The Five Elements Theory or Wu Xing (五行) is a fundamental principle of ancient Chinese philosophy explaining the relationships of all things in the universe. The five elements are Wood (木), Fire (火), Earth (土), Metal (金), and Water (水). In Chinese Medicine, these elements connect to organs, emotions, flavors, seasons, and body characteristics.
Each element corresponds to a pair of organs. Wood relates to the Liver and Gallbladder. Fire relates to the Heart and Small Intestine. Earth relates to the Spleen and Stomach. Metal relates to the Lungs and Large Intestine. Water relates to the Kidneys and Bladder. Each element also connects to emotions: Wood with anger, Fire with joy, Earth with worry, Metal with sadness, and Water with fear.
The Five Elements have generating (生) and controlling (克) relationships. Wood generates Fire, Fire generates Earth, Earth generates Metal, Metal generates Water, and Water generates Wood. Meanwhile, Water controls Fire, Fire controls Metal, Metal controls Wood, Wood controls Earth, and Earth controls Water. Balance among elements keeps the body healthy.
TCM practitioners use Five Element Theory in diagnosis. For example, someone who angers easily, has lateral headaches, and red eyes likely has Wood element (Liver) issues and needs Liver-balancing treatment. Someone who worries excessively with poor digestion likely has Earth element (Spleen) issues and needs Spleen nourishment.
Knowing your element helps with self-care. Wood types should avoid stress and eat green leafy vegetables. Fire types should avoid spicy hot foods and get enough sleep. Earth types should eat warm foods and avoid worry. Metal types should protect the lungs and avoid cold air. Water types should nourish the kidneys and conserve energy.