What is a PDAACS and how do vegan proteins measure up?

PDCAAS is an acronym that stands for PROTEIN DIGESTIBILITY CORRECTED AMINO ACID SCORE. It’s a method that was adopted by the WHO in 1999 as a way to evaluate the quality of an individual protein source based on both the amino acid requirements of humans and how easy each one is to digest.

The score is calculated by comparing the amino acid composition of a specific protein with the essential amino acid requirements of pre-school aged children, with the highest possible score being 1.

This measurement in isolation is not a wholly accurate way to grade different proteins and doesn’t cover the many other factors that determine what a “good” source of protein is when taking it as a supplement. It is however an easy to understand barometer of protein quality and as long as one takes a balanced and informed view of the protein, it is a useful indicator as to whether a particular protein should be used as a way of supplementing your diet.

So how do the most common proteins used in supplementation measure up and in particular plant based/vegan proteins? The below table shows each proteins score:


Whey and milk protein: 1

Egg protein: 1

Soy protein: 0.98

Pea protein: 0.89

Hemp protein: 0.63-0.66

Brown rice protein: 0.42

Beef protein isolate/collagen: 0 (incomplete protein, so doesn’t score)


In isolation, based on the PDCAAS, we should all supplement our diets with milk and egg proteins however there are other factors to be considered like environmental impact, animal welfare, sustainability, cost, organoleptic properties and a consumers individual ethical beliefs.

So while some plant proteins don’t have a high PDCAAS when compared to animal derived proteins, once consumers look at the overall situation, many prefer a combination 2 or 3 different plant based proteins that deliver a more optimized amino acid profile when they are combined.

Opalbond create, develop and deliver plants based protein powders. For more information, complete the enquiry form on our website.