To explore the association of Life's Essential 8 (LE8) levels with leukocyte telomere length (LTL) and mitochondrial DNA copy number (mtDNA-CN).

A cross-sectional study.

225,692 participants aged 37-73 year from the UK Biobank cohort enrolled from 2006-2010.

The LE8 score (0–100) was divided into low (<50), moderate (50–79), and high cardiovascular health (CVH) (≥80) categories, based on health behaviors and factors defined by the American Heart Association. LTL was measured by a validated quantitative polymerase chain reaction method. mtDNA-CN was reacted by standardized SNP probe intensities. The association of CVH (as both a continuous and categorical variable) with LTL and mtDNA-CN was examined using multiple linear regression.

Of 225,692 participants, 5.3% had low CVH, 81.2% had moderate CVH, and 13.4% had high CVH. Participants with higher CVH were usually younger, female, better educated, of higher socioeconomic status, and with a lower prevalence of comorbidities. After adjusting for confounders, a higher LE8 score is associated with longer LTL (Beta = 0.075,P < 0.05) and increased mtDNA-CN (Beta = 0.094, P < 0.05). We also observed that this association was evident in the health behavior score (diet, physical activity, nicotine exposure, and sleep) and the health factors score (BMI, non-HDL cholesterol, blood glucose, and blood pressure), with a stronger positive association of health factors with LTL and mtDNA-CN (Beta =0.019, P < 0.05;Beta = 0.037, P < 0.05).

Higher CVH is associated with longer LTL and increased mtDNA-CN.