Soy protein is generally regarded as the storage protein held in discrete particles called protein bodies which are estimated to contain at least 60-70% of the total soybean protein. Soybeans are a source of complete protein. Soybean protein is essentially the same as that of other legume and vegetable proteins. Additionally, soy protein has the highest yield per square meter of growing area, and is the least expensive source of dietary protein. A complete protein is one that contains significant amounts of all the essential amino acids that must be provided to the human body because of the body's inability to synthesize them. For this reason, soy is important to many vegetarians and vegans.