Aristolochic Acid – History and use in Chinese Herbal Medicines

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Known as "birthwort," this plant has been used by numerous societies throughout history to assist in childbirth

Known as “birthwort,” this plant has been used by numerous societies throughout history to assist in childbirth. Image by Chrizz

Aristolochic acid is not a medicine; it is rather a chemical compound found in eighteen herbs, seven of which have been traditionally used in Chinese Medicine.

Since Aristolochic acid was classified in the 20th century as carcinogenic, herbs containing it have been the focus of research, and all herbal medicines containing Aristolochic acid (even in trace amounts) have been banned in the United States since 2001 – what’s the history of this compound in TCM?

Aristolochic Acid in Herbs Used in TCM

TCM and other medical systems have been using herbs containing Aristolochic acid for thousands of years. For example,  numerous societies all over the world have used an herb called “birthwort” (Aristolochia clematitis), which contains Aristolochic Acid, to assist in childbirth.

Of the approximately 5,000 herbs and other natural substances used in TCM, seven plants contain Aristolochic acid. It is a minor component, existing in trace amounts, in five of these seven.

The two herbs that contain a high proportion of Aristolochic acid are Guang Fang Ji  (Radix Aristolochiae Fangchi) and Guan Mu Tong (Caulis Aristolochiae Manshuriensis).

Most TCM physicians prescribe these herbs very rarely. In their comprehensive work, Chinese Medical Herbology and Pharmacology (2001), Chen and Chen strongly recommend avoiding Guang Fang Ji (Radix Aristolochiae Fangchi) and Guan Mu Tong (Caulis Aristolochiae Manshuriensis) altogether.

The following chart, based on this work, lists the seven herbs used in TCM that contain Aristolochic acid, the amount of the chemical that they contain, and their estimated toxicity:

Chinese name English name: Amount of Aristolochic Acid Estimated Danger of Toxicity
Guang Fang Ji Radix Aristolochiae Fangchi High its use should be avoided (Chen and Chen, p. 310)
Xun Gu Feng Herba Aristolochiae Mollissimae Trace Negligible
Guan Mu Tong Caulis Aristolochiae Manshuriensis High “The use of aristolochia types of Mu Tong is strongly discouraged because of toxicity associated with aristolochic acid,” (Chen and Chen, p. 397).
Xi Xin Herba Asari Trace Negligible
Qing Mu Xiang Radix Aristolochiae Trace Negligible
Tian Xian Teng Herba Aristolochiae Trace Negligible
Ma Dou Ling Fructus Aristolochiae Trace Negligible

The Use of Herbs Containing Aristolochic Acid in TCM

Shay Ravid, TCM practitioner and lecturer at the Tao College of Traditional Chinese Medicine (Israel), told Decoded Science that, of the 5,000 herbs, minerals and animal substances employed in TCM, only about 500-600 are used on a regular basis. The rest –including six of the seven herbs containing Aristolochic acid – are used infrequently, for very specific purposes. Xi Xin, the one herb of the seven which contains negligible amounts of the substance, is the only one prescribed more frequently.

Almost all herbal formulae used in TCM comprise mixtures of dried herbs, which are chopped into a fine powder. Either whole or powdered, the herbs are cooked in hot-to-boiling water before they are consumed. TCM practitioners perform this process, called decoction, in order to reduce the potential toxicity of their chemical components. According to Ravid, failure to decoct Chinese herbs might result in unpleasant side effects but is not likely to be lethal.

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