I can quote some of the relevant sections here (not supposed to share the whole thing). These are just some of the problems listed with the metrics there’s quite a lot more but this comment is getting too long
The relative protein content, IAA content, and IAA profile of a
given food are required to calculate the DIAAS. The FAO has
not prescribed a specific methodology to determine protein
content for the DIAAS but acknowledged that nitrogen con-
tent can be used to estimate protein content for the PDCAAS
[24]. Food-specific nitrogen-to-protein conversion factors
have been determined for various foods and can be used for
this calculation; however, the FAO does not recommend their
use. Instead, it recommends that the generalized nitrogen-to-
protein conversion factor be utilized [29]. The generalized
factor was set at 6.25 because all proteins were originally
estimated to contain 16% nitrogen; however, this varies great-
ly between proteins [32].
Importantly, estimating protein content using the general-
ized or food-specific factors influences the corresponding
PDCAAS and DIAAS. For example, the food-specific factors
for almonds and soybeans are 5.20 and 5.61, respectively. As
a result, using the generalized factor to calculate their DIAAS
yields 16.8% and 10.2% lower values, respectively, than
when they are calculated based on their food-specific factors.
Conversely, the food-specific factors for skim milk and yogurt
are 6.36 and 6.40, respectively [33]. Accordingly, their
DIAAS are higher when generalized factors are used. In ad-
dition, greater discrepancies exist between conversion factors
for plant foods than animal foods, with recent values ranging
from 5.3 to 5.8 for grains compared with 5.85–6.15 for milk
products [34]. The particular methodology used to calculate
protein content therefore influences the DIAAS of plant and
animal foods differently, decreasing scores for plant-based
sources of protein while increasing scores for animal-based
sources of protein. Due to differences in the ranges of food-
specific factors, use of the generalized factor may also lead to
more inaccurate scores for plant foods than animal foods.
Most literature examining dietary protein consumption and
postprandial muscle protein synthesis (MPS) has focused on
isolated protein sources, as used in the DIASS method, with
limited literature focusing on the influence of whole foods on
MPS [31•]. In most settings, protein is not consumed in isolation. Rather, whole foods are consumed with their intrinsic nutrients exhibiting a synergistic and concerted effect [48]
and can influence the post-exercise MPS [49–51].
Raw foodstuff is used for most DIAAS modeling, whereas
protein-rich plant foods (legumes, grains, etc.) typically un-
dergo heat treatment, processing, or both before human con-
sumption. Common cooking techniques modify proteins, with
heat-treated plant-based proteins demonstrating higher digest-
ibility compared with unprocessed sources [30, 52]. One such
modification relates to the protease inhibitor trypsin, and pro-
cessing treatments have been shown to deactivate as much as
80% of its inhibitory activity in raw flour [52]. Malting and
fermentation processes can also increase the digestibility of
some proteins, likely by bacterial protein pre-digestion and
the lessening of “anti-nutrients” like oxalates, tannins, and
phytic acid [31•, 53]. Their effects are significant, both for
foods and supplements. The fermentation of grain coupled
with other cooking techniques, as is often employed in tradi-
tional cooking methods (e.g., sourdough bread), can increase
the digestibility of grain protein to a level approaching that of
meat [53]. Further, compared with untreated pea seeds, pea
protein concentrate demonstrated 12% higher digestibility,
matching the protein digestibility of casein [52].
This is a review study, so it does look at multiple studies over time
(Also note that I did not downvote you, it seems that you have accidentally removed your own default upvote. I had that happen to me earlier)
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I can quote some of the relevant sections here (not supposed to share the whole thing). These are just some of the problems listed with the metrics there’s quite a lot more but this comment is getting too long
Removed by mod
This is a review study, so it does look at multiple studies over time (Also note that I did not downvote you, it seems that you have accidentally removed your own default upvote. I had that happen to me earlier)
Removed by mod
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