Soy protein is obtained from soybeans, usually in the form of soy protein isolate or soy protein concentrate. Compared with many other plant protein sources, soy contains all essential amino acids in a comparatively balanced proportion, which makes it a special source among plant proteins.
In practice, soy protein is one of the most commonly used bases for vegan protein powders and is often combined with other plant sources to improve taste and amino acid pattern further. Because soy is one of the allergens that must be labelled, it has to be declared in the list of ingredients.
How soy protein fits into a vegan diet is explained in the Vegan protein guide, and further plant alternatives are described in the entries Pea protein and Vegan protein.
