Most grains, like wheat and oats, have a hard outer layer. When they are processed, this layer becomes a byproduct, called bran. Likewise, when wheat is processed to get wheat flour, brain is acquired. This brain is packed with nutrition, and offers many dietary benefits.
Wheat bran is commonly found in certain cereals, like Raisin Bran or Bran Flakes, as well as bran muffins, which rose to popularity in the 1980s. Wheat bran is beneficial toward providing digestive regularity and ending constipation because it is very high in dietary fiber. Some also claim that foods containing bran provide a feeling of fullness. This claim may be true, since it tends to absorb water and expand in the digestive system.