GIFSQ Tools · Module 19 — Nutrition, Labeling & Dietary Assessment · Tool 368 of 500
Score a protein from its limiting amino acid score and digestibility — PDCAAS (truncated at 1.00) and DIAAS.
Try sample values — fills the form with the worked example below.
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PDCAAS
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DIAAS (%)
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Quality band
Equation: PDCAAS = lowest amino acid score × true faecal digestibility, truncated at 1.00. DIAAS (%) = lowest digestible indispensable amino acid ratio × 100, not truncated.
Method: FAO/WHO Protein Quality Evaluation (1991) for PDCAAS; FAO Dietary Protein Quality Evaluation in Human Nutrition (2013) for DIAAS, using the FAO/WHO/UNU 2007 amino acid reference pattern. PDCAAS uses faecal digestibility; DIAAS uses true ileal digestibility per amino acid.
Assumptions: the amino acid score entered is already the lowest (limiting) score against the reference pattern; digestibility is the true digestibility for that protein.
Limitations: a single digestibility value is an approximation — DIAAS properly needs per-amino-acid ileal digestibility; truncation hides differences between excellent proteins.
Rounding: PDCAAS to 2 decimal places; DIAAS to 1 decimal place; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: FAO/WHO Protein Quality Evaluation (1991) for PDCAAS; FAO Dietary Protein Quality Evaluation in Human Nutrition (2013) for DIAAS, using the FAO/WHO/UNU 2007 amino acid reference pattern. PDCAAS uses faecal digestibility; DIAAS uses true ileal digestibility per amino acid.
Assumptions: the amino acid score entered is already the lowest (limiting) score against the reference pattern; digestibility is the true digestibility for that protein.
Limitations: a single digestibility value is an approximation — DIAAS properly needs per-amino-acid ileal digestibility; truncation hides differences between excellent proteins.
Rounding: PDCAAS to 2 decimal places; DIAAS to 1 decimal place; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: Limiting amino acid score 0.85, digestibility 95%: PDCAAS = 0.85 × 0.95 = 0.81, DIAAS 80.8%, quality band good.
Enter values above to see results.
PDCAAS of 1.00 is the ceiling — a score above 1.00 is reported as 1.00. Tool 368 of 500 — GIFSQ
