Why are eggs considered a source of high-quality protein?

Eggs are considered a source of high-quality, or complete, protein because they contain all the amino acids necessary for the human diet in proportions that are similar to human requirements.12

During digestion, proteins are broken down into these constituent amino acids, which the body then uses to synthesize its own proteins. Because eggs provide these essential building blocks in an optimal pattern, they are highly effective for meeting human nutritional needs.12