Essential amino acid reference profile affects the evaluation of enteral feeding products

The chemical score is a measure of the predicted metabolic usefulness of a protein in a food based on the comparison (ratio or percentage) of the concentrations of the essential amino acids (EAAs) to a "profile" assumed to reflect the true needs of the body. The score for the limiting EAA is taken to represent the value of the food. Such a chemical score is particularly useful for therapeutic diets where bioassay (such as nitrogen-balance studies) in a large number of patients may be unethical or impractical. Although a major limitation to the chemical-score method previously was scarcity and/or imprecision of data about EAA concentrations in foods, this situation has been mitigated by modern analytic methods. The validity of a chemical score is also exquisitely sensitive to the EAA profile used for comparison. Chemical scores published for a variety of enteral and parenteral feeding products implied a low (approximately 50%) protein value. These computations were based on the EAA profile of egg protein. This pattern is sufficient, in most cases, for body needs, but it may be far more than is necessary. Recently published profiles, based on measurements in human beings of actual protein and EAA requirements, point to a more realistic chemical-score computation. These profiles accommodate age and lifestyle factors and provide greater flexibility in the formulation of therapeutic diets.