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Polygala tenuifolia (Yuan Zhi) in Traditional Chinese Medicine: Benefits, History, Uses, and Side Effects

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Yuan Zhi is a staple of Traditional Chinese Medicine (TCM), and though we aren't sure exactly how long it has been in use, it is one of the oldest continuously used treatments that is still prescribed today by TCM practitioners. Recent scientific analysis and research have proven the mechanisms behind Yuan Zhi's many benefits.

What is Polygala tenuifolia (Yuan Zhi)?

Polygala tenuifolia is a Traditional Chinese Medicine herb that is also known as Yuan Zhi, Senega, Chinese Senega, Mountain Polygala, Seneca/Senega Snakeroot, Snakeroot, Milkwort, Polygala, Polygala Root, Rattlesnake Root, Senega Snakeroot, and Seneka. Many people call Polygala tenuifolia “Senega Root” and “Chinese Senega.” However, there is a separate species called Polygala senega that is also called Yuan Zhi, so there is confusion between the distinction of the two species. Our discussion today focuses specifically on Polygala tenuifolia (Yuan Zhi). [1, 2]

Polygala tenuifolia belongs to the genus Polygala in the family Polygalaceae. Polygala is known as “milkworts” and “snakeroots.” They are annual or perennial small trees and shrubs which have purple flowers. The name Polygala is derived from an ancient Greek word which translates into “much milk” due to the belief that the plant can increase milk production in dairy cattle. [2, 3, 4]

“Yuan Zhi” is a specific species of Polygala tenuifolia called Polygala tenuifolia Willdenow or one of its varieties, P. sibrica Linnaeus. It grows in the mountain slopes, grasslands, prairies, and shrub forests of China, Mongolia, Korea, and Russia. [4, 5]

Yuan Zhi means “Profound Will” in Chinese. The Chinese use the roots of the Polygala tenufolia plant, and therefore, it is also called Radix Polygalae. “Radix” is a term that refers to the root of a plant in botany. [6, 7]

What is the history of Polygala tenuifolia (Yuan Zhi)?

  • China: Polygala tenufolia (Yuan Zhi) was used in ancient China in their Traditional Chinese Medicine (TCM) therapy. It is still a popular treatment in the present-day. Yuan Zhi was first mentioned in a book, Jingyue Quanshu, in 1624 as a treatment for dementia and memory loss; but the Chinese have been using Yuan Zhi for an indefinite amount of time. [8]

TCM defines Yuan Zhi as a neuroprotective agent. It is one of the three most common plants used for memory enhancement in TCM. TCM physicians believe that it balances the qi of the kidneys and heart and can stabilize the emotions and fortitude (will). It is listed as a mucolytic (expectorant) to treat cough in the Chinese Pharmacopoeia. As one of the 50 fundamental herbs that are used in TCM, Yuan Zhi has a history of being used by Buddhist monks for enhanced cognition and focus during meditation. Yuan Zhi was also used traditionally to relax the body for sleep, and it is a nootropic herb. [2, 5, 9]

  • Japan: Kampo, the traditional Japanese medicine philosophy, uses Yuan Zhi in some of their herbal formulations for Yuan Zhi's cognitive benefits. The formulations used in Kampo are Kami-kihi-to, Kami-untan-to, Ninjin-yoei-to, and Kai Xin San. It is called “onji” in Japanese. [2, 10]
  • Korea: Polygala tenuifolia is known as “wonji” in Korean. [11]

What is Polygala tenuifolia (Yuan Zhi) made of?

Yuan Zhi's active constituents include sucrose esters, saponins, acetylated sucrose molecules, xanthones, triterpenoid glycosides, phenyl propanoids, sterols, flavonoids, and polysaccharides.

