Telomere Length

What it is

Average telomere length is most commonly measured in leukocytes from blood, using quantitative PCR (T/S ratio) or flow-FISH. Results are reported in base pairs or relative units.

Why it matters

Telomeres shorten with each somatic cell division and with oxidative stress. Population studies link shorter leukocyte telomere length to cardiovascular disease, type-2 diabetes, frailty, and all-cause mortality.

Why it’s noisy in individuals

• Inter-assay variability is high (~5–10% even on the same sample).
• Inter-individual variability at birth is large.
• Different tissues have different telomere lengths.
• Year-to-year change in an individual is small relative to assay noise.

For an individual, a single telomere-length number is hard to act on; trends across multiple measurements over years are more informative.

What modifies it

• Lengthens (modestly): caloric restriction, exercise, Mediterranean diet, omega-3 (small effect), stress reduction.
• Shortens: smoking, obesity, chronic stress, sleep deprivation, chronic infection.

Related entries

Telomere attrition, Telomerase, Epigenetic clocks.