How does TCM apply the Five Element Theory in tonifying or reducing therapies?

 According to the Five Elements Theory, all things can be divided into five elements (metal, wood, water, fire and earth). Our body's five yin organs (heart, liver, spleen, lung and kidney) correspond to the five elements based on their biological special natures. 

TCM makes use of these relationships to treat diseases of the organs in tonifying or reducing therapies. 

Figure 1.
This cycle shows how the five elements produce one another
Figure 2.
This cycle shows how the five organs promote one another

In case of deficiency syndromes, besides tonifying the deficient organ, it is necessary to tonify its counter-generation partner in order to speed up the recovery. For example, in treating liver (wood) deficiency, water generates wood, so physicians will also tonify the kidney (water) to reinforce treatment. 

In case of excess syndromes, besides reducing the particular organ, it is also necessary to reduce its generation partner in order to depress the excitatory conditions. For example, in treating excessive fire in the liver (wood), wood generates fire, so physicians will also reduce the heart (fire) so as to relieve the excessive fire indirectly. ​