Polyphenole

Polyphenole, or polyphenols, are a large and diverse class of plant secondary metabolites characterized by multiple phenol units. They occur widely in fruits, vegetables, seeds and other plant-derived foods and beverages. Based on chemical structure they are commonly categorized into several groups: flavonoids (including flavones, flavonols, flavanones, isoflavones, anthocyanins), phenolic acids (hydroxybenzoic and hydroxycinnamic acids), stilbenes (such as resveratrol), lignans, and tannins (condensed and hydrolyzable).

Dietary sources include tea, coffee, cocoa and chocolate, wine and grape products, berries, apples, onions, olive oil, spices, nuts and legumes. Intake varies with diet and food processing, which can affect polyphenol content and bioavailability.

Biological effects and health associations: Polyphenols exhibit antioxidant activity in laboratory studies and can modulate cellular signaling, inflammation and gut microbiota. They may contribute to reduced risk of certain chronic diseases in observational studies, but causal evidence in humans remains mixed and highly dependent on bioavailability and metabolism. Most polyphenols are poorly absorbed in the small intestine and are extensively transformed by the liver and gut microbiota, generating metabolites that circulate in the bloodstream.

Analytical aspects and safety: Total polyphenol content is commonly assessed by spectrophotometric methods such as the Folin-Ciocalteu assay and by chromatographic techniques. In the diet they are generally safe; high-dose supplements can interact with drug metabolism or cause adverse effects in susceptible individuals and are not a substitute for medical treatment.