Herbs & Botanicals · Root source of resveratrol

Japanese knotweed

Q: What is Japanese knotweed?

Japanese knotweed is a tall, fast-spreading plant. Its dried root, called hu zhang in Chinese medicine, is used as a herb and is a main commercial source of resveratrol.

Q: Is Japanese knotweed the same as resveratrol?

No. Resveratrol is one compound found in the root, and most human trials tested pure resveratrol. The root also contains polydatin, emodin and many other compounds, so results for resveratrol may not apply to the root.

Q: Does Japanese knotweed treat Lyme disease?

There is no evidence that it does. A laboratory dish study found knotweed extract slowed the Lyme bacterium but did not clear it, and no animal or human trial exists. Lyme disease needs medical care; see a doctor after a tick bite or if you have symptoms.

Q: Is it safe to take Japanese knotweed with Lyme antibiotics?

No interaction study was found. Resveratrol changed liver enzymes that handle some medicines, so tell your doctor or pharmacist about any herb you take alongside Lyme treatment.

Q: Can Japanese knotweed lower blood sugar or blood pressure?

Pooled trials of pure resveratrol found no clear overall effect on blood pressure, and reviews disagree on blood sugar. Nothing was found for the root itself. Do not change diabetes or blood pressure medicines without your doctor.

Q: Does it act as a laxative?

It might. The root contains emodin-type compounds, the same class as rhubarb root and senna, and it is traditionally used for constipation. No trial of knotweed alone for constipation was found.

Q: Is it bad for the liver?

No human liver injury case was found, but the evidence is thin. In animals, emodin raised liver enzymes at high doses and long duration. In 15 trials, pure resveratrol did not change liver enzymes on average. Report yellow skin or eyes or dark urine promptly.

Q: Can it interact with blood thinners or other medicines?

Possibly. Resveratrol slowed the breakdown of some medicines in healthy volunteers, and lab work suggests it may affect platelets. Ask your doctor or pharmacist before combining it with blood thinners or prescription medicines.

Q: Does it have oestrogen-like effects?

In the lab, emodin from the root attached to oestrogen receptors and made oestrogen-sensitive cells multiply. No human study shows what this means. People with hormone-sensitive conditions should ask a doctor first.

Q: Is it safe in pregnancy or breastfeeding?

It should be avoided. No safety data for knotweed in pregnancy or breastfeeding were found, and emodin showed reproductive toxicity in animals at high doses.

Reynoutria japonica · also called Hu zhang, huzhang, itadori, Asian knotweed, Japanese fleece flower, Mexican bamboo, donkey rhubarb

Japanese knotweed is a tall, fast-spreading plant. Its root, called hu zhang in Chinese medicine, is a main commercial source of resveratrol and also holds laxative-type compounds such as emodin. It is sold for heart and blood-sugar health and, more recently, for Lyme disease symptoms, but human evidence is thin: most trials tested pure resveratrol, not the root, and the Lyme findings come from laboratory dishes only. The key cautions are a possible laxative effect, medicine interactions, and that Lyme disease needs medical care.

General information, not medical advice. Last substantive update October 25, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

About Japanese knotweed

Japanese knotweed (Reynoutria japonica, also called Polygonum cuspidatum) is a tall perennial plant. The dried root and underground stem, hu zhang, is used in Chinese medicine and is a main commercial source of resveratrol. This page explains what is known, what is not, and the safety points to check first.

What it is

Japanese knotweed is a tall, fast-spreading plant in the knotweed family. The medicinal part is the dried root and underground stem, called hu zhang in Chinese medicine. Reviews say about 110 compounds have been found in it.

Its main active groups are stilbenes (resveratrol and polydatin), anthraquinones (such as emodin) and flavonoids.

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What makes it distinctive

The root is a major commercial source of resveratrol, the compound behind many supplements. It also contains emodin, an anthraquinone from the same chemical class as the laxatives in rhubarb root and senna.

That mix is why research on pure resveratrol cannot simply be applied to the root. Emodin adds a laxative effect and safety questions that pure resveratrol capsules do not have.

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Historical and current uses

In Chinese, Japanese and Korean medicine hu zhang is used to cool heat, move blood and treat jaundice, scalds, favus and constipation. Fresh plant has been applied to burns and boils.

Today it is sold as a resveratrol source and, in the last few years, as part of plans for lingering symptoms attributed to Lyme disease. That Lyme use is a modern trend, not a tradition.

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What the research shows

Human trials mostly used pure resveratrol. Pooled results show no clear effect on blood pressure, cholesterol, inflammation markers or liver enzymes, and blood sugar results disagree between reviews. A review of memory trials found small gains on one test.

Herbal mixtures that included knotweed helped symptoms of chest infections in trials, but knotweed was never tested alone and most patients also took antibiotics.

In laboratory dishes, knotweed extract slowed the Lyme bacterium but did not clear it. There are no animal or human trials.

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At a glance

Traditional uses history, not proof

Chinese, Japanese and Korean medicine: the dried root and stem (hu zhang) to cool heat, move blood and treat jaundice, scalds and constipation
Fresh plant applied to burns, scalds and boils in tradition

Studied for research

Blood sugar, very low certainty (isolated resveratrol; the reviews disagree)
Blood pressure and cholesterol, low certainty (pooled trials of isolated resveratrol found no clear benefit)
Lyme disease, insufficient (laboratory dishes only)
Respiratory infections, very low certainty (only inside herbal mixtures, usually with antibiotics)

Main compounds

Resveratrol and polydatin (stilbenes)
Emodin and other anthraquinones
Flavonoids and about 110 compounds in all

Common forms

Dried root or rhizome (hu zhang) and decoction in tradition
Capsules, powders and extracts, some labelled for resveratrol
Fresh plant (topical) in tradition

Research links: Review of Reynoutria japonica for heart and digestive illness (Frontiers in Pharmacology, 2022) · Natural and botanical medicines tested against Lyme bacteria in the lab (Frontiers in Medicine, 2020) · Herbal supplements used for persistent Lyme symptoms: review (2023) · Research Library · Genes & Biomarkers Library

The plant and its history

Accepted scientific name: Reynoutria japonica Houtt.
Naming authority: Houtt. (GBIF accepted name, usageKey 2889173).
Synonyms: Fallopia japonica (Houtt.) Ronse Decr. (stated as a synonym in the 2022 Frontiers abstract); Polygonum cuspidatum Sieb. et Zucc. (name used in the 2023 review and Chinese Pharmacopoeia usage; a GBIF match on this name returned only the family, so the synonym link was not confirmed in GBIF)
Common names: Japanese knotweed (English); Asian knotweed (English); Japanese fleece flower (English); Mexican bamboo (English); Donkey rhubarb (English); Hu zhang (Huzhang) (Chinese (pinyin)); Itadori (Japanese); Hierba nudosa japonesa (Spanish)
Botanical family: Polygonaceae (knotweed or buckwheat family).
Classification: Plantae > Caryophyllales > Polygonaceae > Reynoutria > Reynoutria japonica
Native range: Not verified in a source read. The 2022 review names China, Japan and Korea as places where it is used as medicine, and says it is invasive in the United States and many European countries.
Habitat: Not verified in a source read.
What the plant looks like: Roots: Medicinal part is the dried root and rhizome (underground stem) called hu zhang; the 2022 review abstract says 'dry roots and stems'.; Stems: Not verified.; Leaves: Leaves and flowers have different constituents from the rhizome (Ke 2023 abstract).; Flowers: Not verified.; Fruit: Not verified.
Cultivation: Not verified; described as an invasive plant.
Harvest and processing: Not verified. Whether a product is made from cultivated or wild plants is rarely stated on labels.
Look-alikes and adulterants: Name: Polygonum multiflorum (fo-ti, He Shou Wu); Note: A different Chinese medicine plant that also contains emodin (named in the 2016 emodin review). Not interchangeable.; Name: Rhubarb (Rheum palmatum); Note: Another emodin-containing root used as a laxative (named in the 2016 emodin review). Not interchangeable.; Name: Other knotweed species and hybrids; Note: Not verified from any source read; check the Latin name on a label.
Sustainability and conservation: Not applicable in the usual sense: regarded as an invasive plant; no IUCN assessment was retrieved.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Traditional Chinese, Japanese and Korean medicine	The dry root and stem (hu zhang) is used to invigorate blood, cool heat and resolve toxicity, for favus, jaundice, scalds and constipation, according to the 2022 review abstract.	p35770098
Chinese Pharmacopoeia	The root is included in the pharmacopoeia under the name Huzhang; clinic uses listed include dizziness, headaches, traumatic injuries and burns (2023 review abstract). Wikipedia-only history claims were not used and are NOT verified.	p36620922
Modern supplement trend	Marketed as a resveratrol source and, more recently, for persistent symptoms attributed to Lyme disease. The Lyme use is a recent practitioner trend (2023 review), not an old tradition.	p37101730

Traditional use shows how a plant was used. It does not show that a supplement works or is safe today.

What is inside, and how it may work

What the plant contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
trans-Resveratrol PubChem 445154	stilbene	Root Content varies between products; the existing summary says the root is a major commercial source and contains more polydatin than resveratrol (summary-only).	Studied in most human trials of 'resveratrol'; poorly absorbed with low blood levels and short half-life; modulates drug-metabolising enzymes in people. ^{1 3 26}	Human data
Polydatin (piceid) PubChem 5281718	stilbene glycoside (resveratrol bound to a sugar)	Root Not stated in a source read.	Little human research on its own; one trial used a polydatin plus palmitoylethanolamide combination for IBS pain. ^{4 26}	Human data
Emodin PubChem 3220	anthraquinone	Root Not stated in a source read.	Laxative-type class; binds human oestrogen receptors in the lab; liver, kidney and reproductive toxicity in animals at high dose and long duration. ^{6 15 9 26}	Animal research
Emodin 8-O-beta-D-glucoside	anthraquinone glycoside	Root Not stated in a source read.	Isolated from the root with emodin as an oestrogenic principle in cells. ¹⁵	Laboratory research
Flavonoids and other anthraquinones PubChem not assigned	flavonoids; anthraquinones	Root About 110 compounds have been isolated from hu zhang in total (2022 abstract).	Named with stilbenes and anthraquinones as the main active groups; individual compounds not covered here. ^{13 11}	Review

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Liver drug-metabolising enzymes	CYP3A4, CYP2D6, CYP2C9 (inhibited); CYP1A2 (induced)	In 42 healthy volunteers, isolated resveratrol inhibited CYP3A4, CYP2D6 and CYP2C9 and induced CYP1A2; in 12 volunteers it raised carbamazepine exposure. ^{3 2}	Human data
Oestrogen receptors	ER alpha and ER beta	Emodin blocked 17-beta-estradiol binding to human oestrogen receptors and made MCF-7 cells multiply in the lab. ¹⁵	Laboratory research
Liver enzyme pathways	CYP2E1, FXR/BSEP	In rodents emodin lowered ALT, AST and ALP in injured liver, linked to lower CYP2E1 and activation of FXR/BSEP, but raised AST at high dose and long duration in healthy animals. ⁹	Animal research
Borrelia burgdorferi viability	Bacterial cells	Knotweed extract inhibited growing and stationary-phase Lyme bacteria in dishes but did not clear them on subculture. ⁷	Laboratory research
Gut mast cells	Mast-cell activation	Proposed for PEA plus polydatin; mast-cell counts did not change in the IBS trial. ⁴	Human data

Absorption, metabolism and elimination

Absorption: Isolated trans-resveratrol: peak blood levels 0.8 to 1.5 hours after a dose and low even at high doses, with high person-to-person variation (healthy volunteers). Emodin: poor oral bioavailability in rats because of extensive glucuronidation. No pharmacokinetic study of knotweed root or its extracts in people was found.
Distribution: Not found.
Metabolism: Emodin: extensive glucuronidation (rats). Resveratrol: strong effects on liver CYP enzymes in people.
Elimination: Resveratrol half-life 1 to 3 hours after one dose and 2 to 5 hours after repeated dosing (healthy volunteers).
Bioavailability: Low for resveratrol and emodin in the studies read; the 2023 review says pharmacokinetics of the plant need further investigation.

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Isolated compounds versus whole extracts

Knotweed root is a mixture of about 110 compounds. Almost all human trials tested isolated resveratrol or, in one case, a polydatin combination, so their results and side effects cannot be carried over to the whole root, a decoction or a mixed extract. The root also contains emodin-type anthraquinones that are absent from pure resveratrol capsules and carry their own safety questions (laxative effect, animal liver and reproductive toxicity, oestrogen-receptor binding). Standardised extracts and whole-root powders differ again.

