Amino acids are the building blocks of protein . The body has twenty different amino acids that act as these building blocks.Foods from animal sources are typically rich in essential amino acids. These include chicken, fish, eggs, dairy products, beef, and pork.vegetarian source include dried beans (black, kidney, northern, red, and white beans), peas, soy, nuts, and seeds. Although plant sources generally lack one or more of the essential amino acids, when combined with whole grains such as rice, or by eating nuts or seeds with legumes , all the amino acids can be obtained.