Only animal proteins and soy protein are considered complete proteins (i.e., they contain all nine essential amino acids, which the body cannot synthesize on its own). In developed nation like the United States, where diets are varied and people tend to regularly consume multiple sources of protein, getting complete proteins in a single sitting is not a must, explains David Janow, president and CEO of Axiom Foods, Los Angeles, Calif., a supplier of brown rice protein and other plant-based ingredients.