According to MedlinePlus, the body needs protein to maintain and repair itself. Every cell in the body contains protein, and all fluids in the body, except bile and urine, also contain protein.
Proteins play a vital role in each of the body's critical functions. According to the Science Learning Hub from The University of Waikato, they transport oxygen, vitamins, minerals and lipids throughout the body, helping each organ, gland and muscle to perform its job. There are many types of proteins, and some of them have very specific duties. For example, some proteins have the job of keeping the fluids in the body balanced, while others have the job of contracting and releasing muscles.
Certain proteins are created by the body, while others must be obtained through foods. Food sources of protein include meats, milk, fish, eggs, soy and some grains. The digested form of these foods is called amino acids, which are the small molecules that make up proteins. Eating two to three servings of protein-rich foods each day is sufficient for supplying the body with the amino acids it needs to function efficiently. It is important not to consume too many proteins, as this can cause elevated cholesterol levels, kidney problems and gout, notes MedlinePlus.