Klotho is one of the most consistent predictors of all-cause mortality and cognitive decline in human aging research. Here's what the 2026 evidence shows about Klotho biology, how to test your levels, and the interventions that move the needle.
In 1997, Japanese researchers identified a mouse with a single gene defect that produced a phenotype of dramatically accelerated aging — premature death by 8 weeks (compared to normal mouse lifespan of 2+ years), severe arteriosclerosis, osteoporosis, infertility, cognitive impairment, and skin atrophy. They named the gene Klotho, after the Greek mythological figure who spins the thread of life. Conversely, mice engineered to overexpress Klotho lived 20–30% longer than wild-type controls and remained cognitively intact through old age.
In the decades since, Klotho has emerged as one of the most consistent and biologically powerful aging-relevant proteins identified. It functions as a co-receptor for FGF23 in phosphate regulation, but its longevity effects appear to involve much more — including direct cognitive enhancement that crosses the blood-brain barrier without requiring the protein itself to enter the brain.
This article summarizes the 2026 state of Klotho research, how to test your levels, and the interventions that meaningfully change them.
Klotho exists in three biologically active forms:
The longevity-relevant form is secreted Klotho. Higher circulating levels correlate strongly with: