Every living cell contains protein, complex chemical compounds that break down into amino acids during digestion. These are absorbed into the bloodstream and transported to different parts of the body, where they are then reformed into different types of protein. Essential amino acids include lysine that is found in bread, methionine that is found in beans, and many others. Very young babies need two extra essential amino acids, arginine and histidine.
Proteins are essential for the constant repair and replacement of the body tissues.
For example, proteins are vital ingredients in skin-cell multiplication, hair and nail growth, and gradual replacement of degenerated bone cells. The proteins responsible for digestion are known as enzymes. Extra proteins are particularly important during times of growth in childhood or for pregnant women who are building the bodies of their new babies. Similarly, a woman who is breast-feeding her baby needs extra protein to make milk. After a serious illness a person must eat a high protein diet to regain the protein lost during fever.