By Dr Ananya Mandal, MD
Flavonoids are a group of plant metabolites thought to provide health benefits through cell signalling pathways and antioxidant effects. Flavonoids are found in a variety of fruits and vegetables.
According to the International Union of Pure and Applied Chemistry, flavonoids can be subdivided into the following groups:
- Flavonoids - These are derived from 2-phenylchromen-4-one (2-phenyl-1,4-benzopyrone)
- Isoflavonoids - These are derived from 3-phenylchromen-4-one (3-phenyl-1,4-benzopyrone)
- Neoflavonoids - These are derived from 4-phenylcoumarine (4-phenyl-1,2-benzopyrone)
Flavonoids are abundant in plants, in which they perform several functions. They are essential pigments for producing the colors needed to attract pollinating insects. In higher order plants, flavonoids are also required for UV filtration, nitrogen fixation, cell cycle inhibition, and as chemical messengers. Flavonoids secreted by a plant’s roots aid the symbiotic relationship between rhizobia and certain vegetables such as peas, clover and beans. The rhizobia present in soil produce Nod factors in response to the presence of flavonoids. These Nod factors are then recognized by the plant, which induces certain responses such as ion fluxes and root nodule formation. Some flavonoids also inhibit certain spores to protect against certain plant diseases. Flavonoids are ubiquitous in plants and are the most common type of polyphenolic compound found in the human diet
The abundance of flavonoids coupled with their low toxicity relative to other plant compounds means they can be ingested in large quantities by animals, including humans. Examples of foods that are rich in flavonoids include onions, parsley, blueberries, bananas, dark chocolate and red wine.
Reviewed by Sally Robertson, BSc
Last Updated: Jul 2, 2014