Japanese Knotweed
Also known as: Polygonum cuspidatum, Fallopia japonica, Reynoutria japonica, Hu Zhang, resveratrol source
Effective Dosage
No established dose (insufficient research data)
What the Science Says
Japanese knotweed is an invasive plant species whose roots and rhizomes are rich in polyphenols, including resveratrol and polydatin. Lab studies suggest its extracts can scavenge free radicals, protect red blood cells from oxidative damage, and inhibit SARS-CoV-2 in cell cultures. It is also used in herbal protocols for Lyme disease symptoms, though evidence for this use comes only from in-vitro antimicrobial studies with no human clinical trials to support it.
What It Doesn't Do
Not proven to treat Lyme disease in humans — zero clinical trials exist. Lab results against viruses and bacteria don't automatically translate to benefits in your body. No evidence it prevents or treats COVID-19 in people. Don't confuse it with purified resveratrol supplements — the two are not the same thing.
Evidence-Based Benefits
Japanese Knotweed is primarily known for its high content of resveratrol, which is thought to have antioxidant properties. However, the clinical evidence supporting its health benefits is very limited, with no large-scale trials confirming its efficacy in humans.
Weak EvidenceEffective at: Unknown (insufficient research data)
Source: auto-research
Absorption & Bioavailability
Unknown — no human pharmacokinetic or absorption data in the provided studies. Resveratrol (a key compound) is known generally to have poor bioavailability, but this was not assessed in the provided papers.
Red Flags to Watch For
- Zero human clinical trials in the provided research — all evidence is from lab (in vitro) or animal studies
- Widely marketed for Lyme disease treatment despite no clinical evidence of efficacy in humans
- Japanese knotweed is an aggressive invasive species; sourcing and contamination standards may vary widely between supplement products
- Potential drug interactions not well studied; the Lyme disease review notes this concern for herbal supplements in this category
- High doses in cell studies showed cytotoxic effects — more is not necessarily safer
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-04-06