These include beef, lamb, pork, poultry, fish, shellfish , eggs, milk, and milk products. Protein in foods such as grains, fruits, and vegetables are either low incomplete protein or lack one of the essential amino acids. These food sources are considered incomplete proteins. Plant proteins can be combined to include all of the essential amino acids and form a complete protein. Examples of combined, complete plant proteins are rice and beans, milk and wheat cereal, and corn and beans.
Protein is the main component of muscles, organs, and glands.
Every living cell and all body fluids, except bile and urine, contain protein. The cells of muscles, tendons, and ligaments are maintained with protein. Children and adolescents require protein for growth and development. The body does not make more protein than usual when dietary protein is increased. The extra protein is broken down in the body and the amino acids are used for energy or turned into fat .