What is Flavonoids?Flavonoids are water soluble polyphenolic molecules containing 15 carbon atoms. Flavonoids belong to the polyphenol family. Flavanoids can be visualized as two benzene rings which are joined together with a short three carbon chain. One of the carbons of the short chain is always connected to a carbon of one of the benzene rings, either directly or through an oxygen bridge, thereby forming a third middle ring, which can be five or six-membered. The flavonoids consist of 6 major subgroups: chalcone, flavone, flavonol, flavanone, anthocyanins and isoflavonoids.
Together with carotenes, flavanoids are also responsible for the coloring of fruits, vegetables and herbs.
DistributionFlavonoids are found in most plant material. The most important dietary sources are fruits, tea and soybean. Green and black tea contains about 25% percent flavonoids. Other important sources of flavonoids are apple (quercetin), citrus fruits (rutin and hesperidin),
Health Benefits of FlavonoidsFlavonoids have antioxidant activity. Flavonoids are becoming very popular because they have many health promoting effects. Some of the activities attributed to flavonoids include: anti-allergic, anti-cancer, antioxidant, anti-inflammatory and anti-viral. The flavonoids quercetin is known for its ability to relieve hay fever, eszema, sinusitis and asthma.
Epidemiological studies have illustrated that heart diseases are inversely related to flavonoid intake. Studies have shown that flavonoids prevent the oxidation of low-density lipoprotein thereby reducing the risk for the development of atherosclerosis.
The contribution of flavonoids to the total antioxidant activity of components in food can be very high because daily intake can vary between 50 to 500 mg.
Red wine contains high levels of flavonoids, mainly quercetin and rutin. The high intake of red wine (and flavonoids) by the French might explain why they suffer less from coronary heart disease then other Europeans, although their consumption of cholesterol rich foods is higher (French paradox). Many studies have confirmed that one or two glasses of red wine daily can protect against heart disease.
Tea flavonoids have many health benefits. Tea flavonoids reduce the oxidation of low-density lipoprotein, lowers the blood levels of cholesterol and triglycerides.
Soy flavonoids (isoflavones) can also reduce blood cholesterol and can help to prevent osteoporis. Soy flavonoids are also used to ease menopausal symptoms.
Research ReviewsA flavonoid fraction from cranberry extract inhibits proliferation of human tumor cell lines
Flavonoids and Heart Health: Proceedings of the ILSI North America Flavonoids Workshop