What is second class protein?

Second-class proteins, also known as incomplete proteins, are those that do not contain all nine essential amino acids in sufficient quantities required by the body. They are typically derived from plant sources, such as legumes, grains, and nuts. While they may be lower in certain amino acids, they can be complemented with other protein sources to achieve a complete amino acid profile. Examples include combining rice with beans or peanut butter with whole wheat bread.