Flavanols

PhytochemicalFlavonoidBest with a meal

What is it

Flavanols (flavan-3-ols) are a subclass of flavonoids including (epi)catechin, (epi)gallocatechin, EGCG, and their oligomers (proanthocyanidins). They are concentrated in cocoa, tea, grapes, apples, and berries.

Evidence for 2 uses

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

Cardiovascular function (cocoa flavanols)

Strong Evidence

Multiple RCTs and the COSMOS trial show cocoa flavanols improve endothelial function and modestly reduce cardiovascular events.

Blood pressure

Good Evidence

Meta-analyses of cocoa flavanol trials show small but consistent BP reductions (~2-3 mm Hg).

How it works

Flavanols improve endothelial nitric oxide bioavailability, reduce blood pressure modestly, and improve flow-mediated dilation. Cocoa flavanols have the strongest cardiovascular evidence. Tea catechins (especially EGCG) have been studied for metabolic effects. Bioavailability is moderate, and gut microbiota produce smaller phenolics that account for some of the systemic effects.

Dosage

Cocoa flavanol RCTs typically use 200-900 mg/day. Tea catechin studies use 200-800 mg EGCG/day.

When and how to take it

Take with meals. Whole-food sources are first-line.

3 commercial forms

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

Cocoa flavanol extract

Used in COSMOS and other major trials.

Standardized to specific catechin content.

Green tea catechin extract

Watch hepatotoxicity at high doses.

Standardized to EGCG.

Grape seed proanthocyanidins

Antioxidant marketing claims; modest clinical evidence.

Larger polymers; minimally absorbed intact.

Safety

Whole-food flavanols are very safe. Concentrated EGCG extracts carry rare hepatotoxicity warnings above ~800 mg/day, especially on an empty stomach.

Who should be cautious

Liver disease and iron deficiency: be cautious with concentrated tea catechin extracts. Take with food.

Interactions

Catechins may reduce iron absorption when consumed with meals. EGCG may modulate some drug-metabolizing enzymes.

Food sources

Dark chocolate (1 oz, 70%+)

Amount
~100-200 mg flavanols
%DV
—

Green tea (1 cup)

Amount
~100-200 mg flavanols
%DV
—

Apple (medium with skin)

Amount
~50 mg flavanols
%DV
—

Frequently asked questions

Is dark chocolate good for blood pressure?⌄

Cocoa flavanols modestly lower blood pressure in trials; effect is small. Choose minimally processed (Dutched cocoa has lower flavanol content).

Do I need a supplement?⌄

Most evidence supports whole-food sources (cocoa, tea, berries). High-dose EGCG capsules carry hepatic risk.

References

Flavanols on Wikidata — Wikidata link

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

Research on Flavanols (PubMed search) — PubMed link

Track Flavanols with Pilora

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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.