Question

Explain factors that are involved in protein quality and how protein quality may play a role in requirement for protein malnutrition in vegetarians/vegans.

Answer 1

It is frequently claimed that different proteins vary in quality and that some are more beneficial than others. There are a number of factors which may affect the protein quality from food :

• the amino acid profile of the protein
• the structure of the protein
• the digestibility of the protein
• the amount of protein consumed in one meal
• other nutrients and food constituents present in the meal, eg- fibre, carbohydrate
• how the food has been prepared
• recent intake of protein
• the metabolic state of the individual, eg. illness, excercise, sleep
• the individual's age, weight, sex and general health

Protein foods that have large amounts of all essential amino acidsare often referred to as high quality proteins. These include foods of animal origin as well as a few plant foods. Other plant protein sources usually have all of the essential amino acids, but the amounts of one or two of these amino acids may be low. In comparison to animal proteins, plant proteins have lower levels of leucine, methionine, lysine and tryptophan. The protein quality of a given food can be determined by the Protein Digestibility Corrected Amino Acid Score ( PDCAAS). Vegans may be at increased risk for deficiencies in Vitamin B12, iron, calcium, vitamin D, omega-3 fatty acids, and proteins.