Background. Essential amino acids (EAAs) are key factors in determining dietary protein quality. Their Recommended Daily Allowances (RDAs) have been estimated. However, although non essential amino acids (NEAAs) are utilized for protein synthesis too, no estimates of their usage for body protein replenishment have been proposed so far. Objective. To provide minimum, approximate estimates, of NEAA usage for body protein replenishment/conservation in humans. Methods. A correlation between the pattern of both EAAs and NEAAs in body proteins, and their usage, was assumed. In order to reconstruct an “average” amino acid pattern/composition of total body protein(s) (as g amino acid x g protein-1), published data of relevant human organs/tissues (skeletal muscle, liver, kidney, gut and collagen, making up ~74% of total proteins) were retrieved. The (unknown) amino acid composition of residual proteins (~26% of total) was assumed to be the same as the sum of the above-listed organs excluding collagen. Using international EAA RDA values, an average ratio between EAA RDA, and the calculated whole-body EAA composition, was derived. This ratio was then used to back-calculate NEAA “usage” for protein replenishment. The data were calculated also using estimated organ/tissue amino acid turnover. Results: The individual ratios between WHO/FAO/UNU RDA and EAA content ranged between 1.35 ([phenylalanine+tyrosine]) and 3.68 (leucine), with a mean value of 2.72±0.81 (±SD). In a reference 70-kg subject, calculated NEAA “usage” for body protein replenishment ranged from 0.73 g x day-1 for asparagine, to 3.61 g for proline. Use of amino acid turnover data yielded similar results. Total NEAAs usage for body protein replenishment was ~19 g x day-1 (45% of total NEAA intake), whereas ~24 g x day-1 were used for other routes. Conclusions: This method may provide indirect, minimum estimates, of the ”usage” of NEAAs for body protein replacement in humans.
Non essential amino acids usage for protein replenishment in humans: a method of estimation.
Tessari P.
2019
Abstract
Background. Essential amino acids (EAAs) are key factors in determining dietary protein quality. Their Recommended Daily Allowances (RDAs) have been estimated. However, although non essential amino acids (NEAAs) are utilized for protein synthesis too, no estimates of their usage for body protein replenishment have been proposed so far. Objective. To provide minimum, approximate estimates, of NEAA usage for body protein replenishment/conservation in humans. Methods. A correlation between the pattern of both EAAs and NEAAs in body proteins, and their usage, was assumed. In order to reconstruct an “average” amino acid pattern/composition of total body protein(s) (as g amino acid x g protein-1), published data of relevant human organs/tissues (skeletal muscle, liver, kidney, gut and collagen, making up ~74% of total proteins) were retrieved. The (unknown) amino acid composition of residual proteins (~26% of total) was assumed to be the same as the sum of the above-listed organs excluding collagen. Using international EAA RDA values, an average ratio between EAA RDA, and the calculated whole-body EAA composition, was derived. This ratio was then used to back-calculate NEAA “usage” for protein replenishment. The data were calculated also using estimated organ/tissue amino acid turnover. Results: The individual ratios between WHO/FAO/UNU RDA and EAA content ranged between 1.35 ([phenylalanine+tyrosine]) and 3.68 (leucine), with a mean value of 2.72±0.81 (±SD). In a reference 70-kg subject, calculated NEAA “usage” for body protein replenishment ranged from 0.73 g x day-1 for asparagine, to 3.61 g for proline. Use of amino acid turnover data yielded similar results. Total NEAAs usage for body protein replenishment was ~19 g x day-1 (45% of total NEAA intake), whereas ~24 g x day-1 were used for other routes. Conclusions: This method may provide indirect, minimum estimates, of the ”usage” of NEAAs for body protein replacement in humans.
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
