Antioxidant Activity of Green Tea and The Wise Herb Company Drinks
Antioxidant Activity of Green Tea, Health Benefits and relation to amounts of Green Tea in The Wise Herb Company Products
Luo et al, have assessed the antioxidant effect of green tea and compared it with equimolar concentrations of vitamins C and E by the in-vitro LDL oxidation method (11). A classic metal chelator edetic acid (EDTA) was used to elucidate the possibility of anti-oxidisability of Green Tea polyphenols by metal chelation. Results clearly demonstrate the antioxidant power of green tea extract standardised for polyphenolic content (the minimum concentration of green tea extract used was 0·25 μmol/L). The antioxidant effect of green tea was greater than vitamin C, but equivalent to vitamin E on a molar basis, and the antioxidant effect of Green Tea was not attributable to metal chelation. These findings are relevant to antioxidant usage and safety since green tea is a natural antioxidant that has been used in traditional cultures such as India, China and Japan – and relevant to the safety concerns about nutrient supplements such as vitamin C, vitamin E, and β-carotene.
From The Lancet (Lancet 2004 Sep 18; 364(9439):1021-2.) :
Green Tea (1) has been considered by many cultures including the Chinese and Indian help with the maintenance of health and even endowed with the power to prolongue life. Recently, Lee et al (2) studied the effects of the main active Green Tea component, epigallocatechin-3 gallate (EGCG) on chronic lymphocytic leukaemia B cells isolated from leukaemic patients. These cells are characterised by their resistance to apoptosis because they secrete and bind vascular endothelial growth factor (VEGF), a potent cytokine that also acts as a crucial survival factor for tumour cells. The investigators indicated that addition of EGCG to these cells markedly decreased VEGF-receptor phosphorylation, leading to the disruption of the VEGF-dependent autocrine pathway that protects the cells from apoptosis and cell death.
These results support other results (3) via the inhibition of the activity of VEGF-receptor tyrosine kinase by components of Green Tea, and provide support evidence that this inhibitory property may have repercussions on tumours that depend on this cytokine for progression. VEGF-receptor activity was inhibited (3) and apoptosis of leukaemia B cells can be induced (2) with concentrations of EGCG in the plasma after moderate drinking of green tea (2-4 cups a day) (4) . These findings raise the interesting possibility that green tea could be used as a combination agent for treating leukaemia.
VEGF is also crucially important to tumour angiogenesis, the process by which tumours grow and invade surrounding host tissues(5). In the initial phases of tumour growth, angiogenesis by low-dose delivery of EGCG, as seen in vitro, (3-7) could thus have beneficial in-vivo effects against several other types of cancer. This mechanism also provides a strong scientific basis for the chemopreventive property of green tea that has been inferred from several epidemiological studies which showed that frequent drinking of green tea is inversely associated with the risk of developing several types of human cancer, such as oesophageal cancer.(8)
With the notable exception of the use of retinoic acid for the treatment of promyelocytic leukaemia, (9) the importance of nutraceuticals in cancer prevention and treatment remains largely under-exploited. Green tea and other diet-dervived compounds, (10) offer advantages as anticancer products, because these compounds are non-toxic, produce few side effects, are widely available, and are cheap. Recent studies on cognitive function also suggest that Green Tea Polyphenols possibly protect against Parkinson’s and Alzheimer’s diseases and other neurodegenerative diseases (15,16). Green Tea polyphenols have demonstrated neuro-protectant activity in cell cultures and animal models, such as the prevention of neurotoxin-induced cell injury; the biological effects of Green Tea components may benefit patients with Parkinson’s disease. Other benefits which have been documented are Cardiovascular Health, Bone Health and Weight Loss amongst other positive benefits.
Amounts of Bioactives found in Green Tea typically and what to be expected in The Wise Herb Company’s Drinks:
According to Luo et al (11) each cup of green tea (100 mL) typically contains 50 -100 mg of polyphenols (12) equal to 1·6 – 3·2 mmol/L, which would be 6300 -12 600 times higher than the dose used in this in-vitro LDL oxidation study. Therefore, if completely absorbed, as little as one cup of green tea per day may provide an adequate intake of antioxidant polyphenols. In The Wise Herb Company’s products this is typically around 1 g (grams) of Green Tea. This equates to half the recommended amount (2g) of green tea needed to make a 100 ml cup. So, it is expected that the level of polyphenols and therefore antioxidants would be around 25-50 mg per cup.