Nutritional composition

Not a nutrient; no essential role. The root is a medicinal plant, not a food in the sources read.

13benefits and uses looked at

27studies and sources checked

Low certaintybest evidence rating found

14lab markers tracked in trials

3 low certainty6 very low certainty4 not enough evidence

What is Japanese knotweed good for?

The main proposed uses and how strong the human evidence is for each. 'Low' is the best rating any knotweed use reached here. 'Very low' and 'insufficient' mean few, small, mixed, lab-only or animal-only studies, and none of these is a proven treatment for you. Most human data are for pure resveratrol, so they may not carry over to the whole root. Ratings are this profile's own reading, not formal grades. Lyme disease and infections need a doctor.

Blood sugar and type 2 diabetesVery low certaintyThree small trials of pure resveratrol showed no change in blood sugar. A broader review saw a short-term fall in HbA1c, so the reviews disagree. Not shown for the root. Blood pressureLow certaintyPooled trials of pure resveratrol found no clear overall change. Some subgroups looked better, which is weak evidence. Cholesterol and blood fatsLow certaintyNo benefit on total or LDL cholesterol or triglycerides in 10 trials of pure resveratrol, and HDL was slightly lower. InflammationVery low certaintyPure resveratrol did not change C-reactive protein. The anti-inflammatory reputation rests mostly on lab and animal work. Memory and moodLow certaintyA review of 10 trials of pure resveratrol found a small gain on one memory test and slightly lower negative mood. The authors call the literature inconsistent. Lyme diseaseNot enough evidenceKnotweed extract slowed Lyme bacteria in dishes, but did not clear them, and no animal or human trial exists. Not a substitute for medical care. Respiratory infectionsVery low certaintyChinese herbal mixtures that included knotweed helped symptoms in small trials, but knotweed was never tested alone and most patients also took antibiotics. ConstipationNot enough evidenceTraditionally used, and the root contains laxative-type compounds. No trial of knotweed alone was found. Irritable bowel painVery low certaintyOne 12-week trial of a polydatin and palmitoylethanolamide combination found less belly pain than placebo. The combination means polydatin's own effect is unknown. Pain and bone markers after menopauseVery low certaintyPooled trials of pure resveratrol in postmenopausal women found lower pain scores and one lower bone-breakdown marker, but no change in menopausal symptoms or mood. Liver healthVery low certaintyPure resveratrol did not change liver enzymes across 15 trials. In animals, emodin both protected and harmed the liver depending on dose and time. Anti-ageing and longevityNot enough evidenceA 2011 expert review found the evidence not strong enough to recommend resveratrol to people for health beyond food amounts. Burns, boils and jaundice (traditional)Not enough evidenceLong traditional use in East Asia; no human trials were found.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Blood sugar and type 2 diabetes (resveratrol)

Very low certainty

Trials of isolated resveratrol, the compound sold from knotweed, show small and inconsistent effects on blood sugar. No trial of the root itself was found.

2 studiesIsolated resveratrol (the compound sold from knotweed), not knotweed …

Studies, doses and limits

What the trials found

Cochrane review (3 small trials, 50 people with type 2 diabetes, 4 to 5 weeks): no change in HbA1c, fasting glucose or insulin resistance (very low certainty). Umbrella review of 11 meta-analyses in type 2 diabetes: most effects trivial or low certainty, but HbA1c fell in the short term (under 12 weeks) with moderate GRADE; the authors still said the evidence does not support resveratrol for cardiometabolic risk factors.

Results

Mixed and weak. The Cochrane review and the umbrella review disagree on HbA1c.

Effect sizes as reported

Cochrane: HbA1c MD 0.1% (95% CI -0.02 to 0.2); fasting glucose MD 2 mg/dL (95% CI -2 to 7). Umbrella: HbA1c MD -1.05% (95% CI -2.09 to -0.02; 6 trials).

Why this rating

Few, short, small trials of isolated resveratrol; the two reviews disagree; nothing on knotweed root.

Form and dose studied

Isolated resveratrol (the compound sold from knotweed), not knotweed root or whole extracts.

Who was studied

Adults with type 2 diabetes, metabolic syndrome or fatty liver disease.

Limits

Results cannot be applied to the root, which also contains emodin-type compounds and has not been tested for blood sugar in people.

Why researchers looked

Knotweed root is a commercial source of resveratrol, which has lowered blood sugar in animals.

Traditional use

Hu zhang is not a traditional blood-sugar herb in the sources read; the interest comes from its resveratrol content.

Proposed mechanism Laboratory research

Lab work on resveratrol and polydatin points to effects on cell-energy pathways. This was not read in detail here and has not been shown to explain any effect in people.

A proposed mechanism does not show that the effect happens in people.

Resveratrol may add to the effect of diabetes medicines (no interaction study read). Ask a doctor or pharmacist if you take any.

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Blood pressure (resveratrol)

Low certainty

Pooled trials of isolated resveratrol found no clear overall change in blood pressure. Some subgroups looked better, but that is weak evidence.

2 studiesIsolated resveratrol (the compound sold from knotweed), not knotweed …

Studies, doses and limits

What the trials found

Meta-analysis of 17 trials: systolic BP fell 2.5 mmHg on average, but the confidence interval crossed zero (not significant); diastolic and mean pressures also not significant. Subsets with higher daily dose and with diabetes showed significant falls. A second meta-analysis of 10 trials (Sahebkar 2015) found no change in systolic or diastolic pressure.

Results

Null overall; positive only in subgroups.

Effect sizes as reported

Systolic WMD -2.5 mmHg (95% CI -5.5 to 0.6; I2 62%); diastolic -0.5 mmHg (95% CI -2.2 to 1.3).

Why this rating

Moderate to high inconsistency; positive results come from subgroup analyses; isolated resveratrol only.

Form and dose studied

Isolated resveratrol (the compound sold from knotweed), not knotweed root or whole extracts.

Who was studied

Adults in 17 randomised trials, some with diabetes or obesity.

Limits

Subgroup findings may be chance. Only abstracts were read.

Why researchers looked

Resveratrol is marketed for heart health, so blood pressure is a common outcome.

Traditional use

Hu zhang was traditionally used to move blood and clear heat; blood pressure was not a traditional target in the sources read.

Proposed mechanism Animal research

Proposed effects on blood vessel lining and nitric oxide come from lab and animal work.

A proposed mechanism does not show that the effect happens in people.

Do not stop or change blood pressure medicines because of any supplement.

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Cholesterol and blood fats (resveratrol)

Low certainty

A meta-analysis of 10 trials found no benefit of isolated resveratrol on total or LDL cholesterol or triglycerides, and HDL ('good') cholesterol was slightly lower.

2 studiesIsolated resveratrol (the compound sold from knotweed), not knotweed …

Studies, doses and limits

What the trials found

Meta-analysis of 10 randomised trials (Sahebkar 2015): no significant change in total cholesterol, LDL or triglycerides; HDL cholesterol was lower. The umbrella review (type 2 diabetes, metabolic syndrome, fatty liver) found lipid effects that were trivial or low certainty.

Results

Null or slightly unfavourable on HDL.

Effect sizes as reported

Total cholesterol WMD 1.49 mg/dL (95% CI -14.96 to 17.93); LDL WMD -0.31 mg/dL; triglycerides WMD 2.67 mg/dL; HDL WMD -4.18 mg/dL (95% CI -6.54 to -1.82).

Why this rating

Small, older meta-analysis of isolated resveratrol; no trial of the root.

Form and dose studied

Isolated resveratrol (the compound sold from knotweed), not knotweed root or whole extracts.

Who was studied

Adults in 10 randomised trials.

Limits

Search ended in 2014; newer trials not covered.

Why researchers looked

Chinese reviews say hu zhang has anti-atherosclerosis effects, and resveratrol is studied for blood fats.

Traditional use

Hu zhang is described in reviews as traditionally used to resolve toxicity and invigorate blood; lowering blood fats is a modern framing.

Proposed mechanism Animal research

Reviews list anti-atherosclerotic activity for the plant, mainly from lab and animal work.

A proposed mechanism does not show that the effect happens in people.

None specific beyond general resveratrol cautions.

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Inflammation marker (C-reactive protein)

Very low certainty

Isolated resveratrol did not change C-reactive protein, a blood marker of inflammation, in a meta-analysis of 10 trials. Knotweed's anti-inflammatory reputation rests mostly on lab and animal work.

3 studiesIsolated resveratrol (the compound sold from knotweed), not knotweed …

Studies, doses and limits

What the trials found

Sahebkar 2015 meta-analysis: CRP WMD -0.144 mg/L (95% CI -0.968 to 0.680), no significant effect. The umbrella review found inflammation markers improved in fatty liver but with trivial or low-certainty effects. Reviews of the whole plant (Ke 2023) list anti-inflammatory effects as lab and animal findings.

Results

Null in people; positive in the lab.

Effect sizes as reported

CRP WMD -0.144 mg/L (95% CI -0.968 to 0.680; p=0.731).

Why this rating

Human data are for isolated resveratrol; whole-plant findings are lab and animal.

Form and dose studied

Isolated resveratrol (the compound sold from knotweed), not knotweed root or whole extracts.

Who was studied

Adults in randomised trials.

Limits

A lab effect on inflammation is not evidence of a health benefit.

Why researchers looked

Reviews describe knotweed extracts and compounds as anti-inflammatory and antioxidant in cells and animals.

Traditional use

Hu zhang is traditionally used for skin inflammation, burns and scalds.

Proposed mechanism Laboratory research

Resveratrol, polydatin and emodin dampen inflammatory signals in cell and animal experiments.

A proposed mechanism does not show that the effect happens in people.

Emodin-type compounds can irritate the gut (see Safety).

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Memory, thinking and mood (resveratrol)

Low certainty

A review of 10 trials of isolated resveratrol found small gains on one memory test (delayed recognition) and slightly lower negative mood, but the literature is inconsistent and limited.

3 studiesIsolated resveratrol (the compound sold from knotweed), not knotweed …

Studies, doses and limits

What the trials found

Marx 2018 systematic review (10 randomised trials): 3 found improvement, 2 mixed, 5 no effect. Pooled results showed a small gain in delayed recognition (3 studies, 166 people) and a small fall in negative mood (3 studies, 163 people). A 2025 meta-analysis in postmenopausal women (10 trials, 928 women) found no significant effect on cognition, memory or mood.

Results

Inconsistent: small positive pooled results on two measures, null in other reviews.

Effect sizes as reported

Delayed recognition SMD 0.39 (95% CI 0.08 to 0.70); negative mood SMD -0.18 (95% CI -0.31 to -0.05).

Why this rating

Pooled results rest on three trials per outcome; authors call the literature inconsistent and limited.

Form and dose studied

Isolated resveratrol (the compound sold from knotweed), not knotweed root or whole extracts.

Who was studied

Healthy adults and clinical groups; postmenopausal women in the 2025 review.

Limits

MSK (summary only) also reports no cognitive benefit in recent trials; not re-read.

Why researchers looked

Resveratrol is studied for brain health because of lab findings on blood flow and nerve-cell protection.

Traditional use

No traditional use of hu zhang for memory was found in the sources read.

Proposed mechanism Animal research

Proposed effects on brain blood flow and antioxidant defences come from lab and animal work.

A proposed mechanism does not show that the effect happens in people.

No cognitive trial of knotweed root was found.

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Lyme disease and persistent symptoms

Not enough evidence

Knotweed extract slowed or killed the Lyme bacterium in laboratory dishes, which is why it appears in some Lyme supplement plans. No animal or human trial shows it treats Lyme disease.

3 studiesExtracts tested in dishes; not comparable to capsules or teas.

Studies, doses and limits

What the trials found

Feng 2020 (laboratory): of 15 natural products, knotweed extract was among the two most active against growing and stationary-phase B. burgdorferi in dishes, but in 21-day subculture it did not clear the bacteria (only Cryptolepis did). Thompson 2023 review of 18 Lyme-linked herbs: 7 had lab activity including knotweed; animal and clinical trial data are lacking. The IDSA/AAN/ACR 2020 guideline covers diagnosis and treatment of Lyme disease and is the clinical standard.

Results

Lab only. No evidence in animals or people.

Effect sizes as reported

Knotweed extract MIC for growing B. burgdorferi 0.25 to 0.5% in culture.

