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Japanese knotweed (Polygonum cuspidatum, Reynoutria japonica, Fallopia japonica)

Synonyms/Common Names/Related Substances:

  • Anthraquinones, astringin, emodin, Fallopia japonica, flavonoid, fuyanke granule, Hu chang, Hu zhang, Phellodendron chinense Schneid, physcion, phytoalexin, phytoestrogens, piceatannol, piceid, polydatin, Polygonaceae (family), Polygoni cuspidati radix, Polygonum cuspidatum roots, Polygonum cuspidatum water extract, Polygonum cuspidatum Sieb. et Zucc., polyphenolic hydroxyanthraquinones, polyphenolic phytoalexin, Protykin®, resveratrol, Reynoutria japonica, stilbenes.

Clinical Bottom Line/Effectiveness

Brief Background:

  • Japanese knotweed originated in China and Japan. It was imported into Great Britain and the United States as an ornamental garden plant in the 1800s. Its three Latin names are used in different regions of the world. Reynoutria japonica was given by Houttyn in 1777 and is used in much of Europe. In 1846, Siebold named it Polygonum cuspidatum, which is the preferred name in North America, whereas Fallopia japonica is often used in Britain.
  • Active constituents of Japanese knotweed include resveratrol, emodin, polydatin (piceid), piceatannol, physcion, and astringin. Japanese knotweed is a common commercial source of resveratrol, a hydroxystilbene. Resveratrol from Japanese knotweed has been included in supplements advertised for their antiaging and antioxidant activities.
  • There is a lack of well-designed clinical trials investigating the efficacy of Japanese knotweed extracts.
  • Traditionally, root extracts have been used for treating acute hepatitis and high cholesterol, and for improving oral hygiene. Other described uses include alleviation of menopausal symptoms, dermatitis, and inflammation, and improvement of cardiovascular health.
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Dosing/Toxicology

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Precautions/Contraindications

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Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

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Mechanism of Action

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History

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Evidence Table

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Evidence Discussion

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Products Studied

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Author Information

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References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.