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heart-health
According to Harvard Medical School, “lowering your risk of cardiovascular disease may be as easy as drinking green tea. Studies suggest this light, aromatic tea may lower LDL cholesterol and triglycerides, which may be responsible for the tea's association with reduced risk of death from heart disease and stroke.”
Recent Research Papers on
heart-health
The effect of green tea on blood pressure and lipid profile: A systematic review and meta-analysis of randomized clinical trials
Author: I. Onakpoya and E. Spencer and C. Heneghan and M. Thompson
Introduction Many different dietary supplements are currently marketed for the management of hypertension, but the evidence for effectiveness is mixed. The aim of this systematic review was to evaluate the evidence for or against the effectiveness of green tea (Camellia sinensis) on blood pressure and lipid parameters. Methods and results Electronic searches were conducted in Medline, Embase, Amed, Cinahl and the Cochrane Library to identify relevant human randomized clinical trials (RCTs). Hand searches of bibliographies were also conducted. The reporting quality of included studies was assessed using a checklist adapted from the CONSORT Statement. Two reviewers independently determined eligibility, assessed the reporting quality of the included studies, and extracted the data. As many as 474 citations were identified and 20 RCTs comprising 1536 participants were included. There were variations in the designs of the RCTs. A meta-analysis revealed a significant reduction in systolic blood pressure favouring green tea (MD: −1.94 mmHg; 95% CI: −2.95 to −0.93; I2 = 8%; p = 0.0002). Similar results were also observed for total cholesterol (MD: −0.13 mmol/l; 95% CI: −0.2 to −0.07; I2 = 8%; p < 0.0001) and LDL cholesterol (MD: −0.19 mmol/l; 95% CI: −0.3 to −0.09; I2 = 70%; p = 0.0004). Adverse events included rash, elevated blood pressure, and abdominal discomfort. Conclusion Green tea intake results in significant reductions in systolic blood pressure, total cholesterol, and LDL cholesterol. The effect size on systolic blood pressure is small, but the effects on total and LDL cholesterol appear moderate. Longer-term independent clinical trials evaluating the effects of green tea are warranted.
Green tea decoction improves glucose tolerance and reduces weight gain of rats fed normal and high-fat diet
Author: Chahira Snoussi and Robert Ducroc and Mohamed Hédi Hamdaoui and Karima Dhaouadi and Houda Abaidi and Francoise Cluzeaud and Corinne Nazaret and Maude Le Gall and André Bado
Green tea containing polyphenols exerts antidiabetic and antiobesity effects, but the mechanisms involved are not fully understood. In this study, we first analyzed and compared polyphenol compounds [epigallocatechin gallate (EGCG), epigallocatechin (EGC)] in decoction of green tea leaves versus usual green tea extracts. Second, the effects of acute (30 min) or chronic (6 weeks) oral administration of green tea decoction (GTD) on intestinal glucose absorption were studied in vitro in Ussing chamber, ex vivo using isolated jejunal loops and in vivo through glucose tolerance tests. Finally, we explore in rat model fed normal or high-fat diet the effects of GTD on body weight, blood parameters and on the relative expression of glucose transporters SGLT-1, GLUT2 and GLUT4. GTD cooked for 15 min contained the highest amounts of phenolic compounds. In fasted rats, acute administration of GTD inhibited SGLT-1 activity, increased GLUT2 activity and improved glucose tolerance. Similarly to GTD, acute administration of synthetic phenolic compounds (2/3 EGCG+1/3 EGC) inhibited SGLT-1 activity. Chronic administration of GTD in rat fed high-fat diet reduced body weight gain, circulating triglycerides and cholesterol and improved glucose tolerance. GTD-treated rats for 6 weeks display significantly reduced SGLT-1 and increased GLUT2 mRNA levels in the jejunum mucosa. Moreover, adipose tissue GLUT4 mRNA levels were increased. These results indicate that GTD, a traditional beverage rich in EGCG and EGC reduces intestinal SGLT-1/GLUT2 ratio, a hallmark of regulation of glucose absorption in enterocyte, and enhances adipose GLUT4 providing new insights in its possible role in the control of glucose homeostasis.
