Egg Effects on the Immunomodulatory Properties of HDL

The purpose of this study is to investigate the effects of egg intake on markers of HDL function and immune inflammation in healthy adults.

28 healthy men and women (age 18-35 years old) will be recruited to participate in a 16-week randomized crossover study. Upon enrollment, all subjects will enter a 4-week run-in egg-free period where they will refrain from consuming any egg-based foods (Period 1). Subjects will then enter the first intervention period, where they be randomly assigned to consume either 3 whole eggs/day or the equivalent amount of egg white-based egg substitute/day for 4 weeks (Period 2). Afterwards, subjects will enter a 4-week washout period where egg-based foods are restricted (Period 3), followed by a second intervention period, where they be assigned to the alternative whole egg- or egg white-based treatment for 4 weeks (Period 4). Subjects will come to the Department of Biology at Fairfield University every two weeks to check-in, and to pick up their egg products during the intervention periods. Subjects will be asked to maintain their normal diet and physical activity practices throughout all periods of the study. Subjects will complete 5-day dietary records and physical activity logs at the end of each study period.

Measurement of fasted plasma HDL-cholesterol levels (mg/dL) at the end of the run-in period, and two intervention arms.

HDL subfractions (d = 1.063-1.21) will be isolated from plasma by ultracentrifugation collected at the end of the run-in period and two intervention arms. HDL fractions will be analyzed for glycerphospholipid (phosphatidylcholine, phosphatidylethanolamine, lysophosphatidylcholine, phosphatidylinositol) and sphingolipid (sphingomyelin) composition by mass spectrometry. Each lipid class will be presented as a percent (%) of total HDL lipids.

The cholesterol efflux from macrophages to subject serum will be measured at the end of the egg-free run-in period and both intervention periods using a fluorescent cholesterol efflux kit. Results will be expressed as % cholesterol efflux, calculated as (fluorescence intensity of media/[fluorescent intensity of cell lysates + media]) x 100.

Peripheral blood mononuclear cells (PBMCs) will be isolated at the end of the egg-free run-in period and both intervention periods. PBMCs will be cultured ex vivo and stimulated with lipopolysaccharide. Media will be collected to measure tumor necrosis factor alpha concentrations (pg/mL) in cell media.

Inclusion Criteria: 18-35 years old Body mass index (BMI) < 30 kg/m2, or < 30% body fat for men and < 40% body fat for women Willingness to consume eggs or egg whites on a daily basis during study periods Exclusion Criteria: < 18 years old; > 35 years old BMI ≥ 30 kg/m2, or ≥ 30% body fat for men and ≥ 40% body fat for women Self-reported history of diabetes mellitus, coronary heart disease, stroke, renal problems, liver disease, cancer, pregnancy or lactation, autoimmunity, chronic infections, or egg allergy Taking lipid-lowering medications (e.g. statins, fibrates) A preexisting medical condition or implanted medical device that prevents participation in bioelectrical impedance measurements of body composition Clinical lipid and glucose values that are highly elevated, including fasting triglycerides levels higher than 500 mg/dL, fasting glucose higher than 126 mg/dL, and plasma total cholesterol greater than 240 mg/dL