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Catechins are bioflavonoids, polyphenols and powerful anti-oxidants. The best source of catechins is white tea, with green tea coming close. Catechins are linked to evidence of fighting tumors as well as enhancing immune system function, due to their polyphenol antioxidant character, which is well established in scavenging reactive oxygen species.
Catechins in Tea
Catechins make up some 25% of the dry weight of fresh tea leaf The concentration of catechins is higher in green and white tea. In black tea the oxidation process allows polyphenol oxidase to oxidize the polyphenols[2 and so inactivates the catechins.
Tea contains four main catechin substances: catechin (EC), epicatechin gallate (ECg), epigallocatechin (EGC) and epigallocatechin gallate (EGCg. Catechin gallates are esters of a catechin and callic acid whereas gallocatechins have the same carbon skeleton as other catechins but have an extra hydroxyl function. Epigallocatechin gallate (EGCG) is the one most abundant catechins in tea. EGCG as an antioxidant is about 25-100 times more potent than vitamins C and E.
Tea flavour, colour and astringency is in part due to the condensation of the catechins to form the bright orange-red pigment theaflavin.*
Tea, Catechins and Antioxidants
One cup of green tea provides 10-40 mg of polyphenols and has antioxidant effects greater than a serving of broccoli, spinach, carrots, or strawberries. The high antioxidant activity of green tea makes it beneficial for protecting the body from oxidative damage due to free radicals. Research shows that green tea may help the arterial wall by reducing oxidized lipidsSerafini M, Laranjinha JA, Almeida LM, Maiani G, Inhibition of human LDL lipid peroxidation by phenol-rich beverages and their impact on plasma total antioxidant capacity in humans, J Nutr Biochem 2000 Nov;11(11-12):585-590. Green tea can protect against experimentally induced DNA damage, and slow or halt the initiation and progression of undesirable cell colonies . Studies show evidence that green tea provides immunoprotective qualities , particularly in the case of patients undergoing radiation or chemotherapy . White blood cell count appear to be maintained more effectively in patients consuming green tea compared to non-supplemented patients.
A 2006 study showed that elderly Japanese people who drank more than 2 cups of green tea a day had a 50 per cent lower chance of cognitive impairment than those who drank less green tea, or who consumed other tested beverages. The high amount of catechins in green tea was believed to be responsible. White tea, (which is higher in catechins than green tea), was not tested. The study was published in "The American Journal of Clinical Nutrition" (Vol. 83, pp. 355-361). Reference: *.
Researchers believe that catechin is effective because it easily sticks to proteins, blocking bacteria from adhering to cell walls and disrupting their ability to destroy them. Viruses have ‘hooks’ on their surfaces and can attach to cell walls. The catechin in green tea prevents viruses from adhering and causing harm. Catechin reacts with toxins created by harmful bacteria (many of which belong to the protein family) and harmful metals such as lead, mercury, chrome, and cadmium.
Notes
References
- Linus Pauling Institute (Oregon State University) [http://lpi.oregonstate.edu/infocenter/phytochemicals/flavonoids/index.html#intro Micronutrient Information Center - Flavonoids
- * Science and Plants for Schools Website http://www-saps.plantsci.cam.ac.uk/records/rec281.htm
External links
Alcohols | Flavonoids | Phenols | Benzenediols | Antioxidants
"Catechin"