Scientific analysis of various studies undertaken till date.
When the FAO/WHOIUNU amino acid requirement estimates for the adult, which are expressed per unit of protein need, are compared with the amino acid pattern of various plant and animal protein sources, it should be evident that the amounts of amino acids in these food sources is much higher (per unit of protein) than required.
As a result, all of the indispensable amino acids, including the sulphur amino acids, in soy proteins and lysine in cereal proteins are predicted to be in considerable excess of adult needs. Thus, all usual food proteins would readily meet and even exceed the requirement for the indispensable amino acids. On the above basis it would be concluded that there is little reason to be further concerned with an assessment of the nutritional quality of plant proteins in adults.
Thus, we conclude that consumers do not need to be at all concerned about amino acid imbalances when the dietary amino acid supply is from the plant-food proteins that make up our usual diets. Mixtures of plant proteins can be fully adequate for meeting human requirements. From the standpoint of the composition of a healthful diet, they serve as a desirable vehicle for carrying nitrogen and indispensable amino acids to meet both our needs and wants.
Plant proteins in relation to human protein and amino acid nutrition