Effect Of Green Tea Consumption Research Articles

Impact of Green Tea Consumption on the Prevalence of Cardiovascular Outcomes: A Systematic Review.

Cardiovascular diseases (CVDs) represent a major global health concern, responsible for significant morbidity, mortality, and disability. To mitigate the impact of CVDs, individuals often seek preventive measures, and one such approach is the consumption of green tea. This study aims to provide a comprehensive and up-to-date assessment of the effects of green tea consumption on the prevalence of cardiovascular outcomes. Following PRISMA guidelines, we conducted a systematic review using PubMed and Google Scholar databases to identify relevant studies. Our analysis revealed that the risk factors associated with CVDs can vary across different diseases, with hypertension being a common risk factor for CVD mortality and CVD. Notably, the consumption of green tea exhibited a positive effect on reducing the prevalence of cardiometabolic risks and hypercholesterolemia. Furthermore, green tea consumption was observed to have a beneficial impact on lowering both diastolic and systolic blood pressure. In conclusion, the studies reviewed in this research suggest that the consumption of green tea has a significant and positive influence on cardiovascular health. These findings highlight the potential of green tea as a valuable component of a healthy lifestyle, offering a promising avenue for its use as a dietary supplement to reduce the risk of CVDs.

Effects of green tea catechins and exercise training on body composition parameters

The impact of phytochemicals, as green tea catechins, on body composition measures has become a relevant topic as ongoing epidemiological evidence suggests their potential role in weight loss. Although catechins have been shown to modulate fat and energy metabolism, clinical effects of green tea consumption still remain controversial. Given the role played by physical exercise in weight management, it is important to determine whether the association of catechins and exercise is able to improve outcomes over and above the beneficial effects of exercise alone. Considering that scientific findings on this topic are not entirely consistent, aim of the present review was to assess the current scientific literature regarding the interplay between green tea catechins and exercise in overweight and obese populations. In particular, it was evaluated whether the addition of green tea supplementation to exercise training was able to further improve the exercise‐induced changes in body composition parameters.

THE ASSOCIATION BETWEEN KNOWLEDGE OF DIETARY BENEFITS OF GREEN TEA AND ITS CONSUMPTION ON PERCEPTIONS OF BODY WELL- BEING AMONG NURSING STUDENTS IN UNIKL-RCMP, IPOH, PERAK


 
 
 This study was conducted to determine the level of knowledge of the benefit of green tea consumption and its association with perceptions of body well-being among nursing students in UniKL-RCMP, Ipoh, Perak. A stratified random sampling technique was applied to get samples. The data was collected by using an online survey (Google Forms) which comprises sociodemographic characteristics, knowledge of the beneficial effects of green tea consumption, consumption of green tea intake and perceptions of general well-being. 53.4% of the respondents were found to have high knowledge of the beneficial effects of green tea intake and 85.8% had drunk it. Female nurses significantly consumed more green tea (87.8%) as compared to males (57.1%). There was a significant association between level of knowledge and perception of body well-being. 86.3% of nurses having a high knowledge of the beneficial effects of green tea consumption had a good perception of their body well-being, however, no significant association was found between green tea intake and perception of body wellbeing. In conclusion, most of the nursing students were knowledgeable about the dietary effects of green tea consumption, however, the positive benefits of green tea intake have not yet been seen in the present study.
 
 

Therapeutic effectiveness of green tea leaf extract on clinical symptoms in children suffering viral gastroenteritis: A randomized clinical trial.

The use of tea plant extract has been reported to reduce viral complications, but its role in improving viral gastritis has not been investigated. The aim of this randomized clinical trial was to evaluate the effect of green tea consumption in improving pediatric viral gastroenteritis. This clinical trial study was performed on children aged 12 to 17 years with diarrhea who were not treated within 48 hours of the onset of clinical symptoms during September 2019 to September 2020. The children were randomly assigned to a green tea leaf extract (GTE) tablet. The placebo group was considered as a control. Treatment (prescribing the tablets) was continued until a Bristol Stool Scale of 3 or 4 was obtained. Two groups were compared in terms of clinical symptoms. The complete and partial improvement was revealed in 63.2% and 31.6% respectively in the GTE group while only in 15.8% and 57.9% respectively in control group indicating a significant difference (p <0.001). The increase in the number of tablets led to higher improvement rate in response to GTE prescription. The mean hospital stay in GTE and control groups was also 1.66 ± 0.63 days and 3.36 ± 0.4 days indicated shorter hospitalization in former group (p < 0.001). The use of GTE leads to effectively improve the diarrhea as well as to reduce the hospital stay in children suffering viral gastroenteritis.

