The easiest way to obtain an indispensable protein would be by eating animal protein. Animal proteins contain complete proteins which contain all the indispensable (essential amino acids). Vegetarians often have a hard time consuming complete proteins. This is due to the fact that single vegetables contain incomplete proteins. These incomplete proteins are missing some indispensable amino acids. For example, grains are low in lysine; and beans are low in methionine. While both of these vegetables themselves are incomplete, combining these two vegetables creates a complete protein. Another common protein source for vegetarians is through the consumption of soy protein isolate which is usually comparable to animal protein.