Chinese herbology


Chinese herbology is the theory of traditional Chinese herbal therapy, which accounts for the majority of treatments in traditional Chinese medicine. A Nature editorial described TCM as "fraught with pseudoscience", and said that the most obvious reason why it has not delivered many cures is that the majority of its treatments have no logical mechanism of action.
The term herbology is misleading in the sense that, while plant elements are by far the most commonly used substances, animal, human, and mineral products are also used, some of which are poisonous. In the they are referred to as 毒藥 which means "poison-medicine". Paul U. Unschuld points out that this is similar etymology to the Greek and so he uses the term pharmaceutic. Thus, the term medicinal is usually preferred as a translation for 藥.
Research into the effectiveness of traditional Chinese herbal therapy is of poor quality and often tainted by bias, with little or no rigorous evidence of efficacy. There are concerns over a number of potentially toxic Chinese herbs, including Aristolochia which is thought to cause cancer.

History

The practice of Chinese herbal medicine stretches back for millennia. The earliest written record of prescriptions is the manuscript Recipes for 52 Ailments, discovered in the Mawangdui tombs, which were sealed in 168 BCE.
Later tradition credits the legendary figure Shénnóng as the founder of Chinese herbology. He is said to have lived around 2800 BCE and to have tasted hundreds of herbs to ascertain their medicinal value. The first and most important herbal classic attributed to him is the . While the original text has been lost, it was transcribed and preserved in later commentaries. Modern scholarly research suggests that the text was compiled in the late Western Han period, likely around the first century BCE, and was not written by a single author. The Běn Cǎo Jīng classifies 365 substances, including plants, animals, and minerals into three categories:
  1. "Superior" : herbs considered safe for long-term consumption to maintain health, with few to no side effects.
  2. "Medium" : substances with some therapeutic action that may have mild toxicity depending on the dosage.
  3. "Inferior" : substances taken for specific illnesses, often for shorter periods, as they are considered to have a higher potential for toxicity.
The next pivotal work was the Treatise on Cold Damage Disorders and Miscellaneous Illnesses, compiled by Zhang Zhongjing near the end of the Han dynasty. It is the first medical text that organized therapeutic principles around the diagnosis of symptom patterns, and it combined Yinyang and Five Phases theory with specific herbal prescriptions. After passing through numerous changes, the original work now circulates as two separate books: the Treatise on Cold Damage Disorders and the Essential Prescriptions of the Golden Casket, which were edited separately in the eleventh century during the Song dynasty.
Succeeding generations augmented these works, as in the , a 7th-century Tang dynasty Chinese treatise on herbal medicine.
There was a shift in emphasis in treatment over several centuries. A section of the Huangdi Neijing Suwen including Chapter 74 was added by Wang Bing in his 765 edition. In which it says: 主病之謂君, 佐君之謂臣, 應臣之謂使, 非上下三品之謂也. "Ruler of disease it called Sovereign, aid to Sovereign it called Minister, comply with Minister it called Envoy, not upper lower three classes it called." The last part is interpreted as stating that these three rulers are not the three classes of Shénnóng mentioned previously. This chapter in particular outlines a more forceful approach. Later on Zhang Zihe is credited with founding the 'Attacking School' which criticized the overuse of tonics.
Arguably the most important of these later works is the Compendium of Materia Medica compiled during the Ming dynasty by Li Shizhen, which is still used today for consultation and reference.
The use of Chinese herbs was popular during the medieval age in western Asian and Islamic countries. They were traded through the Silk Road from the East to the West. Cinnamon, ginger, rhubarb, nutmeg and cubeb are mentioned as Chinese herbs by medieval Islamic medical scholars Such as Rhazes, Haly Abbas and Avicenna. There were also multiple similarities between the clinical uses of these herbs in Chinese and Islamic medicine.

Raw materials

There are roughly 13,000 medicinals used in China and over 100,000 medicinal recipes recorded in the ancient literature. Plant elements and extracts are by far the most common elements used. In the classic Handbook of Traditional Drugs from 1941, 517 drugs were listed – out of these, only 45 were animal parts, and 30 were minerals. For many plants used as medicinals, detailed instructions have been handed down not only regarding the locations and areas where they grow best, but also regarding the best timing of planting and harvesting them.
Some animal parts used as medicinals can be considered rather strange such as cows' gallstones.
Furthermore, the classic materia medica describes the use of 35 traditional Chinese medicines derived from the human body, including bones, fingernail, hairs, dandruff, earwax, impurities on the teeth, feces, urine, sweat, and organs, but most are no longer in use.