The interaction effect of green tea consumption and exercise training on fat oxidation, body composition and blood lipids in humans: a review of the literature

The interaction effect of green tea consumption and exercise training on fat oxidation, body composition and blood lipids in humans: a review of the literature

The Effects of Green Tea Consumption during Pregnancy on the Cytokeratin-18 in Maternal and Neonatal Hepatocytes in Rats

Amaç: Bu çalışmada, gebelikleri süresince yeşil çay ekstraktıyla beslenen sıçanların ve yavrularının karaciğer dokularında sSitokeratin-18 (SK-18) düzey ve ekspresyonunu değerlendirmek amaçlanmıştır.Yöntem: On sekiz adet Wistar albino gebe sıçan, iki gruba ayrıldı: kontrol grubu ve (oral gavaj ile 50 mg/kg yeşil çay ekstraktı verilenuygulanan) yeşil çay grubu. Yirmi bir günlük gebelikten sonra, her iki gruptaki anne sıçanların ve doğdukları ilk gün yavruların karaciğer dokuları çıkarıldı. Bu doku örneklerinde SK-18 ekspresyonu ve düzeyi immünohistokimyasal olarak ve enzime bağlı immünosorbent analiz (ELISA) ile değerlendirildi.Bulgular: İki grupta da maternal dokularda santral venlerin çevresindeki hepatositlerin hücre zarları yakınında kuvvetli SK-18 immünoreaksiyonu gözlendi. Kontrol grubu yenidoğan dokularında santral ven çevresindeki hepatositlerde zayıf SK-18 immünoreaksiyonu gözlenirken, yeşil çay grubunda hepatositlerin hücre zarı yakınında oldukça kuvvetli SK-18 immünoreaksiyonu gözlendi. Biyokimyasal incelemede de, maternal SK-18 düzeyleri her iki grupta da yüksek olup birbirinden istatistiksel olarak anlamlı farklılık göstermezken, neonatal SK-18 düzeyleri kontrol grubuna kıyasla yeşil çay grubunda anlamlı biçimde daha yüksekti.Sonuç: İmmünohistokimya ve ELISA sonuçlarımız gebelik süresince maternal yeşil çay tüketiminin yenidoğan karaciğerinde hücre hasarına neden olabileceğini düşündürmektedir.

Sex differences in the association between green tea consumption and hypertension in elderly Chinese adults

BackgroundGreen tea has been one of the most popular beverages in China since ancient times. Mixed results concerning the effect of green tea consumption on the incidence of hypertension have been published over the past decades. However, no previous studies have focused on longevous individuals in China and the sex differences in the association between habitual green tea intake and hypertension.MethodsThe data extracted from the database of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) in 2018 were used for a secondary analysis. Logistic regression models were employed to examine the odds ratio (OR) of daily green tea consumption on the incidence of hypertension by sex.ResultsA total of 9277 individuals were included in the analysis (39.8% were men). The included individuals had a mean age of 80.9 and 84.8 years for those who drank green tea daily and those who had never, respectively (p < 0.001). The incidence of hypertension varied at baseline according to green tea drinking habit and sex. For women who had a habitual green tea intake or had never drunk green tea, the incidence of hypertension was 47.3 and 43.9%, respectively (p = 0.241), whereas it was 51.6 and 39.7% for men (p < 0.001). After adjusting for potential confounders, a 38% increase in the risk of hypertension was observed in men who consumed green tea daily (OR, 1.38; 95% CI, 1.15–1.67; p < 0.001).ConclusionsChinese longevous men had a 38% higher risk of developing hypertension when drinking green tea daily. However, no effect of green tea consumption on the incidence of hypertension in women was found. More attention should be paid to the lifestyle of longevous individuals for health promotion, and a sex-specific approach to deliver care for very elderly people is warranted.