Green tea supplementation in mice mitigates senescence-induced changes in brain antioxidant abilities
Author: Yu-Wen Hsu and Chia-Fang Tsai and Hung-Chih Ting and Wen-Kang Chen and Cheng-Chieh Yen
Catechin composition of green tea extract and its anti-senescence effect was investigated with a study of senescence-related redox imbalance in the brains of aged mice. Oral administration of green tea extract at doses of 125, 625 and 1250 mg/kg for 4 weeks alleviated the senescence-mediated redox imbalance, as observed from the significantly reduced (p < 0.05) levels of thiobarbituric acid-reactive substances (TBARS) in the serum and increased glutathione (GSH) and total thiol levels in the plasma compared with that in the aged control group. Moreover, the activities of superoxide dismutase (SOD), catalase, glucose-6-phosphate dehydrogenase (G6PD), glutathione peroxidase (GSH-Px) and glutathione reductase (GSH-Rd) in the brain were also increased, whereas protein carbonyls were reduced. Taken together, these results clearly indicate that green tea extract exhibits potent protective effects against senescence-mediated redox imbalance in the brains of mice by inhibiting oxidative damage and increasing antioxidant enzyme activities.
Influence of in vitro simulated gastroduodenal digestion on the antibacterial activity, metabolic profiling and polyphenols content of green tea (Camellia sinensis)
Author: Anna Marchese and Erika Coppo and Anatoly P. Sobolev and Daniela Rossi and Luisa Mannina and Maria Daglia
The antistaphylococcal activity as well as the metabolic profiling and polyphenols content of green tea (Camellia sinensis) before and after in vitro simulated gastric, duodenal and gastroduodenal digestion were investigated. Gastric and duodenal digested samples showed antistaphylococcal activity, whereas gastroduodenal digested samples did not show any antibacterial activity. Metabolite analysis, carried out using an explorative untargeted NMR-based approach and a RP-HPLC-PAD-ESI–MSn method, showed that green tea polyphenols are stable under gastric conditions. Duodenal digested sample maintained the antibacterial activity, even if some polyphenols are widely degraded. Epicatechin 3-gallate, under duodenal digestive conditions, is hydrolyzed to produce epicatechin, whereas epigallocatechin 3-gallate reacts with digestive enzymes and a galloyl-high molecular weight derivative is produced. Gastroduodenal digestion results in degradation of polyphenols, especially gallocatechins, considered the main responsible for the antibacterial activity. These results explain the loss of activity of gastroduodenal digested samples and why in vivo green tea has neither protective nor therapeutic effects against intestinal and systemic bacterial infections.
Effect of consumption of catechin-rich green tea on pharmacokinetics of simvastatin in healthy volunteers
Author: S. Yamada and S. Misaka and K. Tanabe and A. Osano and K. Takeuchi and J.P. Werba and H. Watanabe
Background and purpose: Green tea has been reported to have various health benefits including cancer prevention and antiox- idative effect. Catechins, the main flavonoids in green tea, are considered to be potential components of these effects. Recently, a case report suggested that the consumption of catechin-rich green tea is associated with simvastatin intolerance. The present study aimed to evaluate the effect of catechin-rich green tea consumption on the pharmacokinetics of simvastatin lactone (SIM) and simvas- tatin acid (SVA), which are a prodrug and an active metabolite of simvastatin, respectively. Methods: In an open-label, two-way crossover study with 14 days washout, a single oral dose of 10mg SIM was administered to 12 healthy Japanese male volunteers (23–26 years old; body weight, 65.1±2.4 kg) after drinking of green tea (700mL/day, total catechinsof1080mg)orwater for2weeks. Bloodsampleswerecol- lected up to 24h after the administration. Plasma concentrations of SIM and SVA were determined using LC/MS/MS. Pharmacokinetic parameters were estimated by noncompartmental analysis. Results and discussion: Chronic consumption of catechin- rich green tea led to increases in the area under the plasma concentration-time curve (AUC0–∞) andmaximum concentration (Cmax) of SIM by 1.6- and 1.3-folds, respectively, as compared to water. No change was observed in the elimination half-life of SIM between green tea andwater, indicating that catechinsmainlymay inhibit SIMmetabolism in the intestine. In addition, green tea con- sumption significantly increased AUC0–∞ and Cmax of SVA by 1.5 and 1.6-folds, respectively, suggesting that green teamay affect not only the pharmacokinetics, but also the pharmacodynamics of SVA. Conclusion: The chronic consumption of catechin-rich green tea may cause the clinically relevant interaction with simvastatin.