  • Tenuifolisides A, B, C
  • Tenuifoliose A-X
  • 3,6′-disaponylsucrose (DISS)
  • Tenuifolin: 0.006% of dried root
  • Saponins: tenuigenin, senegenin, senegenin III, tenuifoside A, polygalasaponin F, polygalasaponin XXXII
  • Onjisaponins
  • Sibiricose A1, A5, A6
  • Yuanzhi-1: pentacyclic triterpenoid
  • Tetrahydrocolumbamine
  • 7-O-methylmangiferin, lancerin, shibiricaxanthone A
  • Assorted triterpenoid glycosides
  • Chondrillasterol
  • 3β-O-β-Pyranoglucosyl Chondrillasterol
  • Clionasterol and its derivatives
  • Poligapolide
  • Phenyl propanoids: 3,4,5-trimethoxy methyl cinnamate; 3,4,5-trimethoxycinnamic acid
  • Xanthones
  • Flavonoid: 3'4,'-Dimethoxy-7-diglucosyl-O-methylenoxy-5-hydroxyl-flavol
  • Sterols
  • Polysaccharides: 5.27% of weight from dried root [2]

How is Polygala Tenuifolia (Yuan Zhi) prepared?

Yuan Zhi is harvested in the fall and then dried in the sunlight. The dried root bark is split open and the xylem (the tissue in the plant that transports water from the roots) is extracted through vigorous rubbing. The xylem is then dried again and can be used directly or in a liquid medium. [12, 13]

How to Use Polygala tenuifolia (Yuan Zhi)

Yuan Zhi can be purchased as a dried roots, dried root powder, and tinctures. Use of Yuan Zhi is

best supervised by a Traditional Chinese Medicine practitioner.

Safety and Side Effects of Polygala tenuifolia (Yuan Zhi)

Long-term use of Yuan Zhi can cause gastrointestinal irritation, and large quantities may cause dizziness, diarrhea, nausea, and vomiting. [1]

Due to its gastrointestinal effects, it is not advisable to use Yuan Zhi if you have a gastrointestinal condition or disease, such as gastric ulcers or gastritis. It is believed that the saponins cause irritation of the mucosa of the GI tract. [1]


  1. “Senega.” Foods, Herbs & Supplements. https://naturalmedicines.therapeuticresearch.com/databases/food,-herbs-supplements/professional.aspx?productid=679
  2. “Polygala tenuifolia.” Examine.com, last updated Jun 14, 2018. https://examine.com/supplements/polygala-tenuifolia/.
  3. “Polygala.” Wikipedia, en.wikipedia.org/wiki/Polygala.
  4. “Polygala Linn.” www.efloras.org/florataxon.aspx?flora_id=3&taxon_id=126390.
  5. Tang, Weici, and Gerhard Eisenbrand. “Polygala Tenuifolia Willd.” Chinese Drugs of Plant Origin, pp. 781–786., link.springer.com/chapter/10.1007/978-3-642-73739-8_99.
  6. P, Liu, et al. “Potential Antidepressant Properties of Radix Polygalae (Yuan Zhi).” Phytomedicine, vol. 17, no. 10, Aug. 2010, pp. 794–9., www.ncbi.nlm.nih.gov/pubmed/20541923.
  7. Xie, Huisheng, and Vanessa Preast. ” Xie's Chinese Veterinary Herbology.” ISBN 978-0-8138-0369-2.
  8. Liu, Ping, et al. “History and Experience: A Survey of Traditional Chinese Medicine Treatment for Alzheimer's Disease.” Evid Based Compelement Alternat Med, vol. 2014, doi: http://dx.doi.org/10.1155/2014/642128.
  9. Van der Linden, Michael. “Yuan Zhi Therapeutic Uses – Polygala Tenuifolia, Seneca.” 21 Jan. 2018, www.lindenbotanicals.com/2018/01/21/yuan-zhi-therapeutic-uses/.
  10. “Yuan Zhi.” www.rootdown.us/Herbs/Yuan Zhi?
  11. HK, Park, et al. “Occupational Asthma and Rhinitis Induced by a Herbal Medicine, Wonji (Polygala Tenuifolia).” J Korean Med Sci., vol. 20, no. 1, Feb. 2005, pp. 46–9., www.ncbi.nlm.nih.gov/pubmed/15716601.
  12. “Yuan Zhi.” tcmwiki.com/wiki/yuan-zhi.
  13. “Polygala Tenuifolia – Willd.” pfaf.org/user/Plant.aspx?LatinName=Polygala tenuifolia.
  14. Shin, Ki Young et al. “Preclinical Safety of the Root Extract of Polygala tenuifolia Willdenow in Sprague-Dawley Rats and Beagle Dogs.” Evidence-based complementary and alternative medicine : eCAM vol. 2014 (2014): 570134. doi:10.1155/2014/570134


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