Grain Cereals & Legumes

Cereals

The cereals are all grasses that have been bred over millennia to bear large seeds (i.e., grain). The most important cereals for human consumption are rice, wheat, and corn (maize). Others include barley, oats, and millet.

Starchy roots

Starchy roots consumed in large quantities include potatoes, sweet potatoes, yams, taro, and cassava. Their nutritive value in general resembles that of cereals. The potato, however, provides some protein (2 percent) and also contains vitamin C. The yellow-fleshed varieties of sweet potato contain the pigment beta-carotene, convertible in the body into vitamin A. Cassava is extremely low in protein, and most varieties contain cyanide-forming compounds that make them toxic unless processed correctly.

Legumes

Beans and peas are the seeds of leguminous crops that are able to utilize atmospheric nitrogen via parasitic microorganisms attached to their roots. Legumes contain at least 20 percent protein, and they are a good source of most of the B vitamins and of iron. Like cereals, most legumes are low in fat; an important exception is the soybean (17 percent), a major commercial source of edible oil.