The diet theory of ancient China is based on the concept of the "Four Seasons and Five Nourishments." Traditional Chinese Medicine places great emphasis on "Yin and Yang" and the "Five Elements," and it pays close attention to the relationship between climate changes and the human body. The seasons are divided into spring, summer, autumn, and winter. However, because summer is the longest season, a period called "Long Summer" was designated between summer and autumn, thus giving rise to the theory of "Four Seasons and Five Nourishments."

Specifically, the Wood, Fire, Earth, Metal, and Water elements correspond to spring, summer, Long Summer, autumn, and winter, respectively. This establishes the relationship between the "Four Seasons and Five Nourishments," the Five Elements, and the five Zang organs: the Liver, Heart, Spleen, Lungs, and Kidneys. The ancients used this theory to guide dietary principles. In the Yuan Dynasty of China, Husi Hui wrote in his book "Yin Zheng Yao" (Essentials of Diet and Health): "In spring, the weather is warm; it is advisable to eat wheat to cool it down. Do not rely solely on warming foods. Avoid warming foods and hot clothing. In summer, the weather is hot; it is advisable to eat beans (mung beans) to cool it down. Do not rely solely on heating foods. Avoid warming foods, overeating, and damp or wet clothing. In autumn, the weather is dry; it is advisable to eat sesame to moisten the dryness. Avoid cold foods and cold clothing. In winter, the weather is cold; it is advisable to eat millet to treat the cold with its warming nature. Avoid hot foods and warm clothing." Husi Hui's clear explanation of the foods suitable for each of the four seasons laid the foundation for the theory of "Four Seasons and Five Nourishments."

In the hot summer, the body prefers coolness. The corresponding organ is the Heart, and this is called "Clear Nourishment." It is advisable to eat mung bean congee, qi-restoring and heat-clearing soup, and honeysuckle drink. During Long Summer, the climate is humid, and the weather turns from hot to cool. The corresponding organ is the Spleen, and this is called "Mild Nourishment." It is advisable to eat Cordyceps duck, pork knuckle with Job's tears, porcini mushroom buns, and three-snake wine. In autumn, the climate is cool. The corresponding organ is the Lungs, and this is called "Balanced Nourishment." It is advisable to eat ginseng and astragalus soft-shelled turtle, and duck with two types of nuts. In winter, the climate is cold, and Yang energy is stored deeply within the body. The corresponding organ is the Kidney, and cold pathogenic factors can easily damage Kidney-Yang. This is the most suitable time for middle-aged and elderly people to nourish themselves. It is advisable to eat dual-penis soup for strengthening Yang, dragon and boy chicken, aconite lamb soup, and universe dog meat. Additionally, there are dietary recipes suitable for all seasons, such as cardamom steamed buns, porcini mushroom buns, glutinous rice balls with ginseng, tremella soup, Ten Great Tonifying Soup, healthy wontons, tremella with pigeon eggs, and rice congee.

If we follow the theory of "Four Seasons and Five Nourishments" to guide our diets, it will play a role in health preservation, strengthening the body, preventing and treating diseases, and prolonging life. I. Dietary Regimen for the Four Seasons

The earliest medical book in China, "Huangdi Neijing" (The Yellow Emperor's Inner Canon), already recognized the close relationship between humans and nature. For example, "Suwen - Siqi Tiaoshen Dalun" (Simple Questions - Great Treatise on Regulating the Mind in Four Seasons) states: "The Yin and Yang of the four seasons are the root of all things." In order to adapt to the changes of nature, humans must "follow the four seasons and adapt to cold and heat." Therefore, people must not only master the laws of natural changes but also actively adapt to their characteristics. "Suwen - Yijing Bianqi Lun" (Simple Questions - Great Treatise on Transforming Qi by Shifting the Essence) points out: "Move to avoid cold, and dwell in the shade to avoid summer heat." "Suwen - Siqi Tiaoshen Dalun" also points out the principle of "nourishing Yang in spring and summer, and nourishing Yin in autumn and winter." Therefore, in terms of diet, people must also adapt to this changing law.

