Klotho

Dosing from the Literature

Published for longevity: no dose; the mice that lived longer had extra klotho genes, not injections of the protein. The doses below come from memory and kidney studies in animals and from one promoter’s stated 10 mcg every two weeks. Not published: any study giving klotho to people.

No published study has given klotho protein, or the seller’s alphaKlothoLR, to a person at any dose. The table records the doses animal studies used, as published, and Jay Campbell’s stated regimens by date. The animal doses are per kilogram of body weight, given once, for a few days, or by pump for 12 weeks; the 10 mcg rows are one promoter’s statements. None of them is a recommendation.

What It Is

Klotho (α-Klotho) is a protein, not a peptide: the human protein is 1,012 amino acids long, with a large outer part, a single stretch that crosses the cell membrane, and a short tail inside the cell (UniProt Q9UEF7). The gene was described in 1997 in mice with a defect in it, which developed “a syndrome that resembles human ageing, including a short lifespan, infertility, arteriosclerosis, skin atrophy, osteoporosis and emphysema” (Kuro-o et al., 1997). The human gene, on chromosome 13q12, makes two transcripts, one for a membrane protein and one for a secreted protein (Matsumura et al., 1998). In cell studies, the enzymes ADAM10 and ADAM17 cut the membrane protein’s outer part free (Chen CD et al., 2007), and the klotho found in serum and cerebrospinal fluid is 130 kDa (Imura et al., 2004).

Blood levels fall with age. In the first ELISA study, 142 healthy adults averaged 562 pg/mL (range 239–1,266) and 39 children 952 pg/mL, and levels were inversely related to age and creatinine (Yamazaki et al., 2010). In 346 healthy adults, mean serum levels were 932.6 pg/mL at 18–34, 796.7 at 35–54 and 612.1 at 55–85 (Espuch-Oliver et al., 2022). PubMed lists 2,619 records with “klotho” in the title (searched September 29, 2026).

What is sold is a modified version. BioLongevity Labs lists “Klotho (alphaKlothoLR) (20mcg)” as pairs of vials and describes “a patented, long-release version of the recombinant Klotho protein” that combines “α-Klotho protein (998 amino acids)” with “a proprietary 29-amino acid albumin binding peptide (GGSGGSGGSGGRLIEDICLPRWGCLWEDD),” with a molecular weight of “~133-135 kDa” and “cellular activity up to 19 days.” The page labels it “For in vitro research use only” (product page). Campbell writes that he “engineered our own version of the Klotho protein” with a co-developer, using “the same proprietary albumin-binding construct” as FLGR242 (Campbell, June 5, 2026), and calls BioLongevity Labs “my company” (Campbell, September 18, 2026).

The binder’s last 18 residues, RLIEDICLPRWGCLWEDD, are SA21, an albumin-binding peptide published in 2002; SA21 bound human albumin with a dissociation constant of 467 nM (Dennis et al., 2002). The seller gives its construct an albumin affinity of “<20 nM” and an FGF23 binding affinity of “15-30 nM (optimized: 16.2 nM)” (product page). Campbell’s November 2025 article gives the klotho part as 1,012 amino acids and the product page as 998; 1,012 is the length of the whole human protein, membrane anchor included (UniProt Q9UEF7). What has not been published: the construct’s full sequence, how it is made beyond “recombinant expression,” its binding, its activity, and its half-life in any species. PubMed returned no record for alphaKlothoLR on September 29, 2026. The seller uses the same binder in its follistatin product, which has its own page: FLGR-242.

Mechanism of Action

These are the published mechanisms of native klotho. None has been published for the seller’s construct.

