By Fanny Hsu, L.A.c., O.M.D.
Qi is often translated and known as vital energy. The book, Simple Questions, states: "A human being results from the Qi of Heaven and Earth...The union of the Qi of Heaven and Earth is called a human being." In Traditional Chinese Medicine theory, qi is the most essential element constituting the human body. Qi is the vital substance, also known as the "vital energy," that runs the physiological functions of organs and meridians.
Human qi comes from two main sources. The first source, also known as "pre-heaven qi," is inherited or given to us at birth from our parents. The second source of qi is called "post-heaven qi," which was derived after birth from essential substances in nature such as air, food, and water. Both vital energies are further processed and transformed by different organs and contribute to the whole body. The process begins with the kidney, which first sends the innate vital substance upward to combine with the food essence absorbed, which is derived from the spleen; it then further mixes with fresh air from the lungs and finally forms into the qi of the body.
Qi is further classified into four different types: pre-heaven qi, pectoral qi, nutritive qi, and protective qi. Pre-heaven qi is the most original, essential type found in the human body and is the power source for all of life’s activities. Pectoral qi is stored in the chest area and formed by combining fresh air inhaled through lungs and food essence derived from the spleen. By flowing through the respiratory system, the pectoral qi supports the breathing function of the lungs and affects how loud the voice can be. Also, when flowing through the blood vessels, it could help regulate heartbeat and support the circulation of qi and blood. Nutritive qi, as its name proposes, supplies and nourishes the body. Nutritive qi mainly comes from the food essence that circulates through the blood vessels. It has a close relationship with blood and provides some of the necessary substances needed to produce new blood. Nutritive qi also gives the needed nutrients to support all physiological functions of the organs. Protective qi is a shield for our body that protects us against evils, such as environmental factors that lead to illness. In a western point of view, the protective qi functions like the immune system, which helps prevent disease.
TCM has identified two important factors necessary to create and maintain a healthy balance in the body. By eating a healthy diet and breathing fresh air, the body extracts their most valuable essences and uses them to help form the vital energy.