Why this rating

Laboratory dish findings only; no in-vivo or clinical data.

Form and dose studied

Extracts tested in dishes; not comparable to capsules or teas.

Who was studied

None in people.

Limits

A dish result does not show that a supplement reaches or kills the bacterium in the body.

Why researchers looked

Herbal practitioners use knotweed for symptoms that last after Lyme treatment; a lab study tested it against the bacterium.

Traditional use

Not a traditional Lyme herb. Use in Lyme care is a recent trend, not a Chinese or Japanese tradition.

Proposed mechanism Laboratory research

A knotweed extract was active against growing and non-growing forms of Borrelia burgdorferi in culture. The active compounds were not identified.

A proposed mechanism does not show that the effect happens in people.

Lyme disease needs medical care. Untreated or incompletely treated infection can involve nerves, heart and joints. Herbs can also interact with medicines (see Safety).

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Acute respiratory infections (in herbal mixtures)

Very low certainty

Chinese herbal mixtures that included knotweed helped symptoms of chest and throat infections in small trials, but knotweed was never tested alone and most patients also took antibiotics.

1 studiesHerbal formulas that include knotweed root.

Studies, doses and limits

What the trials found

Systematic review (8 randomised trials, 1,123 people with acute respiratory infections): mixtures containing knotweed raised the symptom-improvement rate (RR 1.14; 7 trials), shortened fever and improved a lung injury score without increasing adverse events (RR 0.33, 95% CI 0.11 to 1.00; p=0.05). All trials used knotweed as one ingredient of a mixture and in all but one trial antibiotics were also given.

Results

Small positive result for combinations; not attributable to knotweed.

Effect sizes as reported

Symptom improvement RR 1.14 (95% CI 1.09 to 1.20; I2 0%).

Why this rating

Knotweed cannot be separated from the other herbs and antibiotics; only one trial lacked antibiotics; authors call the evidence limited.

Form and dose studied

Herbal formulas that include knotweed root.

Who was studied

Adults and children with acute respiratory infections.

Limits

Funding and trial quality were not read beyond the abstract.

Why researchers looked

Knotweed is used in Chinese medicine to clear heat and relieve cough.

Traditional use

Hu zhang is traditionally used to clear heat and resolve phlegm, according to the review authors.

Proposed mechanism Pharmacological theory

Not established. The review notes resveratrol and glycosides as possible active parts.

A proposed mechanism does not show that the effect happens in people.

Chest infections with fever, breathlessness or in children and older people need medical assessment.

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Constipation and bowel movements

Not enough evidence

Knotweed root has long been used for constipation and contains laxative-type anthraquinones such as emodin. No trial of knotweed alone for constipation was found.

3 studiesDried root or decoction in traditional use.

Studies, doses and limits

What the trials found

Liu 2022 review lists constipation among the traditional uses of hu zhang; the Dong 2016 emodin review names Polygonum cuspidatum as an emodin-containing herb. The stimulant-laxative class is reviewed by Whorwell 2024 (senna and others, not knotweed). No clinical trial of knotweed alone for constipation was found in the sources read.

Results

No direct human evidence for the plant.

Effect sizes as reported

None.

Why this rating

No trial; class-level inference only.

Form and dose studied

Dried root or decoction in traditional use.

Who was studied

None studied.

Limits

The Whorwell review covers senna and other drugs, not knotweed.

Why researchers looked

Anthraquinones such as emodin are the compound class behind plant stimulant laxatives such as rhubarb root and senna.

Traditional use

Reviews list constipation among traditional uses of hu zhang.

Proposed mechanism Pharmacological theory

Anthraquinones act on the gut lining and gut movement; this is inferred from related plants and the compound class, not tested for knotweed here.

A proposed mechanism does not show that the effect happens in people.

A laxative effect can cause cramps, loose stools and loss of fluids and salts if overused (see Safety).

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Irritable bowel syndrome pain (polydatin combination)

Very low certainty

One 12-week trial of a supplement combining palmitoylethanolamide and polydatin found less belly pain than placebo in people with irritable bowel syndrome. It was a combination, so polydatin's own role is unknown.

1 studiesA branded palmitoylethanolamide 200 mg plus polydatin 20 mg combinati…

Studies, doses and limits

What the trials found

Cremon 2017 (randomised, double-blind, placebo-controlled pilot, 54 people with IBS plus 12 controls, 12 weeks): the combination did not change mast-cell count or the gut biology measured, but abdominal pain severity improved against placebo (p<0.05).

Results

Possible pain benefit from a combination product.

Effect sizes as reported

Pain severity improved (p<0.05; numbers not in the abstract).

Why this rating

Small pilot; combination product; funding not stated in the abstract; mechanism not supported.

Form and dose studied

A branded palmitoylethanolamide 200 mg plus polydatin 20 mg combination (the polydatin source was not stated).

Who was studied

Adults with irritable bowel syndrome.

Limits

Cannot be used to claim that knotweed helps IBS.

Why researchers looked

Polydatin, found in knotweed, is thought to quiet gut immune cells together with palmitoylethanolamide.

Traditional use

Not a traditional use.

Proposed mechanism Human data

The authors propose reduced mast-cell activation, but mast-cell counts did not change in the trial.

A proposed mechanism does not show that the effect happens in people.

Did not raise safety concerns in the abstract; not otherwise assessed.

⁴

Postmenopausal pain and bone breakdown (resveratrol)

Very low certainty

In women after menopause, pooled trials of isolated resveratrol found lower pain scores and a lower bone-breakdown marker, but no change in menopausal symptoms, mood, cognition or blood fats.

2 studiesIsolated resveratrol (the compound sold from knotweed), not knotweed …

Studies, doses and limits

What the trials found

Wu 2025 meta-analysis (10 randomised trials, 928 postmenopausal women): pain scores and a bone-breakdown marker (CTX) fell; no significant effect on cognition, mood, glucose, lipids, blood pressure, sleep, menopausal symptoms, quality of life or the other bone markers.

Results

Small benefit on pain and one bone marker; null on most other outcomes.

Effect sizes as reported

Pain VAS WMD -7.585 (95% CI -12.912 to -2.257); CTX WMD -0.137 (95% CI -0.204 to -0.070).

Why this rating

Small trials; only abstract read; isolated resveratrol.

Form and dose studied

Isolated resveratrol (the compound sold from knotweed), not knotweed root or whole extracts.

Who was studied

Postmenopausal women.

Limits

One bone marker is not a fracture outcome.

Why researchers looked

Resveratrol is studied for its oestrogen-like lab effects in postmenopausal women.

Traditional use

Not a traditional use.

Proposed mechanism Laboratory research

Oestrogen-receptor effects are shown in the lab for knotweed's emodin; resveratrol's receptor action was not read here.

A proposed mechanism does not show that the effect happens in people.

Because emodin from knotweed binds oestrogen receptors in the lab, women with hormone-sensitive conditions should ask a doctor first (see Safety).

^{21 15}

Liver health and fatty liver (resveratrol)

Very low certainty

Pooled trials of isolated resveratrol found no change in liver enzymes. Animal studies of emodin show both liver protection and liver harm depending on dose and time.

3 studiesIsolated resveratrol (people); isolated emodin (rodents).

Studies, doses and limits

What the trials found

Darand 2021 meta-analysis (15 trials, 714 people): ALT, AST, GGT, ALP and bilirubin did not change significantly. Hu 2025 meta-analysis of 28 rodent studies: emodin lowered liver enzymes in injured animals but higher doses and longer treatment raised AST in healthy animals. Umbrella review: some improvement in body weight and inflammation markers in fatty liver, but effects trivial or low certainty.

Results

Null in people (resveratrol); dose-dependent benefit and harm in animals (emodin).

Effect sizes as reported

Human ALT WMD 0 IU/L (95% CI -3.17 to 3.17); AST WMD -2.40 IU/L (95% CI -5.45 to 0.65). Rodent AST up at high dose SMD 2.19 (95% CI 0.91 to 3.47).

Why this rating

Human data are isolated resveratrol; animal data are isolated emodin; none is the whole root.

Form and dose studied

Isolated resveratrol (people); isolated emodin (rodents).

Who was studied

Adults in 15 trials; rats and mice.

Limits

Animal dose thresholds cannot be applied to people.

Why researchers looked

Knotweed constituents are studied for protecting the liver; emodin can also be toxic in animals.

Traditional use

Hu zhang is traditionally used for jaundice, according to the 2022 review abstract.

Proposed mechanism Animal research

In rodents, emodin lowers liver enzymes in injured liver through CYP2E1 and bile-acid pathways, but raises them at high dose or long duration in healthy animals.

A proposed mechanism does not show that the effect happens in people.

Liver cautions are covered in Safety. Report yellow skin or eyes or dark urine promptly.

^{5 9 22}

Anti-ageing and longevity claims

Not enough evidence

Marketing links resveratrol to ageing and long life. The 2011 expert review found the evidence not strong enough to recommend it to people beyond what food supplies.

1 studiesIsolated resveratrol (the compound sold from knotweed), not knotweed …

Studies, doses and limits

What the trials found

Vang 2011 systematic review of human and animal resveratrol literature: published evidence is not sufficient to justify recommending resveratrol to people beyond dietary amounts; animal data promising. Newer trials exist and are summarised in the more recent meta-analyses in this profile.

Results

No human evidence of longer life.

Effect sizes as reported

None.

Why this rating

No human outcome data on lifespan or ageing markers were found for knotweed.

Form and dose studied

Isolated resveratrol (the compound sold from knotweed), not knotweed root or whole extracts.

Who was studied

Not applicable.

Limits

Dated (2011).

Why researchers looked

Resveratrol drew attention from lab and animal ageing research.

Traditional use

Not a traditional use of hu zhang in the sources read.

Proposed mechanism Laboratory research

Lab work on cell pathways; not shown in people.

A proposed mechanism does not show that the effect happens in people.

None specific.

¹⁸

Traditional uses: burns, boils, jaundice and 'heat'

Not enough evidence

In Chinese medicine hu zhang is used to cool heat, move blood, treat jaundice, and (applied fresh) burns, scalds and boils. These are traditional uses; no human trials were found.

2 studiesDried root; fresh plant (topical) in tradition.

Studies, doses and limits

What the trials found

Liu 2022 and Ke 2023 reviews describe these traditional and clinic uses, and lab or animal anti-inflammatory, antioxidant and antimicrobial findings. No clinical trial of the plant on skin conditions was found in the sources read.

Results

Traditional use only.

Effect sizes as reported

None.

Why this rating

Tradition and lab data; no trials.

Form and dose studied

Dried root; fresh plant (topical) in tradition.

Who was studied

None studied.

Limits

Fresh plant on broken skin is untested; irritation is possible.

Why researchers looked

Long traditional use in China, Japan and Korea.

Traditional use

Reviews state it is used for favus (a fungal skin disease), jaundice, scald and constipation, and to invigorate blood, cool heat and resolve toxicity.

Proposed mechanism Laboratory research

Anti-inflammatory and antimicrobial lab effects have been reported for the plant's stilbenes, anthraquinones and flavonoids.

A proposed mechanism does not show that the effect happens in people.

Burns and infected wounds need medical care.