• FGF23 co-receptor (FGFR1c) — Klotho converts the receptor FGFR1(IIIc) into a specific receptor for FGF23, a hormone made in bone that regulates kidney function; an antibody against klotho blocked FGF23’s action in mice (Urakawa et al., 2006). FGF23 is secreted in response to phosphate intake and acts through klotho–FGFR complexes, most abundant in the renal tubules, to regulate mineral metabolism (Kuro-o, 2019). In the crystal structure, the shed outer part of klotho holds FGF23 and FGFR1c together as a non-enzymatic scaffold; activating the receptor still needs heparan sulfate (Chen G et al., 2018).
• Shedding (ADAM10 and ADAM17) — In transfected cells, ADAM10 and ADAM17 cut klotho’s outer part free and insulin increased the shedding; in rat kidney slices, insulin raised shedding and a metalloproteinase inhibitor lowered it (Chen CD et al., 2007).
• Insulin and IGF-1 receptor signaling — Klotho protein suppressed tyrosine phosphorylation of the insulin and IGF-1 receptors; at 100 pM it cut insulin-stimulated glucose uptake in cultured L6 muscle cells by 55%. Male mice overexpressing klotho were somewhat insulin resistant, and both sexes resisted IGF-1 (Kurosu et al., 2005).
• FoxO and manganese superoxide dismutase — Klotho activated FoxO forkhead transcription factors, induced manganese superoxide dismutase, and increased resistance to oxidative stress at the cell and whole-animal level (Yamamoto et al., 2005).
• Wnt — Klotho bound Wnt family members and suppressed their activity; tissues of klotho-deficient mice showed increased Wnt signaling (Liu et al., 2007).
• NMDA receptor subunit GluN2B (brain) — Mice overexpressing klotho had more synaptic GluN2B, and blocking GluN2B abolished klotho’s effects on learning and memory (Dubal et al., 2014). An injected klotho fragment was detected in the kidney but not the brain, yet it improved cognition, and a GluN2B blocker abolished that too (Leon et al., 2017).
• The seller’s construct — The product page says the albumin binder allows “sustained delivery of Klotho with cellular activity up to 19 days” while “maintaining native FGF23 binding activity (15-30 nM).” Campbell’s November 2025 article adds “(Yes, we have full analytical documentation and extensive independent 3rd-party testing that supports all of the numbers above).” None of that documentation is published. For injected rhesus klotho, the monkey study estimated a putative serum half-life of 29.5 hours, from 8 samples in two animals (Castner et al., 2023).

What the Research Shows

The research below is on native klotho in animals. None of it tested alphaKlothoLR.

• Klotho-deficient mice (1997) — Mice with a defect in the gene had a short lifespan, infertility, arteriosclerosis, skin atrophy, osteoporosis and emphysema (Kuro-o et al., 1997).
• Extra klotho, longer life (mice, 2005) — Two lines of mice engineered to overexpress klotho outlived normal controls by 20.0% and 30.8% (males) and 18.8% and 19.0% (females); average male lifespan was 715 days in controls against 858 and 936. The engineered breeding pairs had fewer offspring (Kurosu et al., 2005).
• Gene therapy in normal mice (2025) — A single dose of a virus carrying the secreted form of klotho (s-KL), given at 12 months, raised total longevity in male mice by 19.7% (31.5 against 26.3 months) and median survival from 24.6 to 28.3 months, with 11–12 males per group. Female longevity could not be analyzed because dermatitis and anal bleeding occurred across all groups (Roig-Soriano et al., 2025).
• Kidney disease (mice) — With chronic kidney disease, mice overexpressing klotho had better kidney function and much less vascular calcification; in people, urinary klotho fell from an early stage of kidney disease (Hu et al., 2011). Recombinant klotho given for 4 days after acute kidney injury kept the injury from progressing to chronic disease and protected the heart at 20 weeks, and it raised the mice’s own klotho levels long after treatment stopped; there were 4 mice per group (Hu et al., 2017).
• Memory (mice) — Mice overexpressing klotho did better on several learning and memory tests (Dubal et al., 2014). An injected klotho fragment improved memory in young mice, and a single injection improved spatial and working memory in 18-month-old mice (Leon et al., 2017).
• Memory (aged monkeys, 2023) — Eighteen aged rhesus macaques (15–28 years) were tested on a spatial memory task. A single injection of 10 µg/kg rhesus klotho, given to 9 of them, improved performance at 4 hours, and the effect was still present at 2 weeks; 20 and 30 µg/kg did not significantly improve it. The monkeys were not drug-naive, one task was tested, and blinding covered most but not all sessions. Unity Biotechnology co-funded the work and “had a role in the monkey study design”; authors are inventors on a klotho patent and a patent application, and two founded a company to continue developing klotho therapeutics (Castner et al., 2023).