The Effect of Green Tea Drinking on the Depression of Elderly People

The world’s older population continues to grow at an unprecedented rate. Iran is 1 of the countries where the aging population is higher than the global average. Depression is 1 of the most common issues in older adults that can be managed by nonpharmacologic interventions such as the consumption of green tea. The aim of this study was to determine the effect of green tea consumption on depression in the elderly people. In this quasi-experimental study, 76 elderly people who were residents in a nursing home and met the inclusion criteria were selected through simple random sampling. Then, green tea in 3-g tea bags was brewed in 80°C water and half an hour after breakfast and lunch was given to the participants in a 5-week protocol. One day after the last time of brewing green tea, participants were assessed with a standard depression questionnaire. The obtained data were analyzed using SPSS Version 19 software (IBM Corp, Armonk, NY). The descriptive statistics and Wilcoxon statistical test analysis were also conducted at a significant level of P < .05. Based on the findings, the mean score of the participants’ depression level decreased by 2.5 points after the intervention, which is statistically significant at a 99.9% confidence interval (P = .001). The findings also suggest that the severe depression decreased from 23.6% to 11.1%, moderate depression decreased from 45.8% to 26.4%, and mild depression increased from 30.6% to 45.8%; only severe and moderate depression cases were reduced (P = . 001). The findings of the present study reveal that regular consumption of green tea can lead to a considerable reduction of depression in the elderly people. Accordingly, the consumption of this tea in the elderly people’s diet is recommended, especially those who are resident in the care centers.

Interaction effect of green tea consumption and resistance training on office and ambulatory cardiovascular parameters in women with high-normal/stage 1 hypertension.

This study aimed to investigate the chronic effects of green tea (GT) extract and resistance training (RT) on ambulatory and office blood pressure (BP), heart rate (HR), and rate‐pressure product (RPP) in a sample of Iranian women with high‐normal/stage 1 hypertension. Forty‐four middle‐aged sedentary women participated in this randomized, double‐blind, placebo‐controlled study. They were randomly assigned to one of four groups: GT and RT (GR, n = 11), RT (n = 10), GT (n = 10), or control (n = 13). Three weeks of GT consumption were followed by six weeks of the interaction with RT. GR and RT groups performed two circuits of RT at %50 of 1RM two days per week. RT and control groups also received placebo (maltodextrin) with the same timing. The changes of each variable from baseline to post‐intervention were compared between the groups using the ANOVA test, and effect size (ES) statistic was also calculated. In comparison with the control group, significant reductions were found for office systolic BP (SBP, 8%, ES = 1.22), and 24 h‐SBP (5%, ES = 1.2) in the RT group. However, GR group showed significant decreases in office SBP (10.5%, ES = 1.45), mean BP (8%, ES = 1.11), RPP (13%, ES = 1.47), 24 h‐SBP (5%, ES = 1.21), and 24 h‐RPP (10%, ES = 1.15). The interaction of regular RT and GT consumption seems to induce more beneficial effects on some important parameters including MBP and RPP when compared to RT or GT alone.

Effects of green tea on glycemic status in female metabolic syndrome patients

Background: According to International Diabetic Federation, around 20-25% of world adult population have the clinical features of metabolic syndrome (MetS). Different organizations recommend to modify lifestyle and dietary habit as primary intervention. Green tea has several pharmacological effects on metabolic diseases including MetS.&#x0D; Objective: To evaluate the effects of green tea consumption on two glycemic variables in women with MetS.&#x0D; Method: This interventional study was conducted in the Department of Physiology, Dhaka Medical College from January 2016 to December 2016. After fulfilling the ethical aspect, a total number of 42 female patients with MetS aged 40 to 50 years were selected from the outpatient department of Endocrinology, Dhaka Medical College Hospital. Participants were randomly assigned in study group (n=22) and control group (n=20). Study group consumed green tea for 12 weeks and the control group did not consume green tea. In both groups fasting serum glucose (FSG) and glycosylated hemoglobin (HbA1c) were measured by glucose oxidase (GOD/ PAP) method and modified high performance liquid chromatography (HPLC) method respectively 2 times (before and after 12 weeks). Data were analyzed by paired Student’s ‘t’ test and unpaired Student’s ‘t’ test.&#x0D; Results: After 12 weeks of intervention, FSG &amp; HbA1c significantly (p&lt;0.001) decreased in the study group than those of their baseline value and these values were also significantly (p&lt;0.05) lower in comparison to those of control group.&#x0D; Conclusions: Regular consumption of green tea may improve glycemic status in patients with metabolic syndrome.&#x0D; J Bangladesh Soc Physiol. 2020, December; 15(2): 85-90

