This is the result of our bodies burning or using alkaline to remain alive. Since our bodies do not manufacture alkaline, we must supply the alkaline from an outside source to keep us from becoming acid and dying. Food is the means of replenishing the alkaline to the body. The main determining factor of alkaline is the organic minerals. One can equate organic minerals with alkaline for better understanding.
Foods are of two types, acid or alkaline.
This refers to the ash value of a food. The acid is neutralized with alkaline. Ideally there is adequate alkaline in the diet to do this. However, if there is not, the body must extract alkaline from its cells to neutralize the acid. This, of course, causes the cells to become acid, and thus diseased.