Human Data

No published study has given klotho protein to a person: PubMed and ClinicalTrials.gov, searched September 29, 2026, returned none. Campbell: “Human dosing trials for exogenous Klotho do not exist yet” (Campbell, August 14, 2026). What exists is below.

• Blood levels and survival — In 804 adults aged 65 and over in the InCHIANTI study in Tuscany, 194 (24.1%) died over 6 years. After adjustment, those in the lowest third of plasma klotho (<575 pg/mL) had a higher risk of death than those in the highest third (>763 pg/mL): hazard ratio 1.78, 95% CI 1.20–2.63 (Semba et al., 2011).
• Frailty and strength — In 774 InCHIANTI participants, each natural-log unit of higher plasma klotho went with lower odds of frailty versus robustness (odds ratio 0.46, 95% CI 0.21–0.98) (Shardell et al., 2019). Among those with plasma klotho below 681 pg/mL, higher klotho went with stronger grip (Semba et al., 2012).
• Memory — In 833 InCHIANTI participants aged 55 and over, each natural-log unit of higher klotho went with a 35% lower risk of a meaningful drop on the Mini-Mental State Examination; there was no significant association with the Trail-Making tests (Shardell et al., 2016).
• The KL-VS gene variant — Elderly people carrying two copies of the variant were underrepresented in three populations (combined odds ratio 2.59) (Arking et al., 2002). In 718 people aged 52–85, the 26% carrying one copy scored higher on cognitive tests, and in the cohort where it was measured they had higher serum klotho; the 3% carrying two copies were excluded (Dubal et al., 2014). Among APOE4 carriers aged 60 and over, one copy went with a lower risk of Alzheimer disease (odds ratio 0.75, 95% CI 0.67–0.84, in case-control studies totaling 20,928 participants) (Belloy et al., 2020). In 243 people, klotho in cerebrospinal fluid tracked lower amyloid and tau independent of KL-VS status; the authors wrote that the outcomes were “more clearly mediated by the protein directly rather than the KL-VS heterozygosity variant,” and cerebrospinal-fluid and plasma levels correlated weakly (r = 0.377) (Grøntvedt et al., 2022).
• Exercise — In a 12-week randomized trial in 74 sedentary middle-aged adults, all three exercise programs raised plasma soluble klotho (Amaro-Gahete et al., 2019).
• Two genetic extremes — A patient with a chromosome translocation next to the klotho gene had markedly raised plasma klotho, hypophosphatemic rickets, hyperparathyroidism and markedly raised FGF23 (Brownstein et al., 2008). A 13-year-old girl with a loss-of-function mutation in both copies of the gene had severe tumoral calcinosis, with calcium deposits in the dura and carotid arteries (Ichikawa et al., 2007).
• Registered trials: genes and mRNA, not the protein — Minicircle’s pilot of a klotho plasmid gene therapy injected under the skin enrolled 14 healthy adults, is active and not recruiting, and has posted no results; its record says the product “will be administered at a site outside of the U.S. which is not under FDA jurisdiction” (NCT07216781). Its klotho-plus-follistatin gene therapy pilot (14 adults) was completed on April 30, 2026, with no results posted (NCT07285629). Klothea Bio’s randomized, placebo-controlled Phase 1b of 0.5 mg klotho mRNA, given intravenously twice, 4 weeks apart, to about 21 healthy adults aged 50–75, is not yet recruiting (NCT07544420).
• Self-report — Campbell: “a few weeks of Klotho use has led to a huge boost in energy and pheromone response for me and my wife” (Campbell, November 21, 2025). To his own question, whether decades of human trial data exist for klotho as they do for testosterone, he answers “Absolutely not… at least not yet” (Campbell, September 18, 2026).

None of these shows that injecting klotho does anything in people. The cohort and gene studies measure the body’s own klotho, and an association cannot separate cause from effect; Campbell’s own chapter says “Most human Klotho data is observational” (Campbell, August 14, 2026). The evidence meter on the Klotho card reads “Animal only” because no published human study has given it, for longevity or anything else.

