PDCAAS Score: The Protein Quality Metric Explained

You see it more often on protein powders: "PDCAAS score 1.0" or "highest protein quality". But what does that score actually mean? And should you factor it into choosing your protein powder?

What is PDCAAS?

PDCAAS stands for Protein Digestibility-Corrected Amino Acid Score. A mouthful, but it boils down to:

1. Does the protein have all essential amino acids?
2. How well can your body absorb it?

The score runs from 0 to 1.0, where 1.0 is the maximum. A score of 1.0 means: this protein contains all essential amino acids in the right ratios, AND your body can digest it optimally.

PDCAAS Scores of Popular Proteins

Does a lower score mean worse?

Not necessarily. PDCAAS looks at the limiting amino acid — the amino acid present in the smallest amount. For rice protein that's lysine, for pea protein it's methionine.

But here's the clever part: pea + rice are complementary. Pea has lots of lysine, rice has lots of methionine. Combine them and you have a complete amino acid profile.

That's why most vegan protein blends mix pea and rice (or other sources). The blend's PDCAAS is higher than the individual components.

Limitations of PDCAAS

• Capped at 1.0: Even if a protein is theoretically "better" than 1.0, it gets truncated.
• Only measures essential amino acids: Says nothing about non-essential amino acids or other benefits.
• Doesn't account for anti-nutritional factors: Some plant proteins contain compounds that inhibit absorption.

Practical conclusion

For most people: don't stress about PDCAAS. If you're using whey, casein or a good vegan blend, you're fine.

The main factor remains: are you eating enough total protein per day? A "perfect" PDCAAS score doesn't help if you're only getting 40g protein per day when you need 120g.

Check your protein needs with our protein calculator.