Plasma lipoprotein paticle size and carotenoid content are positively influenced by egg consumption and the response to dietary cholesterol in an elderly population

Abstract

29 postmenopausal women (50–68y) and 13 men (60–80y) were assigned to either 3 eggs (EGG, 640 mg cholesterol /d) or an equal volume of cholesterol-free egg substitute (SUB, 0 mg cholesterol/d) for 30d. Following a 3 wk wash out, subjects crossed over to the alternate diet. Individuals with a response to dietary cholesterol > 2.2 mg/dL for each additional 100 mg of dietary cholesterol were classified as hyper-responders (HYPER) while hypo-responders (HYPO) were those with a response ≤ to 2.2 mg/dL. HYPER had higher concentrations of both LDL and HDL cholesterol (HDL-C) but maintained their LDL/HDL ratio after EGG. In contrast, the concentrations of plasma LDL-C and HDL-C did not differ between the EGG and SUB for the HYPO. NMR spectroscopy determined LDL and HDL size & particle concentrations. After EGG, HYPER experienced an increase in the larger (≥ 21.2 nm) less atherogenic LDL particle (P < 0.001) and in the largest HDL particle (> 8.8 nm) (P < 0.01), associated with reverse cholesterol transport. HPLC was used to analyze plasma carotenoids. All individuals had an increase in plasma lutein (from 32.4 ± 15.2 to 46.4 ± 23.3 ng/L) and zeaxanthin (from 8.8 ± 4.8 to 10.7 ± 5.8 ng/L) during EGG, yet HYPER displayed higher concentrations of carotenoids when compared to HYPO. These findings suggest that the increases in LDL-C and HDL-C due to increased egg consumption in HYPER are related to increases in the lipoprotein subfractions associated with less atherogenic particles. Also, increases in plasma caroteniods after EGG may provide a valuable dietary source for this population. [Supported by the American Egg Board/Egg Nutrition Center and USDA NRI]