Explain how complementary proteins can be used to make up for a limiting amino acid:

Answer

Complementary proteins are pairs or groups of plant-based protein sources that, when eaten together or over the course of a day, provide all nine essential amino acids in adequate amounts. A limiting amino acid is the specific essential amino acid that is present in the lowest quantity in a food source, preventing it from being a 'complete' protein on its own. By combining two incomplete protein sources with different limiting amino acids, the amino acid deficient in one food is supplied by the other food. Common examples include grains and legumes: grains are typically low in lysine but high in methionine, while legumes are low in methionine but high in lysine. When combined, such as in rice and beans or peanut butter on whole-wheat bread, they create a complete protein profile that fulfills the body's nutritional requirements.