A mixture of vegetable foods eaten at one meal, such as a cereal and a legume (e.g. maize or millet and cowpeas) or a root, a cereal and a legume (e.g. cassava, sorghum and groundnuts), provides better-quality protein than larger quantities of a single vegetable food would; the mixture usually contains all the essential amino acids, whereas a single cereal, root or legume is usually deficient in o