Effects of Egg Intake on Choline Metabolism and HDL Functionality in a Healthy Population

A major risk factor for cardiovascular disease (CVD) is elevated low-density lipoprotein cholesterol (LDL-C). High-density lipoprotein (HDL) functionality can play a role in reducing risk for CVD by assisting in cholesterol homeostasis. Additionally, high plasma trimethylamine-N-oxide (TMAO) concentrations are related to increased CVD risk and increased atherosclerosis progression. Eggs are a rich source of dietary choline, a precursor for TMAO formation. Therefore, the effects of egg intake in comparison to a choline bitartrate supplement were explored in a young, healthy population. The aim was to show the benefits of egg consumption without increasing risk for CVD in young adults. The hypothesis was that choline from eggs would increase plasma choline concentrations and would not negatively increase plasma TMAO in comparison to choline bitartrate. Thirty participants (48% males; 25.6 ± 2.3 years old; body mass index (BMI) 24.3 ± 2.9 kg/m2) consumed 3 eggs per day or choline bitartrate (~400 mg dietary choline in eggs or supplement) for 4 weeks each in a randomized crossover study, followed by a washout period and then allocated to the alternate treatment. Anthropometrics data, dietary records, and blood samples were collected at the end of each interventional arm for analyses. When comparing treatments, no change was observed in BMI, waist circumference, blood pressure, plasma fasting glucose, triglycerides, creatinine, and liver enzymes. Total cholesterol, LDL-C, and HDL cholesterol (HDL-C) was higher, and C-reactive protein was lower with egg intake, with no changes in LDL-C/HDL-C ratio. Dietary total fat, cholesterol, selenium, and vitamin E were higher, and carbohydrates were lower as a result of egg consumption. For HDL functionality, egg intake resulted in higher apolipoprotein (apo) AI and E with no changes in apo B or paraoxonase 1 activity. Cholesterol biosynthesis was down regulated with egg intake at the gene expression level. Fasting plasma choline was increased with egg intake. Surprisingly, no difference in plasma TMAO was seen with treatments. Data suggest that egg intake contributes to choline availability in plasma when comparing to choline bitartrate supplementation, while the dietary cholesterol regulates the endogenous synthesis of cholesterol without negatively impacting risk for CVD in young, healthy individuals