What telomeres are
Telomeres are repetitive DNA sequences that cap and protect the ends of chromosomes, a bit like the plastic tips on shoelaces. Each time a cell divides they get a little shorter; when they become critically short the cell stops dividing or becomes senescent.
Why they matter for longevity
Telomere attrition is one of the hallmarks of aging and links cell division to cellular senescence. Short telomeres are associated with some age-related diseases.
What the evidence shows
The relationship is not simply “longer is better”: the enzyme that lengthens telomeres (telomerase) is also exploited by cancers, so artificially extending telomeres carries real theoretical risk. Telomere-length tests sold to consumers have wide measurement variability and limited individual predictive value.
Bottom line
Useful as a research biomarker and a piece of the ageing puzzle — not a validated target you can safely “max out”.