A pH of 0 is totally acidic, while a pH of 14 is completely alkaline. A pH of 7 is neutral. Those levels vary throughout your body. Your blood is slightly alkaline, with a pH between 7.35 and 7.45. Your stomach is very acidic, with a pH of 3.5 or below, so it can break down food. And your urine changes, depending on what you eat -- that's how your body keeps the level in your blood steady. The alkaline diet claims to help your body maintain its blood pH level.