Randomized crossover intervention in older adults (with low baseline macular pigment) taking cholesterol-lowering statins: 2 egg yolks/day for 5 weeks, then 4 egg yolks/day for 5 weeks, each preceded by a 4-week egg-free washout, with serum lutein/zeaxanthin and macular pigment optical density (MPOD, at 0.25°/0.5°/1° retinal eccentricity) measured throughout. Both serum carotenoids and MPOD rose dose-dependently with egg-yolk intake; subjects with low baseline MPOD showed up to ~50% increases in MPOD at 4 egg yolks/day, despite statin use (which lowers endogenous cholesterol synthesis, the yolk lipid matrix that aids lutein/zeaxanthin absorption).
relevance_note: A primary intervention linking egg-yolk intake directly to a validated retinal biomarker (MPOD) tied to age-related macular degeneration risk, in an older, statin-using population — the “eye health” beneficial-nutrient primary.