Eggs provide protein in the white and the yolk with a particularly complete amino acid profile, which is why egg protein is often used in nutrition science as the reference for the biological value of other proteins. An average egg provides around 13 g of protein per 100 g, spread across the white and the yolk. The size of an egg and how the hen was kept can also affect the nutritional value slightly, although the protein content remains comparatively stable overall.
The egg white contains mainly protein with almost no fat, while the yolk contains fat and fat-soluble vitamins as well as protein. In practice, eggs are prepared in many ways, boiled, scrambled or in baked goods, and combine well with plant protein sources to round off a meal. Because of their good bioavailability, eggs are often used in nutrition science as a benchmark for other protein sources.
More on biological value as a yardstick for protein quality is explained in the entry Biological value, and an isolated form of egg protein is described in the entry Egg protein. Further animal protein sources are listed on the page High-protein foods.
