Updated: Nov 23, 2020
Both the white and yolk of an egg are rich in nutrients, including proteins, vitamins and minerals. The yolk also contains cholesterol, fat-soluble vitamins (such as vitamins D and E) and essential fatty acids. Eggs are also an important and versatile ingredient for cooking, as their particular chemical make-up is literally the glue of many important baking reactions.
Eggs are a very good source of inexpensive, high-quality protein. More than half the protein of an egg is found in the egg white, which also includes vitamin B2 and lower amounts of fat than the yolk. Eggs are rich sources of selenium, vitamin D, B6, B12 and minerals such as zinc, iron and copper. Egg yolks contain more calories and fat than the whites. They are a source of fat-soluble vitamins A, D, E and K and lecithin, the compound that enables emulsification in recipes such as hollandaise or mayonnaise.
Some brands of egg now contain omega-3 fatty acids, depending on what the chickens have been fed (always check the box). Eggs are regarded as a 'complete' source of protein as they contain all nine essential amino acids, the ones we cannot synthesise in our bodies and must obtain from our diet.