Grains are split into two categories: whole grains and refined grains.
Simply put: whole grains contain the entire grain kernel – the bran, germ and endosperm. Refined grains have been milled to remove the bran and the germ and just have the endosperm. This is done to give the grain a finer texture. Most white breads and white rice, for example, are made from refined grains.
Refined grains are often enriched with nutrients, but the USDA recommends that half of the grains eaten each day be whole grains.
Daily recommendations change based on age, gender and activity level, but an adult woman should eat 6 ounces of grains and adult men should eat 7 to 8 ounces.