What is PDCAAS?

PDCAAS (Protein Digestibility Corrected Amino Acid Score) is a standard used to know the quality and efficiency of protein in a particular food. The PDCAAS (Protein Digestibility Corrected Amino Acid Score) evaluation procedure is considered to be superior to other methods.

PDCAAS has been adapted by the U.S. Food & Drug Administration (FDA), the United Nations Food & Agricultural Organization (FAO) and the World Health Organization (WHO) as the preferred method for evaluating food protein.

How PDCAAS works?

PDCAAS measures the quality of a food protein based on the amino acid requirements of 2-5 year olds, who are considered the most protein-requiring age group.

The amount of different amino acids in a particular food is calculated. It is then compared to the amount of essential amino acids required by a 2-5 year old. The following is the requirement of different amino acids for a 2-5 year old.

Amino acid


(mg/g crude protein)
Isoleucine 28

Leucine 66
Lysine 58
Total sulfur amino acids 25
Total aromatic amino acids 63
Threonine 34
Tryptophan 11
Valine 35
Total 320

The digestibility of the food protein is also taken into account. That is, how much of the protein is absorbed by the body after digestion. The fecal method is used to evaluate digestibility.

A food must have all the essential amino acids in required amounts to be considered a good source of protein. So, only the amino acid with the least presence in the food is taken into consideration for getting PDCAAS.

For example, a food contributes only 36 mg/g of Leucine to the body, but can contribute more than required amounts of other amino acids. Still, only the 36 mg/g of Leucine is considered to get PDCAAS.

The highest possible PDCAAS is 1.0. A score of 1.0 means that after digestion of the food, it provides 100% or more of the recommended amount of essential amino acids per unit of protein.

A score above 1.0 is rounded off to 1.0. This is because excess protein is not absorbed by the body. It is either converted into fat or thrown out as waste.

PDCAAS of various foods

Here is a list of the PDCAAS of various foods

Whey (1.0)
Egg white  (1.0)
Casein (1.0)
Milk (1.0)
Soy protein isolate (1.0)
Beef (0.92)
Soybean (0.91)
Tubercles (0.74)
Vegetables (0.74)
Legumes in general (0.69)
Kidney beans (0.68)
Rye (0.68)
Cereals and derivatives  (0.58)
Whole wheat (0.54)
Lentils (0.52)
Peanuts (0.52)

If you are looking for a protein supplement, look for the PDCAAS score on the box. If it is less than 1.0, do not take it.

7 responses to What is PDCAAS?

  1. Its a valuable information for me.


  2. Thank you for such a clear explanation!!


  4. thanxx! very valuable info for my nutrition exam!!

  5. thank you for very very important information for selection of food protein.

  6. it is very good article i got much information about PDCAAS, THANKS

  7. It is very informative. I learned a lot of important facts about PDCAAS. Thanks