Flavonoids

Flavonoids (wiki)

Biological effects

Flavonoids are widely distributed in plants fulfilling many functions including producing yellow or red/blue pigmentation in flowers and protection from attack by microbes and insects.

Flavonoids have been referred to as "nature's biological response modifiers" because of strong experimental evidence of their inherent ability to modify the body's reaction to allergens, viruses, and carcinogens. They show anti-allergic, anti-inflammatory^[1] , anti-microbial and anti-cancer activity. In addition, flavonoids act as powerful antioxidants, protecting against oxidative and free radical damage.

Consumers and food manufacturers have become interested in flavonoids for their medicinal properties, especially their potential role in the prevention of cancers and cardiovascular disease. The beneficial effects of fruit, vegetables, and tea or even red wine have been attributed to flavonoid compounds rather than to known nutrients and vitamins.

Good sources of flavonoids include all citrus fruits, berries, onions, parsley, legumes, green tea, red wine, seabuckthorn, and dark chocolate (that with a cocoa content of seventy percent or greater).

Citrus

The citrus bioflavonoids include hesperidin, quercetin, rutin (a sugar of quercetin), and tangeritin. In addition to possessing antioxidant activity and an ability to increase intracellular levels of vitamin C, rutin and hesperidin exert beneficial effects on capillary permeability and blood flow. They also exhibit some of the anti-allergy and anti-inflammatory benefits of quercetin. Quercetin can also inhibit reverse transcriptase, part of the replication process of retroviruses (Spedding et al. 1989). The therapeutical relevance of this inhibition has not been established. Hydroxyethylrutosides (HER) have been used in the treatment of capillary permeability, easy bruising, hemorrhoids, and varicose veins.

Green Tea

Green tea polyphenols are potent antioxidant compounds that have demonstrated greater antioxidant protection than vitamins C and E. Green tea may also increase the activity of antioxidant enzymes. Green tea polyphenols may inhibit cancer by blocking the formation of cancer-causing compounds and suppressing the activation of carcinogens. The major polyphenols in green tea are flavonoids (catechin, epicatechin, epicatechin gallate, epigallocatechin gallate(EGCG), and proanthocyanidins).

Though both green tea and black tea are derived from the same plant (Camellia sinensis), they possess different antioxidants. In producing black tea the leaves are allowed to oxidize, during which enzymes present in the tea convert many polyphenols to larger molecules with different biological effects. However, green tea is produced by lightly steaming the fresh-cut leaf, which inactivates these enzymes, and oxidation does not occur.