Assessment of TMAO Formation With Egg Intake Versus Choline Supplement in a Healthy Population

Epidemiological data in short term studies, suggests that egg intake does not increase risk for cardiovascular disease (CVD). In fact, eggs are a great source of phospholipids (phosphatidylcholine) where choline has many metabolic roles, specially in lipid metabolism and cell membrane structure. Choline is present in the diet as free choline, which is absorbed in the small intestines, or choline esters, which is absorbed intact primarily through the lymphatic system. In addition, recent evidence suggests that the choline found in eggs may be metabolized by intestinal microbes into trimethylamine N-oxide (TMAO), a compound that may increase the risk for CVD. However, it is not known to what extent egg intake may contribute to plasma TMAO concentrations.

Therefore, the objective of this study is to determine the impacts of daily intake of 3 eggs versus a choline supplement on plasma TMAO as well as other biomarkers for CVD risk, with the goal of determining if the same amount of choline given as phosphatidylcholine from eggs will increase plasma choline levels without a concomitant increase in plasma TMAO, such that CVD risk is not negatively impacted.

Inclusion criteria

• Men and women (18-30 years), BMI 18.5 - 29.9 kg/m2, proficient in English, and willing to consume 3 eggs per day or 397.5 mg of choline supplement (1½ tablets/day) for 4 weeks each.

Exclusion criteria

• Self-reported diabetes mellitus, cardiovascular disease, history of stroke, renal problems, liver disease, cancer, or a diagnosed eating disorder
• Taking any glucose-lowering prescriptions or supplements, triglyceride-lowering medications, bile acid sequestrants, or high dose chromium or cinnamon supplements
• Taken antibiotics in the previous 1 months, or if they are vegetarian or vegan
• BMI ≤ 18.4 or ≥ 30 kg/m2, or extreme clinical values, such as plasma triglycerides > 500 mg/dL, plasma glucose > 126 mg/dL, plasma cholesterol > 240 mg/dL, plasma creatinine ≤ 0.5 or ≥ 0.9 mg/dL for females and ≤ 0.7 or ≥ 1.2 mg/dL for males, or blood pressure > 140/90 mm Hg (average of 3 readings)
• Allergic to eggs or any component of the choline supplement