^{13 11}

Connections to the rest of health

How Japanese knotweed connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Evidence status	Context	Studies
Blood Sugar Balance	Very low certainty	Blood sugar and type 2 diabetes (resveratrol): Trials of isolated resveratrol, the compound sold from knotweed, show small and inconsistent effects on blood sugar. No trial of the root itself was found.	^{10 22}
Metabolic Health	Very low certainty	Blood sugar and type 2 diabetes (resveratrol): Trials of isolated resveratrol, the compound sold from knotweed, show small and inconsistent effects on blood sugar. No trial of the root itself was found.	^{10 22}
Blood Pressure Support	Low certainty	Blood pressure (resveratrol): Pooled trials of isolated resveratrol found no clear overall change in blood pressure. Some subgroups looked better, but that is weak evidence.	^{8 16}
Heart Health	Low certainty	Blood pressure (resveratrol): Pooled trials of isolated resveratrol found no clear overall change in blood pressure. Some subgroups looked better, but that is weak evidence. Cholesterol and blood fats (resveratrol): A meta-analysis of 10 trials found no benefit of isolated resveratrol on total or LDL cholesterol or triglycerides, and HDL ('good') cholesterol was slightly lower.	^{8 16 22}
Cholesterol Balance	Low certainty	Cholesterol and blood fats (resveratrol): A meta-analysis of 10 trials found no benefit of isolated resveratrol on total or LDL cholesterol or triglycerides, and HDL ('good') cholesterol was slightly lower.	^{16 22}
Inflammation Balance	Very low certainty	Inflammation marker (C-reactive protein): Isolated resveratrol did not change C-reactive protein, a blood marker of inflammation, in a meta-analysis of 10 trials. Knotweed's anti-inflammatory reputation rests mostly on lab and animal work.	^{16 22 11}
Cellular Protection	Very low certainty	Inflammation marker (C-reactive protein): Isolated resveratrol did not change C-reactive protein, a blood marker of inflammation, in a meta-analysis of 10 trials. Knotweed's anti-inflammatory reputation rests mostly on lab and animal work.	^{16 22 11}
Memory Support	Low certainty	Memory, thinking and mood (resveratrol): A review of 10 trials of isolated resveratrol found small gains on one memory test (delayed recognition) and slightly lower negative mood, but the literature is inconsistent and limited.	^{14 21 25}
Mood Balance	Low certainty	Memory, thinking and mood (resveratrol): A review of 10 trials of isolated resveratrol found small gains on one memory test (delayed recognition) and slightly lower negative mood, but the literature is inconsistent and limited.	^{14 21 25}
Brain Health	Low certainty	Memory, thinking and mood (resveratrol): A review of 10 trials of isolated resveratrol found small gains on one memory test (delayed recognition) and slightly lower negative mood, but the literature is inconsistent and limited.	^{14 21 25}
Immune Support	Not enough evidence	Lyme disease and persistent symptoms: Knotweed extract slowed or killed the Lyme bacterium in laboratory dishes, which is why it appears in some Lyme supplement plans. No animal or human trial shows it treats Lyme disease.	^{7 17 12}
Immune Support	Very low certainty	Acute respiratory infections (in herbal mixtures): Chinese herbal mixtures that included knotweed helped symptoms of chest and throat infections in small trials, but knotweed was never tested alone and most patients also took antibiotics.	¹⁹
Breathing Support	Very low certainty	Acute respiratory infections (in herbal mixtures): Chinese herbal mixtures that included knotweed helped symptoms of chest and throat infections in small trials, but knotweed was never tested alone and most patients also took antibiotics.	¹⁹
Digestive Support	Not enough evidence	Constipation and bowel movements: Knotweed root has long been used for constipation and contains laxative-type anthraquinones such as emodin. No trial of knotweed alone for constipation was found.	^{13 6 20}
Gut Health	Not enough evidence	Constipation and bowel movements: Knotweed root has long been used for constipation and contains laxative-type anthraquinones such as emodin. No trial of knotweed alone for constipation was found.	^{13 6 20}
Digestive Support	Very low certainty	Irritable bowel syndrome pain (polydatin combination): One 12-week trial of a supplement combining palmitoylethanolamide and polydatin found less belly pain than placebo in people with irritable bowel syndrome. It was a combination, so polydatin's own role is unknown.	⁴
Gut Health	Very low certainty	Irritable bowel syndrome pain (polydatin combination): One 12-week trial of a supplement combining palmitoylethanolamide and polydatin found less belly pain than placebo in people with irritable bowel syndrome. It was a combination, so polydatin's own role is unknown.	⁴
Womens Wellness	Very low certainty	Postmenopausal pain and bone breakdown (resveratrol): In women after menopause, pooled trials of isolated resveratrol found lower pain scores and a lower bone-breakdown marker, but no change in menopausal symptoms, mood, cognition or blood fats.	^{21 15}
Menopause Support	Very low certainty	Postmenopausal pain and bone breakdown (resveratrol): In women after menopause, pooled trials of isolated resveratrol found lower pain scores and a lower bone-breakdown marker, but no change in menopausal symptoms, mood, cognition or blood fats.	^{21 15}
Bone Health	Very low certainty	Postmenopausal pain and bone breakdown (resveratrol): In women after menopause, pooled trials of isolated resveratrol found lower pain scores and a lower bone-breakdown marker, but no change in menopausal symptoms, mood, cognition or blood fats.	^{21 15}
Liver Support	Very low certainty	Liver health and fatty liver (resveratrol): Pooled trials of isolated resveratrol found no change in liver enzymes. Animal studies of emodin show both liver protection and liver harm depending on dose and time.	^{5 9 22}
Healthy Aging	Not enough evidence	Anti-ageing and longevity claims: Marketing links resveratrol to ageing and long life. The 2011 expert review found the evidence not strong enough to recommend it to people beyond what food supplies.	¹⁸
Anti Aging Support	Not enough evidence	Anti-ageing and longevity claims: Marketing links resveratrol to ageing and long life. The 2011 expert review found the evidence not strong enough to recommend it to people beyond what food supplies.	¹⁸
Longevity	Not enough evidence	Anti-ageing and longevity claims: Marketing links resveratrol to ageing and long life. The 2011 expert review found the evidence not strong enough to recommend it to people beyond what food supplies.	¹⁸
Healthy Skin	Not enough evidence	Traditional uses: burns, boils, jaundice and 'heat': In Chinese medicine hu zhang is used to cool heat, move blood, treat jaundice, and (applied fresh) burns, scalds and boils. These are traditional uses; no human trials were found.	^{13 11}
Inflammation Balance	Not enough evidence	Traditional uses: burns, boils, jaundice and 'heat': In Chinese medicine hu zhang is used to cool heat, move blood, treat jaundice, and (applied fresh) burns, scalds and boils. These are traditional uses; no human trials were found.	^{13 11}

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Metabolism Weight	Biological association	Very low certainty	Studied for: Blood sugar and type 2 diabetes (resveratrol) Studied for: Cholesterol and blood fats (resveratrol)	^{10 22 16 5 9}
Blood Sugar Support	Biological association	Very low certainty	Studied for: Blood sugar and type 2 diabetes (resveratrol)	^{10 22}
Cardiovascular System	Biological association	Low certainty	Studied for: Blood pressure (resveratrol) Studied for: Cholesterol and blood fats (resveratrol)	^{8 16 22 11}
Immune System	Biological association	Very low certainty	Studied for: Inflammation marker (C-reactive protein) Studied for: Lyme disease and persistent symptoms	^{16 22 11 7 17 12 19}
Nervous System	Biological association	Low certainty	Studied for: Memory, thinking and mood (resveratrol)	^{14 21 25}
Respiratory Health	Biological association	Very low certainty	Studied for: Acute respiratory infections (in herbal mixtures)	¹⁹
Digestive System	Biological association	Not enough evidence	Studied for: Constipation and bowel movements Studied for: Irritable bowel syndrome pain (polydatin combination)	^{13 6 20 4}
Bones Joints Muscles	Biological association	Very low certainty	Studied for: Postmenopausal pain and bone breakdown (resveratrol)	^{21 15}
Hormone Health	Biological association	Very low certainty	Studied for: Postmenopausal pain and bone breakdown (resveratrol)	^{21 15}
Liver Detox	Biological association	Very low certainty	Studied for: Liver health and fatty liver (resveratrol)	^{5 9 22}
Whole Body Balance	Biological association	Not enough evidence	Studied for: Anti-ageing and longevity claims	¹⁸
Skin Hair Beauty	Biological association	Not enough evidence	Studied for: Traditional uses: burns, boils, jaundice and 'heat'	^{13 11}
Integumentary System	Biological association	Not enough evidence	Studied for: Traditional uses: burns, boils, jaundice and 'heat'	^{13 11}

C. Body parts and organs

Connected to	Kind of connection	Evidence status	Context	Studies
Liver	Adverse effect or risk	Animal	Liver enzymes rose in healthy rodents at higher dose and longer duration; human data lacking. Emodin raised liver enzymes in healthy rodents at higher dose and longer duration; no human data. Preparation or compound: Emodin (rodents)	^{9 6}
Digestive system	Adverse effect or risk	Low certainty	Laxative-type effects expected from the compound class; not tested for knotweed. Preparation or compound: Root (anthraquinone content)	^{6 13}
Reproductive system	Adverse effect or risk	In vitro	Oestrogen-receptor binding in cells; reproductive toxicity in animals at high dose. Preparation or compound: Emodin	^{15 6}

D. Symptoms

Connected to	Kind of connection	Evidence status	Context	Studies
Constipation	Traditional use	Not enough evidence	Traditional use; laxative-type compounds present; no trial of knotweed alone. Preparation or compound: Root	^{13 6}

E. Health conditions

Connected to	Kind of connection	Evidence status	Context	Studies
Lyme disease		Not enough evidence	Lab activity in dishes only; guideline care is the standard. Preparation or compound: Knotweed extract (lab)	^{7 12}
Lyme disease	Biological association	Not enough evidence	Activity against the Lyme bacterium in laboratory dishes only; no animal or human data. Preparation or compound: Root extract (lab)	^{7 17}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
HbA1c (3-month blood sugar average)	Biological association	Very low certainty	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{10 22}
Fasting blood glucose	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	^{10 16}
Insulin resistance index	Biological association	Very low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	¹⁰
Systolic blood pressure	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	^{8 16}
LDL and HDL cholesterol	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	¹⁶
C-reactive protein (CRP)	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	¹⁶
Delayed recognition (memory test)	Biological association	Low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	¹⁴
Negative mood score	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	¹⁴
Lyme bacterium in culture (lab dish)	Biological association	Not enough evidence	Measured in trials: lowered. A lab change is not the same as a health benefit.	⁷
Liver enzymes (ALT and AST)	Biological association	Low certainty	Measured in trials: no-change. A lab change is not the same as a health benefit.	^{5 9}
Symptom improvement rate (respiratory infection)	Biological association	Very low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	¹⁹
Pain score (visual analogue scale)	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	²¹
CTX (bone-breakdown marker)	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	²¹
Abdominal pain severity (IBS)	Biological association	Very low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	⁴

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
CYP3A4, CYP2D6, CYP2C9 (inhibited) and CYP1A2 (induced)	Preliminary mechanism	Human	Drug-metabolising enzymes altered by isolated resveratrol in healthy volunteers.	^{3 2}
ESR1 and ESR2 (oestrogen receptors alpha and beta)	Preliminary mechanism	In vitro	Emodin competes with estradiol for binding in the lab.	¹⁵
CYP2E1 and FXR/BSEP (liver pathways)	Preliminary mechanism	Animal	Emodin's reported liver pathways in rodents.	⁹

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
trans-Resveratrol	Biological association	Human	Studied in most human trials of 'resveratrol'; poorly absorbed with low blood levels and short half-life; modulates drug-metabolising enzymes in people. Preparation or compound: Root	^{1 3 26}
Polydatin (piceid)	Biological association	Human	Little human research on its own; one trial used a polydatin plus palmitoylethanolamide combination for IBS pain. Preparation or compound: Root	^{4 26}
Emodin	Biological association	Animal	Laxative-type class; binds human oestrogen receptors in the lab; liver, kidney and reproductive toxicity in animals at high dose and long duration. Preparation or compound: Root	^{6 15 9 26}
Emodin 8-O-beta-D-glucoside	Biological association	In vitro	Isolated from the root with emodin as an oestrogenic principle in cells. Preparation or compound: Root	¹⁵
Flavonoids and other anthraquinones	Biological association	Review	Named with stilbenes and anthraquinones as the main active groups; individual compounds not covered here. Preparation or compound: Root	^{13 11}

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).

Evidence at a glance: what changed in 14 lab markers

Tap a number to show only those markers. Counts are markers, not people.

Metabolic11 Other525

The evidence

The research centre for Japanese knotweed. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Blood sugar and type 2 diabetes (resveratrol) 2 studies Very low certainty Blood pressure (resveratrol) 2 studies Low certainty Cholesterol and blood fats (resveratrol) 2 studies Low certainty Inflammation marker (C-reactive protein) 3 studies Very low certainty Memory, thinking and mood (resveratrol) 3 studies Low certainty Lyme disease and persistent symptoms 3 studies Not enough evidence Acute respiratory infections (in herbal mixtures) 1 studies Very low certainty Constipation and bowel movements 3 studies Not enough evidence Irritable bowel syndrome pain (polydatin combination) 1 studies Very low certainty Postmenopausal pain and bone breakdown (resveratrol) 2 studies Very low certainty Liver health and fatty liver (resveratrol) 3 studies Very low certainty Anti-ageing and longevity claims 1 studies Not enough evidence Traditional uses: burns, boils, jaundice and 'heat' 2 studies Not enough evidence

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from an existing summary of this herb and searched PubMed for the main uses and safety topics. We checked identity records (GBIF, PubChem) and looked for NIH NCCIH, EMA, LiverTox and LactMed pages on knotweed, which could not be opened or found. We recorded each study's design, people, product and result as reported. Only abstracts were read. Certainty ratings are the compiler's own reading, not formal grades. No study is cited that we could not verify.

