During the Medieval era in Europe, peas were know as "poor man's meat". Beans and peas contain about 20-25% protein but it does not have the balanced amino acid content needed for human consumption. For a protein to be utilized by the body, it should contain the eight essential amino acids (valine, isoleucine, leucine, phenylalanine, threonine, tryptophan, methionine, and lysine). Grains however can be combined with legumes because the amino acids absent in one are supplied by those present in the other. Grains and Legumes amino acids are complementary which makes the protein "complete".