Japanese knotweed (Polygonum cuspidatum, Reynoutria japonica, Fallopia japonica)
Natural Standard Bottom Line Monograph, Copyright © 2013 (www.naturalstandard.com). Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.
While some complementary and alternative techniques have been studied scientifically, high-quality data regarding safety, effectiveness, and mechanism of action are limited or controversial for most therapies. Whenever possible, it is recommended that practitioners be licensed by a recognized professional organization that adheres to clearly published standards. In addition, before starting a new technique or engaging a practitioner, it is recommended that patients speak with their primary healthcare provider(s). Potential benefits, risks (including financial costs), and alternatives should be carefully considered. The below monograph is designed to provide historical background and an overview of clinically-oriented research, and neither advocates for or against the use of a particular therapy.
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.
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.
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.
No available studies qualify for inclusion in the evidence table.
*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 against this use (it may not work); F: Strong scientific evidence against this use (it likely does not work).
The below uses are based on tradition or scientific theories. 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 health care professional.
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.
The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
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.
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.
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.
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.
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.
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).
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.
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. View Abstract
Bralley EE, Greenspan P, Hargrove JL, et al. Topical anti-inflammatory activity of Polygonum cuspidatum extract in the TPA model of mouse ear inflammation. J Inflamm.(Lond) 2008;5:1. View Abstract
Chang JS, Liu HW, Wang KC, et al. Ethanol extract of Polygonum cuspidatum inhibits hepatitis B virus in a stable HBV-producing cell line. Antiviral Res 2005;66(1):29-34. View Abstract
Feng L, Zhang LF, Yan T, et al. [Studies on active substance of anticancer effect in Polygonum cuspidatum]. Zhong.Yao Cai. 2006;29(7):689-691. View Abstract
Hsu CY, Chan YP, Chang J. Antioxidant activity of extract from Polygonum cuspidatum. Biol.Res 2007;40(1):13-21. View Abstract
Kim KW, Ha KT, Park CS, et al. Polygonum cuspidatum, 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. View Abstract
Leu YL, Hwang TL, Hu JW, et al. Anthraquinones from Polygonum cuspidatum as tyrosinase inhibitors for dermal use. Phytother.Res 2008;22(4):552-556. View Abstract
Lim BO, Lee JH, Ko NY, et al. Polygoni cuspidati radix inhibits the activation of Syk kinase in mast cells for antiallergic activity. Exp.Biol.Med (Maywood.) 2007;232(11):1425-1431. View Abstract
Park, CS, Lee, YC, Kim, JD, et al. Inhibitory effects of Polygonum cuspidatum 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. View Abstract
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. View Abstract
Song, JH, Kim, SK, Chang, KW, et al. In vitro inhibitory effects of Polygonum cuspidatum on bacterial viability and virulence factors of Streptococcus mutans and Streptococcus sobrinus. Arch Oral Biol. 2006;51(12):1131-1140. View Abstract
Wang C, Zhang D, Ma H, et al. Neuroprotective effects of emodin-8-O-beta-D-glucoside in vivo and in vitro. Eur.J Pharmacol 12-22-2007;577(1-3):58-63. View Abstract
Wang D, Xu Y, Liu W. Tissue distribution and excretion of resveratrol in rat after oral administration of Polygonum cuspidatum extract (PCE). Phytomedicine. 2008;15(10):859-866. View Abstract
Xing WW, Wu JZ, Jia M, et al. Effects of polydatin from Polygonum cuspidatum on lipid profile in hyperlipidemic rabbits. Biomed.Pharmacother. 2009;63(7):457-462. View Abstract
Zhang CZ, Wang SX, Zhang Y, et al. In vitro estrogenic activities of Chinese medicinal plants traditionally used for the management of menopausal symptoms. J Ethnopharmacol. 4-26-2005;98(3):295-300. View Abstract
Copyright © 2013 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.
March 22, 2017