What is the main dietary source of complete proteins?

Complete proteins are those that contain all nine essential amino acids in adequate amounts, which are necessary for human health. The main dietary sources of complete proteins primarily include animal products, such as meat, dairy products, and eggs. These sources are known to provide the full spectrum of essential amino acids that the body cannot synthesize on its own, making them vital components of a balanced diet.

While other food groups like grains and legumes can provide some of these amino acids, they often lack one or more essential amino acids and are therefore considered incomplete proteins. For instance, grains like rice and wheat typically do not contain sufficient lysine, while legumes may be low in methionine. Vegetables and fruits do not serve as adequate sources of complete proteins on their own, as they generally have lower protein content and similar limitations in amino acid profiles.

Consequently, meat and dairy products stand out as the primary and most reliable sources of complete proteins in a typical diet, validating the choice identified as correct.