Memory deficits and oxidative stress in cerebral ischemia–reperfusion: Neuroprotective role of physical exercise and green tea supplementation
Author: Helen L. Schimidt and Aline Vieira and Caroline Altermann and Alexandre Martins and Priscila Sosa and Francielli W. Santos and Pâmela B. Mello-Carpes and Ivan Izquierdo and Felipe P. Carpes
Ischemic stroke is a major cause of morbidity and mortality all over the world. Among impairments observed in survivors there is a significant cognitive learning and memory deficit. Neuroprotective strategies are being investigated to minimize such deficits after an ischemia event. Here we investigated the neuroprotective potential of physical exercise and green tea in an animal model of ischemia–reperfusion. Eighty male rats were divided in 8 groups and submitted to either transient brain ischemia–reperfusion or a sham surgery after 8 weeks of physical exercise and/or green tea supplementation. Ischemia–reperfusion was performed by bilateral occlusion of the common carotid arteries during 30 min. Later, their memory was evaluated in an aversive and in a non-aversive task, and hippocampus and prefrontal cortex were removed for biochemical analyses of possible oxidative stress effects. Ischemia–reperfusion impaired learning and memory. Reactive oxygen species were increased in the hippocampus and prefrontal cortex. Eight weeks of physical exercise and/or green tea supplementation before the ischemia–reperfusion event showed a neuroprotective effect; both treatments in separate or together reduced the cognitive deficits and were able to maintain the functional levels of antioxidant enzymes and glutathione.
Green tea and type 2 diabetes
Author: Jae-Hyung Park and Jae-Hoon Bae and Sung-Soon Im and Dae-Kyu Song
Green tea and coffee consumption have been widely popular worldwide. These beverages contain caffeine to activate the central nervous system by adenosine receptor blockade, and due to the caffeine, addiction or tolerance may occur. In addition to this caffeine effect, green tea and coffee consumption have always been at the center of discussions about human health, disease, and longevity. In particular, green tea catechins are involved in many biological activities such as antioxidation and modulation of various cellular lipid and proteins. Thus, they are beneficial against degenerative diseases, including obesity, cancer, cardiovascular diseases, and various inflammatory diseases. Some reports also suggest that daily consumption of tea catechins may help in controlling type 2 diabetes. However, other studies have reported that chronic consumption of green tea may result in hepatic failure, neuronal damage, and exacerbation of diabetes, suggesting that interindividual variations in the green tea effect are large. This review will focus on the effect of green tea catechins extracted from the Camellia sinensis plant on type 2 diabetes and obesity, and the possible mechanistic explanation for the experimental results mainly from our laboratory. It is hoped that green tea can be consumed in a suitable manner as a supplement to prevent the development of type 2 diabetes and obesity.
