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      Low dose of green tea catechins improves endothelial function and vascular smooth muscle cell reactivity in obese women


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          BACKGROUND: The high prevalence of obesity in the world is associated with several health problems, with endothelial dysfunction figuring as a frequent feature. We investigated whether low dose consumption of green tea extract (catechins,< 200 mg/day) could modify endothelial function, lipid profile, fasting glucose and insulin, post load plasma glucose, inflammatory/oxidative stress biomarkers and blood pressure in obese women. METHODS: Sixteen obese women with body mass index (BMI) between 30 and 40 Kg/m2, mean age 38 [33-40] years, consumed 600 ml green tea (3 × 200 ml) per day, containing 153.3 mg of catechins and 72.5 mg of caffeine, during three months. Endothelial function was evaluated through venous occlusion plethysmography by increment of peak forearm blood flow (FBF), after 5 min ischemia, during the reactive hyperemia response/baseline FBF. Endothelium-independent vasodilation was analyzed through peak FBF after 0.4 mg sublingual nitroglycerin/baseline FBF. RESULTS: After 3 months, this consumption of green tea reduced BMI from 34.02 to 33.13, and diastolic blood pressure by 4 mmHg. The reactive hyperemia response/baseline FBF improved by 27%, and the endothelium-independent vasodilation by 12%. The blood biochemical profile, where all parameters were within the normal range, remained unaltered. CONCLUSIONS: A low dose of green tea ameliorated the endothelial dysfunction present in obesity, indicating that its consumption should be encouraged in these patients, because endothelial dysfunction is an early marker of atherosclerosis.

          Translated abstract

          RESUMO OBJETIVO: A alta prevalência de obesidade no mundo traz vários problemas de saúde com a disfunção endotelial como um problema frequente. Investigamos se o consumo de baixa dose de extrato de chá verde (catequinas < 200 mg/dia) pode modificar a função endotelial, o perfil lipídico, a glicemia e a insulina de jejum, a glicose plasmática pós carga, todos biomarcadores inflamatórios de estresse oxidativo e a pressão arterial em mulheres obesas. MÉTODOS: Dezesseis mulheres obesas com índice de massa corporal (IMC) entre 30 e 40 kg/m2, com idade média de 38 [33-40] anos, consumiram 600 ml (3 × 200 ml) chá verde por dia, contendo 153,3 mg de catequinas e 72,5 mg de cafeína, durante três meses. A função endotelial foi avaliada através da pletismografia de oclusão venosa por aumento de pico de fluxo sanguíneo no antebraço, após 5 min de isquemia, durante a resposta hiperemia reativa comparada com a condição basal do fluxo sanguíneo de antebraço. A vasodilatação endotélio-independente foi analisada através de pico fluxo sanguíneo de antebraço após 0,4mg de nitroglicerina sublingual vs fluxo basal. RESULTADOS: Após três meses, o consumo de chá verde reduziu o índice de massa corpórea 34,02 de 33,13 e pressão arterial diastólica em 4 mmHg; a resposta de hiperemia reativa vs. fluxo basal de antebraço melhorou em 27%; a vasodilatação endotélio-independente melhorou em 12%; o perfil bioquímico do sangue, onde todos os parâmetros estiveram sempre dentro da faixa de normalidade, permaneceu inalterado. CONCLUSÕES: Uma dose baixa de chá verde melhorou o quadro de disfunção endotelial presente na obesidade, reconhecidamente um marcador precoce da aterosclerose, indicando que o seu consumo deve ser incentivado nesses pacientes.

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          Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study.

          Green tea polyphenols have been extensively studied as cardiovascular disease and cancer chemopreventive agents in vitro and in animal studies. However, the effects of green tea consumption in humans remain unclear. To investigate the associations between green tea consumption and all-cause and cause-specific mortality. The Ohsaki National Health Insurance Cohort Study, a population-based, prospective cohort study initiated in 1994 among 40,530 Japanese adults aged 40 to 79 years without history of stroke, coronary heart disease, or cancer at baseline. Participants were followed up for up to 11 years (1995-2005) for all-cause mortality and for up to 7 years (1995-2001) for cause-specific mortality. Mortality due to cardiovascular disease, cancer, and all causes. Over 11 years of follow-up (follow-up rate, 86.1%), 4209 participants died, and over 7 years of follow-up (follow-up rate, 89.6%), 892 participants died of cardiovascular disease and 1134 participants died of cancer. Green tea consumption was inversely associated with mortality due to all causes and due to cardiovascular disease. The inverse association with all-cause mortality was stronger in women (P = .03 for interaction with sex). In men, the multivariate hazard ratios of mortality due to all causes associated with different green tea consumption frequencies were 1.00 (reference) for less than 1 cup/d, 0.93 (95% confidence interval [CI], 0.83-1.05) for 1 to 2 cups/d, 0.95 (95% CI, 0.85-1.06) for 3 to 4 cups/d, and 0.88 (95% CI, 0.79-0.98) for 5 or more cups/d, respectively (P = .03 for trend). The corresponding data for women were 1.00, 0.98 (95% CI, 0.84-1.15), 0.82 (95% CI, 0.70-0.95), and 0.77 (95% CI, 0.67-0.89), respectively (P<.001 for trend). The inverse association with cardiovascular disease mortality was stronger than that with all-cause mortality. This inverse association was also stronger in women (P = .08 for interaction with sex). In women, the multivariate hazard ratios of cardiovascular disease mortality across increasing green tea consumption categories were 1.00, 0.84 (95% CI, 0.63-1.12), 0.69 (95% CI, 0.52-0.93), and 0.69 (95% CI, 0.53-0.90), respectively (P = .004 for trend). Among the types of cardiovascular disease mortality, the strongest inverse association was observed for stroke mortality. In contrast, the hazard ratios of cancer mortality were not significantly different from 1.00 in all green tea categories compared with the lowest-consumption category. Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer.
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            Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans.

