Amino acids caloric value

Amino acids are the building blocks of body proteins. There is no excess storage form of protein in the body, so amino acids are an essential component of the PN admixture. Amino acids are provided to preserve or replete lean body mass and visceral proteins and to promote protein anabolism and wound healing. Amino acids are a source of calories with a caloric value of 4 kcal/g. 

The resulting reduction in caloric value of browned or caramelized foods is of little significance for well-fed Americans. Loss of biologically available amino acids is of concern only for those consuming diets of marginal protein quality. 

Aspartame is non-cariogenic and, like all amino acids and protein products, has a caloric value of 4 kcal/g. However, as the level at which it is used is so low, its contribution to the caloric value of soft drinks is negligible. 

Proteins are not required for their caloric value, but for their content of amino acids. This presents two nutritional problems (1) Does a food protein contain the correct numbers of types of amino acids (2) How accessible are the amino acids, i.e., how digestible is the food These qualities of a dietary protein are expressed as its biological value. 

A protein s biological value will be less than 100 if it is incompletely digestible, or if it has only a small percentage of even one essential amino acid. In the latter case, one must ingest large quantities to obtain the essential amino acid, while those in abundance will be used calorically. A somewhat different, but experimentally useful classification is called the chemical score. 

Cheese is a high-protein food, and the protein (principally casein) is partially digested. It is rich in the essential amino acids, calcium, phosphorus, certain other minerals, and vitamins, and has a high caloric value. Only a trace of the lactose present in milk remains in the cheese. 

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