According to Cabrera et al, (13) Polyphenols constitute the most interesting group of Green Tea leaf components, and in consequence, green tea can be considered an important dietary source of polyphenols, particularly flavonoids. Flavonoids are phenol derivatives synthesized in substantial amounts (0.5–1.5%) and more than 4000 identified. United States Department of Agriculture (USDA) has recently published a Database for the Flavonoid Content of Selected
Foods (14). The main flavonoids present in green tea include catechins (flavan-3-ols). The four major catechins are (-)- epigallocatechin-3-gallate (EGCG), that represents approximately 59% of the total of catechins; (-)-epigallocatechin (EGC) (19% approximately); (-)-epicatechin-3-gallate (ECG) (13.6% approximately); and (-)-epicatechin (EC) (6.4% approximately) . Green tea also contains gallic acid (GA) and other phenolic acids such as chlorogenic acid and caffeic acid, and flavonols such as kaempferol, myricetin and quercetin . The authors state that a substantial number of human intervention studies with Green Tea demonstrate a significant increase in plasma antioxidant capacity in humans after consumption of moderate amounts (1–6 cups/day). This would be equivalent to a minimum of 2 cups of one of our natural infusions (CALM&RELAX, SLIM&FIT, UP&GO, YOUNG&FUN).
In terms of Flavonols (Quercetin, Kaempferol and Myricetin) Green Tea has between 19 and 47 mg / L. In terms of the infusions this equates to approximately 1 and 2.5 mg of flavonols per 100 ml cup of one of our natural health drinks. (17)
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2. Lee YK, Bone ND, Strege AK, Jelinek DF, Kay NE. VEGF receptor phospho- rylation status and apoptosis is modulated by a green tea component, epi- gallocatechin-3-gallate (EGCG) in B cell chronic lymphocytic leukemia. Blood. 2004;104:788-94.
3. Lamy S, Gingras D, Beliveau R. Green tea catechins inhibit vascular endothelial growth factor receptor phosphorylation. Cancer Res. 2002;62:381-5.
4. Pisters KM, Newman RA, Coldman B, et al. Phase I trial of oral green tea extract in adult patients with solid tumors. J Clin Oncol. 2001 Mar 15;19(6):1830-8.
5. Folkman J. Fundamental concepts of the angiogenic process. Curr Mol Med. 2003;3:643-51.
6. Bergers G, Song S, Meyer-Morse N, Bergsland E, Hanahan D. Benefits of targeting both pericytes and endothelial cells in the tumor vasculature with kinase inhibitors. J Clin Invest. 2003;111:1287-95.
7. Cao Y, Cao R. Angiogenesis inhibited by drinking tea. Nature. 1999;398:381.
8. Gao TY, McLaughlin JK, Blot WJ, Ji BT, Dai Q, Fraumeni JF, Jr. Reduced risk of esophageal cancer associated with green tea consumption. J Natl Cancer Inst. 1994;86:855-8.
9. de Botton S, Coiteux V, Chevret S. Outcome of childhood acute promyelo- cytic leukemia with all-trans-retinoic acid and chemotherapy. J Clin Oncol. 2004;22:1404-12.
10. Gescher AJ, Sharma Ra, Steward WP. Cancer chemoprevention by dietary constituents: a tale of failure and promise. Lancet Oncol. 2001;2:371-9.
11. M Luo, K Kannar, ML Wahlqvist, RC O’Brien The Lancet, Volume 349, Issue 9048, Pages 360 – 361, 1 February 1997
12. Sakanaka S, Kim M, Taniguchi M, Yamamoto T. Antibacterial substances in Japanese green tea extract against streptococcus mutans, a cariogenic bacterium. Agric Biol Chem 1989; 53: 2307-2311
13. Carmen Cabrera, Reyes Artacho, Rafael Giménez. J Am Coll Nutr April 2006 vol. 25 no. 2 79-99
14. USDA: “USDA Database for the Flavonoid Contents of Selected Foods.” Beltsville: US Department of Agriculture, 2003
15. Pan TH, Jankovic J, Le WD: Potential therapeutic properties of green tea polyphenols in Parkinson’s disease. Drugs Aging 20: 711–721, 2003.
16. Weinreb O, Mandel S, Amit T, Youdim MB: Neurological mechanisms of green tea polyphenols in Alzheimer’s and Parkinson’s diseases. J Nutr Biochem 15:506–516, 2004.
17. Michael G. L. Hertog, Peter C. H. Hollman, Betty. van de Putte. Content of potentially anticarcinogenic flavonoids of tea infusions, wines, and fruit juices. J. Agric. Food Chem., 1993, 41 (8), pp 1242–1246.