Chang Woock Lee, B.A.
The chicken or the egg? No, this is not about the famous causality dilemma of “which came first?” but rather about excellent sources of dietary protein. Eggs are a complete protein, provide protein digestibility similar to chicken, and are a good source of protein. Two large eggs (100 grams), according to USDA data, provide 12 grams of protein, while a chicken thigh (meat only, 52 grams) provides 13 grams of protein. However, eggs are much higher in an important nutrient, choline (100g of whole egg contain 250mg of choline and 100g of chicken meat have 66mg of choline).
Choline is an essential micronutrient which plays many vital roles in our bodies. First of all, choline is a backbone of phospholipids a main component of all cell membranes. Choline is also required to make acetylcholine which relays signals between nerves and muscles. Liver uses choline to make lipoprotein for lipid/cholesterol transport from/to other tissues/organs. Choline works to maintain cardiovascular health by lowering hom*ocysteine levels in our bodies. hom*ocysteine is a cardiovascular risk factor so keeping its levels low is very important to maintain healthy heart and blood vessels. Moreover, betaine, the product of choline metabolism, contributes to the synthesis of creatine which plays a key role in 
energy metabolism and is known to positively impact muscular strength/mass. Choline deficiency can result in many serious health conditions including muscle and liver damage, fatty liver, birth defects, neurological disorders, DNA damage, and atherosclerosis.
While our bodies can produce small amounts of choline in the liver when dietary consumption is low, it isn’t enough. The recommended daily allowance (RDA) value of choline has not been set due to lack of sufficient data, and only adequate intake (AI) values exist currently. The AI of choline for women is 425mg/day and 550mg/day for men. However, recent surveys showed that many Americans don’t consume enough choline. Thus it is recommended that people eat more choline-rich foods such as eggs.
But wait. Doesn’t egg contain cholesterol? Isn’t it bad for health? Yes, eggs are high in cholesterol. That is why many people simply ditch eggs (especially egg yolk). One of our laboratory’s studies found that dietary cholesterol increases muscle mass and strength in healthy, weight lifting people without negative impacts on cardiovascular risk factors.
So, what do you think? The chicken or the egg?
References
- Zeisel SH and da Costa KA. Choline: an essential nutrient for public health. Nutrition Reviews. 2009; 67(11): 615-623. http://onlinelibrary.wiley.com/doi/10.1111/j.1753-4887.2009.00246.x/pdf
- Jäger R, Purpura M, and Kingsley M. Phospholipids and sports performance. J Int Soc Sports Nutr. 2007;4:5. http://www.jissn.com/content/pdf/1550-2783-4-5.pdf
- Riechman SE, Lee CW, Chikani G, Chen VCW, and Lee TV. Cholesterol and Skeletal Muscle Health. World Rev Nutr Diet. 2009;100:71-79. http://www.karger.com/Article/FullText/235713
- Huffines Institute text article wby Chang Woock Lee titled"It's OK to Eat Cholesterol: It May Even Be Good For You"
