most physiologically meaningful panel. |
| eGFR and cystatin C | kidney function determines Klotho production. |
| Fasting glucose and insulin | insulin/IGF-1 suppression mechanism. |
| Cognitive testing (validated digital batteries) | the outcome most members are interested in; needs a proper baseline to mean anything. |
Free for everyone. Safety information is never behind a paywall.
5Reconstitution and handling
Genuine recombinant Klotho is a research-grade glycoprotein shipped frozen with carrier protein, handled in a laboratory, and not stable in at fridge temperature for weeks. There is no established home-use preparation, and the calculator below should be used only for mass-to-volume arithmetic on a labelled product, not as an endorsement that such products contain what they claim.
Open in calculator, pre-loaded →6Commonly studied alongside
GDF-11 (#90) — the two are the "young blood factor" proteins most often discussed together; Humanin (#15) and MOTS-c as fellow "longevity" signals; in the literature, FGF23 and vitamin D as the biochemical partners. Exercise and vitamin D status are the only interventions with human data for raising endogenous soluble Klotho †.
Informational cross-links. Not stack recommendations.
7Regulatory status by region
| Region | Status (checked —) |
|---|---|
| United States | Not FDA-approved. No approved product; not on the compounding bulk-substance lists † |
| European Union | Not authorised |
| United Kingdom | Not licensed |
| Australia | Not approved |
| South Africa | Not registered |
| Sport (WADA) | Not specifically named; as a non-approved substance S0 applies, and as a growth-factor-pathway modulator S2 is arguable † |
8Open questions
- How does peripherally given Klotho improve cognition without crossing into the brain?
- Why is the dose-response bell-shaped, and what does that mean for any future human dosing?
- Will any human trial of a Klotho protein or gene therapy report cognitive or ageing outcomes?
- Does anything sold as "Klotho" outside a lab contain the active protein? No independent analysis is published.
9References
- 1Kuro-o M et al. (1997). Mutation of the mouse klotho gene leads to a syndrome resembling ageing. Nature. PubMed · DOI
- 2Kurosu H et al. (2005). Suppression of aging in mice by the hormone Klotho. Science. PubMed · DOI
- 3Arking DE et al. (2002). Association of human aging with a functional variant of klotho. Proc Natl Acad Sci USA. PubMed · DOI
- 4Semba RD et al. (2011). Plasma klotho and mortality risk in older community-dwelling adults: the InCHIANTI study. J Gerontol A Biol Sci Med Sci. PubMed · DOI
- 5Dubal DB et al. (2014). Life extension factor klotho enhances cognition. Cell Rep. PubMed · DOI
- 6Leon J et al. (2017). Peripheral elevation of a klotho fragment enhances brain function and resilience in young, aging, and α-synuclein transgenic mice. Cell Rep. PubMed · DOI
- 7Castner SA et al. (2023). Longevity factor klotho enhances cognition in aged nonhuman primates. Nat Aging. PubMed · DOI
† Being confirmed by our reviewers against current sources.
10Community
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Self-reported side effects Phase 2
11Page history
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