evidence: The pH scale Universal Indicator pH Color Chart diagram acidic alkaline values common substances. Image Credit: Trgrowth / Shutterstock pH of Different Body Fluids Although the pH of blood ranges from 7.35-7.45, the pH of other body fluids is different. pH indicates the level of H+ ions, where low pH indicates too many H+ ions and high pH indicates too many OH- ions. If the pH levels drop below 6.9, it can lead to coma. However, different body fluids have different pH values. The pH of saliva is ranges from 6.5 to 7.5. After swallowing, the food reaches the stomach where upper and lower parts of stomach have different pH values. The upper part has a pH of 4−6.5, while the lower part is highly acidic with a pH of 1.5−4.0. It then enters the intestine which is slightly alkaline, with a pH of 7−8.5. Maintaining the pH values of different regions is critical for their function. [...] Different organs function at their optimal level of pH. For example, the enzyme pepsin requires low pH to act and break down food, while the enzymes in intestine require high pH or alkaline environment to function. Similarly, any increase or decrease in the blood pH can lead to several disorders.