Featured article in the March, 2019 Issue of Nutrition Research Update; written by Bruno S. Lemos, PhD
Currently one in every four deaths in the United States is from cardiovascular disease (CVD)1. The major cause of CVD is atherosclerosis due to cholesterol accumulation in the arterial wall, building up to form a plaque that upon rupturing, can lead to major cardiovascular events such as stroke, heart attack and sudden death2. With that, consumption of cholesterol-rich foods have historically been a concern to the American population in regards to association with CVD risk.
Eggs are a nutritious and inexpensive food, which have essential nutrients, vitamins and minerals3. Hence dietary cholesterol has not shown an association with CVD risk in healthy individuals4,5. Now with the removal of the dietary cholesterol intake of less than 300mg/day from the 2015 Dietary Guidelines for Americans, an emerging topic regarding egg consumption is the fact that eggs are good sources of dietary choline. Choline is an essential nutrient needed for neurological health, lipid metabolism and cell signaling7. One large egg contains an average of 147mg of phosphatidylcholine8. Since the average adult American consumes less than the adequate intake (AI) (550mg males and 425mg females)9, consumption of eggs is a great way to meet the AI and prevent choline deficiency. Choline deficiency causes liver and kidney disease10. Choline also serves as a precursor to trimethylamine-N-oxide (TMAO), a compound that has been shown to increase CVD risk as well as promote atherogeneis6.Therefore, while dietary choline may serve to increase circulating plasma choline and prevent choline deficiency, there is need to determine if choline intake affects levels of TMAO.
A study was conducted with twenty-nine healthy young men and women with an average age of 25 years and body mass index of 24 kg/m2 11. Following a 2-week washout period, participants were randomized to consume 3 eggs per day or choline bitartrate supplement for 4 weeks each. After the first phase, participants went through another 3-week washout and started the alternate intervention. The amount of choline was matched between conditions (~400mg). Blood samples were collected for analysis of choline and metabolites (choline, betaine, TMAO), and overall nutrient intake was assessed by dietary records.
Consumption of eggs resulted in higher intake of fat, vitamin E and selenium in comparison to the choline supplement, while both interventions met the AI of dietary choline for American adults. During the egg intervention participants consumed fewer carbohydrates. The most important finding was that consumption of three eggs per day increased plasma choline compared to baseline and also compared to supplement intake, indicating that choline from eggs was more available to serve its various biological functions. Eggs did not increase fasting plasma TMAO or genes associated with atherogenesis. Therefore, the present study indicates that in healthy adults, eggs are a bioavailable source of choline that does not impact levels of TMAO. Further research is needed to determine if these results would be consistent in different populations at risk for CVD, such as individuals with metabolic syndrome, type 2 diabetes or overweight and obese individuals.
- Soliman, G. Dietary Cholesterol and the Lack of Evidence in Cardiovascular Disease. Nutrients 10, 780 (2018).
- Torres, N., Guevara-Cruz, M., Velázquez-Villegas, L. A. & Tovar, A. R. Nutrition and Atherosclerosis. Arch. Med. Res. 46, 408–426 (2015).
- Andersen, C. J. Bioactive Egg Components and Inflammation. Nutrients 7889–7913 (2015). doi:10.3390/nu7095372
- DiMarco, D. M. et al. Intake of up to 3 Eggs/Day Increases HDL Cholesterol and Plasma Choline While Plasma Trimethylamine-N-oxide is Unchanged in a Healthy Population. Lipids 52, 255–263 (2017).
- Lemos, B. S., Medina-Vera, I., Blesso, C. N. & Fernandez, M. Intake of 3 Eggs per Day When Compared to a Choline Bitartrate Supplement, Downregulates Cholesterol Synthesis without Changing the LDL/HDL Ratio. Nutrients 10, 258 (2018).
- Wang, Z. et al. Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease. Nature 472, 57–63 (2011).
- Zeisel, S. H., Klatt, K. C. & Caudill, M. A. Choline. Adv. Nutr. 9, 58–60 (2018).
- Blesso, C. N. Egg phospholipids and cardiovascular health. Nutrients 7, 2731–2747 (2015).
- Wallace, T. C. & III, V. L. F. Assessment of Total Choline Intakes in the United States. J. Am. Coll. Nutr. 35, 108–112 (2016).
- Fischer, L. M. et al. Sex and menopausal status influence human dietary requirements for the nutrient choline. Am J Clin Nutr 85, 1275–1285 (2007).
- Lemos, B. S., Medina-Vera, I., Malysheva, O. V., Caudill, M. A. & Fernandez, M. L. Intake of Three Eggs/Day Increased Plasma Choline Without Increasing Plasma Trimethylamine-N-Oxide While Choline Supplementation had no Effect in These Parameters in a Young Population. J Am Coll Nutr (2018).