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Defining the future of protein quality.

Protein is an essential nutrient that mainly serves as the “building blocks” for the cells in our bodies. It is a crucial component of any diet, regardless of your health and performance goals. However, not all proteins are created equal. At Radix, we use the Digestible Indispensable Amino Acid Score (DIAAS) to drive innovation and ensure our protein formulations are of the best possible quality.

What is DIAAS?

DIAAS stands for Digestible Indispensable Amino Acid Score and is a method of measuring protein quality. Effectively, it evaluates the proportion of consumed amino acids absorbed and utilised by the body. It compares the amount of each essential amino acid absorbed from a protein source to a reference value for the human body [1]. Generally, the lowest score of the nine essential amino acids determines the overall DIAAS score, which makes it a good measurement for identifying a whole protein (a protein that provides adequate amounts of all nine essential amino acids). DIAAS is considered the gold standard for protein quality evaluation, as it accounts for both the amino acid profile of a protein and its digestibility [1].


Up until recently, another method of protein quality evaluation was commonly used; the protein digestibility-corrected amino acid score (PDCAAS). This method functions similarly to DIAAS but has several drawbacks that make it less accurate and no longer appropriate.


The assessment of the nutritional value of a protein should reflect its ability to satisfy the metabolic demands for nitrogen and amino acids. Its capacity to do so is determined by amino acid availability and digestibility [1]. There are several reasons why PDCAAS does not adequately account for these factors.


Firstly, PDCAAS is taken from faecal samples, where the presence of amino acids will determine their relative digestibility. This can lead to an inaccurate evaluation, as many processes in the gut can introduce amino acids into the faeces, such as the synthesis of methionine and lysine and microbial metabolic functions. This can result in “false positives” when measuring quantities of amino acids to determine absorption [1].


On the other hand, DIAAS samples are taken from the ilium. This leads to greater accuracy when assessing digestibility, as amino acid absorption practically ceases once it reaches this point in the digestive tract [1]. Measurement at the ilium also precedes the processes in the gut that can introduce additional amino acids.


Another factor to consider is that the PDCAAS system only allows for a maximum score of 1. It does not permit extra nutritional value to be evaluated in higher quality proteins. Under the DIAAS method, a protein that exceeds the human requirements for all essential amino acids can score higher than 1. This makes it a more effective way to evaluate and compare high-quality protein sources [1].


In 2011, the Food and Agriculture Organisation (FAO) recommended using DIAAS over PDCAAS for protein quality evaluation [1].

DIAAS scores of protein sources

The following is a list of protein sources and their corresponding DIAAS score [1].

Animal-derived protein

Goat milk


Milk protein concentrate


Whole milk powder


Cow milk




Whole egg, boiled






Sheep milk


Chicken breast


Whey protein concentrate


Skimmed milk protein


Whey protein isolate


Fish (Tilapia)


Plant-derived protein

Soya flour


Soya protein isolate


Oat protein isolate




Pea protein concentrate


Cooked rice


Cooked kidney beans


Cooked rolled oats








Roasted peanuts




Corn-based cereal


Using DIAAS to pursue excellence

Here at Radix, we’ve used the DIAAS score to guide the development of the most effective, technologically advanced protein on the market.


Made from ultra-filtered whey protein isolate, ultra-filtered whey protein concentrate & ultra-filtered milk protein concentrate, our whey protein complex is designed to provide the highest amino acid profile across all essential amino acids and BCAAs with exceptionally high digestibility of DIAAS 1.61. This was achieved through a technical partnership with Fonterra and by simulating over 50 formulations before finalising our blend.  


Made from precisely defined concentrations of yellow pea protein isolate and brown rice protein isolate, our plant protein complex is also designed to provide a complete amino acid profile with exceptionally high digestibility of DIAAS 1.30. This scores higher than traditional pure whey isolate.


Using the DIAAS score to drive the improvement of our products, we have achieved protein formulations of the highest quality, providing your body with the building blocks it needs to function at its best. By achieving a class-leading amino acid profile and ensuring exceptionally high digestibility, our protein powders are now able to unlock a new level of performance for athletes.

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  1. Dietary protein quality evaluation in human nutrition. Report of an FAQ Expert Consultation. FAO Food Nutr Pap, 2013. 92: p. 1-66.
  2. Burd, N.A., et al., Food-First Approach to Enhance the Regulation of Post-exercise Skeletal Muscle Protein Synthesis and Remodeling. Sports Med, 2019. 49(Suppl 1): p. 59-68.