Amino acids are often called the building blocks of protein. This is because proteins are made from strands of various amino acids. There are 22 known amino acids; your body needs 20 of these to function. Eleven of those 20 are created by your body, often called nonessential amino acids; the other 9, referred to as essential amino acids or Branched Chain Amino Acids (BCAAs), must be taken in through your diet. You may have also heard of the term "complete protein." This term reffers to a protein molecule that contains all of the essential amino acids. Meat is a great source of complete proteins, and in most diets, the main source. This is why vegetarians must be so careful in their diets to ensure that they are not missing out on any proteins. A complete protein can also be formed by consuming multiple foods with different amino acids that combine to form complete proteins. This is because when you digest proteins (complete or incomplete) your body processes the individual amino acids and combines them to form appropriate proteins where they are needed within the body.