Protein combining

Protein combining or protein complementing is a dietary theory for protein nutrition that purports to optimize the biological value of protein intake. According to the theory, vegetarian and vegan diets may provide an insufficient amount of some essential amino acids, making protein combining with multiple foods necessary to obtain a complete protein food. The terms complete and incomplete are outdated in relation to plant protein. In fact, all plant foods contain all 20 amino acids including the 9 essential amino acids in varying amounts.^[1]

Though it is undisputed that diverse foods can be combined to make up for their respective limiting amino acids, a general consensus has emerged among nutrition scientists and writers contrary to the original vegetarian nutrition dogmas of the 1970s. Though historically, protein combining was promoted as a method of compensating for supposed deficiencies in vegetables as foods, studies on essential amino acid contents in plant proteins have shown that vegetarians and vegans typically do not need to complement plant proteins in each meal to reach the desired level of essential amino acids as long as their diets are varied and caloric requirements are met.^[2] The position of the Academy of Nutrition and Dietetics is that protein from a variety of plant foods eaten during the course of a day supplies enough of all essential amino acids when caloric requirements are met.^[3]