Commonly consumed grains in the United States include wheat, corn, oat, barley, and rye. Many other grains exist but are not typically consumed in the United States. Whole grains are made up of the endosperm, the germ, and the bran of the grain. The endosperm makes up about 80% of the whole grain, while the germ and bran components vary among different grains.
Whole grains are cholesterol-free and low in fat, high in dietary fiber and vitamins (especially B-vitamins), and are good sources of minerals (particularly trace minerals). Whole grains are concentrated sources of starch and are about 10% to 15% protein.
In the refining process, the bran and germ are separated from the starchy endosperm, which is ground to flour. When the bran is removed in refining, important disease-preventing nutrients and phytochemicals (such as lignans, tocotrienols, and phenolic compounds),and anti nutrients (including phytic acid, tanning, and enzyme inhibitors) are removed as well.
Whole grains retain the nutritious bran and germ, making foods made from whole grains important sources of these nutrients and phytochemical compounds.
