Dietary amino acids refer to the naturally occurring amino acids that are present in foods, particularly those from animal sources. These amino acids play a crucial role in human nutrition as they serve as building blocks for proteins and enzymes within our bodies. There are 20 different types of dietary amino acids, nine of which are considered essential because the body cannot produce them on its own and must obtain them through food consumption. These include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.