Effect of green tea consumption in treatment of mild to moderate depression in Iranian patients living with HIV: A double-blind randomized clinical trial

ObjectiveDepression affects people living with HIV (PLWH) compliance leading to poor control infection. Previous observational studies showed an anti-depression effect of green tea extract (GTE). The therapeutic effect of GTE on depression were investigated in PLWH receiving antiretroviral therapy (ART). MethodsFifty PLWH on ART with diagnose of mild to moderate of depression, participated in a double-blind, placebo-controlled trial and underwent 12 weeks of treatment with either 400 mg GTE capsules or placebo twice daily. The Hamilton depression scale of patients was measured before, 6 weeks and 12 weeks after treatment in two groups. The primary outcome measure was performed to evaluate the efficacy of GTE in improving depressive symptoms. ResultsThe mean of Hamilton score showed a significant difference between the two groups after 12 weeks (P = 0.035). Repeated measures ANOVA test showed a significant effect for time × treatment interaction on the Hamilton mean score between the two groups (P = 0.000). ConclusionIt seems the use of GTE capsules in PLWH on ART is safe and could lead to greater and more rapid improvement in depressive symptoms than placebo. Thus it can be considered as an alternative therapy for mild to moderate depression. Further studies with higher sample size and longer follow-up and comparisons with other antidepressive drugs are warranted.

Associations of Green Tea Consumption and Cerebrospinal Fluid Biomarkers of Alzheimer’s Disease Pathology in Cognitively Intact Older Adults: The CABLE Study

Green tea has been widely recognized in ameliorating cognitive impairment and Alzheimer's disease (AD), especially the progression of cognitive dysfunction. But the underlying mechanism is still unclear. This study was designed to determine the role of green tea consumption in the association with cerebrospinal fluid (CSF) biomarkers of AD pathology and to ascertain whether specific population backgrounds showed the differences toward these relationships. Multivariate linear models analyzed the available data on CSF biomarkers and frequency of green tea consumption of 722 cognitively intact participants from the Chinese Alzheimer's Biomarker and LifestylE (CABLE) database, and we additionally detected the interaction effects of tea consumption with APOEɛ4 status and gender using a two-way analysis of covariance. Frequent green tea consumption was associated with a decreased level of CSF total-tau protein (t-tau) (p = 0.041) but not with the levels of CSF amyloid-β 42 (Aβ42) and CSF phosphorylated tau. The more pronounced associations of green tea consumption with CSF t-tau (p = 0.007) and CSF t-tau/Aβ42 (p = 0.039) were observed in individuals aged 65 years or younger. Additionally, males with frequent green tea consumption had a significantly low level of CSF t-tau/Aβ42 and a modest trend toward decreased CSF t-tau. There were no interaction effects of green tea consumption with APOEɛ4 and gender. Collectively, our findings consolidated the favorable effects of green tea on the mitigation of AD risk. The constituents of green tea may improve abnormal tau metabolism and are promising targets in interventions and drug therapies.

Associations between Green Tea Consumption and Coffee Consumption and the Prevalence of Coronary Artery Disease.

Green tea and coffee contain various bioactive compounds (e.g., polyphenols), and their consumption has been proposed to decrease the risk of cardiovascular diseases. Here, we investigated the associations between the consumption of green tea and that of coffee and the prevalence of coronary artery disease (CAD) in Japanese patients. The study group was 612 patients who underwent coronary angiography at Tokyo Medical Center between July 2008 and February 2017. CAD was confirmed in 388 of the patients: one-vessel disease (1-VD, n=166); two-vessel disease (2-VD, n=112); three-vessel disease (3-VD, n=110). Myocardial infarction (MI) was found in 138 patients. After adjustment for well-known atherosclerotic risk factors and other dietary habits, greater green tea consumption was significantly inversely associated with CAD prevalence (p for trend=0.044), and the patients who drank >3 cups/d had a lower prevalence of CAD compared to those who drank <1 cup/d (odds ratio [OR]: 0.54, 95% CI: 0.30-0.98). Greater green tea consumption (>3 cups/d) was also associated with a decreased prevalence of 3-VD (OR: 0.49, 95% CI: 0.24-0.98, p-trend=0.047) and MI (OR: 0.51, 95% CI: 0.27-0.97, p-trend=0.037). In contrast, coffee consumption was not associated with CAD or MI. In subgroup analyses, the inverse association between green tea consumption and CAD or MI was found in the high intake groups of vegetables or fruits but not in the low intake groups of vegetables or fruits. These results suggest a beneficial effect of green tea consumption, especially with a diet rich in vegetables and fruits, against coronary atherosclerosis in Japanese.

