Final answer:
Complementary proteins are combinations of plant-based foods that together provide all essential amino acids needed by the body. Grains and legumes, such as rice and beans, are examples of complementary proteins. It is not necessary to eat them at the same meal as long as the daily amino acid requirements are met.
Step-by-step explanation:
Complementary Proteins and Essential Amino Acids
A combination of foods that provides a good example of complementary proteins to meet essential amino acid needs includes grains and legumes, such as rice and beans. Complete proteins contain all nine essential amino acids and are found in animal products like meat, fish, and eggs. Plant-based foods like grains, nuts, and beans often contain incomplete proteins, lacking one or more essential amino acids. However, when plant foods with different limiting amino acids are consumed together or throughout a day, they can provide the complete spectrum of essential amino acids. This is like combining puzzle pieces to create a complete picture.
For example, the grain corn is limited in the amino acids lysine and tryptophan, whereas beans supply these missing amino acids. Together, they form a complete protein profile. Similarly, rice is low in lysine but high in methionine, while beans are high in lysine and low in methionine. Consuming both rice and beans either in one meal or separately over the course of a day can sufficiently meet the body's essential amino acid requirements, making this a practical strategy for vegetarians and others following a plant-based diet. It's no longer necessary to eat complementary proteins at the same meal. As long as the body's daily need for essential amino acids is met, the timing of consuming these complementary proteins can be varied, which offers flexibility for meal planning. This concept supports a varied diet, particularly for those on restricted diets, such as vegetarians, to ensure ingestion of a wide range of protein sources.