Which type of protein is considered lower quality, found mainly in plant sources?

The classification of proteins into complete and incomplete categories is based on their amino acid profiles. Incomplete proteins are those that do not contain all nine essential amino acids in sufficient quantities needed for the body to function optimally. These proteins are typically found in many plant sources, such as legumes, grains, and vegetables.

Most plant foods tend to provide a limited array of amino acids, making their protein content less balanced compared to animal sources, which offer complete proteins that contain all essential amino acids. While certain plant foods can be combined to form complementary proteins (for example, rice and beans), individually, many plant proteins are classified as incomplete.

Understanding this distinction is crucial in nutrition, particularly for individuals following a vegetarian or vegan diet, as they must be mindful of combining different plant proteins to ensure they meet their amino acid needs and achieve a balanced intake of dietary protein.