The pH of a substance is a chemical reading of how acidic or basic/alkaline it is. Your body tightly regulates pH levels to maintain overall good health. Different organs, cell types and compartments within cells maintain various pH levels depending on their physiological roles. Exercise, diet and medications may alter your body's pH.

In chemical terms, acids are molecules that contain an extra proton that can be donated, while bases can accept an additional proton. The pH scale ranges from 0 to 14; pure water has a neutral pH of 7. Acids range from 0 to 7, and bases range from 7 to 14 on the scale. The website Alkalize for Health reports that human blood maintains a steady pH of 7.4, making it slightly alkaline.

Faulty regulation of your body's pH may result in serious health consequences. Enzymes require a specific pH level to work efficiently. Increases or decreases in pH denature enzymes, halting important metabolic processes. Proponents of an alkaline diet say a low body pH can increase the risk of osteoporosis, cancer, heart disease and arthritis, according to the Wolfe Clinic. High acidity may also cause fatigue, muscle cramping and low energy.

Exercise, diet and certain medications modify pH levels in the body. During physical exercise, burning glucose for energy releases carbon dioxide and protons into the blood. This causes blood pH to decrease and become more acidic. Eating large quantities of acidic or alkaline foods can change your blood pH as well. Meats, cheeses, legumes, most grains, blueberries, cranberries and plums tend to be acidic. Most fruits, vegetables and juices have an alkalizing effect in the body. The University of California San Diego reports that alcohol, tobacco and most other drugs increase the acidity of the body.

Although exercise, diet and medications alter pH levels, your body compensates through a complicated buffering system. Acid-base buffers accept and donate extra protons, keeping pH levels within a tightly regulated range. Washington University at St. Louis reports that the body counters exercise-induced decreases in pH by recruiting the lungs and kidneys to remove chemicals from the blood. This restores equilibrium and prevents pH levels from changing drastically, which could neutralize important enzymes.

Some dieters believe eating acidic foods causes negative health consequences. However, no scientific evidence suggests that alkaline foods or water decreases rates of chronic disease, reports MayoClinic.com. Alkaline water may confer some protection against osteoporosis, but experts do not recommend adopting an alkalizing diet to prevent cancer or other diseases. Talk to your doctor before beginning an alkalizing diet to prevent or treat a serious illness. Medical treatments may better alleviate your symptoms.