            Current interest in the role of functional foods in weight control has focused on plant ingredients capable of interfering with the sympathoadrenal system. We investigated whether a green tea extract, by virtue of its high content of caffeine and catechin polyphenols, could increase 24-h energy expenditure (EE) and fat oxidation in humans. Twenty-four-hour EE, the respiratory quotient (RQ), and the urinary excretion of nitrogen and catecholamines were measured in a respiratory chamber in 10 healthy men. On 3 separate occasions, subjects were randomly assigned among 3 treatments: green tea extract (50 mg caffeine and 90 mg epigallocatechin gallate), caffeine (50 mg), and placebo, which they ingested at breakfast, lunch, and dinner. Relative to placebo, treatment with the green tea extract resulted in a significant increase in 24-h EE (4%; P < 0.01) and a significant decrease in 24-h RQ (from 0.88 to 0.85; P < 0.001) without any change in urinary nitrogen. Twenty-four-hour urinary norepinephrine excretion was higher during treatment with the green tea extract than with the placebo (40%, P < 0.05). Treatment with caffeine in amounts equivalent to those found in the green tea extract had no effect on EE and RQ nor on urinary nitrogen or catecholamines. Green tea has thermogenic properties and promotes fat oxidation beyond that explained by its caffeine content per se. The green tea extract may play a role in the control of body composition via sympathetic activation of thermogenesis, fat oxidation, or both.
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              Green tea extract reduces blood pressure, inflammatory biomarkers, and oxidative stress and improves parameters associated with insulin resistance in obese, hypertensive patients.

              Green tea (GT) consumption is known to be associated with enhanced cardiovascular and metabolic health. The purpose of this study is to examine the hypothesis that supplementation with GT alters insulin resistance and associated cardiovascular risk factors in obese, hypertensive patients. In a double-blind, placebo-controlled trial, 56 obese, hypertensive subjects were randomized to receive a daily supplement of 1 capsule that contained either 379 mg of GT extract (GTE) or a matching placebo, for 3 months. At baseline and after 3 months of treatment, the anthropometric parameters, blood pressure, plasma lipid levels, glucose levels, creatinine levels, tumor necrosis factor α levels, C-reactive protein levels, total antioxidant status, and insulin levels were assessed. Insulin resistance was evaluated according to the homeostasis model assessment-insulin resistance protocol. After 3 months of supplementation, both systolic and diastolic blood pressures had significantly decreased in the GTE group as compared with the placebo group (P < .01). Considerable (P < .01) reductions in fasting serum glucose and insulin levels and insulin resistance were observed in the GTE group when compared with the placebo group. Serum tumor necrosis factor α and C-reactive protein were significantly lower, whereas total antioxidant status increased in the GTE group compared with the placebo (P < .05). Supplementation also contributed to significant (P < .05) decreases in the total and low-density lipoprotein cholesterol and triglycerides, but an increase in high-density lipoprotein cholesterol. In conclusion, daily supplementation with 379 mg of GTE favorably influences blood pressure, insulin resistance, inflammation and oxidative stress, and lipid profile in patients with obesity-related hypertension. Copyright © 2012 Elsevier Inc. All rights reserved.

                Author and article information

                Role: ND
                Role: ND
                Role: ND
                Role: ND
                Role: ND
                Role: ND
                MedicalExpress (São Paulo, online)
                Mavera Edições Técnicas e Científicas Ltda
                October 2014
                : 1
                : 5
                : 262-267
                [1 ] Universidade do Estado do Rio de Janeiro Brazil
                [2 ] Universidade de São Paulo Brazil
                [3 ] Apis Flora Indl. Coml. Ltda. Brazil

                This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.


                SciELO Brazil

                Self URI (journal page): http://www.scielo.br/scielo.php?script=sci_serial&pid=2358-0429&lng=en

                Health & Social care
                Obesity,green tea,microcirculation,venous occlusion plethysmography,endothelial function


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