Study library: every study we checked 27

Design Research type Plant part Year from Search

Study	Design	People	Product, dose, length	Result
Almeida 2009 Pharmacokinetic and safety profile of trans-resveratrol in a rising multiple-dose study in healthy volunteers. Molecular nutrition & food research · PMID 19194969 · DOI	Controlled trial	40 healthy adults (4 groups of 10) Healthy adults, 5 men and 5 women per group.	trans-Resveratrol (isolated) n/a (isolated compound) 25, 50, 100 or 150 mg six times a day for 13 doses (as tested) 13 doses · vs Placebo	Peak blood levels were reached 0.8 to 1.5 hours after a dose and were low despite the high doses. Half-life 2 to 5 hours with repeated dosing. Adverse events were mild and similar across groups. Cmax 3.89, 7.39, 23.1 and 63.8 ng/mL at the four dose levels. Methods, limits and funding Outcomes: Blood levels of trans-resveratrol and adverse events Limitations: Small, short, healthy volunteers. Isolated trans-resveratrol, not knotweed root. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
Bedada 2015 Effect of resveratrol on the pharmacokinetics of carbamazepine in healthy human volunteers. Phytotherapy research : PTR · PMID 25624269 · DOI	Clinical trial	12 healthy volunteers Healthy adult volunteers.	Resveratrol (isolated) with carbamazepine n/a (isolated compound) 500 mg once daily for 10 days, then one 200 mg carbamazepine dose (as tested) 10 days · vs Own control phase (open-label, sequential)	After resveratrol, carbamazepine peak level and exposure rose and clearance fell, consistent with CYP3A4 inhibition. Cmax, AUC and half-life significantly higher; clearance lower (values not in the abstract). Methods, limits and funding Outcomes: Carbamazepine blood levels and half-life Limitations: Small, open-label, sequential, single carbamazepine dose; healthy people. Not tested with knotweed root. Funding and conflicts: Not stated in the abstract. Read: abstract
Chow 2010 Resveratrol modulates drug- and carcinogen-metabolizing enzymes in a healthy volunteer study. Cancer prevention research (Philadelphia, Pa.) · PMID 20716633 · DOI	Clinical trial	42 healthy volunteers Healthy adult volunteers.	Resveratrol (isolated) n/a (isolated compound) 1 g once daily (as tested) 4 weeks · vs Own baseline (before and after)	Resveratrol inhibited CYP3A4, CYP2D6 and CYP2C9 and induced CYP1A2. The authors warn that pharmacological doses could increase adverse drug reactions or change drug effect. Qualitative inhibition/induction of enzyme activity indices (numbers not in the abstract). Methods, limits and funding Outcomes: Activity of drug-metabolising enzymes CYP1A2, CYP2D6, CYP2C9, CYP3A4 and phase II enzymes Limitations: Before/after design with no placebo group. Pharmacological dose of isolated resveratrol; the amount delivered by a knotweed supplement is not known. Funding and conflicts: Research support from the US National Institutes of Health (extramural), per PubMed record. Read: abstract
Cremon 2017 Randomised clinical trial: the analgesic properties of dietary supplementation with palmitoylethanolamide and polydatin in irritable bowel syndrome. Alimentary pharmacology & therapeutics · PMID 28164346 · DOI	Controlled trial	54 IBS patients and 12 healthy controls Adults with irritable bowel syndrome.	Palmitoylethanolamide 200 mg + polydatin 20 mg combination supplement (branded combination, twice daily) n/a (isolated compounds) 200 mg PEA/20 mg polydatin twice daily 12 weeks · vs Placebo	The supplement did not change the biological profile, including mast cell count, but abdominal pain was better than placebo (p<0.05). Abdominal pain severity improved vs placebo (p<0.05; numbers not in the abstract). Methods, limits and funding Outcomes: Mast cell count, gut biology, abdominal pain Limitations: A combination product: any effect cannot be assigned to polydatin alone. Small pilot trial. Funding is not stated in the abstract; check the full text for sponsor. Funding and conflicts: Not stated in the abstract. Read: abstract
Darand 2021 Effects of resveratrol supplementation on liver enzymes: A systematic review and meta-analysis of randomised controlled trials. International journal of clinical practice · PMID 32869460 · DOI	Meta-analysis	15 RCTs, 714 participants Adults in randomised trials of resveratrol.	Resveratrol supplements (isolated) n/a (isolated compound) Varied Varied · vs Placebo/control	No significant change in any liver enzyme; results varied by dose, study length and population. ALT WMD 0 IU/L (95% CI -3.17 to 3.17); AST WMD -2.40 IU/L (95% CI -5.45 to 0.65). (-3.17 to 3.17) Methods, limits and funding Outcomes: ALT, AST, GGT, ALP, bilirubin Limitations: High inconsistency (I2 74% to 83% for ALT and AST). Isolated resveratrol, not root or emodin. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
Dong 2016 Emodin: A Review of its Pharmacology, Toxicity and Pharmacokinetics. Phytotherapy research : PTR · PMID 27188216 · DOI	Narrative review review (mainly animal and lab)	Review of laboratory, animal and a few human reports on emodin.	Emodin (anthraquinone found in Rheum palmatum, Polygonum cuspidatum and Polygonum multiflorum) root (source herbs) Not applicable (review) Not applicable · vs None	Emodin has anticancer, liver-protective, anti-inflammatory, antioxidant and antimicrobial effects in the lab, but can also cause liver, kidney and reproductive toxicity, particularly at high doses and with long-term use. Oral bioavailability in rats is poor because of extensive glucuronidation. No effect sizes. Methods, limits and funding Outcomes: Pharmacology, toxicity, pharmacokinetics of emodin Limitations: About an isolated compound, mostly animal and cell data; not the same as eating or taking the whole root. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
Feng 2020 Evaluation of Natural and Botanical Medicines for Activity Against Growing and Non-growing Forms of B. burgdorferi. Frontiers in medicine · PMID 32154254 · DOI	Laboratory research bacteria in the lab	Borrelia burgdorferi grown in the laboratory (growing and stationary-phase forms).	Extract of Polygonum cuspidatum (Japanese knotweed) among 15 natural products root (extract, source not detailed in the abstract) 1% extract in culture Culture and 21-day subculture · vs Doxycycline and cefuroxime; untreated controls	Knotweed extract was among the two most active products and active against both growing and stationary-phase bacteria in dishes (MIC 0.25 to 0.5% for growing forms). In subculture only Cryptolepis extract wiped out the bacteria; knotweed did not. MIC for growing B. burgdorferi 0.25 to 0.5% (knotweed extract). Methods, limits and funding Outcomes: Killing of growing and stationary-phase Borrelia in dishes Limitations: Laboratory dish study. No animal or human data. Does not show a person can clear Lyme with knotweed. Funding and conflicts: Not stated in the abstract. Read: abstract
Fogacci 2019 Effect of resveratrol on blood pressure: A systematic review and meta-analysis of randomized, controlled, clinical trials. Critical reviews in food science and nutrition · PMID 29359958 · DOI	Meta-analysis	17 trials Adults in randomised trials of resveratrol and blood pressure.	Resveratrol supplements (isolated) n/a (isolated compound) Varied; subgroup at 300 mg/day or more Not stated in the abstract · vs Placebo/control	No significant change overall; significant changes only in subsets (higher daily dose and people with diabetes). Fairly well tolerated; no serious adverse events in most trials. Systolic BP WMD -2.5 mmHg (95% CI -5.5 to 0.6; p=0.116; I2 62%); diastolic -0.5 mmHg (95% CI -2.2 to 1.3). (-5.5 to 0.6) Methods, limits and funding Outcomes: Systolic, diastolic and mean blood pressure Limitations: Moderate to high inconsistency between trials. Positive findings come from subgroups. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
Hu 2025 The efficacy and toxicity equilibrium of emodin for liver injury: A bidirectional meta-analysis and machine learning. Phytomedicine : international journal of phytotherapy and phytopharmacology · PMID 40339537 · DOI	Meta-analysis rodent	28 rodent studies, 537 animals Rats and mice with and without liver injury.	Emodin (isolated compound) n/a (compound) Machine-learning estimate of a threshold in rodents (not applicable to people) Rodent study durations · vs Control animals	At controlled doses and durations emodin lowered liver enzymes in injured animals; higher doses and longer durations raised AST in healthy animals. AST up in healthy animals at high dose/long duration (SMD 2.19, 95% CI 0.91 to 3.47). Protective effect in injured animals (AST SMD -3.29). Methods, limits and funding Outcomes: Blood liver enzymes (AST, ALT, ALP) in rodents Limitations: Animal studies only; the dose threshold the authors report cannot be applied to people. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
Jeyaraman 2020 Resveratrol for adults with type 2 diabetes mellitus. The Cochrane database of systematic reviews · PMID 31978258 · DOI	Systematic review	3 RCTs, 50 participants Adults with type 2 diabetes.	Oral resveratrol (isolated, not combined with other plant polyphenols) n/a (isolated compound) 10, 150 or 1000 mg daily (as tested in the trials) 4 to 5 weeks · vs Placebo	Neutral effects on HbA1c, fasting glucose and insulin resistance; no adverse events observed; very low-certainty evidence. Authors: research insufficient to judge benefit or harm. HbA1c MD 0.1% (95% CI -0.02 to 0.2); fasting glucose MD 2 mg/dL (95% CI -2 to 7); HOMA-style insulin resistance MD -0.35 (95% CI -0.99 to 0.28). Methods, limits and funding Outcomes: HbA1c, fasting glucose, insulin resistance, adverse events Limitations: Only three small, short trials. About isolated resveratrol, not knotweed root. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
Ke 2023 Advances for pharmacological activities of Polygonum cuspidatum - A review. Pharmaceutical biology · PMID 36620922 · DOI	Narrative review review	Review of laboratory, animal and clinical reports on Polygonum cuspidatum.	Polygonum cuspidatum root and extracts (hu zhang) root/rhizome (aerial parts also discussed) Not applicable (review) Not applicable · vs None	Rhizomes, leaves and flowers have different constituents; flavonoids, anthraquinones and stilbenes. Anti-inflammatory, antioxidant, anticancer and heart-protective effects reported (mostly lab and animal). Clinic uses listed include dizziness, headaches, traumatic injuries and burns. Root is in the Chinese Pharmacopoeia as Huzhang. Pharmacokinetics need more study. No effect sizes (narrative review). Methods, limits and funding Outcomes: Constituents, pharmacology, clinical applications, pharmacokinetics Limitations: Only the abstract was read. Most pharmacology is lab or animal work. Funding and conflicts: Not stated in the abstract. Read: abstract
Lantos 2021 Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA), American Academy of Neurology (AAN), and American College of Rheumatology (ACR): 2020 Guidelines for the Prevention, Diagnosis and Treatment of Lyme Disease. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · PMID 33483734 · DOI	Guideline n/a (guideline)	Lyme disease guidance for clinicians (North America).	Not applicable (guideline) n/a Not applicable Not applicable · vs None	Sets out evidence-based care for Lyme disease including early skin rash, nervous system, heart and joint forms. The abstract does not mention herbal products. No effect sizes. Methods, limits and funding Outcomes: Prevention, diagnosis and treatment of Lyme disease Limitations: Only the abstract was read, so what the guideline says about specific treatments is not reproduced here. Funding and conflicts: Not stated in the abstract. Read: abstract
Liu 2022 The Invasive Species Reynoutria japonica Houtt. as a Promising Natural Agent for Cardiovascular and Digestive System Illness. Frontiers in pharmacology · PMID 35770098 · DOI	Narrative review review	Review of laboratory, animal and some clinical literature on hu zhang (Reynoutria japonica).	Dried root and stem (Polygoni Cuspidati Rhizoma et Radix, hu zhang) root/rhizome and stem Not applicable (review) Not applicable · vs None	About 110 compounds identified; anthraquinones, stilbenes and flavonoids named as the main active groups. Traditional uses include jaundice, scald and constipation. Described as invasive in the United States and many European countries. The authors state it has no obvious toxicity. No effect sizes (narrative review). Methods, limits and funding Outcomes: Traditional uses, main compound groups, pharmacology, toxicity statement Limitations: Only the abstract was read here. The "no obvious toxicity" statement sits against animal findings for emodin (p27188216) and is not backed by a human safety study. Listed as a systematic review in PubMed but described by the authors as a general review. Funding and conflicts: Not stated in the abstract. Read: abstract
Marx 2018 Effect of resveratrol supplementation on cognitive performance and mood in adults: a systematic literature review and meta-analysis of randomized controlled trials. Nutrition reviews · PMID 29596658 · DOI	Meta-analysis	10 studies (meta-analysis of 3 per outcome) Healthy adults and clinical groups.	Resveratrol supplements (isolated) n/a (isolated compound) Varied Varied · vs Placebo	3 studies improved some cognitive measures, 2 were mixed and 5 found no effect. Pooled: small gain on delayed recognition and a small fall in negative mood. Delayed recognition SMD 0.39 (95% CI 0.08 to 0.70; 3 studies, 166 people); negative mood SMD -0.18 (95% CI -0.31 to -0.05; 3 studies, 163 people). (0.08 to 0.70) Methods, limits and funding Outcomes: Processing speed, number facility, memory, mood Limitations: Authors call the literature inconsistent and limited. Pooled findings rest on three studies each. Isolated resveratrol. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
Matsuda 2001 Phytoestrogens from the roots of Polygonum cuspidatum (Polygonaceae): structure-requirement of hydroxyanthraquinones for estrogenic activity. Bioorganic & medicinal chemistry letters · PMID 11459643 · DOI	Laboratory research cell/in-vitro	Cell lines (MCF-7 breast cancer cells) and receptor-binding assays.	Methanol extract of Polygonum cuspidatum root; emodin and emodin 8-O-glucoside isolated from it root 30 or 100 microg/mL extract in cells Not applicable · vs Untreated cells	The root extract made oestrogen-sensitive MCF-7 cells multiply faster. Emodin and emodin glucoside were the active compounds; emodin blocked 17-beta-estradiol binding to human oestrogen receptors alpha and beta. Emodin Ki 0.77 microM (ER-alpha) and 1.5 microM (ER-beta). Methods, limits and funding Outcomes: Cell growth and binding to human estrogen receptors Limitations: Test-tube work only; no human or animal data in the abstract. Does not show that a person taking knotweed would have an oestrogen-like effect. Funding and conflicts: Not stated in the abstract. Read: abstract
Sahebkar 2015 Lack of efficacy of resveratrol on C-reactive protein and selected cardiovascular risk factors--Results from a systematic review and meta-analysis of randomized controlled trials. International journal of cardiology · PMID 25885871 · DOI	Meta-analysis	10 RCTs (11 arms) Adults in randomised trials of resveratrol.	Resveratrol supplements (isolated) n/a (isolated compound) Varied Not stated in the abstract · vs Placebo/control	No benefit on CRP, total or LDL cholesterol, triglycerides, glucose or blood pressure; HDL cholesterol was slightly lower. CRP WMD -0.144 mg/L (95% CI -0.968 to 0.680); HDL WMD -4.18 mg/dL (95% CI -6.54 to -1.82). (-0.968 to 0.680) Methods, limits and funding Outcomes: C-reactive protein, cholesterol, triglycerides, glucose, blood pressure Limitations: Older search (to August 2014); small trials. About isolated resveratrol. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
Thompson 2023 A Comprehensive Review of Herbal Supplements Used for Persistent Symptoms Attributed to Lyme Disease. Integrative medicine (Encinitas, Calif.) · PMID 37101730	Narrative review review	Review of evidence for 18 herbs used for persistent symptoms attributed to Lyme disease.	18 herbal supplements, including Japanese knotweed (Polygonum cuspidatum) mixed Not applicable Not applicable · vs None	Seven of 18 herbs, including Japanese knotweed, had some lab activity against B. burgdorferi. Clinical trial and in-vivo data are lacking. Many compounds have drug interactions and additive effects that could raise the risk of bleeding, low blood pressure and low blood sugar. No effect sizes. Methods, limits and funding Outcomes: Antimicrobial activity, safety, drug interactions Limitations: Narrative review; only the abstract was read. Does not isolate knotweed. Funding and conflicts: Not stated in the abstract. Read: abstract
Vang 2011 What is new for an old molecule? Systematic review and recommendations on the use of resveratrol. PloS one · PMID 21698226 · DOI	Systematic review review (human and animal)	Review of human and animal resveratrol literature (2010 expert conference).	Resveratrol (isolated) n/a (isolated compound) Not applicable Not applicable · vs None	Published evidence not strong enough to justify recommending resveratrol to people beyond what diet provides; animal data promising and call for human trials. No effect sizes. Methods, limits and funding Outcomes: Whether resveratrol can be recommended; side effects; dose; mechanisms Limitations: Published 2011; newer trials exist (see the more recent meta-analyses). Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
Wang 2022 Reynoutria japonica Houtt for Acute Respiratory Tract Infections in Adults and Children: A Systematic Review. Frontiers in pharmacology · PMID 35281919 · DOI	Systematic review	8 RCTs, 1,123 participants Adults and children with acute respiratory tract infections (mostly in China).	Reynoutria japonica (Fallopia japonica) as part of herbal mixtures (formulas) root (as part of formulas) Not stated in the abstract Not stated in the abstract · vs Usual care; in most trials antibiotics were also given in the herbal group	Herbal mixtures including knotweed raised the symptom improvement rate and shortened fever; adverse events were not increased. Only one trial used knotweed in a mixture without antibiotics. Symptom improvement RR 1.14 (95% CI 1.09 to 1.20; 7 trials, 1,013 people; I2 0%). Adverse events RR 0.33 (95% CI 0.11 to 1.00; p=0.05; 5 trials, 676 people). (1.09 to 1.20) Methods, limits and funding Outcomes: Symptom improvement rate, fever clearance time, Murray lung injury score, adverse effects Limitations: All trials used knotweed inside a mixture, so its own effect cannot be separated. Mostly combined with antibiotics. Only the abstract was read; funding not stated. Funding and conflicts: Not stated in the abstract. Read: abstract
Whorwell 2024 Review article: do stimulant laxatives damage the gut? A critical analysis of current knowledge. Therapeutic advances in gastroenterology · PMID 38887508 · DOI	Narrative review review	Review of 43 publications on stimulant laxatives.	Stimulant laxatives bisacodyl, sodium picosulfate and senna (not knotweed) n/a Not applicable Not applicable · vs None	At very high doses changes to surface gut cells were reversible and not considered clinically relevant; no convincing link with colon cancer found. Many harm studies did not account for confounders. No effect sizes. Methods, limits and funding Outcomes: Gut structure changes, nerve and muscle effects, colon cancer risk Limitations: Reviewed senna and other stimulant laxatives, not knotweed. Useful only to show what is known about the laxative class. Funding and conflicts: Not stated in the abstract. Read: abstract
Wu 2025 Effects of resveratrol on postmenopausal women: a systematic review and meta-analysis. Frontiers in pharmacology · PMID 40771919 · DOI	Meta-analysis	10 RCTs, 928 participants Postmenopausal women.	Resveratrol supplements (isolated) n/a (isolated compound) Varied Varied · vs Placebo/control	Lower pain scores and a lower bone-breakdown marker (CTX); no significant effect on cognition, mood, glucose, lipids, blood pressure, sleep, menopausal symptoms or quality of life. Pain VAS WMD -7.585 (95% CI -12.912 to -2.257); CTX WMD -0.137 (95% CI -0.204 to -0.070). (-12.912 to -2.257) Methods, limits and funding Outcomes: Pain scores, bone markers, cognition, mood, metabolism, menopausal symptoms Limitations: Small trials; isolated resveratrol. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
Zeraattalab-Motlagh 2021 The effects of resveratrol supplementation in patients with type 2 diabetes, metabolic syndrome, and nonalcoholic fatty liver disease: an umbrella review of meta-analyses of randomized controlled trials. The American journal of clinical nutrition · PMID 34320173 · DOI	Umbrella review	11 + 17 + 10 meta-analyses (about 1,476 / 727 / 271 people) Adults with type 2 diabetes, metabolic syndrome or fatty liver disease.	Resveratrol supplements (isolated) n/a (isolated compound) Varied across trials Mostly short term · vs Placebo/control	Most effects were trivial in size or rated very low to low certainty; HbA1c fell in the short term with moderate GRADE. The authors conclude current evidence does not support resveratrol for cardiometabolic risk factors. HbA1c MD -1.05% (95% CI -2.09 to -0.02; 6 trials; GRADE moderate), under 12 weeks. (-2.09 to -0.02) Methods, limits and funding Outcomes: Blood pressure, lipids, glucose, insulin resistance, waist, weight, inflammation markers Limitations: Umbrella review of meta-analyses; its HbA1c finding contrasts with the Cochrane review (p31978258) which found no HbA1c change in 3 trials. About isolated resveratrol. Only the abstract was read. Funding and conflicts: Not stated in the abstract. Read: abstract
s-eu-invasive-reynoutria Neobiota.lu note on EU invasive alien species list and Reynoutria japonica (Regulation 2025/1422 mentioned) · Source	Secondary web page n/a			Methods, limits and funding Read: summary-only
s-gbif-reynoutria-japonica GBIF Backbone: Reynoutria japonica Houtt. (usageKey 2889173) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-msk-resveratrol Memorial Sloan Kettering Cancer Center: Resveratrol (patient education herb page) · Source	Patient education page n/a			Methods, limits and funding Read: summary-only
s-pubchem-knotweed-compounds PubChem compound records: resveratrol (CID 445154), polydatin (CID 5281718), emodin (CID 3220) · Source	Reference database n/a			Methods, limits and funding Read: full-text
s-regulators-japanese-knotweed-not-found Regulator lookups for Japanese knotweed (EMA/HMPC, NCCIH, LiverTox, LactMed): not found or not readable · Source	Regulatory search n/a			Methods, limits and funding Read: summary-only

