Table of Contents > Herbs & Supplements > Japanese knotweed (Polygonum cuspidatum, Reynoutria japonica, Fallopia japonica) Print

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

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Also listed as: Polygonum cuspidatum, Reynoutria japonica, Fallopia japonica
Related terms
Background
Evidencetable
Tradition
Dosing
Safety
Interactions
Attribution
Bibliography

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

Background
  • Japanese knotweed (Polygonum cuspidatum), a perennial herb native to Japan, China and Korea, was imported into Great Britain and the United States in the 1800s as an ornamental plant. The shoots, leaves, and stems are edible, but contain oxalic acid, a chemical that may hinder calcium absorption. The three Latin names of Japanese knotweed are used in different regions of the world: Reynoutria japonica in much of Europe; Polygonum cuspidatum, in North America; and Fallopia japonica, in Britain.
  • Japanese knotweed is a common commercial source of resveratrol, a chemical well-known for its presence in red wine. Resveratrol, which is available as a dietary supplement, has reported antiaging, antioxidant, anti-inflammatory, anticancer, and lipid-lowering effects.
  • Traditional medicinal uses of Japanese knotweed root extracts include improvement of oral hygiene and cardiovascular health and treatment of acute hepatitis, high cholesterol, inflammation, skin rash, and constipation.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)


Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

  • Aging, allergy, antibacterial, anti-inflammatory, antioxidant, arrhythmia, breast cancer prevention, cancer treatment, cardiotonic, dermatitis, gout, hepatitis B, hormone replacement therapy (HRT), laxative, leukemia, lipid lowering effects, menopausal signs and symptoms, osteoporosis prevention.

Dosing

Adults (18 years and older)

  • There is no proven safe or effective dose for Japanese knotweed in adults.

Children (under 18 years old)

  • There is no proven safe or effective dose for Japanese knotweed in children.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. 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. Consult a healthcare provider immediately if you experience side effects.

Allergies

  • Avoid with known allergy or hypersensitivity to Japanese knotweed, its components, or members of the Polygonaceae family. Some people who ingested Japanese knotweed and were exposed to sunlight developed a rash.

Side Effects and Warnings

  • Use cautiously in patients with blood clotting disorders or in those taking blood thinners.
  • Use cautiously in fair-skinned patients or in individuals using photosensitizing agents. Photosensitivity has been reported in some people who have ingested Japanese knotweed extracts.
  • Avoid with known allergy or hypersensitivity to Japanese knotweed, its components, or members of the Polygonaceae family.
  • Avoid during pregnancy and breastfeeding.

Pregnancy and Breastfeeding

  • Avoid during pregnancy and breastfeeding due to a lack of sufficient data.

Interactions

Interactions with Drugs

  • Japanese knotweed may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
  • Because Japanese knotweed contains estrogen-like chemicals, the effects of drugs believed to have estrogen-like properties may be altered.
  • Japanese knotweed may also interact with antibiotics, anticancer agents, antiviral drugs, anti-inflammatory agents, cardiovascular drugs, cholesterol lowering drugs, drugs used for osteoporosis, lipoxygenase inhibitors, and photosensitizing agents (agents that cause sun sensitivity).

Interactions with Herbs and Dietary Supplements

  • Japanese knotweed may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
  • Because Japanese knotweed contains estrogen-like chemicals, the effects of herbs and supplements believed to have estrogen-like properties, such as phytoestrogens, may be altered.
  • Japanese knotweed may also interact with antibacterials, anticancer herbs and supplements, antioxidants, antivirals, anti-inflammatory herbs and supplements, cardiovascular herbs and supplements, cholesterol lowering herbs and supplements, herbs and supplements used for osteoporosis, herbs and supplements that cause sun sensitivity, and resveratrol.

Attribution
  • This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography
  1. Bagchi D, Das DK, Tosaki A, et al. Benefits of resveratrol in women's health. Drugs Exp.Clin Res 2001;27(5-6):233-248.
  2. Bralley EE, Greenspan P, Hargrove JL, et al. Topical anti-inflammatory activity of extract in the TPA model of mouse ear inflammation. J Inflamm.(Lond) 2008;5:1.
  3. Chang JS, Liu HW, Wang KC, et al. Ethanol extract of inhibits hepatitis B virus in a stable HBV-producing cell line. Antiviral Res 2005;66(1):29-34.
  4. Feng L, Zhang LF, Yan T, et al. [Studies on active substance of anticancer effect in ]. Zhong.Yao Cai. 2006;29(7):689-691.
  5. Hsu CY, Chan YP, Chang J. Antioxidant activity of extract from . Biol.Res 2007;40(1):13-21.
  6. Kim KW, Ha KT, Park CS, et al. , compared with baicalin and berberine, inhibits inducible nitric oxide synthase and cyclooxygenase-2 gene expressions in RAW 264.7 macrophages. Vascul.Pharmacol 2007;47(2-3):99-107.
  7. Leu YL, Hwang TL, Hu JW, et al. Anthraquinones from as tyrosinase inhibitors for dermal use. Phytother.Res 2008;22(4):552-556.
  8. Lim BO, Lee JH, Ko NY, et al. radix inhibits the activation of Syk kinase in mast cells for antiallergic activity. Exp.Biol.Med (Maywood.) 2007;232(11):1425-1431.
  9. Park, CS, Lee, YC, Kim, JD, et al. Inhibitory effects of water extract (PCWE) and its component resveratrol [correction of rasveratrol] on acyl-coenzyme A-cholesterol acyltransferase activity for cholesteryl ester synthesis in HepG2 cells. Vascul.Pharmacol. 2004;40(6):279-284.
  10. Qu, Y, Wang, JB, Li, HF, et al. [Study on relationship of laxative potency and anthraquinones content traditional Chinese drugs]. Zhongguo Zhong.Yao Za Zhi. 2008;33(7):806-808.
  11. Song, JH, Kim, SK, Chang, KW, et al. inhibitory effects of on bacterial viability and virulence factors of and . Arch Oral Biol. 2006;51(12):1131-1140.
  12. Wang C, Zhang D, Ma H, et al. Neuroprotective effects of emodin-8-O-beta-D-glucoside and . Eur.J Pharmacol 12-22-2007;577(1-3):58-63.
  13. Wang D, Xu Y, Liu W. Tissue distribution and excretion of resveratrol in rat after oral administration of extract (PCE). Phytomedicine. 2008;15(10):859-866.
  14. Xing WW, Wu JZ, Jia M, et al. Effects of polydatin from on lipid profile in hyperlipidemic rabbits. Biomed.Pharmacother. 2009;63(7):457-462.
  15. Zhang CZ, Wang SX, Zhang Y, et al. estrogenic activities of Chinese medicinal plants traditionally used for the management of menopausal symptoms. J Ethnopharmacol. 4-26-2005;98(3):295-300.

Copyright © 2011 Natural Standard (www.naturalstandard.com)


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.

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