36 healthy young adults: 2-week zero-egg washout, then 3 eggs/d (540 mg additional dietary cholesterol) for 4 weeks, with LDL/HDL particle counts by NMR and carotenoid/choline levels by HPLC/mass spec. 12/36 (~1/3) classified as hyperresponders (total-cholesterol rise >12 mg/dL) vs. 24 hyporesponders (range -16 to +9 mg/dL). Hyperresponders had significant total/LDL/HDL-C rises and more large LDL particles; both groups showed equal increases in large HDL particles, plasma lutein, zeaxanthin, and choline — i.e., the carotenoid/choline benefit is independent of cholesterol-response phenotype.
relevance_note: A 2019 replication confirming the ~1/3 hyperresponder fraction is stable across three decades of Fernandez-lab cohorts, and cleanly separates the (near-universal) micronutrient benefit from the (phenotype-dependent) cholesterol effect.