Reconstitution & Storage

alphaKlothoLR is sold freeze-dried; the product page says “We do not use any fillers in this process.” The certificates of analysis give each vial a labeled quantity of 10 mcg. None of the documents read for this page gives a mixing volume, a storage temperature or a use-by time for the product, and no stability data on the construct are published. The table is arithmetic only: how volume maps to micrograms in a 10 mcg vial (U-100 insulin syringe: 100 units = 1 mL). It is not a recommendation.

• Micrograms, not milligrams — The stated amount is 10 mcg, which is 0.01 mg. Campbell: “Even taking milligrams, or way too many micrograms if you get the math wrong, could be too much for your system to handle!” (Campbell, November 21, 2025).
• Route in the documents — SubQ or IM (Campbell, November 21, 2025; Longevity Protocol page); SubQ (Campbell, June 5 and September 16–17, 2026). The animal studies injected under the skin or into the abdominal cavity.
• Storage — No klotho-specific storage instructions appear in the seller’s or promoter’s documents read for this page. In the monkey study, the recombinant klotho was kept frozen at −80 °C, stored at 4 °C once thawed and used within a week (Castner et al., 2023); that describes a research laboratory’s own protein, not the product.

→ Peptide Calculator — vial-to-syringe math

Side Effects & Risks

No published study has recorded side effects of klotho in people. What exists is what its promoter has written, and what animal and genetic studies show:

• No human safety data — Campbell: “we’re still waiting on decade-long safety data” (Campbell, September 16, 2026), and “the long-term human safety picture is still being built in real time” (Campbell, September 18, 2026).
• Phosphate, calcium and bone — Campbell writes that “supraphysiological levels of Klotho” can promote vascular calcification and cause the loss of phosphate (hypophosphatemia) and potassium (hypokalemia) (Campbell, November 21, 2025). What is documented: the patient whose translocation raised plasma klotho had hypophosphatemic rickets and hyperparathyroidism (Brownstein et al., 2008), and in mice, gene transfer of the shed form of klotho altered blood phosphate and calcium, raised bone FGF23 expression fourfold and worsened bone structure, while the secreted form did not (Roig-Soriano et al., 2023). In the kidney-injury studies, injected recombinant klotho lowered plasma phosphate, and the authors called it “safe and efficacious” in those mice (Hu et al., 2017). Neither the product page nor Campbell says whether the construct is the shed or the secreted form.
• Blood sugar (mice) — Klotho protein injected at 10 µg/kg raised blood glucose in mice, more in males than females, and blunted the glucose-lowering effect of insulin (Kurosu et al., 2005). No human data exist.
• More did not help (monkeys) — 20 and 30 µg/kg did not improve memory in the monkey study, and the authors wrote that “it remains to be determined whether doses even higher than those tested could impair cognition” (Castner et al., 2023). Campbell: “More is not better here” (Longevity Protocol page).
• Fertility (mice) — Breeding pairs of klotho-overexpressing mice had fewer births and fewer offspring over 12 months (Kurosu et al., 2005).
• What Campbell reports — Feeling “more energized than usual,” and “Your body may feel slightly warm (i.e. a burning sensation)” (Campbell, November 21, 2025).
• Immune response — alphaKlothoLR is a fusion protein injected repeatedly; no immunogenicity data on it are published.
• WADA — Klotho is not named on the 2026 Prohibited List. Its section S0 prohibits at all times any pharmacological substance not addressed elsewhere on the List “and with no current approval by any governmental regulatory health authority for human therapeutic use.” No klotho product is FDA-approved.
• Drug interactions — Unstudied.

