The egg yolk, the orange viscous part of the egg, is intended to feed the developing embryo. However, the egg yolk is commonly regarded as the least desirable part of an egg for human nutrition. The egg yolk contains fat and cholesterol, which some nutritionists believe contributes to ill health, heart disease and weight gain. Contrary to this belief, there is little actual evidence linking egg yolk consumption to coronary heart disease; moreover, the yolk is also the most nutrient dense part of the egg.
Nutrition
The egg yolk is high in protein. Nutritionist and author Mike Geary states that the amino acid profile of the protein in egg yolks balances out the protein in egg whites and makes them more bio-available, meaning that their ability to be assimilated and used by the body is improved. Egg yolks contain the fat-soluble vitamins A,D,E and K. They also contain vitamins B6, B12, folate, choline, thiamin and 90 percent of the iron, phosphorus, calcium and zinc present in eggs. Egg yolks contain the antioxidants lutein and zeaxanthin, which help protect against macular degeneration.
Types
Egg yolks are high in omega-3 essential fatty acids. Omega-3 fat helps the brain, heart and immune system function optimally and also plays a role in metabolizing fat and weight control. Eat whole eggs, including the yolk. However some eggs are healthier than others. A Penn State study found that eggs from organic pasture-fed hens were considerably healthier than eggs from caged hens on an industrial diet. Organic eggs contain three times omega-3 fats, twice as much Vitamin E and 40 percent more vitamin A than eggs from industrial fed hens.
Cholesterol
Egg yolks contain cholesterol. The common perception is eating egg yolks can lead to high blood cholesterol, which increases the risk of heart disease. However, according to a University of Connecticut study published in the January 2006 issue of "Current Opinion in Clinical Nutrition and Metabolic Care" most healthy adults experience little or no increase in cholesterol levels from eating egg yolks. The study says eating eggs makes low density lipoprotein or LDL, also known as bad cholesterol, less atherogenic or less liable to cause arterial disease.
Taste
Egg yolks add flavor to the bland taste of egg whites. If you are on a high protein diet and your breakfast includes four to six eggs, you may be concerned with eating too many egg yolks in one siting. Add two to three yolks to your egg whites.
Egg yolks are part of the ingredients for many delicious recipes. Two recipes highlighted by the BBC food ingredients website include the tail fillet of beef with blue cheese 'bonbons,' and avocado with poached egg and Hollandaise. Egg yolks are an integral part of popular foods such as ice cream, mayonnaise and Hollandaise sauce.
References
- Truth About Abs; Are Whole Eggs or Egg Whites Better for You? ; Mike Geary
- Penn State Online: Pasture-ized Poultry; May 2003
- PubMed.gov; Current Opinion in Clinical Nutrition and Metabolic Care; Dietary Cholesterol Provided by Eggs and Plasma Lipoproteins in Healthy Populations; M.L Fernandez
- BBC Food Ingredients; Egg Yolk Recipes; Gennaro Contaldo
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