The Tang Dynasty physician Sun Simiao placed great importance on diet therapy and nourishment. He said: "The foundation for a stable body must be in food..." and "One who does not know the proper diet cannot preserve their life." Chen Jiyuan said: "Many diseases and premature deaths are caused by diet. The harm from diet is greater than that from sensual pleasures. Sensual pleasures can be abstained from for a year, but diet is a daily necessity."

In spring, all things grow upwards. The corresponding organ is the Liver, which needs to be nourished. This is called "Ascending Nourishment," and daily diet should not be neglected. The benefits are many, and the risks are also significant. This fully illustrates that moderate diet can extend life, while unmoderated diet can bring disaster. Zhang Zhongjing of the Han Dynasty stated clearly: "Regulate the cold, heat, bitter, sour, spicy, and sweet nature of your food." This means that due to the different climates in the four seasons, the choice of food's cold, heat, bitter, sour, spicy, and sweet nature also varies.

Based on the understanding that "the spirit governs the body, essence nourishes Qi, Qi benefits essence, and food provides Qi for the body," and the theory that the five flavors correspond to the five Zang organs, Chen Zhi pointed out: "In spring, the taste of food should be reduced in sourness and increased in sweetness to nourish the Spleen's Qi"; "In summer, the taste of food should be reduced in bitterness and increased in spiciness to nourish the Lung's Qi"; "In autumn, the taste of food should be reduced in spiciness and increased in sourness to nourish the Liver's Qi"; "In winter, the taste of food should be reduced in saltiness and increased in bitterness to nourish the Heart's Qi." Chen believed that by supplementing with flavors according to the four seasons, one can prevent the flourishing Qi from becoming excessive and avoid damaging the Qi that it overcomes.

Liu Wan-su also proposed using the five aromas—musky, scorched, fragrant, fishy, and rotten—to assist the Qi that is overcome. He said: "Therefore, when Wood flourishes in spring,圣人 (the sage) uses fragrant fats to aid the Spleen; when Fire flourishes in summer, the sage uses fishy fats to aid the Lungs; when Metal is in charge, the diet uses musky fats to aid the Liver; when Water is in charge, the diet uses rotten fats to aid the Heart. This is what is meant by assisting what it cannot overcome." Liu's theory laid the theoretical foundation for the dietary regimen of the four seasons. II. The Five Flavors and Their Correspondences

Our ancestors, through long-term practice, deeply realized that the food people eat has a close relationship with the five Zang organs, leading to the theory of the five flavors corresponding to the five organs. The "Huangdi Neijing" says: "Sour enters the Liver, pungent enters the Lungs, bitter enters the Heart, salty enters the Kidneys, and sweet enters the Spleen." This is the ancients' summary of the nature and flavor of food and its correspondence to the five organs. Therefore, in different seasons, people should choose different foods to make dietary preparations. Additionally, for patients with different diseases, the dietary preparations they consume also differ. For example, "The Liver's color is blue, and it is suitable to eat sweet things; japonica rice, beef, and jujubes are all sweet. The Heart's color is red, and it is suitable to eat sour things; red beans, dog meat, plums, and chives are all sour. The Lung's color is white, and it is suitable to eat bitter things; wheat, mutton, apricots, and xie (a type of onion) are all bitter. The Spleen's color is yellow, and it is suitable to eat salty things; soybeans and chestnuts are salty." This shows that the combination of medicinal diets and the relationship between the five flavors and the five organs are very close.

If the five flavors of diet are excessive or deficient, it will inevitably cause an imbalance of Yin and Yang in the organs and lead to disease. Therefore, by using the partial nature of the five flavors to adjust the imbalance between organs, for example, medicinal diets made with pungent medicinal herbs and foods can disperse stagnation in the Lung's Qi; medicinal diets made with sweet medicinal herbs and foods can tonify the deficiency of the Spleen and Stomach. Therefore, only with a medicinal diet that harmonizes the five flavors can the five organs be properly nourished. "Suwen - Zangqi Fashi Lun" (Simple Questions - Great Treatise on the Qi of the Organs in Accordance with the Seasons) says: "The five grains are for nourishment, the five fruits are for assistance, the five domestic animals are for benefit, and the five vegetables are for supplementation. When their flavors and aromas are combined and consumed, they can nourish essence and Qi." Here, the five grains refer to hemp, wheat, millet, rice, and beans; the five vegetables refer to chives, xie, kale, scallions, and hu (a type of bean sprout); the five domestic animals refer to dog, lamb, beef, chicken, and pork. Therefore, the staple and non-staple foods people use throughout the year are all made from these grains, meats, vegetables, and fruits.