Bloodwork & Monitoring

No published study has set monitoring for people taking klotho. The documents and the biology point to these:

• Phosphate and calcium — Campbell’s chapter lists serum phosphate and serum calcium, “Because Klotho sits directly upstream of phosphate and calcium handling” (Campbell, August 14, 2026). Klotho and FGF23 regulate mineral metabolism (Kuro-o, 2019), and the patient with genetically high klotho had low-phosphate (hypophosphatemic) rickets (Brownstein et al., 2008).
• Kidney function — Campbell lists eGFR and creatinine (Campbell, August 14, 2026) and cystatin C (Campbell, September 17, 2026). In healthy adults, serum klotho was inversely related to creatinine (Yamazaki et al., 2010).
• FGF23 and parathyroid hormone — Campbell’s September 17 list includes serum FGF23. FGF23 was raised at both genetic extremes, and parathyroid hormone was raised or the parathyroids overactive in both (Brownstein et al., 2008; Ichikawa et al., 2007).
• Blood glucose — Injected klotho raised blood glucose in mice (Kurosu et al., 2005); no human data exist.
• Blood pressure — On Campbell’s September 17 list.
• Serum klotho — Research ELISAs exist, with published reference values by age (Yamazaki et al., 2010; Espuch-Oliver et al., 2022). Campbell calls direct testing “an inexact science at best” (Campbell, August 14, 2026). The registered gene-therapy pilot measures serum α-Klotho by ELISA as a primary outcome (NCT07216781).
• Which tests fit a given person — A question for a licensed healthcare provider. This page can’t answer it.

Commonly Stacked With

Campbell’s published stacks, recorded as he published them. No study has tested alphaKlothoLR with anything; one registered pilot combined klotho and follistatin gene therapy (see Follistatin-344 below).

→ Peptide Calculator — vial-to-syringe math

Legal Status

Related Compounds

People researching Klotho often also look at these:

