The acidity or alkalinity of a substance is measured using pH. The pH scale runs from 0 to 14, with 0 being the most acidic, 14 being the most alkaline, and 7 being neutral. To survive, our bodies must maintain the pH very close to 7.4, which is just on the alkaline side of neutral. If your body’s pH varies too much from this ideal, it becomes difficult for various enzymes to function properly.