Effects of green tea consumption and aerobic- resistance training on lipid profile and body composition in overweight and obese postmenopausal women

Effects of green tea consumption and aerobic- resistance training on lipid profile and body composition in overweight and obese postmenopausal women

Green tea (Camellia sinensis) for the prevention of cancer.

This review is an update of a previously published review in the Cochrane Database of Systematic Reviews (2009, Issue 3).Tea is one of the most commonly consumed beverages worldwide. Teas from the plant Camellia sinensis can be grouped into green, black and oolong tea, and drinking habits vary cross-culturally. C sinensis contains polyphenols, one subgroup being catechins. Catechins are powerful antioxidants, and laboratory studies have suggested that these compounds may inhibit cancer cell proliferation. Some experimental and nonexperimental epidemiological studies have suggested that green tea may have cancer-preventative effects. To assess possible associations between green tea consumption and the risk of cancer incidence and mortality as primary outcomes, and safety data and quality of life as secondary outcomes. We searched eligible studies up to January 2019 in CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, and reference lists of previous reviews and included studies. We included all epidemiological studies, experimental (i.e. randomised controlled trials (RCTs)) and nonexperimental (non-randomised studies, i.e. observational studies with both cohort and case-control design) that investigated the association of green tea consumption with cancer risk or quality of life, or both. Two or more review authors independently applied the study criteria, extracted data and assessed methodological quality of studies. We summarised the results according to diagnosis of cancer type. In this review update, we included in total 142 completed studies (11 experimental and 131 nonexperimental) and two ongoing studies. This is an additional 10 experimental and 85 nonexperimental studies from those included in the previous version of the review. Eleven experimental studies allocated a total of 1795 participants to either green tea extract or placebo, all demonstrating an overall high methodological quality based on 'Risk of bias' assessment. For incident prostate cancer, the summary risk ratio (RR) in the green tea-supplemented participants was 0.50 (95% confidence interval (CI) 0.18 to 1.36), based on three studies and involving 201 participants (low-certainty evidence). The summary RR for gynaecological cancer was 1.50 (95% CI 0.41 to 5.48; 2 studies, 1157 participants; low-certainty evidence). No evidence of effect of non-melanoma skin cancer emerged (summary RR 1.00, 95% CI 0.06 to 15.92; 1 study, 1075 participants; low-certainty evidence). In addition, adverse effects of green tea extract intake were reported, including gastrointestinal disorders, elevation of liver enzymes, and, more rarely, insomnia, raised blood pressure and skin/subcutaneous reactions. Consumption of green tea extracts induced a slight improvement in quality of life, compared with placebo, based on three experimental studies. In nonexperimental studies, we included over 1,100,000 participants from 46 cohort studies and 85 case-control studies, which were on average of intermediate to high methodological quality based on Newcastle-Ottawa Scale 'Risk of bias' assessment. When comparing the highest intake of green tea with the lowest, we found a lower overall cancer incidence (summary RR 0.83, 95% CI 0.65 to 1.07), based on three studies, involving 52,479 participants (low-certainty evidence). Conversely, we found no association between green tea consumption and cancer-related mortality (summary RR 0.99, 95% CI 0.91 to 1.07), based on eight studies and 504,366 participants (low-certainty evidence). For most of the site-specific cancers we observed a decreased RR in the highest category of green tea consumption compared with the lowest one. After stratifying the analysis according to study design, we found strongly conflicting results for some cancer sites: oesophageal, prostate and urinary tract cancer, and leukaemia showed an increased RR in cohort studies and a decreased RR or no difference in case-control studies. Overall, findings from experimental and nonexperimental epidemiological studies yielded inconsistent results, thus providing limited evidence for the beneficial effect of green tea consumption on the overall risk of cancer or on specific cancer sites. Some evidence of a beneficial effect of green tea at some cancer sites emerged from the RCTs and from case-control studies, but their methodological limitations, such as the low number and size of the studies, and the inconsistencies with the results of cohort studies, limit the interpretability of the RR estimates. The studies also indicated the occurrence of several side effects associated with high intakes of green tea. In addition, the majority of included studies were carried out in Asian populations characterised by a high intake of green tea, thus limiting the generalisability of the findings to other populations. Well conducted and adequately powered RCTs would be needed to draw conclusions on the possible beneficial effects of green tea consumption on cancer risk.