Next Steps

References

1. Campbell J. Klotho: The Future “Holy Grail” Of Longevity And Anti-Aging Optimization. jaycampbell.com/blog/klotho-the-future-holy-grail-of-longevity-and-anti-aging-optimization/. Last updated November 21, 2025. Read September 29, 2026. (The 10 mcg every-two-weeks regimen for “α-Klotho LR,” the 1,012-amino-acid figure, the self-report and the side-effect warnings.)
2. Campbell J. Recombinant Follistatin: The Future Of True Muscle Growth. jaycampbell.com/blog/recombinant-follistatin-the-future-of-true-muscle-growth/. Last updated November 22, 2025. Read September 29, 2026. (“The Ultimate Recombinant Follistatin with Klotho Stack.”)
3. Campbell J. The 2026 Jay Campbell GOD Stack For High-Performance Men & Women. jaycampbell333.substack.com/p/the-2026-jay-campbell-god-stack-for. June 5, 2026. Read September 29, 2026.
4. Campbell J. Biolongevity Labs’ Revolutionary Precision Tools: Klotho & FLGR242. jaycampbell333.substack.com/p/biolongevity-labs-revolutionary-precision. August 14, 2026. Read September 29, 2026. (The Klotho chapter of his book Living Leaner Longer Stronger.)
5. Campbell J. Klotho: Rebuild Your Anti-Aging Stack After 45. jaycampbell.com/blog/klotho-supplement-anti-aging-stack/. Last updated September 16, 2026. Read September 29, 2026.
6. Campbell J. Klotho and Kidney Function: The Longevity Biomarker Almost Nobody Tracks. jaycampbell.com/blog/klotho-and-kidney-function/. Last updated September 17, 2026. Read September 29, 2026.
7. Campbell J. Klotho vs Epitalon vs NAD+: What Actually Works. jaycampbell.com/blog/klotho-vs-epitalon-vs-nad/. Last updated September 18, 2026. Read September 29, 2026. (“my company, BioLongevity Labs.”)
8. Campbell J. Jay Campbell’s Longevity Protocol. jaycampbell.com/protocols/longevity-protocol/. Read September 29, 2026.
9. BioLongevity Labs. Klotho (alphaKlothoLR) (20mcg) product page. biolongevitylabs.com/product/klotho/. Read September 29, 2026.
10. MDx BioAnalytical Laboratory. Certificates of Analysis COA260086 (reported January 21, 2026) and COA260797 (reported February 20, 2026), client BioLongevity Labs, labeled identity “a-Klotho MAB,” labeled quantity 10 mcg. Posted on biolongevitylabs.com/product/klotho/. Read September 29, 2026.
11. Kuro-o M, Matsumura Y, Aizawa H, et al. Mutation of the mouse klotho gene leads to a syndrome resembling ageing. Nature. 1997;390(6655):45-51. PMID: 9363890.
12. Matsumura Y, Aizawa H, Shiraki-Iida T, Nagai R, Kuro-o M, Nabeshima Y. Identification of the human klotho gene and its two transcripts encoding membrane and secreted klotho protein. Biochem Biophys Res Commun. 1998;242(3):626-630. PMID: 9464267.
13. Arking DE, Krebsova A, Macek M Sr, et al. Association of human aging with a functional variant of klotho. Proc Natl Acad Sci USA. 2002;99(2):856-861. PMID: 11792841.
14. Dennis MS, Zhang M, Meng YG, et al. Albumin binding as a general strategy for improving the pharmacokinetics of proteins. J Biol Chem. 2002;277(38):35035-35043. PMID: 12119302. (SA21.)
15. Imura A, Iwano A, Tohyama O, et al. Secreted Klotho protein in sera and CSF: implication for post-translational cleavage in release of Klotho protein from cell membrane. FEBS Lett. 2004;565(1-3):143-147. PMID: 15135068.
16. Kurosu H, Yamamoto M, Clark JD, et al. Suppression of aging in mice by the hormone Klotho. Science. 2005;309(5742):1829-1833. PMID: 16123266.
17. Yamamoto M, Clark JD, Pastor JV, et al. Regulation of oxidative stress by the anti-aging hormone klotho. J Biol Chem. 2005;280(45):38029-38034. PMID: 16186101.
18. Urakawa I, Yamazaki Y, Shimada T, et al. Klotho converts canonical FGF receptor into a specific receptor for FGF23. Nature. 2006;444(7120):770-774. PMID: 17086194.
19. Chen CD, Podvin S, Gillespie E, Leeman SE, Abraham CR. Insulin stimulates the cleavage and release of the extracellular domain of Klotho by ADAM10 and ADAM17. Proc Natl Acad Sci USA. 2007;104(50):19796-19801. PMID: 18056631.
20. Liu H, Fergusson MM, Castilho RM, et al. Augmented Wnt signaling in a mammalian model of accelerated aging. Science. 2007;317(5839):803-806. PMID: 17690294.
21. Ichikawa S, Imel EA, Kreiter ML, et al. A homozygous missense mutation in human KLOTHO causes severe tumoral calcinosis. J Clin Invest. 2007;117(9):2684-2691. PMID: 17710231.
22. Brownstein CA, Adler F, Nelson-Williams C, et al. A translocation causing increased alpha-klotho level results in hypophosphatemic rickets and hyperparathyroidism. Proc Natl Acad Sci USA. 2008;105(9):3455-3460. PMID: 18308935.