Survival and metabolic activity of probiotic bacteria in green tea
Author: A.M. López de Lacey and E. Pérez-Santín and M.E. López-Caballero and P. Montero
The aim of this study was to determine the enzymatic activity and survival of three probiotic strains (Lactobacillus paracasei LAFTI-L26, Lactobacillus acidophilus LAFTI-L10 and Bifidobacterium animalis ssp. lactis LAFTI-B94) during incubation in six different varieties of green tea extracts. The polyphenol content, antioxidant, antimicrobial and antihypertensive properties in green tea (variety Wu Lu Mountain) and in two standards (epigallocatechin-3-gallate and rutin) were also investigated before and after incubation with B. animalis B94. The green tea extracts permitted the survival of the selected probiotic strains better than the saline solution, with B. animalis B94 maintaining the highest levels of viable cells. These selected probiotic bacteria exhibited β-glucosidase, β-galactosidase and α-rhamnosidase activity. The antioxidant and antihypertensive properties of standard solutions of epigallocatechin-3-gallate and rutin increased after incubation with B. animalis B94, caused by polyphenol content reduction and the formation of other more highly biologically active metabolites. However, during the incubation of green tea with B. animalis B94, changes in the concentration of the most abundant green tea polyphenols did not enhance the biological activity.
Effect of defined green tea extract in various dosage schemes on drug-metabolizing enzymes in mice in vivo
Author: Petra Matoušková and Hana Bártíková and Iva Boušová and Barbora Szotáková and Jan Martin and Jana Skorkovská and Veronika Hanušová and Veronika Tománková and Eva Anzenbacherová and Barbora Lišková and Pavel Anzenbacher and Lenka Skálová
Green tea represents a favourite beverage and green tea extracts are popular components of dietary supplements. The aim of present in vivo study was to report on the effect of defined green tea extract (Polyphenon) in various dosage schemes on drug-metabolizing enzymes in mice. The specific activities and expressions of a panel of drug-metabolizing enzymes (totally 16) were tested in liver and small intestine. Nine enzymes were significantly altered by Polyphenon treatment. The intestinal enzymes were more affected than the hepatic ones. The effects were mostly dose-dependent but short-term treatment had more pronounced impact than the long-term administration. Based on the results, normal consumption of green tea seems to be safe but extremely high doses of green tea extracts in dietary supplements could influence drugs metabolism and efficacy.
Association of green tea consumption with risk of coronary heart disease in Chinese population
Author: Jun Pang and Zheng Zhang and Tongzhang Zheng and Yue-jin Yang and Na Li and Min Bai and Yu Peng and Jin Zhang and Qiang Li and Bo Zhang
Tea is a kind of popular beverage in the world [1,2]. According to the published researches, tea could be beneficial to one's health, such as reduction of the incidence of hyperlipidemia, atherosclerosis and antioxidant [3]. However, whether the green tea could be beneficial to reduce the risk of coronary heart disease (CHD) is pending in Chinese population, so our study is to find the association between the green tea consumption and CHD in Chinese general population.
Other Popular Research Topics
Cognitive Function
Matcha consumption leads to much higher intake of green tea phytochemicals compared to regular green tea. Previous research on caffeine, L-theanine, and epigallocatechin gallate (EGCG) repeatedly demonstrated benefits on cognitive performance.
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Mental Health
Matcha contains an amino acid called L-theanine, which has been shown to reduce physiological and psychological stresses. L-theanine also improves cognition and mood in a synergistic manner with caffeine, and promotes alpha wave production in the brain
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Cancer Prevention
Matcha/green tea has for many centuries been regarded as an essential part of good health in Japan and China. Many believe it can help reduce the risk of cancer, and a growing body of evidence backs this up.
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Immunity
A recent study in the journal Proceedings of the National Academy of Sciences concluded that drinking matcha daily greatly enhanced the overall response of the immune system. The exceedingly high levels of antioxidants in matcha mainly take the form of polyphenols, catechins, and flavonoids, each of which aids the body’s defense in its daily struggles against free radicals that come from the pollution in your air, water and foods.
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