Nutrients are chemical elements that are essential to plant and animal nutrition. While no one food (other than mother’s milk, perhaps) provides all the nutrients a human needs, the egg contains a wide array of essential nutrients. After all, the egg was designed by nature to supply everything needed for the creation and nourishment of a baby chick.
All eggs contain the nutrients; protein and fat. Egg protein is of such high quality that it is often used as the standard by which other protein foods are measured. Egg protein contains all the essential amino acids (building blocks of protein which the body needs but cannot make) in a pattern that matches very closely the pattern the human body needs. This is why eggs are classified with meat in the Protein Food Group and why egg protein is called complete protein.
With the exception of vitamin C, an egg contains varying amounts of all the essential vitamins plus many minerals. An egg yolk is one of the few foods which naturally contain vitamin D, the sunshine vitamin.
Altogether, according to the USDA National Nutrient Database for Standard Reference, Release 23 (2010), a single large egg (50 grams) supplies 72 calories and contains the following nutrients: 6.3 grams of protein, 0.4 grams of carbohydrates, 4.8 grams of total fat.
As is true for most foods, cooking causes some minor nutrient losses in the egg. Of the nutrients in an egg, the vitamins riboflavin, thiamin and folic acid are generally less heat stable than other nutrients. You can preserve the highest nutrient content possible by proper cooking.