Traditional Chinese medicine emphasizes harmony between humans and nature, following the natural cycles of spring growth, summer flourishing, autumn harvest, and winter storage. Therefore, people should nourish "yang" energy in spring and summer, and "yin" energy in autumn and winter. Furthermore, the five Zang-organs correspond to the four seasons. Spring is associated with the element of wood, and the liver's energy flourishes. In TCM, an "exuberant liver energy" roughly corresponds to the state of modern medicine's "stress response," where the sympathetic nervous system becomes excited when a person is tense. When liver energy is excessive, a person is prone to anger, nervousness, and irritability."
The Tang dynasty physician Sun Simiao said: "During the 72 days of spring, reduce sour and increase sweet foods to nourish the spleen energy." This is also recorded in the Ming dynasty text "Eighteen Discourses on Nouraging Life" by Gao Lian: "In spring, one should reduce sour and increase sweet foods to nourish the spleen energy." This means that when the liver energy is strong in spring, one should consume fewer sour foods, as this would further exacerbate liver heat and damage the spleen and stomach. At this time, one can eat more foods with a sweet and neutral nature. The dietary principle for the entire spring is to reduce sourness, increase sweetness, and thereby nourish the spleen energy. Because a flourishing liver in spring can easily overcome the spleen (earth) and cause digestive issues, and sourness is the natural flavor of the liver, it should be reduced to prevent further stoking liver energy and thus protect the spleen. Sweetness is the natural flavor of the spleen; to defend against the possible invasion of liver energy, increasing sweetness can strengthen the spleen and enhance the body's defenses. In spring, eat more cold-mixed dishes.
TCM classifies food into five flavors: sour, bitter, sweet, pungent, and salty. For dietary regulation in spring, it is advisable to choose foods that are pungent and sweet in nature, and to avoid sour and astringent flavors. The diet should be light and palatable, avoiding greasy, raw, cold, and irritating foods. The term "sour" in this context does not refer to acidic or alkaline foods as commonly understood today. The nature and flavor are generally similar, but not absolutely so. TCM's "sweet" foods not only refer to a slightly sweet taste but, more importantly, must have the effect of tonifying the spleen and stomach, such as red dates and Chinese yam. Most grains and cereals are considered "sweet." Among foods that are warm in nature and sweet in flavor, grains are the top choice, such as glutinous rice, black rice, sorghum, broomcorn millet, and oats. For vegetables and fruits, examples include sword beans, pumpkin, hyacinth beans, red dates, walnuts, and chestnuts. This classification is not based solely on taste. Mistaking "sweet" to mean eating more sugar would be incorrect.
As the temperature rises in spring, bacteria and viruses become more active. One should eat more foods that help regulate immune function. For instance, wild vegetables can be frequently consumed. Houttuynia cordata, for example, is excellent for its anti-infection properties. Briefly blanching it can remove much of its strong, distinctive fishy smell, after which it can be lightly seasoned and served as a cold salad.