What we do not know yet

No trial of Japanese knotweed root or a standardised extract on blood sugar, blood pressure, cholesterol, memory or Lyme disease was found.
Almost all human data are for pure resveratrol, whose amount in knotweed products varies and is not known from the sources read.
No animal or human study shows knotweed treats Lyme disease.
No human safety study of the root was found.
No pharmacokinetic study of knotweed root in people was found.
No regulator statement (EMA/HMPC, NCCIH, LiverTox, LactMed) on knotweed was read.
Pregnancy, breastfeeding and children: no safety data.
Contamination and wild-harvest studies: none found.
Only abstracts were read.

How new research is added

New studies are found by a saved PubMed search and are placed in a review queue. A person reads each one before it changes any evidence rating, safety wording or dose information. New publications never change ratings automatically.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Metabolic 2

↕

HbA1c (3-month blood sugar average)

Mixed results in trials

A blood test that shows average blood sugar over about three months.

Very low certainty

Results and what it means

Why it was measured

Used to follow long-term blood sugar control in diabetes.

Statistical vs. clinical meaning

The two reviews disagree; very wide interval in the umbrella review.

Safety implication

Can add to the effect of diabetes medicines.

Study	Result	People	Product
¹⁰	No change (MD 0.1%, 95% CI -0.02 to 0.2; 2 trials, 31 people).	Adults with type 2 diabetes	Isolated resveratrol, 4 to 5 weeks
²²	Short-term fall (MD -1.05%, 95% CI -2.09 to -0.02; 6 trials; moderate GRADE).	Adults with type 2 diabetes	Isolated resveratrol, under 12 weeks

^{10 22}

●

Fasting blood glucose

No clear change in trials

Blood sugar after an overnight fast.

Low certainty

Results and what it means

Why it was measured

A basic marker of blood sugar control.

Statistical vs. clinical meaning

Consistent null results across two reviews.

Safety implication

Not applicable.

Study	Result	People	Product
¹⁰	MD 2 mg/dL (95% CI -2 to 7); neutral.	Adults with type 2 diabetes	Isolated resveratrol
¹⁶	WMD 1.28 mg/dL (95% CI -5.28 to 7.84); no effect.	Adults in 10 trials	Isolated resveratrol

^{10 16}

Other 12

●

Insulin resistance index

No clear change in trials

A calculated score of how hard the body works to control sugar.

Very low certainty

Results and what it means

Why it was measured

Early warning sign for diabetes.

Statistical vs. clinical meaning

Two small trials, 36 people.

Safety implication

None specific.

