Wikipedia Article About Wheat bran on Wikipedia Bran is the hard outer layer of cereal grains, and consists of combined aleurone and pericarp. Along with germ, it is an integral part of whole grains, and is often produced as a by-product of milling in the production of refined grains. When bran is removed from grains, they lose a portion of their nutritional value. Bran is present in and may be milled from any cereal grain, including rice, wheat, maize, oats, and millet.