Electroencephalographical investigation of drinking green tea to the human brain

Background: Nowadays green tea has become one of the most popular drinks all over the world. Evidences suggest that green tea become second most consumer following regular drinking water. Green tea contains Theanine, an amino acid primarily found in green tea and black tea. The content is generally found 1-2% of dried tea or around 60 milligrams per 200 milliliters of tea drink. In particular, this substance is found in the form of L-theanine that can be absorbed to the blood system and then to the brain within 30 minutes, which causes relaxation and reducing stress.&#x0D; Aims and Objective: The objective was to examine the effect of green tea consumption on electroencephalographic (EEG) activities.&#x0D; Materials and Methods: This study was an experimental design. The participants were twelve Thai healthy, aged between 21-55 years old. During the experiment, all participants were asked to drink green tea every 10 minutes.&#x0D; Results: The influence to brainwave and attentive process were tested by experimental design. The study indicated that alpha brainwave was shown after drinking green tea. Frequency of alpha brainwave along cumulative drinking of green tea was shown significantly since the 10th minute. However, spectrum of the alpha brainwave changed significantly after drinking green tea, after 30th minutes.&#x0D; Conclusion: The benefit of this study was to provide the guideline for planning and campaigning green tea consumption for the purpose of stress reduction resulting in relaxation.

Protective Effect of Green Tea Consumption on Colorectal Cancer Varies by Lifestyle Factors.

The inconsistent findings regarding green tea intake and colorectal cancer (CRC) risk in several epidemiological studies might result from variations in lifestyle factors. Therefore, we examined whether increased green tea intake was associated with a decreased risk of CRC and how the risk of CRC was altered by the protective effect of green tea consumption and five health-related factors. A case-control study including 2742 participants (922 cases and 1820 controls) was conducted in Korea. Green tea consumption was assessed using a semiquantitative food frequency questionnaire. The risk of CRC was approximately 40% less in the participants in the highest green tea intake tertile than in participants in the lowest green tea intake tertile. Of the five lifestyle factors examined, high body mass index and physical inactivity were independent risk factors for CRC. Regarding the interactions between tea consumption and lifestyle factors, high green tea consumption was associated with a decreased risk of CRC, with or without considering lifestyle factors. However, moderate green tea consumption increased the risk of CRC among ever-smokers, ever-drinkers and the high-inflammatory diet group. Increased consumption of green tea might be helpful to reduce the risk of CRC in those with an unhealthy lifestyle.

Epicatechin-3-Gallate Signaling and Protection against Cardiac Ischemia/Reperfusion Injury.

At concentrations found in humans after ingestion of one to two cups of green tea, epicatechin-3-gallate (ECG) modulates Na/K-ATPase conformation and activity. Akin to ouabain, an archetypal Na/K-ATPase ligand of the cardiotonic steroid (CTS) family, ECG also activates protein kinase C epsilon type (PKCε) translocation and increases the force of contraction of the rat heart. This study evaluated whether, like ouabain, ECG also modulates Na/K-ATPase/Src receptor function and triggers pre- and postconditioning against ischemia/reperfusion (I/R) injury. In vitro, ECG activated the purified Na/K-ATPase/Src complex. In Langendorff-perfused rat hearts, submicromolar concentrations of ECG administered either before or after ischemia reduced infarct size by more than 40%, decreased lactate dehydrogenase release, and improved the recovery of cardiac function. ECG protection was blocked by PKCε inhibition and attenuated by mitochondrial KATP channel inhibition. In a unique mammalian cell system with depleted Na/K-ATPase α1 expression, ECG-induced PKCε activation persisted but protection against I/R was blunted. Taken together, these results reveal a Na/K-ATPase- and PKCε-dependent mechanism of protection by ECG that is also distinct from the mechanism of action of ouabain. These ECG properties likely contribute to the positive impact of green tea consumption on cardiovaascular health and warrant further investigation into the role of cardiac Na/K-ATPase signaling in the cardioprotective effect of green tea consumption. SIGNIFICANCE STATEMENT: Consumption of green tea, the richest dietary source of ECG, is associated with a reduced risk of cardiac mortality. Antioxidant effects of ECG and other tea polyphenols are well known, but reported for concentrations well above dietary levels. Therefore, the mechanism underlying the cardioprotective effect of green tea remains incompletely understood. This study provides experimental evidence that ECG concentrations commonly detected in humans after consumption of a cup of tea trigger the Na/K-ATPase/Src receptor in a cell-free system, activate a CTS-like signaling pathway, and provide PKCε-dependent protection against ischemia/reperfusion injury in rat hearts. Mechanistic studies in mammalian cells with targeted Na/K-ATPase depletion revealed that although Na/K-ATPase does not mediate ECG-induced PKCε activation, it is required for ECG-induced protection against ischemia/reperfusion injury.

