Flavonolignan

PhytochemicalBest with a meal

What is it

Flavonolignans are a class of plant secondary metabolites formed by oxidative coupling of a flavonoid (such as taxifolin) with a phenylpropanoid. The best-known flavonolignans are silybin, silydianin, and silychristin, the main components of silymarin from milk thistle (Silybum marianum).

Evidence for 1 use

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

Chronic liver disease (silymarin)

Limited Evidence

Studies in alcoholic and viral hepatitis show mixed results; some show modest improvements in liver enzymes without clear effects on mortality or clinical outcomes. Evidence does not establish silymarin as a primary therapy.

How it works

Silymarin flavonolignans have antioxidant and hepatoprotective activity in laboratory and animal models, with mechanisms including free-radical scavenging, modulation of hepatocyte membranes, inhibition of fibrogenesis, and effects on glutathione metabolism. Bioavailability of unmodified silybin is poor; phosphatidylcholine-complex forms (silybin-phosphatidylcholine) have improved absorption. Human clinical trial evidence is most developed for chronic liver diseases, with mixed results.

Dosage

There is no specific dose for 'flavonolignan' as a class. Silymarin doses in liver studies typically range from 140–600 mg/day in divided doses, standardized to flavonolignan content.

When and how to take it

With food, especially for phosphatidylcholine-complex forms, to optimize absorption.

1 commercial form

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Silymarin (standardized milk thistle extract)

Primary clinical source of flavonolignans.

Poor oral bioavailability; phosphatidylcholine complex improves absorption.

Safety

Silymarin is generally well tolerated; mild GI upset and rare allergic reactions are reported. Asteraceae allergy may cross-react.

Who should be cautious

Avoid in known Asteraceae allergy. Pregnancy and breastfeeding: silymarin appears reasonably tolerated but data is limited.

Interactions

Silymarin has weak inhibitory effects on some CYP isoenzymes (CYP3A4, CYP2C9) in vitro; clinically meaningful interactions are mostly modest. Reported interactions with certain anticancer drugs and immunosuppressants.

Frequently asked questions

Are flavonolignans the same as silymarin?⌄

Silymarin is a mixture of flavonolignans (silybin, silydianin, silychristin) and other compounds from milk thistle. So silymarin is the main commercial source.

References

Flavonolignan on Wikidata — Wikidata link

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

Research on Flavonolignan (PubMed search) — PubMed link

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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.