When you eat protein, your body breaks it into amino acids—commonly known as the “building blocks” of proteins—then uses them to form new proteins.
Complete proteins, like soy, fish, eggs, and whey products, are foods that contain all nine essential amino acids that your body needs in the correct ratios. Many plant-based sources of protein like beans and nuts are considered “incomplete” sources of protein because they are low in one or more of the essential amino acids.
It used to be thought that people following plant-based diets needed to “pair” protein sources with complementary amino acid profiles, like rice and beans, at meals in order to make a “complete” protein. However, protein pairing at the same meal isn’t necessary27 as your body has an amino acid “pool” that contains a variety of amino acids that your body can use to build proteins, create hormones, and more.
So, as long as you’re consuming a varied diet that provides all of the amino acids your body needs on a daily basis, you’re good to go!