Amino Acids

Amino acids are the building blocks of proteins which the body uses for the structure of all cells and tissues, for the regulation of many body processes, and as a potential source of energy. An adequate intake of protein is essential for normal growth of a child to occur. Proteins are composed of combinations of twenty different amino acids which are found in foods and many of which are produced by the body. The human body needs all 20 amino acids for the synthesis of its wide range of proteins. The body can synthesize 11 of these amino acids, but is unable to make 9 others, the essential amino acids, which must be obtained from dietary sources. The diet must regularly supply sources of proteins which contain these essential amino acids so that the body will have enough for new protein synthesis. Amino acid requirements for growing children are greater than for adults. For example, a child aged 10 - 12 years needs 44 milligrams of lysine per kilogram body weight per day compared to 12 milligrams per kilogram per day that an adult needs. This increased need is due to growth spurts which occur during childhood and adolescence when new tissues are being built. During these times the amount of protein consumed must be higher since protein is not only being replaced but there is the need to build new muscle tissue. Protein needs for growth decrease as rates of growth decline. When a food contains amino acids in the proportions and amounts needed by the body for tissue replacement and growth, it is providing protein of high biological value. Such protein is referred to as complete protein. Eggs are an example of a food source of complete protein. Eggs contain all of the essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine) as well as the 9 nonessential amino acids. In fact, egg protein has such an ideal mix of amino acids to satisfy human protein needs that the World Health Organization uses egg protein as the standard by which protein quality of foods is measured. This is one reason why the egg is classified with meat in food categories. One large egg equals one ounce of lean meat, fish, or poultry. Eggs also contain varying amounts of many other essential nutrients which contribute to nutritional balance. Since eggs are such good sources of protein it is wise to include eggs in the diets of children.