Which level of a food pyramid is the most important?

  Based on the food pyramid, I discover that the grains are the most essential level of humans.  Most cereals have essential amino acids lysine.  In addition, only 15 percent of grains contain fat and calories.  The most important elements of grains are their vitamins and minerals.  Nevertheless, more minerals of grains are on the brans or germs instead of the components inside, people always take the healthier things aways from them.  The brans are composed of soluble and insoluble fibers.  The soluble fibers can lower the cholesterol in the blood, and the insoluble fibers are the important factor of digestive system.  Even though the grains are less effective after the removal of brans, the components inside still have fibers and iron; these ingredients are very useful for the lives of humans.