23. Yamazaki Y, Imura A, Urakawa I, et al. Establishment of sandwich ELISA for soluble alpha-Klotho measurement: Age-dependent change of soluble alpha-Klotho levels in healthy subjects. Biochem Biophys Res Commun. 2010;398(3):513-518. PMID: 20599764.
24. Hu MC, Shi M, Zhang J, et al. Klotho deficiency causes vascular calcification in chronic kidney disease. J Am Soc Nephrol. 2011;22(1):124-136. PMID: 21115613.
25. Semba RD, Cappola AR, Sun K, et al. Plasma klotho and mortality risk in older community-dwelling adults. J Gerontol A Biol Sci Med Sci. 2011;66(7):794-800. PMID: 21474560.
26. Semba RD, Cappola AR, Sun K, et al. Relationship of low plasma klotho with poor grip strength in older community-dwelling adults: the InCHIANTI study. Eur J Appl Physiol. 2012;112(4):1215-1220. PMID: 21769735.
27. Dubal DB, Yokoyama JS, Zhu L, et al. Life extension factor klotho enhances cognition. Cell Rep. 2014;7(4):1065-1076. PMID: 24813892.
28. Shardell M, Semba RD, Rosano C, et al. Plasma Klotho and Cognitive Decline in Older Adults: Findings From the InCHIANTI Study. J Gerontol A Biol Sci Med Sci. 2016;71(5):677-682. PMID: 26297657.
29. Leon J, Moreno AJ, Garay BI, et al. Peripheral Elevation of a Klotho Fragment Enhances Brain Function and Resilience in Young, Aging, and α-Synuclein Transgenic Mice. Cell Rep. 2017;20(6):1360-1371. PMID: 28793260.
30. Hu MC, Shi M, Gillings N, et al. Recombinant α-Klotho may be prophylactic and therapeutic for acute to chronic kidney disease progression and uremic cardiomyopathy. Kidney Int. 2017;91(5):1104-1114. PMID: 28131398.
31. Chen G, Liu Y, Goetz R, et al. α-Klotho is a non-enzymatic molecular scaffold for FGF23 hormone signalling. Nature. 2018;553(7689):461-466. PMID: 29342138.
32. Kuro-o M. The Klotho proteins in health and disease. Nat Rev Nephrol. 2019;15(1):27-44. PMID: 30455427.
33. Shardell M, Semba RD, Kalyani RR, et al. Plasma Klotho and Frailty in Older Adults: Findings From the InCHIANTI Study. J Gerontol A Biol Sci Med Sci. 2019;74(7):1052-1057. PMID: 29053774.
34. Amaro-Gahete FJ, De-la-O A, Jurado-Fasoli L, et al. Exercise training increases the S-Klotho plasma levels in sedentary middle-aged adults: A randomised controlled trial. The FIT-AGEING study. J Sports Sci. 2019;37(19):2175-2183. PMID: 31164040.
35. Belloy ME, Napolioni V, Han SS, Le Guen Y, Greicius MD; Alzheimer’s Disease Neuroimaging Initiative. Association of Klotho-VS Heterozygosity With Risk of Alzheimer Disease in Individuals Who Carry APOE4. JAMA Neurol. 2020;77(7):849-862. PMID: 32282020.
36. Espuch-Oliver A, Vázquez-Lorente H, Jurado-Fasoli L, et al. References Values of Soluble α-Klotho Serum Levels Using an Enzyme-Linked Immunosorbent Assay in Healthy Adults Aged 18-85 Years. J Clin Med. 2022;11(9):2415. PMID: 35566540.
37. Grøntvedt GR, Sando SB, Lauridsen C, et al. Association of Klotho Protein Levels and KL-VS Heterozygosity With Alzheimer Disease and Amyloid and Tau Burden. JAMA Netw Open. 2022;5(11):e2243232. PMID: 36413367.
38. Castner SA, Gupta S, Wang D, et al. Longevity factor klotho enhances cognition in aged nonhuman primates. Nat Aging. 2023;3(8):931-937. PMID: 37400721.
39. Roig-Soriano J, Sánchez-de-Diego C, Esandi-Jauregui J, et al. Differential toxicity profile of secreted and processed α-Klotho expression over mineral metabolism and bone microstructure. Sci Rep. 2023;13(1):4211. PMID: 36918615.
40. Roig-Soriano J, Edo Á, Verdés S, et al. Long-term effects of s-KL treatment in wild-type mice: Enhancing longevity, physical well-being, and neurological resilience. Mol Ther. 2025;33(4):1449-1465. PMID: 39988871.
41. UniProt Consortium. UniProtKB Q9UEF7 (KLOT_HUMAN), Klotho, entry version 192. rest.uniprot.org/uniprotkb/Q9UEF7. Read September 29, 2026.
42. World Anti-Doping Agency. Prohibited List 2026 (in effect January 1, 2026). S0, Non-approved substances. wada-ama.org.
43. FDA. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act (categories 1–3). Updated May 14, 2026. fda.gov/media/94155/download. With the 503B categories list (updated March 21, 2025; fda.gov/media/94164/download), 21 CFR 216.23 (ecfr.gov) and Drugs@FDA via openFDA (api.fda.gov/drug/drugsfda.json), searched for “klotho” September 29, 2026: no records.
44. ClinicalTrials.gov. Records NCT07216781, NCT07285629 and NCT07544420, and searches for “klotho” as intervention and in all fields, read September 29, 2026.

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