DIAAS vs PDCAAS

For decades, the Protein Digestibility-Corrected Amino Acid Score (PDCAAS) was the standard for evaluating protein quality. The FAO now recommends the Digestible Indispensable Amino Acid Score (DIAAS).

The Problem with PDCAAS

PDCAAS had two major flaws:

1. Fecal Digestibility: It measured digestibility over the entire digestive tract (fecal). However, amino acids are primarily absorbed in the small intestine. Measuring what comes out the end overestimates the absorption of certain plant proteins that are fermented by bacteria in the colon (which doesn't help muscle synthesis).
2. Truncation at 1.0: PDCAAS capped scores at 1.0. This meant that high-quality dairy proteins (which might score 1.2) were artificially grouped together with soy protein (which scores ~1.0). It hid the superiority of animal-based proteins.

The DIAAS Solution

DIAAS measures ileal digestibility (at the end of the small intestine) and does not truncate scores. This provides a much more accurate picture of how much of each essential amino acid is actually absorbed and available for the body to use.

This is why we use DIAAS when evaluating the true biological value of the supplements we review.