What are whole grains? The grain or kernel of any cereal is made up of three edible parts: the bran, the germ and the endosperm. Each part of the grain contains different types of nutrients. The bran is the multi-layered outer skin of the edible kernel. It is fiber-rich and also supplies antioxidants, B vitamins, minerals like zinc, iron, magnesium, and phytochemicals — natural chemical compounds found in plants that have been linked to disease prevention. The germ is the core of the seed where growth occurs. It is rich in lipids and contains vitamin E, as well as B vitamins, phytochemicals and antioxidants. The largest portion of the kernel is the endosperm, an interior layer that holds carbohydrates, protein and smaller amounts of vitamins and minerals.