Hu Zhang

BotanicalBest with a meal

What is it

Hu Zhang (Polygonum cuspidatum, Japanese knotweed) is a traditional Chinese medicine root that is the predominant commercial source of trans-resveratrol used in dietary supplements.

Evidence for 1 use

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Cardiometabolic markers

Limited Evidence

Small randomized trials of resveratrol show modest, inconsistent effects on insulin sensitivity, blood pressure, and lipid profile.

How it works

Hu Zhang root contains resveratrol, polydatin (piceid, a resveratrol glycoside), emodin, and other stilbenes. Resveratrol is studied as a sirtuin-1 activator and AMPK modulator with effects on metabolic and inflammatory pathways in laboratory models. As a whole extract, Hu Zhang also delivers emodin and physcion, anthraquinones with laxative and hepatic activity that are not present in pure synthetic resveratrol. This complicates safety profiling at higher doses.

Dosage

No RDA. Typical resveratrol supplement labels deliver 100-500 mg of trans-resveratrol from Hu Zhang extract daily. Larger trial doses up to 1 g have been used short term.

When and how to take it

WHEN: With meals. HOW: Take with a fat-containing meal for better absorption.

2 commercial forms

Compare the main delivery options and what they’re best suited for.

Standardized 50% trans-resveratrol

Common commercial standardization for cardiometabolic products.

Resveratrol has poor oral bioavailability; rapidly conjugated.

Standardized polydatin (piceid)

Less common but used in some Asian formulations.

Glycoside form, deglycosylated by gut enzymes.

Safety

Generally tolerated at standard doses. Higher doses (above 1 g/day) have been associated with gastrointestinal upset and elevated liver enzymes. Emodin from whole-root extracts has shown hepatotoxic potential in animals.

Who should be cautious

Avoid in pregnancy due to emodin content (stimulates uterus in animal models). Caution with hormone-sensitive cancers (mild phytoestrogen activity) and in people on anticoagulants.

Interactions

Resveratrol may inhibit CYP3A4 and CYP2C9, potentially raising levels of drugs metabolized by these enzymes including some statins and warfarin.

Food sources

Red wine

Amount
5 oz
%DV
—

Red grapes with skin

Amount
1 cup
%DV
—

Frequently asked questions

Is Hu Zhang the same as resveratrol?⌄

Hu Zhang is the plant; resveratrol is one of its compounds. Most resveratrol supplements are Hu Zhang extracts.

References

Hu Zhang on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Hu Zhang (PubMed search) — PubMed link

Track Hu Zhang with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.