Amino acid score

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Amino acids Molecular structures of the 21 proteinogenic amino acids.svg
Amino acids

Amino acid score is used to determine if a protein is complete. It is used along with the measure of protein digestibility that refers to how well a given protein is digested, to compare the proportion of essential amino acids found in one protein to the proportion in a "reference protein" considered to be complete. [1]

Contents

Methods of amino acid score calculation

PDCAAS and DIAAS are the two major protein standards which determine the completeness of proteins by their unique composition of essential amino acids. [2]

Simple AAS, PDCAAS

PDCAAS considers digestibility and AAS separately. It has a single "reference protein" profile, in which the amounts in milligrams of each essential amino acid (EAA) in each gram of the reference protein is listed. To find the AAS given the amino acid profile of the test protein Ti and the amino acid profile of the reference protein Ri: [3]

PDCAAS estimates digestibility in a separate procedure. The estimated PD is multiplied with AAS to get PDCAAS. [3]

Digestibility-corrected AAS, DIAAS

DIAAS considers the profile of the essential amino acids that are actually absorbed. This value is calculated by estimating the amount of each EAA absorbed in the "test protein" by comparing how much of each EAA went into the mouth and how much was pumped out of the end of the small intestines. This was then turned into a profile Ai by dividing the amounts in milligrams of each EAA with the grams of the test protein eaten. From then on, the calculation is similar:

DIAAS provides three separate Ri reference profiles for different human age groups. [2]

References

  1. ↑ Devi, Sarita; Varkey, Aneesia; Sheshshayee, M S; Preston, Thomas; Kurpad, Anura V (1 June 2018). "Measurement of protein digestibility in humans by a dual-tracer method". The American Journal of Clinical Nutrition. 107 (6): 984–991. doi:10.1093/ajcn/nqy062. PMC   6179135 . PMID   29771297.
  2. 1 2 Leser, S. (December 2013). "The 2013 FAO report on dietary protein quality evaluation in human nutrition: Recommendations and implications: FAO dietary protein report" (PDF). Nutrition Bulletin. 38 (4): 421–428. doi:10.1111/nbu.12063.
  3. 1 2 Gilani, G. Sarwar; Sepehr, Estatira (January 2003). "Protein Digestibility and Quality in Products Containing Antinutritional Factors Are Adversely Affected by Old Age in Rats". The Journal of Nutrition. 133 (1): 220–225. doi: 10.1093/jn/133.1.220 .
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