A nutritious substance, many of which are supplied by the egg. While no one food (other than mother's milk, perhaps) provides everything that humans need, the egg contains a wide array of necessary nutrients. It was, after all, made to supply everything for the creation and nourishment of a baby chick.
Egg protein is of such high quality that it is often used as the standard by which other protein is 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 body needs.
That is why eggs are classified with meat in the food groups and why egg protein is called complete protein.
A moderate amount of fat, about 5 grams, is found in a Large egg yolk. About 1.5 grams are saturated and 2.5 grams unsaturated.
An egg contains varying amounts of 13 vitamins (but no vitamin C) plus many minerals. An egg yolk is one of the few foods which contain vitamin D, the sunshine vitamin.
As is true for most foods, some minor nutrient losses do occur in the egg after cooking. Of the nutrients in an egg, riboflavin, thiamin and folic acid are generally less heat stable than other nutrients. Normal cooking simply changes the form of egg protein but it is still just as nutritious. Protein is destroyed only when it is severely overcooked such as in the brown lacy edges or an overcooked fried egg. You can preserve the highest nutrient content possible by avoiding
overcooking.