Intake of up to Three Eggs per Day is Associated with Improvements in Markers of HDL Function and Antioxidant Capacity in a Young, Healthy Population

Abstract

Recent evidence suggests that the composition and function of HDL particles may be more important than HDL cholesterol concentration when assessing risk for cardiovascular disease (CVD). HDL is involved in reverse cholesterol transport, the process by which excess cholesterol is removed from tissues and returned to the liver for biliary excretion. In addition to transporting cholesterol, HDL particles carry antioxidant proteins, enzymes, and carotenoids, all of which help protect against oxidative damage to both HDL and LDL particles. Eggs contain cholesterol and carotenoids and therefore may impact CVD risk by modulating lipoprotein composition and function. The goal of this research was to determine the impact of intake of up to 3 eggs/d on LDL and HDL particle size, function, and associated antioxidants in a young, healthy population. Thirty‐eight healthy individuals (19 men/19 women, 24.1 ± 2.2 y, BMI 24.3 ± 2.5 kg/m2) completed this 14‐week crossover dietary intervention. Qualifying participants underwent a 2‐week washout (0 eggs/d), followed by intake of 1, 2, and 3 eggs/d for 4 weeks each. Following each dietary period, fasting plasma and serum were collected for analysis of lipoprotein particle size and subfractions by nuclear magnetic resonance and concentrations of plasma apolipoproteins and carotenoids (lutein and zeaxanthin). Activities of plasma cholesteryl ester transfer protein (CETP) and lecithin‐cholesterol acyltransferase (LCAT) were assessed using fluorometric kinetic assays. Lastly, serum paraoxonase‐1 (PON1) activity toward phenyl acetate was measured using an in‐house kinetic assay. Compared to 0 eggs/d, intake of 1–3 eggs/d led to increased large LDL and large HDL particle concentrations (p < 0.05), a 9–20% increase in plasma apoA‐I (p < 0.05), and increased LCAT activity (p < 0.05). Furthermore, as compared to 0–1 eggs/d, intake of 2–3 eggs/d resulted in an 11% increase in apoA‐II (p < 0.05) and a 20–31% increase in plasma lutein + zeaxanthin (p < 0.05). Lastly, as compared to lesser quantities of eggs, intake of 3 eggs/d led to increased serum PON1 activity (p < 0.05). In contrast, egg intake had no impact on plasma CETP activity. In summary, intake of 1 egg/d appears sufficient to increase large LDL particle concentration and biomarkers associated with HDL function. However, intake of 2–3 eggs/d supports greater improvements in markers of HDL function and antioxidant capacity. Overall, intake of up to 3 eggs/d improves these biomarkers associated with lipoprotein function and CVD risk in a young, healthy population.Support or Funding InformationThis research was supported by an award to MLF from the Esperance Family Foundation and a grant to DMD from the Egg Nutrition Center.