Green Tea: Health Articles
Database - Green tea research has shown it has an effect on variety of health conditions. The ability to lower blood sugar, chelate iron and control the production of nitric oxide are all especially
important. This ancient beverage seems custom-made to protect health and delay aging. To find how green tea benefits different organs and conditions click a specific topic from our article database below:
Green Tea & Circulation - Animal Hamster Studies
A recent American in vivo study using hamsters found that while both green tea and black tea improved plasma lipid profiles and protected cholesterol against oxidation, green tea also lowered fibrinogen significantly more than black tea. One of the green tea polyphenols, epicatechin, was found to be able to significantly inhibit the production of thromboxane, one of the compounds required for platelet aggregation.
Green Tea & Circulation
The vasodilating effects of tea are documented. One study compared the effect of coffee, tea, hot water with caffeine, and plain hot water on skin temperature, indicating peripheral vasodilation. Tea produced the greatest vasodilating response. The authors speculate that this is due to the action of catechins. An increase in peripheral circulation is valuable for oxygenating tissue, and is also associated with a relaxed mood. Hence some alternative experts have advised drinking green tea in the evening as a relaxant.
Green Tea & Circulation - Animal Rat Studies
A more detailed recent study compared the effectiveness of various catechins as vasorelaxants in rat arteries. All four main catechins present in green tea were shown to have a dose-dependent vasodilating effect, with epigallocatechin gallate being the most potent. Like human estrogens, catechins may act as calcium-channel blockers. Vasodilation is one of the cardioprotective effects of estrogens. Thus, green tea extract might be of particular importance to estrogen-deficient postmenopausal women. Green tea catechins containing the galloyl group (epigallocatechin gallate, epigallocatechin, and epicatechin gallate) have been found to inhibit the proliferation of smooth muscle cells lining blood vessels in vitro (estrogens and progesterone also show this antiproliferative action; hence the natural protection against atherosclerosis seen in premenopausal women). Smooth muscle proliferation is one of the crucial processes involved in atherosclerosis and heart disease. One mechanism of the antiproliferative action of catechins is apparently the inhibition of protein tyrosine kinase activity (which is also involved in tumor growth). The authors conclude that "tea catechins may be useful as a template for the development of drugs to prevent the pathological changes of atherosclerosis and post-angioplasty restenosis." (Restenosis is the narrowing of blood vessels after surgery, usually due to the rapid regrowth of plaque.) It seems more logical to use green tea for prevention of atherosclerosis to start with. Green tea lowers fibrinogen, and inhibits excessive clotting and platelet aggregation.
Anderson JW et al. Selective effects of different antioxidants on oxidation of lipoproteins from rats. Proc Soc Exp Biol Med 1998;218:376-81.
Archives of Dermatology, 2000;136:989-994, 1051.
Bravo L, Abia R et al. Degradation of polyphenols (catechin and tannic acid) in the rat intestinal tract. Effect on colonic fermentation and fecal output. Br J Nutr 1994;71:933-46.
Chan MM et al. Inhibition of inducible nitric oxide synthese gene expression and enzyme activity by epigallocatechin gallate, a natural product from green tea. Biochem Pharmacol 1997; 54:1281-86.
Chen ZY, Chan PT. Antioxidant activity of green tea catechins in canola oil. Chem Phys Lipids 1996; 82:163-72.
Chen PC, et al. A green tea-derived polypheol, epigallocatechin-3-gallate, inhibits IkappaB kinase activation and IL-8 gene expression in respiratory epithelium. Inflammation 2002;26:233-41
Choi JH et al. Effects of green tea catechins on hepatic microsomal phospholipase. J Nutr Sci Vitaminol 1998; 44:673-83.
Chung HY et al. Peroxynitrite-scavenging activity of green tea tannin. J Agric Food Chem 1998; 46:4484-86.
Deng ZY, Tao BY, et al. Effect of green tea and black tea on blood glucose, triglycerides, and antioxidants in aged rats. J Agricult Food Chem 1998;46:3875-78.
Dulloo AG, et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr 1999;70:1040
Gomes A et al. Anti-hyperglycemic effect of black tea (Camellia sinensis) in rat. J Ethnopharmacol 1995; 45: 223-26.
