Subclass of Phenolics

Flavanols

Flavan-3-ols — catechin, epicatechin and EGCG, the single units that tea, cocoa and grape are rich in.

Overview

About Flavanols

Flavan-3-ols — usually shortened to flavanols — are the flavonoid subclass in which the central ring is fully reduced and carries a hydroxyl at position 3. Catechin and epicatechin are the parent molecules, and their gallate esters, of which EGCG is the best known, are the potent members.

Their defining habit is linking up. Two, three or many flavanol units join into chains, the proanthocyanidins or condensed tannins, which have their own page. This page covers the single units.

Where Flavanols Occur

They are among the most abundant polyphenols in the ordinary diet:

Green tea

EGCG, EGC, ECG and epicatechin

Cocoa and dark chocolate

epicatechin and procyanidins

Grape seed and skin

catechin and epicatechin

Apples, berries and broad beans

catechin and epicatechin

Hawthorn

epicatechin, alongside the procyanidins built from it

Pharmacological Importance

Cocoa flavanols carry some of the strongest evidence for any dietary polyphenol: repeated randomized trials show improved flow-mediated dilation and modest blood-pressure reduction, mediated through nitric-oxide-dependent endothelial function.

EGCG, the main catechin of green tea, is the most studied single member, for metabolic, cardiovascular and anticancer effects. Most of that evidence comes from cell and animal work, and the human results are modest.

Toxicity & Safety

As dietary constituents these are safe and consumed in gram quantities by tea and cocoa drinkers.

The genuine concern is concentrated green-tea extract taken on an empty stomach, which has an established association with idiosyncratic hepatotoxicity — enough that several regulators have issued warnings and product-level dose limits. Brewed tea does not carry the same signal. Strong tea taken with meals also reduces the absorption of iron from plant foods, which matters for anyone managing iron-deficiency anaemia.

Source Plants

Herbs Containing Flavanols

30 herbs

Plants in the materia medica documented to carry flavanols, with the compounds each one is listed for. The bar counts how many DISTINCT flavanols are on record for a plant, relative to the best-documented — it measures breadth of record, not potency, so a plant with one well-studied compound can outrank a richer source that has simply been analysed less. Where a measured concentration is on record it is quoted inline; most entries have none yet.