PDCAAS
Definition
What 'PDCAAS' means
The Protein Digestibility-Corrected Amino Acid Score (PDCAAS) is a method endorsed by the FAO/WHO for evaluating protein quality. It calculates the ratio of limiting amino acids in a test protein to a reference pattern, multiplied by fecal digestibility. Values are capped at 1.0, with soy and egg scoring highest.
Related terms
In depth
The longer answer
PDCAAS stands for Protein Digestibility-Corrected Amino Acid Score, a method used to evaluate protein quality based on both the amino acid profile and digestibility of a food. It is commonly encountered on nutrition labels or in discussions about plant versus animal protein, especially in contexts like sports nutrition, dietary guidelines, and food product development. The score ranges from 0 to 1, with 1 indicating a complete protein that is fully digestible.
The PDCAAS is calculated by comparing the amino acid content of a food to a reference pattern for human requirements, then multiplying by a digestibility factor derived from animal studies. For example, soy protein isolate scores near 1.0, while wheat gluten scores around 0.25 due to its low lysine content. This method is endorsed by the FAO/WHO and widely used by food manufacturers to label protein quality, though it relies on fecal rather than ileal digestibility, which can overestimate absorption for some plant proteins.
For someone eating plant-based, PDCAAS highlights that combining complementary proteins—like rice and beans—can achieve a complete amino acid profile, though the old idea of needing to pair them at every meal is outdated. A limitation is that PDCAAS does not account for anti-nutritional factors or the effects of processing on digestibility, and newer methods like DIAAS are considered more accurate. Still, it remains a practical benchmark for comparing protein sources in a mixed diet.
At a glance
Quick facts
| Detail | What to know |
|---|---|
| Score range | 0 to 1, with 1 being highest |
| Top plant source | Soy protein isolate scores 1.0 |
| Common low scorer | Wheat gluten scores about 0.25 |
| Regulatory body | FAO/WHO established the method |
In practice
What this means for you
- Check PDCAAS on protein powders: soy, pea, and potato isolates often score 0.9–1.0, while rice protein may score lower.
- Combine grains and legumes in meals—like lentil soup with bread—to naturally boost overall protein quality without precise tracking.
- For athletes, choose a plant protein blend (e.g., pea and rice) to ensure a complete amino acid profile post-workout.
- Ignore the myth that plant proteins are inferior; a varied diet easily meets needs, as PDCAAS is just one metric.
FAQ