What characteristic defines complete proteins?

Complete proteins are defined by their ability to provide all essential amino acids in sufficient quantities necessary for the body's needs. Essential amino acids are those that cannot be synthesized by the body and must be obtained through diet. Complete proteins, such as those found in animal products (meat, poultry, fish, eggs, and dairy), contain adequate amounts of these amino acids, thus supporting various bodily functions, including tissue repair, hormone production, and immune responses.

This characteristic is crucial for individuals, especially those recovering from illness or engaging in activities that require muscle repair and growth. In contrast, incomplete proteins lack one or more essential amino acids and are typically found in many plant-based foods. While many plant foods can provide essential amino acids, they often need to be combined in diets to make a complete protein profile.