Graham HN. Green tea composition, consumption, and polyphenol chemistry. Prev Med 1992;21:334-50
Guo Q et al. Studies on protective mechanisms of four components of green tea polyphenols against lipid peroxidation in synaptosomes. Biochim Biophys Acta 1996; 1304:210-22.
Haqqi, Tariq M., Antioxidants in green tea may prevent and reduce the severity of rheumatoid arthritis, CWRU's School of Medicine study published in the April 13 issue of the Proceedings of the National
Hara Y., Academy of Sciences.Influence of tea catechins on the digestive tract. J Cel Biochem 1997; Suppl 27: 52-58.
Hayashi M et al. Effects of green tea extract on galactosamine-induced hepatic injury in rats. Nippon Yakurigaku Zasshi 1992; 100:391-99.
He YH, Kies C. Green and black tea consumption by humans: impact on polyphenol concentrations in feces, blood, and urine. Plant Foods Hum Nutr 1994; 46:221-9
Huang Y, Zhang AQ, et al. Vasorelaxant effects of purified green tea catechin derivatives in rat mesenteric artery. Life Sciences 1998;63:275-283.
Imai K, Nakachi K. Cross-sectional study of effects of drinking green tea on cardiovascular and liver diseases. BMJ 1995;310:693-96.
Kabuto H et al. Monoamine metabolites, iron induced seizures, and the anticonvulsant effects of tannins. Neurochem Res 1992; 6:585-90.
Kaneko T, Matsuo M, Baba N. Inhibition of linoleic acid hydroperoxide-induced toxicity in cultured human umbilical vein endothelial cells by catechins. Chem Biol Interact 1998; 114:109-19.
Karawya Ms. Et al. Diphenylamine, an antihyperglycemic agent from onion and tea. J Natural Prod 1984; 47:775-80.
Keli SO et al. Dietary flavonoids, antioxidant vitamins, and incidence of stroke: the Zutphen study. Arch Intern Med 1995; 156:637-42.
Kooa, Marcel W.L. and Cho, Chi H. Corresponding Author Contact Information, Department of Pharmacology, Faculty of Medicine, The University of Hong Kong
Kreydiyyeh SI et al. Tea extract inhibits intestinal absorption of glucose and sodium in rats. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol 1994;108:359-65.
Lean ME et al. Dietary flavonols protect diabetic human lymphocytes against oxidative damage to DNA. Diabetes 1999; 48:176-81.
Lin AM et al. The antioxidant property of green tea against iron-induced oxidative stress in rat brain. Chin J Physiol 1998; 41:189-94.
Lin YL, Cheng CY, et al. Hypolipidemic effect of green tea leaves through induction of antioxidant and phase II enzymes including superoxide dismutase, catalase, and glutathione S-transferase in rats. J Agricult Food Chem 1998;46:1893-99.
Lin YL, Lin JK. Epigallocatechin gallate blocks the induction of nitric oxide synthase by downregulating lipopolysaccharide-induced activity of transcription factor nuclear factor-kappaB. Mol Pharmacol 1997; 52:465-72.
Lu LH, Lee SS, Huang HC. Epigallocatechin suppression of proliferation of vascular smooth muscle cells: correlation with c-jun and JNK. Brit J Pharmacol 1998;124:1227-37. Matsuoka Y et al. Ameliorative effects of tea catechins on active oxygen-related nerve cell injuries. J Pharmacol Exp Ther 1995; 274:602-8.
Maron D, et al. Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial. Arch Intern Med. 2003 Jun 23;163(12):1448-53.
Mazzio EA et al. Food constituents attenuate monoamine oxidase activity and peroxide levels in C6 astrocyte cells. Planta Med 1998;64:603-6.
Nakane H, Ono K. Differential inhibition of HIV reverse transcriptase and various DNA and RNA polymerases by some catechin derivatives. Nucleic Acids Symp Ser 1989; (21): 115-16.
Nakao M, Takio S, Ono K. Alkyl peroxyl radical scavenging activity of catechins. Phytochemistry 1998;49:2379-82.
Okello, E. Phytotherapy Research, October 2004; vol 18: pp 624-627. News release, University of Newcastle upon Tyne.
Pannala AS et al. Inhibition of peroxynitrite-mediated tyrosine nitration by catechin polyphenols. Biochem Biophys Res Commun 1997; 232:164-68.
