The DIAAS accounts for amino acid digestibility at the end of the small intestine, providing a more accurate measure of the amounts of amino acids absorbed by the body and the protein's contribution to human amino acid and nitrogen requirements. This is in contrast to the PDCAAS, which is based on an estimate of digestibility over the total digestive tract. Values stated using this method generally overestimate the amount of amino acids absorbed.[1]
Reference pattern
Amino acid requirements were determined in two parts. The amino acid distribution of breast milk was used for the 0 to 6 month age range, and existing amino acid data was used for older ages after adjustment for digestibility. The reference amino acid requirements are presented below.[2]: 29
The table shows the ratings of selected foods comparing PDCAAS to DIAAS.[3][4][5][6][7][8][9][10][11][12][13][14] The quality of various sources of protein depends on how it is processed, refined, stored, or cooked.[12][15][16] (preparation is unspecified for some values in the table, but does not necessarily differ in preparation from the foods where preparation is specified). A major difference between DIAAS and PDCAAS, is that PDCAAS is truncated at 100%, while DIAAS is not. Multiple protein sources can also be combined to increase DIAAS, which can be effective at raising the max DIAAS of plant-based diets.[13]
The PDCAAS uses the faecal digestibility while the DIAAS considers the ileal digestibility.
The PDCAAS is truncated at 100% while DIAAS is not
The PDCAAS experimentation protocol that determines the digestibility involves rats while the DIAAS advises to use pigs preferably as the pig digestive system is closer to the human's system.
The PDCAAS considers the global digestibility of the product's protein (a single figure) while the DIAAS accounts for a specific digestibility percentage for each indispensable amino acid
The reference values for the PDCAAS are based on a unique age group, the 2 to 5-year-old child which is deemed to be the more demanding. The DIAAS provides values for three different age groups, with more up to date data about human needs.
^House JD, Neufeld J, Leson G (November 2010). "Evaluating the quality of protein from hemp seed (Cannabis sativa L.) products through the use of the protein digestibility-corrected amino acid score method". Journal of Agricultural and Food Chemistry. 58 (22): 11801–11807. doi:10.1021/jf102636b. PMID20977230.
^Zarkadas CG, Yu Z, Hamilton RI, Pattison PL, Rose NG (January 1995). "Comparison between the Protein Quality of Northern Adapted Cultivars of Common Maize and Quality Protein Maize". Journal of Agricultural and Food Chemistry. 43 (1): 84–93. doi:10.1021/jf00049a016. ISSN0021-8561.
^ abRuales J, de Grijalva Y, Lopez-Jaramillo P, Nair BM (March 2002). "The nutritional quality of an infant food from quinoa and its effect on the plasma level of insulin-like growth factor-1 (IGF-1) in undernourished children". International Journal of Food Sciences and Nutrition. 53 (2): 143–154. doi:10.1080/09637480220132157. PMID11939108. S2CID12001819.