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Soy rates as a top quality protein


Choosing a high quality protein is difficult if you follow a vegetarian diet. The WHO and FAO recently rated soy as the highest quality plant-based protein.

Meat eaters rely on meat, eggs, and dairy products for quality sources of protein. But choosing a high quality protein is more difficult for those following a vegan or vegetarian diet because their choices are limited to plant sources of protein.

Now the World Health Organization (WHO) and the Food and Agriculture Organization (FAO) have rated soy’s protein quality similar to that of meat, eggs, and dairy.

A new study in the Journal of Agriculture and Food Chemistry examined the method used to determine protein quality. Traditionally, plant proteins, such as pea protein, have rated as lower quality proteins than their animal-based counterparts.

Rating protein quality
The WHO and FAO recommend using the protein digestibility-corrected amino acid score (PDCAAS) to assess protein quality. It focuses on three criteria:

  • the amount of each essential amino acid contained in a protein
  • the ease with which the protein can be digested, and
  • after looking at these two factors, whether the protein meets the FAO/WHO’s amino acid requirements for children ages two to five.

Young children who are growing and developing have higher protein needs than adults.

Using these parameters, soy received a PDCAAS of 1.00, an identical score to eggs, meat, and dairy. Of all the plant-based proteins tested, soy was the only one to obtain a 1.00 score.

PDCAAS scores
Here’s how common sources of protein rate:

  • whey                1.14               
  • milk                  1.00                           
  • soy                   1.00                                                        
  • eggs                 1.00                                                      
  • ground beef      1.00                                      
  • canned lentils    0.52                                   
  • peanuts             0.52      



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