Study	Result	People	Product
¹⁰	MD -0.35 (95% CI -0.99 to 0.28); neutral.	Adults with type 2 diabetes	Isolated resveratrol

¹⁰

●

Systolic blood pressure

No clear change in trials

The top number of a blood pressure reading.

Low certainty

Results and what it means

Why it was measured

High pressure raises heart and stroke risk.

Statistical vs. clinical meaning

Null in both; subgroup positives only.

Safety implication

Do not change blood pressure medicines.

Study	Result	People	Product
⁸	WMD -2.5 mmHg (95% CI -5.5 to 0.6); not significant.	Adults in 17 trials	Isolated resveratrol
¹⁶	WMD 0.82 mmHg (95% CI -8.86 to 10.50); not significant.	Adults in 10 trials	Isolated resveratrol

^{8 16}

●

LDL and HDL cholesterol

No clear change in trials

LDL is often called 'bad' and HDL 'good' cholesterol.

Low certainty

Results and what it means

Why it was measured

Part of heart-disease risk.

Statistical vs. clinical meaning

One older meta-analysis.

Safety implication

A small HDL fall is the opposite of what was hoped.

Study	Result	People	Product
¹⁶	LDL WMD -0.31 mg/dL (no effect); HDL WMD -4.18 mg/dL (95% CI -6.54 to -1.82), a small fall.	Adults in 10 trials	Isolated resveratrol

¹⁶

●

C-reactive protein (CRP)

No clear change in trials

A blood marker that rises with inflammation.

Low certainty

Results and what it means

Why it was measured

Used as a general inflammation signal.

Statistical vs. clinical meaning

Single meta-analysis of small trials.

Safety implication

None.

Study	Result	People	Product
¹⁶	WMD -0.144 mg/L (95% CI -0.968 to 0.680); no effect.	Adults in 10 trials	Isolated resveratrol

¹⁶

▲

Delayed recognition (memory test)

Raised in trials

A test of whether you recognise items shown earlier.

Low certainty

Results and what it means

Why it was measured

A simple measure of memory.

Statistical vs. clinical meaning

Three studies; authors call results inconsistent.

Safety implication

A test score is not everyday memory.

Study	Result	People	Product
¹⁴	SMD 0.39 (95% CI 0.08 to 0.70); 3 studies, 166 people.	Healthy adults and clinical groups	Isolated resveratrol

¹⁴

▼

Negative mood score

Lowered in trials

Self-rated sadness, tension or irritability.

Low certainty

Results and what it means

Why it was measured

A basic mood measure.

Statistical vs. clinical meaning

Small effect from three trials.

Safety implication

None.

Study	Result	People	Product
¹⁴	SMD -0.18 (95% CI -0.31 to -0.05); 3 studies, 163 people.	Adults	Isolated resveratrol

¹⁴

▼

Lyme bacterium in culture (lab dish)

Lowered in trials

How well the bacteria that cause Lyme disease survive in a laboratory dish.

Not enough evidence

Results and what it means

Why it was measured

A first screen for anti-bacterial activity.

Statistical vs. clinical meaning

Laboratory only; no human relevance shown.

Safety implication

Not a measure of anything in a person.

Study	Result	People	Product
⁷	Knotweed extract inhibited growing bacteria (MIC 0.25 to 0.5%) and stationary forms in dishes; did not clear them in 21-day subculture.	Bacteria in dishes	Japanese knotweed root extract at 1%

⁷

●

Liver enzymes (ALT and AST)

No clear change in trials

Blood tests that rise when liver cells are damaged.

Low certainty

Results and what it means

Why it was measured

Common check for liver harm or fatty liver.

Statistical vs. clinical meaning

Human null with high inconsistency; animal results are dose-dependent.

Safety implication

Animal findings are a reason for caution with emodin-rich products.

Study	Result	People	Product
⁵	ALT WMD 0 IU/L (95% CI -3.17 to 3.17); AST WMD -2.40 IU/L (95% CI -5.45 to 0.65); not significant.	Adults in 15 trials	Isolated resveratrol
⁹	AST rose in healthy rodents at higher dose and longer duration (SMD 2.19).	Healthy rodents	Isolated emodin

^{5 9}

▲

Symptom improvement rate (respiratory infection)

Raised in trials

The share of patients whose symptoms improved by the end of treatment.

Very low certainty

Results and what it means

Why it was measured

Main outcome in the respiratory infection trials.

Statistical vs. clinical meaning

Not attributable to knotweed alone.

Safety implication

Adverse events not increased (RR 0.33, p=0.05).

Study	Result	People	Product
¹⁹	RR 1.14 (95% CI 1.09 to 1.20); 7 trials, 1,013 people.	Adults and children with acute respiratory infections	Knotweed-containing herbal mixtures, mostly with antibiotics

¹⁹

▼

Pain score (visual analogue scale)

Lowered in trials

A 0 to 100 self-rating of pain.

Very low certainty

Results and what it means

Why it was measured

What patients feel.

Statistical vs. clinical meaning

Small trials; mixed pain measures.

Safety implication

None specific.

Study	Result	People	Product
²¹	WMD -7.585 (95% CI -12.912 to -2.257).	Postmenopausal women	Isolated resveratrol

²¹

▼

CTX (bone-breakdown marker)

Lowered in trials

A blood marker of how fast bone is being broken down.

Very low certainty

Results and what it means

Why it was measured

Used as an early marker of bone turnover.

Statistical vs. clinical meaning

A marker, not fractures.

Safety implication

None specific.

Study	Result	People	Product
²¹	WMD -0.137 (95% CI -0.204 to -0.070); other bone markers (ALP, OC) unchanged.	Postmenopausal women	Isolated resveratrol

²¹

▼

Abdominal pain severity (IBS)

Lowered in trials

Self-rated belly pain in irritable bowel syndrome.

Very low certainty

Results and what it means

Why it was measured

Main symptom of IBS.

Statistical vs. clinical meaning

Small pilot; combination.

Safety implication

None reported in the abstract.

Study	Result	People	Product
⁴	Improved vs placebo (p<0.05); mast-cell count unchanged.	Adults with IBS	Palmitoylethanolamide/polydatin combination, 12 weeks

⁴

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 7

The root is not the same as resveratrol capsules. Nearly all human safety and effect data are for isolated resveratrol. Knotweed root also contains emodin and other anthraquinones that act on the bowel and, in animals, can affect the liver, kidneys and reproduction at high doses. No human safety study of the root was found. Mixed ^{13 6 5}
Laxative effect from anthraquinones. The root contains emodin-type compounds, the same class as rhubarb root and senna. Cramps, loose stools and diarrhoea are therefore plausible, especially with repeated use. This is inferred from the compound class and the traditional constipation use, not from a knotweed trial. Pharmacological theory ^{6 13 20}
Liver: animal warning, no human case found. Emodin lowered liver enzymes in injured rodents but raised AST in healthy rodents at higher doses and longer durations. In people, isolated resveratrol did not change liver enzymes across 15 trials. No case of liver injury from knotweed was found, and LiverTox was not readable, so absence of reports is not proof of safety. Animal research ^{9 6 5 27}
Medicine interactions. In healthy volunteers, resveratrol slowed the breakdown of drugs handled by CYP3A4, CYP2D6 and CYP2C9 and raised levels of carbamazepine. A review of Lyme-linked herbs lists bleeding, low blood pressure and low blood sugar as possible additive risks. Resveratrol is also reported to affect platelets in lab tests (MSK, summary only). These were studied with isolated resveratrol, not knotweed root. Human data ^{3 2 17 25}
Oestrogen-like activity. Emodin from Polygonum cuspidatum root stimulated oestrogen-sensitive breast cancer cells and bound human oestrogen receptors in the lab. No human study shows what this means for someone taking knotweed. People with hormone-sensitive conditions should ask a doctor first. Laboratory research ¹⁵
Lyme disease needs medical care. A knotweed extract slowed Lyme bacteria in laboratory dishes, but it did not clear them in 21-day subculture and no animal or human data exist. Lyme disease is treated with antibiotics under clinical guidelines. Using herbs instead of care, or alongside it without telling your doctor, is not supported by the evidence read. Laboratory research ^{7 17 12}
Invasive plant: do not harvest or spread it carelessly. Japanese knotweed is described as invasive in the United States and many European countries. Digging, cutting or moving it can spread it, and its sale or transport may be regulated where you live. Wild plants may grow in polluted places. No study of wild-harvest contamination was found. Regulatory ^{13 23}

Side effects 4

Effect	How often	Severity and recovery	Evidence
Loose stools, cramps or diarrhoea Inferred from the anthraquinone content and the traditional constipation use. The Whorwell review covers senna and other drugs, not knotweed.	Not established	mild to moderate Expected to ease when stopped (not studied for knotweed)	Pharmacological theory ^{6 13 20}
Mild side effects in resveratrol trials Rising-dose trial in 40 healthy adults: adverse events mild and similar to placebo. Blood-pressure meta-analysis: fairly well tolerated, no serious events in most trials. Cochrane: no adverse events in three small trials.	Not established	mild Not stated	Systematic review ^{1 8 10}
No excess adverse events in knotweed-containing respiratory mixtures RR 0.33 (95% CI 0.11 to 1.00; p=0.05; 5 trials, 676 people). Knotweed was one ingredient of a mixture, so this does not clear the plant alone.	Not established	not stated Not stated	Systematic review ¹⁹
Possible liver, kidney or reproductive harm at high dose or long use Emodin findings in animals; the doses involved cannot be translated into amounts for people.	Not established	potentially serious (animal data) Not studied	Animal research ^{6 9}

Liver

No human case of liver injury from knotweed was found in the sources read, and no LiverTox entry could be opened. In rodents, emodin lowered liver enzymes in injured animals but raised AST in healthy animals at higher doses and longer durations. In 15 human trials, isolated resveratrol did not change liver enzymes on average, though results varied between trials. ^{9 6 5 27}

How often. No frequency of liver injury in people is available. Not finding reports is not proof of safety.

Monitoring. No agency monitoring advice was found. Stop and seek care for yellow skin or eyes, dark urine, pale stools or unexplained tiredness. Ask your doctor about liver tests if you already have liver disease or take liver-affecting medicines.

This is a safety connection. It is not evidence that Japanese knotweed supports liver health.

Medicines and supplements 6

With	Why it matters	Importance	Evidence	What to do
Medicines broken down by liver enzymes CYP3A4, CYP2D6 or CYP2C9 (for example carbamazepine) prescription	Resveratrol inhibited CYP3A4, CYP2D6 and CYP2C9 and induced CYP1A2 in healthy volunteers; carbamazepine levels rose after resveratrol.	Could raise or lower the effect of some medicines. Studied with isolated resveratrol in healthy volunteers; knotweed capsules vary in resveratrol content.	Human data Low certainty ^{3 2}	Tell your doctor or pharmacist before starting knotweed if you take prescription medicines, especially ones with a narrow safety margin.
Blood thinners and antiplatelet medicines (for example warfarin, aspirin, clopidogrel) and NSAIDs prescription	Resveratrol inhibited platelet clumping in lab tests; MSK says it may raise bleeding risk with blood thinners; the Lyme herb review lists bleeding as a possible additive risk.	Clinical relevance not determined; no knotweed-specific study.	Laboratory research Very low certainty ^{25 17}	Do not combine without asking your doctor or pharmacist. Mention it before surgery or dental work.
Diabetes medicines prescription	Theory: possible additive blood-sugar lowering; the Lyme herb review lists low blood sugar as a possible additive risk. Resveratrol trials found little effect on glucose.	No interaction study found.	Pharmacological theory Very low certainty ^{17 10}	Ask your doctor or pharmacist how to monitor your blood sugar if you add knotweed.
Blood pressure medicines prescription	Theory: possible additive effect on blood pressure; the Lyme herb review lists low blood pressure as a possible additive risk; pooled resveratrol trials showed no clear change.	No interaction study found.	Pharmacological theory Very low certainty ^{17 8}	Do not stop or change blood pressure medicines. Tell your doctor or pharmacist.
Hormone therapy, oestrogen medicines or oestrogen-blocking medicines prescription	Emodin from the root bound human oestrogen receptors alpha and beta in the lab.	No human interaction study.	Laboratory research Not enough evidence ¹⁵	Ask your doctor before use if you take hormone-related medicines or have had a hormone-sensitive cancer.
Other laxatives or herbs containing anthraquinones (rhubarb root, senna, cascara, aloe latex) herb	Theory: stacking compounds from the same class could add to the laxative effect.	No study.	Pharmacological theory Not enough evidence ⁶	Avoid stacking several laxative herbs.