Preparation

Decoction

Typically, one batch of medicinals is prepared as a decoction of about 9 to 18 substances. Some of these are considered as main herbs, some as ancillary herbs; within the ancillary herbs, up to three categories can be distinguished. Some ingredients are added to cancel out toxicity or side-effects of the main ingredients; on top of that, some medicinals require the use of other substances as catalysts.

Chinese patent medicine

Chinese patent medicine is a kind of traditional Chinese medicine. They are standardized herbal formulas. From ancient times, pills were formed by combining several herbs and other ingredients, which were dried and ground into a powder. They were then mixed with a binder and formed into pills by hand. The binder was traditionally honey. Modern teapills, however, are extracted in stainless steel extractors to create either a water decoction or water-alcohol decoction, depending on the herbs used. They are extracted at a low temperature to preserve essential ingredients. The extracted liquid is then further condensed, and some raw herb powder from one of the herbal ingredients is mixed in to form a herbal dough. This dough is then machine cut into tiny pieces, a small amount of excipients are added for a smooth and consistent exterior, and they are spun into pills.
These medicines are not patented in the traditional sense of the word. No one has exclusive rights to the formula. Instead, "patent" refers to the standardization of the formula. In China, all Chinese patent medicines of the same name will have the same proportions of ingredients, and manufactured in accordance with the PRC Pharmacopoeia, which is mandated by law. However, in western countries there may be variations in the proportions of ingredients in patent medicines of the same name, and even different ingredients altogether.
Several producers of Chinese herbal medicines are pursuing FDA clinical trials to market their products as drugs in U.S. and European markets.

Chinese herbal extracts

Chinese herbal extracts are herbal decoctions that have been condensed into a granular or powdered form. Herbal extracts, similar to patent medicines, are easier and more convenient for patients to take. The industry extraction standard is 5:1, meaning for every five pounds of raw materials, one pound of herbal extract is derived.

Categorization

There are several different methods to classify traditional Chinese medicinals:
  • The Four Natures
  • The Five Flavors
  • The meridians
  • The specific function.

    Four Natures

The Four Natures are: hot, warm, cool, cold or neutral. Hot and warm herbs are used to treat cold diseases, while cool and cold herbs are used to treat hot diseases.

Five Flavors

The Five Flavors, sometimes also translated as Five Tastes, are: acrid/pungent, sweet, bitter, sour, and salty. Substances may also have more than one flavor, or none. Each of the Five Flavors corresponds to one of the zàng organs, which in turn corresponds to one of the Five Phases: A flavor implies certain properties and presumed therapeutic "actions" of a substance: saltiness "drains downward and softens hard masses"; sweetness is "supplementing, harmonizing, and moistening"; pungent substances are thought to induce sweat and act on qi and blood; sourness tends to be astringent in nature; bitterness "drains heat, purges the bowels, and eliminates dampness".

Specific function

These categories mainly include:
  • exterior-releasing or exterior-resolving
  • heat-clearing
  • downward-draining or precipitating
  • wind-damp-dispelling
  • dampness-transforming
  • promoting the movement of water and percolating dampness or dampness-percolating
  • interior-warming
  • qi-regulating or qi-rectifying
  • dispersing food accumulation or food-dispersing
  • worm-expelling
  • stopping bleeding or blood-stanching
  • quickening the Blood and dispelling stasis or blood-quickening or blood-moving.
  • transforming phlegm, stopping coughing and calming wheezing or phlegm-transforming and cough- and panting-suppressing
  • Spirit-quieting or Shen-calming.
  • calming the Liver and expelling wind or liver-calming and wind-extinguishing
  • orifice-opening
  • supplementing or tonifying: this includes qi-supplementing, blood-nourishing, yin-enriching, and yang-fortifying
  • astriction-promoting or securing and astringing
  • vomiting-inducing
  • substances for external application