bioflavonoid

Bioflavonoids are a large and diverse group of plant-derived polyphenolic compounds. They occur in high concentrations in fruits, vegetables, legumes, nuts, seeds, herbs, flowers, and in beverages such as tea, wine, and citrus juices. The term bioflavonoid is historical; most scientists now refer to flavonoids or flavonoid subclasses. They are not vitamins, but they are commonly consumed as part of plant-based diets and were once marketed as vitamin P.

Chemically, flavonoids share a basic skeleton of two phenyl rings (A and B) joined by a three-carbon bridge to form a heterocyclic C ring (a C6-C3-C6 framework). They are divided into subclasses, including flavonols (quercetin, kaempferol), flavones (apigenin, luteolin), flavanones (hesperidin, naringenin), flavanols (catechins), isoflavones (genistein, daidzein), and anthocyanins (pigmented forms such as cyanidin).

In plants, flavonoids contribute to color, UV protection, and defense against pathogens. In humans, they are studied for antioxidant, anti-inflammatory, and possible cardioprotective effects. Observational studies link higher flavonoid intake with reduced risk of cardiovascular disease and some cancers, but controlled trials generally show modest or inconsistent benefits, influenced by dose, food matrix, and individual metabolism.

Bioavailability varies by compound; absorption occurs mainly in the small intestine with phase II metabolism and extensive transformation by gut microbiota. Some flavonoids can modulate drug-metabolizing enzymes and transporters, potentially affecting medications. High-dose supplements may cause adverse effects or interact with anticoagulants or other drugs; it is best to obtain flavonoids primarily from a varied diet.