Genetic polymorphism of catechol-O-methyltransferase modulates the association of green tea consumption and lung cancer.

Tea polyphenols are strong antioxidants, which can be rapidly O-methylated by catechol-O-methyltransferase (COMT). Thus, it is possible that the genetic polymorphism of COMT can modulate the association of green tea consumption and lung cancer. Here, we designed a case-control study to evaluate the combined effect of green tea consumption and COMT genotypes on the risk of lung cancer. A total of 237 lung cancer patients and 474 healthy controls were recruited. Questionnaires were administered to obtain demographic data, smoking status, green tea consumption, fruits and vegetables intake, exposure to cooking fumes, and family history of lung cancer. Genotypes for COMT were identified by PCR. Smoking, green tea consumption, exposure to cooking fumes, and family history of lung cancer were associated with the development of lung cancer. When green tea drinkers carrying COMT HL/LL genotypes were selected as the reference group, drinkers carrying the COMT HH genotype had a higher risk for the development of lung cancer (odds ratio: 1.97, 95% confidence interval: 0.99-3.91). Among the current and ever smokers, the elevated risk for lung cancer was more apparent in green tea drinkers carrying the COMT HH genotype compared with green tea drinkers carrying COMT HL/LL genotypes (odds ratio: 5.84, 95% confidence interval: 1.75-19.45). Green tea drinkers with greater activity of the COMT genotype, whereby polyphenols are effectively excluded, will gain fewer protective benefits against lung cancer development.

Inhibitory Effects of Green Tea Polyphenols on Microbial Metabolism of Aromatic Amino Acids in Humans Revealed by Metabolomic Analysis.

The bioactivities and potential health benefits of green tea polyphenols (GTP) have been extensively investigated, but the metabolic impact of chronic GTP intake on humans is not well defined. In this study, fecal and urine samples from postmenopausal female subjects taking a GTP supplement or placebo for 12 months were compared by liquid chromatography-mass spectrometry-based metabolomic analysis. The GTP-derived and GTP-responsive metabolites were identified and characterized by structural elucidation and quantitative analysis of the metabolites contributing to the separation of control and treatment samples in the multivariate models. Major GTP and their direct sulfate and glucuronide metabolites were absent in feces and urine. In contrast, GTP-derived phenyl-γ-valerlactone and phenylvaleric acid metabolites were identified as the most abundant GTP-derived metabolites in feces and urine, suggesting extensive microbial biotransformation of GTP in humans. Interestingly, GTP decreased the levels of microbial metabolites of aromatic amino acids (AAA), including indoxyl sulfate, phenylacetylglutamine, and hippuric acid, in urine. However, it did not affect the levels of AAA, as well as other microbial metabolites, including short-chain fatty acids and secondary bile acids, in feces. 16S rRNA gene sequencing indicated that the fecal microbiome was not significantly affected by chronic consumption of GTP. Overall, microbial metabolism is responsible for the formation of GTP metabolites while GTP metabolism may inhibit the formation of AAA metabolites from microbial metabolism. Because these GTP-derived and GTP-responsive metabolites have diverse bioactivities, microbial metabolism of GTP and AAA may play important roles in the beneficial health effects of green tea consumption in humans.