Chinese food therapy (simplified Chinese: 食疗; traditional Chinese: 食療; pinyin: shíliáo; literally: "food therapy", also called nutrition therapy and dietary therapy) is a mode of dieting rooted in Chinese beliefs concerning the effects of food on the human organism, and centered on concepts such as eating in moderation. Its basic precepts are a mix of folk views and concepts drawn from traditional Chinese medicine.
Food therapy has long been a common approach to health among Chinese people both in China and overseas, and was popularized for western readers in the 1990s with the publication of books like The Tao of Healthy Eating (Flaws 1995a) and The Wisdom of the Chinese Kitchen (Young 1999).
A number of ancient Chinese cookbooks and treatises on food (now lost) display an early Chinese interest in food, but no known focus on its medical value. The literature on "nourishing life" (养生; 養生; yangsheng) integrated advice on food within broader advice on how to attain immortality. Such books, however, are only precursors of "dietary therapy", because they did not systematically describe the effect of individual food items. In the volume on "Fermentations and Food Science" of Joseph Needham's Science and Civilization in China, H. T. Huang considers the Recipes for Fifty-Two Ailments (ca. 200 BCE) and the Yellow Emperor's Inner Canon as precursors of the "dietary therapy" tradition, the former because it recommends food products as remedies for various illnesses, the latter because it discusses the impact of food on health. The materia medica literature, exemplified by the Shennong Bencao Jing (1st century CE), also discussed food products, but without specializing on them.
The earliest extant Chinese dietary text is a chapter of Sun Simiao's Prescriptions Worth a Thousand Gold (千金方; Qiānjīn fāng), which was completed in the 650s during the Tang dynasty. Sun's work contains the earliest known use of the term "food (or dietary) therapy" (shiliao). Sun stated that he wanted to present current knowledge about food so that people would first turn to food rather than drugs when suffering from an ailment. His chapter contains 154 entries divided into four sections – on fruits, vegetables, cereals, and meat – in which Sun explains the properties of individual foodstuffs with concepts borrowed from the Yellow Emperor's Inner Canon: qi, the viscera, and vital essence (精; jīng), as well as correspondences between the Five Phases, the "five flavors" (sour, bitter, sweet, pungent, and salty), and the five grains. He also set a large number of "dietary interdictions" (食禁; shíjìn), some based on calendrical notions (no water chestnuts in the 7th month), others on purported interactions between foods (no clear wine with horse meat) or between different flavors.
Sun Simiao's disciple Meng Shen (孟诜; 孟詵; 621–713) compiled the first work entirely devoted to the therapeutic value of food: the Materia Dietetica (食疗本草; 食療本草; Shíliáo běncǎo; "food therapy materia medica"). This work has not survived, but it was quoted in later texts – like the 10th-century Japanese text Ishinpō – and a fragment of it has been found among the Dunhuang manuscripts. Surviving excerpts show that Meng gave less importance to dietary prohibitions than Sun, and that he provided information on how to prepare foodstuffs rather than just describe their properties. The works of Sun Simiao and Meng Shen established the genre of materia dietetica and shaped its development in the following centuries.
An abundant literature developed in China around the medicinal uses of food. A mid-ninth-century work called Candid Views of a Nutritionist-Physician (Shi Yi Xin Jian 食医心鉴／食醫心鑑; now lost) discussed how food could treat various disorders, whereas several works from the Song dynasty (960–1279) explained how to feed the elderly to extend their life.
In the early 14th century, Hu Sihui, who served as Grand Dietician (Yinshan Taiyi 饮膳太医／飲膳太醫) at the court of the Mongol Yuan dynasty (1260–1368), compiled a treatise called the Proper and Essential Things for the Emperor's Food and Drink (Yinshan Zhengyao 饮膳正要), which is still recognized in China as a classic of both materia medica and materia dietetica. Influenced by the culinary and medical traditions of the Turko-Islamic world and integrating Mongol food stuffs like mutton into its recipes, Hu's treatise interpreted the effects of food according to the scheme of correspondences between the Five Phases that had recently been systematized by northern Chinese medical writers of the Jin (1115–1234) and Yuan eras. Before that period, food materials had not yet been comprehensively assigned to one of five flavors systematically correlated with specific internal organs and therapeutic effects.
Chinese understandings of the therapeutic effects of food were influential in East Asia. Cited in Japanese works as early as the 10th century, Chinese dietary works shaped Korean literature on food well into the Joseon period (1392–1897). In the late 17th and early 18th centuries, the imperial court of the Qing dynasty (1644–1912) ordered several works on Chinese food therapy translated into Manchu.
Although the precepts of Chinese food therapy are neither systematic nor identical in all times and places, some basic concepts can be isolated. One central tenet is that "medicine and food share a common origin", and that food materials can therefore be used to prevent or treat medical disorders. Like medicinal drugs, food items are classified as "heating" (热; 熱; rè) or "cooling" (凉; 涼; liáng). In popular understanding, "heating" or "hot" food is typically "high-calorie, subjected to high heat in cooking, spicy or bitter, or 'hot' in color (red, orange)", and includes red meat, innards, baked and deep-fried goods, and alcohol. They are to be avoided in the summer and can be used to treat "cold" illnesses like excessive pallor, watery feces, fatigue, chills, and low body temperature caused by a number of possible causes, including anemia. Green vegetables are the most typical "cooling" or "cold" food, which is "low-calorie, watery, soothing or sour in taste, or 'cool' in color (whitish, green)". They are recommended for "hot" conditions: rashes, dryness or redness of skin, heartburns, and other "symptoms similar to those of a burn", but also sore throat, swollen gums, and constipation.
In more systematic understandings, each medicine or food item has one of five flavors: sour, sweet, bitter, pungent (or "acrid"), and salty. Besides describing the taste of food, each of these "flavors" purportedly has specific effects on particular viscera. The sour flavor, for instance, has "constriction and emollient effects" and "can emolliate the liver and control diarrhea and perspiration", whereas "bitter" food can "purge the heart 'fire', reduce excessive fluids, induce diarrhea, and reinforce the heart 'Yin'".
There are few studies in English on the scientific validity of these beliefs and practices. A few studies conducted in China suggest that a diet designed according to the precepts of Chinese food therapy may help control blood pressure, but these studies are based on different diagnostic categories than those of western medicine ("Yin deficiency" instead of hypertension), and on chiefly qualitative and conceptual evidence rather than on modern randomized controlled trials. Consequently, the claims of efficacy are weaker in scientific evidence than those based on mixed nutritious foods and demonstrated to have health effects by extensive clinical research, such as the DASH diet or Mediterranean diet.