Omara-Otunn, Elizabeth, Retrieved February 11, 2009, The UConn Advance, University of Connecticut, February 2009.
Parshad R, Sanford RR, et al. Protective action of plant polyphenols on radiation-induced chromatid breaks in cultured human cells. Anticancer Res 1998;18:3263-66.
Pricone, Nicholas Perricone, The Wrinkle Cure - The Perricone Prescription, Warner Books; (May 2001).
Pietta P, Simonetti P. Dietary flavonoids and interactions with endogenous antioxidants. Biochem Molec Biol International 1998;44:1069-74.
Plumb GW et al. Antioxidant properties of catechins and proanthocyanidins: effect of polymerization, galloylation and glycosylation. Free Radic Res 1999; 29:351-58.
Quinlan P, Lane J, Aspinall L. Effects of hot tea, coffee and water ingestion on physiological responses and mood: the role of caffeine, water, and beverage type. Psychopharmacology 1997; 134:164-73.
Rasheed A, Haider M. Antibacterial activity of Camellia sinensis extracts against dental caries. Arch Pharm Res 1998;21:348-52.
Sanaka S, Aizawa M, et al. Inhibitory effect of green tea polyphenols on growth and adherence of an oral bacterium, Porphyromonas gingivalis. Biosci Biotechnol Biochem 1996; 60:745-49.
Sato Y et al. Possible contribution of green tea drinking habits to the prevention of stroke. Tohoku J Exp Med 1989; 157:337-43.
Serafini M et al. In vivo antioxidant effect of green and black tea in man. Eur J Clin Nutr 1996;50:28-32.
Soliman KF, Mazzio EA. In vitro attenuation of nitric oxide production in C6 astrocyte cell culture by various dietary compounds. Proc Soc Exp Biol Med 1998; 218:390-97.
Takabayashi F, Harada N. Effects of green tea catechins on cerulein-induced acute pancreatitis in rats. Pancreas 1997; 14:276-79.
Tao P. The inhibitory effects of catechin derivatives on the activities of human immunodeficiency virus reverse transcriptase and DNA polymerases. Chung Kuo 1992; 14:334-38.
Taylor JR, Wilt VM. Probable antagonism of warfarin by green tea. Ann Pharmacother 1999;33:426-8.
Uchida S et al. Effect of epigallocatechin gallate on the life span of stroke-prone spontaneously hypertensive rats. Clin Exp Pharmacol Physiol 1995; Suppl 1: S302-3.
Vinson JA, Dabbagh YA. Tea phenols: antioxidant effectiveness of teas, tea components, tea fractions and their binding with lipoproteins. Nutr Res 1998; 18:1067-75.
Vinson JA, Dabbagh YA. Effect of green and black tea supplementation on lipids, lipid oxidation and fibrinogen in the hamster: mechanisms for the epidemiological benefits of tea drinking. FEBS Let 1998;433:44-46.
Wang H, Wu Y. Inhibitory effect of Chinese tea on N-nitrosation in vitro and in vivo. IARC Sci Publ 1991; 105:546-49.
Yang YC, et al.The protective effect of habitual tea consumption on hypertension. Arch Intern Med. 2004 Jul 26;164(14):1534-40.
Yang FJ et al. Green tea polyphenols block endotoxin-induced tumor necrosis factor alpha production and lethality in murine model. J Nutr 1998; 128:2334-40.
Yang TT, Koo MW. Hypocholesterolemic effects of Chinese tea. Pharmacol Res 1997; 35:505-12.
Yokogoshi H et al. Effect of theanine, r-glutamylethylamide, on brain monoamines and striatal dopamine release in conscious rats. Neurochem Res 1998; 23:667-73.
Yokozawa T et al. In vivo and in vitro studies on the radical scavenging activity of tea. J Agric Food Chem 1998; 46:2143-50.
You S. Study on feasibility of Chinese green tea polyphenols for preventing dental caries. Chung Hua Kou Chiang 1993; 28:197-9.
Zhang J, Kashket S. Inhibition of salivary amylase by black and green teas and their effects on the intraoral hydrolysis of starch. Caries Res 1998: 32:233-38.
Zhao BL et al. Scavenging effect of extracts of green tea and natural antioxidants on active oxygen species. Cell Biophys 1989; 14:175-85.