Who should check first 7

Situation	Advice	Evidence
Pregnancy and breastfeeding	Avoid. No pregnancy or breastfeeding safety data for knotweed were found, and emodin showed reproductive toxicity in animals at high doses. LactMed was not read.	Animal research ^{6 27}
Children	Not studied for safety as a supplement; the respiratory infection trials included children but used mixtures. Ask a paediatrician.	Insufficient ¹⁹
Hormone-sensitive conditions (some breast, uterine or ovarian cancers, endometriosis)	Speak to your doctor before use because of emodin's oestrogen-receptor binding in the lab.	Laboratory research ¹⁵
Liver disease, or taking medicines that can affect the liver	Speak to your doctor first because of animal liver findings for emodin and unknown human risk.	Animal research ^{9 6}
Bowel blockage, inflammatory bowel disease, severe constipation or unexplained belly pain	Common caution for stimulant laxatives; not tested for knotweed. See a doctor rather than self-treating.	Pharmacological theory ²⁰
Taking blood thinners, or planned surgery	Ask your doctor or pharmacist first. Sources suggest possible effects on platelets (lab).	Laboratory research ^{25 17}
Lyme disease, tick bite with rash, or symptoms after a tick bite	See a doctor. Do not use knotweed instead of medical care.	Guideline ^{12 7}

Overdose, product quality and regulators

Summary. The 2022 review says the plant has no obvious toxicity; the 2016 emodin review says emodin can cause liver, kidney and reproductive toxicity, particularly at high doses and with long-term use. Both are about animal and lab data. We state both and do not resolve the conflict. No human toxicity study of knotweed root was found.

Animal. Emodin: liver enzymes rose in healthy rodents at higher doses and longer durations in a meta-analysis of 28 rodent studies.

Human doses studied. Human trials of isolated resveratrol reported mild or no adverse events at the amounts tested; no trial of the root.

High dose or long term signals. Animal: emodin liver, kidney and reproductive toxicity at high dose and long duration. Human: resveratrol in the 40-person rising-dose trial had mild events only.

Overdose response. No overdose case in people was found.

Genotoxicity. Not assessed in the sources read.

Toxic plant parts. Root and rhizome are the medicinal parts. Aerial parts have different constituents (Ke 2023); their safety was not assessed.

No study of contamination, adulteration or substitution in knotweed products was found. Content of resveratrol, polydatin and emodin is said to vary between products; the existing summary says labels may not state compound content (summary-only).

Body	Action	Date
Chinese Pharmacopoeia (China)	The root is included under the name Huzhang (stated in the 2023 review abstract). source

When to get medical help

Yellow skin or eyes, dark urine, pale stools or severe unexplained tiredness.
Severe or lasting stomach pain, ongoing diarrhoea or vomiting, dizziness or signs of dehydration.
Unusual bruising, nosebleeds, blood in urine or stool, especially if you take blood thinners.
A spreading red rash after a tick bite, fever, new joint swelling, facial weakness or heart palpitations (possible Lyme disease: seek medical care).
Swelling of the lips or throat, hives or trouble breathing (possible allergy).
Breast lumps or unusual vaginal bleeding if you have a hormone-sensitive condition.

Stop the supplement and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What is Japanese knotweed?

Japanese knotweed is a tall, fast-spreading plant. Its dried root, called hu zhang in Chinese medicine, is used as a herb and is a main commercial source of resveratrol.

^{13 24}

Is Japanese knotweed the same as resveratrol?

No. Resveratrol is one compound found in the root, and most human trials tested pure resveratrol. The root also contains polydatin, emodin and many other compounds, so results for resveratrol may not apply to the root.

^{6 13 22}

Does Japanese knotweed treat Lyme disease?

There is no evidence that it does. A laboratory dish study found knotweed extract slowed the Lyme bacterium but did not clear it, and no animal or human trial exists. Lyme disease needs medical care; see a doctor after a tick bite or if you have symptoms.

^{7 17 12}

Is it safe to take Japanese knotweed with Lyme antibiotics?

No interaction study was found. Resveratrol changed liver enzymes that handle some medicines, so tell your doctor or pharmacist about any herb you take alongside Lyme treatment.

^{3 17}

Can Japanese knotweed lower blood sugar or blood pressure?

Pooled trials of pure resveratrol found no clear overall effect on blood pressure, and reviews disagree on blood sugar. Nothing was found for the root itself. Do not change diabetes or blood pressure medicines without your doctor.

^{10 22 8}

Does it act as a laxative?

It might. The root contains emodin-type compounds, the same class as rhubarb root and senna, and it is traditionally used for constipation. No trial of knotweed alone for constipation was found.

^{13 6 20}

Is it bad for the liver?

No human liver injury case was found, but the evidence is thin. In animals, emodin raised liver enzymes at high doses and long duration. In 15 trials, pure resveratrol did not change liver enzymes on average. Report yellow skin or eyes or dark urine promptly.

^{9 6 5}

Can it interact with blood thinners or other medicines?

Possibly. Resveratrol slowed the breakdown of some medicines in healthy volunteers, and lab work suggests it may affect platelets. Ask your doctor or pharmacist before combining it with blood thinners or prescription medicines.

^{3 2 25}

Does it have oestrogen-like effects?

In the lab, emodin from the root attached to oestrogen receptors and made oestrogen-sensitive cells multiply. No human study shows what this means. People with hormone-sensitive conditions should ask a doctor first.

¹⁵

Is it safe in pregnancy or breastfeeding?

It should be avoided. No safety data for knotweed in pregnancy or breastfeeding were found, and emodin showed reproductive toxicity in animals at high doses.

⁶

Is Japanese knotweed an invasive plant, and can I harvest it myself?

It is described as invasive in the United States and many European countries. Digging up or moving it can spread it, and rules may apply where you live. Wild plants may grow in polluted places, and no study has checked this. Ask your local authority before collecting any.

^{13 23}

How much should I take?

Amounts are not covered on this page because no safe or effective amount has been shown for the root. Ask a doctor or pharmacist about amounts for your situation.

Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against PubMed records.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-25
Last substantive update: 2026-10-25
How we research: We started from an existing summary of this herb and searched PubMed for the main uses and safety topics. We checked identity records (GBIF, PubChem) and looked for NIH NCCIH, EMA, LiverTox and LactMed pages on knotweed, which could not be opened or found. We recorded each study's design, people, product and result as reported. Only abstracts were read. Certainty ratings are the compiler's own reading, not formal grades. No study is cited that we could not verify.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown. If one is added later it will be labelled and kept apart from the evidence.

Sources 27

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

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Bedada SK, Nearati P. Effect of resveratrol on the pharmacokinetics of carbamazepine in healthy human volunteers.. Phytotherapy research : PTR. 2015. PMID 25624269. DOI 10.1002/ptr.5302. (abstract)
Chow HH, Garland LL, Hsu CH, et al.. Resveratrol modulates drug- and carcinogen-metabolizing enzymes in a healthy volunteer study.. Cancer prevention research (Philadelphia, Pa.). 2010. PMID 20716633. DOI 10.1158/1940-6207.CAPR-09-0155. (abstract)
Cremon C, Stanghellini V, Barbaro MR, et al.. Randomised clinical trial: the analgesic properties of dietary supplementation with palmitoylethanolamide and polydatin in irritable bowel syndrome.. Alimentary pharmacology & therapeutics. 2017. PMID 28164346. DOI 10.1111/apt.13958. (abstract)
Darand M, Farrokhzad A, Ghavami A, et al.. Effects of resveratrol supplementation on liver enzymes: A systematic review and meta-analysis of randomised controlled trials.. International journal of clinical practice. 2021. PMID 32869460. DOI 10.1111/ijcp.13692. (abstract)
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Hu S, Guo X, Tu L, et al.. The efficacy and toxicity equilibrium of emodin for liver injury: A bidirectional meta-analysis and machine learning.. Phytomedicine : international journal of phytotherapy and phytopharmacology. 2025. PMID 40339537. DOI 10.1016/j.phymed.2025.156650. (abstract)
Jeyaraman MM, Al-Yousif NSH, Singh Mann A, et al.. Resveratrol for adults with type 2 diabetes mellitus.. The Cochrane database of systematic reviews. 2020. PMID 31978258. DOI 10.1002/14651858.CD011919.pub2. (abstract)
Ke J, Li MT, Xu S, et al.. Advances for pharmacological activities of Polygonum cuspidatum - A review.. Pharmaceutical biology. 2023. PMID 36620922. DOI 10.1080/13880209.2022.2158349. (abstract)
Lantos PM, Rumbaugh J, Bockenstedt LK, et al.. Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA), American Academy of Neurology (AAN), and American College of Rheumatology (ACR): 2020 Guidelines for the Prevention, Diagnosis and Treatment of Lyme Disease.. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2021. PMID 33483734. DOI 10.1093/cid/ciab049. (abstract)
Liu S, Zhang R, Zhang X, et al.. The Invasive Species Reynoutria japonica Houtt. as a Promising Natural Agent for Cardiovascular and Digestive System Illness.. Frontiers in pharmacology. 2022. PMID 35770098. DOI 10.3389/fphar.2022.863707. (abstract)
Marx W, Kelly JT, Marshall S, et al.. Effect of resveratrol supplementation on cognitive performance and mood in adults: a systematic literature review and meta-analysis of randomized controlled trials.. Nutrition reviews. 2018. PMID 29596658. DOI 10.1093/nutrit/nuy010. (abstract)
Matsuda H, Shimoda H, Morikawa T, et al.. Phytoestrogens from the roots of Polygonum cuspidatum (Polygonaceae): structure-requirement of hydroxyanthraquinones for estrogenic activity.. Bioorganic & medicinal chemistry letters. 2001. PMID 11459643. DOI 10.1016/s0960-894x(01)00318-3. (abstract)
Sahebkar A, Serban C, Ursoniu S, et al.. Lack of efficacy of resveratrol on C-reactive protein and selected cardiovascular risk factors--Results from a systematic review and meta-analysis of randomized controlled trials.. International journal of cardiology. 2015. PMID 25885871. DOI 10.1016/j.ijcard.2015.04.008. (abstract)
Thompson A, Hynicka LM, Shere-Wolfe KD. A Comprehensive Review of Herbal Supplements Used for Persistent Symptoms Attributed to Lyme Disease.. Integrative medicine (Encinitas, Calif.). 2023. PMID 37101730. (abstract)
Vang O, Ahmad N, Baile CA, et al.. What is new for an old molecule? Systematic review and recommendations on the use of resveratrol.. PloS one. 2011. PMID 21698226. DOI 10.1371/journal.pone.0019881. (abstract)
Wang ZJ, Trill J, Tan LL, et al.. Reynoutria japonica Houtt for Acute Respiratory Tract Infections in Adults and Children: A Systematic Review.. Frontiers in pharmacology. 2022. PMID 35281919. DOI 10.3389/fphar.2022.787032. (abstract)
Whorwell P, Lange R, Scarpignato C. Review article: do stimulant laxatives damage the gut? A critical analysis of current knowledge.. Therapeutic advances in gastroenterology. 2024. PMID 38887508. DOI 10.1177/17562848241249664. (abstract)
Wu W, Meng T, Jin F, et al.. Effects of resveratrol on postmenopausal women: a systematic review and meta-analysis.. Frontiers in pharmacology. 2025. PMID 40771919. DOI 10.3389/fphar.2025.1588284. (abstract)
Zeraattalab-Motlagh S, Jayedi A, Shab-Bidar S. The effects of resveratrol supplementation in patients with type 2 diabetes, metabolic syndrome, and nonalcoholic fatty liver disease: an umbrella review of meta-analyses of randomized controlled trials.. The American journal of clinical nutrition. 2021. PMID 34320173. DOI 10.1093/ajcn/nqab250. (abstract)
. Neobiota.lu note on EU invasive alien species list and Reynoutria japonica (Regulation 2025/1422 mentioned). . . (summary-only)
. GBIF Backbone: Reynoutria japonica Houtt. (usageKey 2889173). . . (full-text)
. Memorial Sloan Kettering Cancer Center: Resveratrol (patient education herb page). . . (summary-only)
. PubChem compound records: resveratrol (CID 445154), polydatin (CID 5281718), emodin (CID 3220). . . (full-text)
. Regulator lookups for Japanese knotweed (EMA/HMPC, NCCIH, LiverTox, LactMed): not found or not readable. . . (summary-only)

Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.