Telomere Length

Telomeres are repetitive DNA sequences (TTAGGG) that cap the ends of chromosomes, protecting them from degradation and fusion during cell division — much like the plastic tips (aglets) on shoelaces. With each cell division, telomeres shorten slightly because DNA polymerase cannot fully replicate the chromosome ends. When telomeres become critically short, cells enter a state of senescence (permanent growth arrest) or apoptosis (programmed death).

Telomere length has been associated with biological aging and disease risk in numerous epidemiologic studies. Shorter telomeres correlate with increased risk of cardiovascular disease, cancer, diabetes, dementia, and all-cause mortality. Factors that accelerate telomere shortening include chronic psychological stress, smoking, obesity, sedentary lifestyle, poor sleep, and chronic inflammation. Conversely, exercise, meditation, and a whole-food diet have been associated with slower telomere attrition.

However, the clinical utility of a single telomere length measurement remains debated. Telomere length varies enormously between individuals at any given age, and a single measurement provides limited actionable information. Longitudinal tracking (measuring change over time) is more informative. Many longevity scientists now prefer epigenetic clocks (like DunedinPACE) as more precise and actionable measures of biological aging, though telomere length remains a useful complementary marker.