Most of the cereals we eat are "refined." That means that the bran and germ layers have been removed, taking with them nearly 80% of the nutrients, and much of the flavor. To be metabolized, cereals need mineral molecules. When these molecules don't exist, they try getting these minerals from other food they find in the blood or in the bones. This process makes cereals difficult to digest and sometimes cause bloating and flatulence.
Whole grains provide vitamins, minerals and fiber to enjoy excellent health. Carbohydrates are necessary for the body to have more energy, they are the "fuel" for our brains, muscles and internal organs.