Complete protein foods are those which contain all eight essential amino acids. Eggs, dairy products, and meats are all complete proteins. Non-animal complete protein sources are soybeans and brown rice.

Foods which contain incomplete proteins can usually be combined with each other in a tasty manner, thus completing each other. For instance, grains and legumes complement one another. Complete proteins such as dairy products can also be used to increase the quality of the incomplete protein in grains, as in macaroni and cheese, milk and Wheaties, grilled cheese sandwiches, etc.