Date of Completion

4-28-2017

Embargo Period

4-28-2019

Keywords

Eggs, Cardiovascular Disease, HDL, TMAO, Cholesterol, Antioxidants, Lipoproteins, Carotenoids

Major Advisor

Maria Luz Fernandez, PhD

Associate Advisor

Christopher Blesso, PhD

Associate Advisor

Cameron Faustman, PhD

Associate Advisor

Hedley Freake, PhD

Associate Advisor

Ji-Young Lee, PhD

Field of Study

Nutritional Science

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

Eggs have been a controversial food due to their cholesterol and choline content. Though the intake limit for cholesterol has been removed from the Dietary Guidelines for Americans, there is concern that the choline in eggs may elevate plasma concentrations of trimethylamine-N-oxide (TMAO), a risk factor for cardiovascular disease (CVD). However, previous studies suggest that egg intake also improves many biomarkers associated with CVD risk, including the plasma lipid profile and indicators of HDL function. Therefore, we sought to examine the impacts of increasing daily egg intake on these and other biomarkers with the aim of establishing a threshold of egg intake at which CVD risk is not increased in a young, healthy population. We hypothesized that intake of up to 3 eggs/day would not negatively impact CVD risk biomarkers.

Thirty-eight young, healthy men and women (24.1 ± 2.2 yr, body mass index (BMI) 24.3 ± 2.5 kg/m2, with a healthy lipid profile) consumed 0 eggs/day for 2 weeks, followed by intake of 1, 2, and 3 eggs/day for 4 weeks each. Anthropometric measurements, dietary records, plasma, and serum, were collected following each phase of the study. Peripheral blood mononuclear cells (PBMC) were also isolated for analysis of gene expression.

BMI, waist circumference, systolic blood pressure (BP), plasma glucose, triglycerides, total cholesterol, liver enzymes, and C-reactive protein were unchanged by the intervention. Diastolic BP decreased, and HDL cholesterol (HDL-C) increased while LDL cholesterol (LDL-C) was either decreased or unchanged with egg intake, resulting in a reduced LDL-C/HDL-C ratio.

Intake of nutrients present in eggs, including cholesterol and choline, increased in a dose-dependent manner. Plasma choline also increased dose-dependently while plasma TMAO concentration was unchanged by daily egg consumption. Egg intake improved indicators of HDL function and plasma carotenoid concentrations. Lastly, we observed no change in expression of genes involved in the maintenance of cholesterol homeostasis or those that are regulated by TMAO. Overall, these data suggest that intake of up to 3 eggs/day does not negatively impact – and may in fact improve – biomarkers of CVD risk in a young, healthy population.

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