Grains can be roughly divided into two groups: Whole grains and refined grains. Whole grains, such as brown rice and quinoa, pre-date refined grains, which are a product of modern society. You can think of a whole grain as a three-part package:
Bran (outer layer) - This layer is packed with fiber, trace minerals, phytochemicals, and B vitamins. 50 to 80 percent of the grain’s minerals and other health-promoting plant substances called phytochemicals are contained in the bran.
Germ (inner layer) - This layer is rich in antioxidants, phytochemicals, B vitamins, vitamin E, and trace minerals, as well as containing healthy fats.
Endosperm (middle layer) - This layer contains complex carbohydrates and protein. It also contains small amounts of B vitamins.
When a whole grain is processed in order to make a refined grain, two parts of the package - the bran and germ – are removed, leaving only the endosperm. In this process, 25 percent of the protein is removed along with at least 17 key nutrients. The refined grain also has five to seven times less fiber than the whole grain.
This is why it is so much better to eat whole grains than refined grains.