"Suwen - Shengqi Tongtian Lun" (Simple Questions - Great Treatise on Qi Communicating with Heaven) says: "Therefore, carefully harmonize the five flavors, the bones will be straight and the sinews supple, Qi and blood will flow, and the skin will be tight. If so, the bone Qi will be refined. If one is careful and follows this method, one can have a long destiny." The important role of diet is that "if grain is not taken in, Qi will decline in half a day, and be greatly diminished in a day."

When people consume dietary preparations in the four seasons, they must pay attention to moderation in their diet to achieve good results; otherwise, it can bring some side effects. If diet is unmoderated, in severe cases, it can even lead to death. "Suwen - Bi Lun" (Simple Questions - Great Treatise on Bi Syndrome) says: "Excessively rich food leads to the growth of large carbuncles on the feet." "Suwen - Wuzang Shengcheng Pian" (Simple Questions - Chapter on the Formation of the Five Organs) says: "Eating too much salty food will cause the pulse to congeal and change color." Therefore, when using dietary preparations, one must select them based on one's own physical condition, the climate, and the nature and flavor of the food to achieve better results. III. Food Selection for the Four Seasons

Spring, summer, autumn, and winter are phenomena that occur in nature. In terms of climate, spring is mild, summer is hot, autumn is dry, and winter is cold. The nutrients people need must adapt to this natural law to choose food and medicine. If the selected food and medicine are inappropriate, the body's Yin and Yang will become unbalanced, and illness will occur. For example, in the hot summer, the body prefers coolness. If one eats deer meat or dog meat, it will lead to heat symptoms. Conversely, in the cold winter, the body prefers warmth. If one eats cold foods like oyster meat or soft-shelled turtle meat, it will lead to cold symptoms. Therefore, people should pay attention to the nature and flavor of food and consume it reasonably. Warming foods:

Include dog meat, beef, chicken, turtle meat, lamb, sparrow meat, shrimp meat, white-spotted snake meat, and black-spotted snake meat; soybeans, broad beans, sword beans, mussels, carrots, scallions, garlic, pepper, chives, mustard greens, rapeseed, coriander, and Sichuan pepper; brown sugar, glutinous rice, flour, and sheep's milk. Cooling foods:

Include pork, soft-shelled turtle meat, oyster meat, duck meat, rabbit meat, and goose meat; spinach, cabbage, bean sprouts, celery, Malva verticillata, bamboo shoots, cucumber, bitter gourd, eggplant, winter melon, and laver; pears, watermelon, tangerines, oranges, pomelos, persimmons, barley, wheat, mung beans, millet, white sugar, cow's milk, and raw honey. Neutral foods:

Include carp meat and cuttlefish meat; red beans, black beans, cowpeas, green beans, loofah, wood ear fungus, lily seeds, lotus seeds, jujubes, cauliflower, potatoes, daylilies, duck eggs, almonds, grapes, peaches, and figs. As for the dietary preparations consumed according to the seasons, there are also requirements. Dietary dishes for spring:

Include stir-fried bamboo shoots, cold-mixed shrimp with lettuce, roasted sheep heart with rose petals, liver slices with shouwu (prepared fleeceflower root), clove duck, spareribs with nuts, pork stomach with lotus seeds, loach with tofu, and snow pear with fritillary bulb. Dietary dishes suitable for summer:

Include lotus leaf chicken breast, soft-shelled turtle with ginseng and astragalus, steamed chicken with ginkgo, fish head with Tianma (Gastrodia elata), quail with cordyceps, lotus leaf steamed chicken with rice powder, duck strips with sand ginger and flower, sand ginger crucian carp, braised eggplant with garlic, and eel with crispy green skin. Dietary dishes suitable for autumn:

