flavan3olien

Flavan-3-ols are a class of flavonoids characterized by a saturated C2-C3 bond in the central heterocyclic ring and a hydroxyl group at position 3. They occur as monomeric units such as catechin and epicatechin and serve as the building blocks of larger polymers known as proanthocyanidins or condensed tannins. Common natural monomers include (+)-catechin, (-)-epicatechin, (+)-gallocatechin, and (-)-epigallocatechin.

They are widely distributed in plants and contribute to the flavor and color of many foods and beverages. Major dietary sources include tea (especially green tea), cocoa, grapes, apples, and various berries. In foods, flavan-3-ols can be present as free monomers or bound within tannin complexes, and they may polymerize to form proanthocyanidins during processing and storage.

Chemically, flavan-3-ols are polyphenols with antioxidant properties observed in vitro, capable of scavenging free radicals and chelating metal ions. They influence taste attributes such as bitterness and astringency in foods and can undergo polymerization to condensed tannins, affecting color stability and aging in products like wine and tea.

In humans, evidence on health effects is mixed. Some observational studies associate higher intake with cardiovascular benefits and improved endothelial function, but randomized trials yield inconsistent results, and effects are typically modest. The gut microbiota can metabolize flavan-3-ols to various phenolic compounds, potentially contributing to observed outcomes.

Flavan-3-ols are generally consumed as part of a ordinary diet and are not medicines; health claims should be considered within the context of overall dietary patterns.