Across 52,718 UK Biobank participants followed for 12 years, accelerated biological aging — measured via Phenotypic Age Acceleration and Biological Age Acceleration — mediated between 21.81% and 40.84% of the association between poor diet quality and incident cardiovascular disease, and 16.67% to 35.87% of CVD mortality risk. This held consistently across four validated dietary indices: HEI-2020, AHEI, DASH, and Mediterranean Diet Score, lending notable robustness to the signal.
What makes this finding consequential is the mechanistic framing rather than the association itself. Diet-CVD links are among the most replicated in epidemiology, but the biological pathways remain contested. Positioning accelerated aging — a composite of metabolic, inflammatory, and organ-function dysregulation — as a quantifiable intermediate step shifts the conversation from "eat better for your heart" to "diet quality governs your biological clock, which governs CVD risk." This opens a distinct intervention target: slowing aging-related physiological drift, potentially via dietary pattern changes, metformin, or senolytics.
Limitations are real. UK Biobank skews white, educated, and relatively healthy, limiting generalizability. Mediation analysis in observational cohorts cannot establish causality; unmeasured confounders remain a structural vulnerability. Dietary data rely on self-report, introducing measurement error. Still, the consistency across four dietary indices and two aging biomarkers elevates this beyond incremental — it is a well-powered confirmatory step that strengthens the biological aging hypothesis as a tractable CVD pathway.