Include snowflake chicken soup, astragalus and hericium soup, and Huaiyuan sesame crisp. Dietary dishes suitable for winter:

Include dual-penis soup for strengthening Yang, qi-boosting soup with goji berries, Ten Great Tonifying Soup, deer penis soup for strengthening Yang, black-bone chicken soup with white phoenix, lamb soup with angelica and ginger, universe steamed dog, sheep head with ginseng and goji berries, peach and goji berry chicken rolls, sesame rabbit, and stir-fried walnuts with chives.

The famous Tang Dynasty physician Sun Simiao believed that people should take different medicines according to different seasons. He pointed out that small Xuming Decoction is suitable for spring, kidney and oyster soup is suitable for summer, astragalus soup is suitable for autumn, and health-preserving medicinal wine is suitable for winter. In Sun's "Qianjin Yaofang - Shishi Fa" (Essential Formulas Worth a Thousand Gold - Method of Taking Medicine), he said: "If one follows this for a lifetime, then a hundred diseases will not arise."

In summary, it is very important for people to choose different foods, medicinal diet dishes, and medicines in different seasons to achieve the goals of strengthening the body, preventing and treating diseases, and prolonging life. IV. Diet Therapy Based on Syndrome Differentiation in the Four Seasons

Spring, summer, autumn, and winter, in terms of general climate, have the characteristics of spring warmth, summer heat, summer heat and dampness (Long Summer), autumn coolness and dryness, and winter cold. However, this does not mean that all cold foods are suitable for everyone to eat in the summer. Therefore, when consuming food, four factors must be considered: timing, location, individual, and syndrome. The so-called "syndrome-based diet" is a treatment method that is universally applied based on the syndrome. In terms of treatment and nourishment, the application of dietary preparations varies according to a person's constitution, symptoms, and health condition. The so-called "timing-based diet" means that the climate changes in the four seasons have a certain impact on human physiological and pathological changes, which should be noted when choosing dietary preparations. For example, in Long Summer, Yang heat descends, steam rises, and dampness fills the air, making it the season with the most dampness in a year. It is advisable to choose heat-clearing soups for diet. The so-called "location-based diet" means that in different regions, due to different climatic conditions and living habits, people's physiological activities and pathological characteristics are also different. For example, for the same type of warming and Yang-returning dietary preparation, in the severe cold northwest region, it is advisable to choose one with a heavy dosage and strong effect; in the warm and humid southeast region, one with a light dosage and slightly weaker effect is chosen. The so-called "individual-based diet" refers to the differences in people's constitutions—strong or weak, male or female, young or old—so the diet should also be different. For example, women have situations such as menstruation, pregnancy, and postpartum, and often use Bazhen Decoction (Eight-Treasure Decoction) and gynecological health soup. The elderly have diminished blood and Qi, declining physiological functions, and often suffer from deficiency syndromes. They need mild nourishment, often using Ten Great Tonifying Decoction and Fuyuan Decoction. Children have vigorous vital energy, but their Qi and blood are not yet full, and they cannot take care of themselves, often having irregular hunger and satiety and imbalance of cold and heat. The focus should be on nourishing the "acquired constitution," using Bazhen powder.

The four factors to consider when using dietary preparations are closely related. Therefore, when applying syndrome differentiation for diet therapy, one must first identify the syndrome, and then, based on the season, location, the patient's physical condition, gender, and age, combine the human body with the natural environment for a comprehensive analysis. Only by selecting the right dietary preparations can good results be achieved.

Whether people are sick or healthy, they should pay attention to syndrome differentiation in their diet. For example, in the season when Yang energy is rising, the diet should be light, and it is not advisable to eat greasy or fried foods. It is better to eat some light and sweet-cool foods like sugarcane, water chestnut, cherries, and tangerines to prevent heat from accumulating internally. In the hot summer, when summer heat is prevalent, the pores are open, and sweating is profuse, people often tend to eat raw and cold foods. However, excessive coldness can damage the Spleen and