Characterization of the Trans-Epithelial Transport of Green Tea (C. sinensis) Catechin Extracts with In Vitro Inhibitory Effect against the SARS-CoV-2 Papain-like Protease Activity.

This work describes an untargeted analytical approach for the screening, identification, and characterization of the trans-epithelial transport of green tea (Camellia sinensis) catechin extracts with in vitro inhibitory effect against the SARS-CoV-2 papain-like protease (PLpro) activity. After specific catechin extraction, a chromatographic separation obtained six fractions were carried out. The fractions were assessed in vitro against the PLpro target. Fraction 5 showed the highest inhibitory activity against the SARS-CoV-2 PLpro (IC50 of 0.125 µg mL-1). The untargeted characterization revealed that (-)-epicatechin-3-gallate (ECG) was the most abundant compound in the fraction and the primary molecule absorbed by differentiated Caco-2 cells. Results indicated that fraction 5 was approximately 10 times more active than ECG (IC50 value equal to 11.62 ± 0.47 µg mL-1) to inhibit the PLpro target. Overall, our findings highlight the synergistic effects of the various components of the crude extract compared to isolated ECG.

Matcha consumption maintains attentional function following a mild acute psychological stress without affecting a feeling of fatigue: A randomized placebo-controlled study in young adults.

Tea is a beverage commonly consumed worldwide. Matcha is a type of green tea produced by drying and grinding tea leaves (Camellia sinensis L.) into a fine powder. Matcha contains catechin, theanine, and caffeine, which affect cognitive function. Epidemiological studies conducted in Japan have shown that green tea consumption improves cognitive impairment. Previously, we found that daily matcha intake improves attention and executive function in middle-aged and older people. However, its effect on cognitive function in younger adults remains unclear. Moreover, it is unclear which cognitive functions are impaired by stress. This study aimed to clarify whether the administration of matcha improves the attentional function of young adults after mild acute stress and which cognitive function is improved. We included 42 participants aged 25 to 34 years who consumed 2 g of matcha daily for 2 weeks. The Uchida-Kraepelin test was used to induce mild acute psychological stress. Memory, attention, facial expression recognition, working memory, visual information, and motor function were evaluated. Reaction times on the Stroop test for attentional function were significantly lower in the matcha group than in the placebo group. Correct hits in the emotion perception test increased significantly for participants in the matcha group compared to those in the placebo group. We found no significant between-group differences in the other tests. In conclusion, after 2 weeks of matcha intake, the attentional function was maintained after mild acute psychological stress. Thus, matcha might improve cognitive function during or after stress conditions in young adults.

Tea and coffee consumption and the risk of urinary stones-a systematic review of the epidemiological data.

OBJECTIVE: To explore the relationship between the consumption of coffee and tea with urolithiasis. We evaluated large epidemiological and small clinical studies to draw conclusions regarding their lithogenic risk. METHODS: A systematic review was performed using the Medline and Scopus databases, in concordance with the PRISMA statement. English, French, and Spanish language studies regarding the consumption of caffeinated and decaffeinated coffee and tea, and the relationship to urinary stone disease were reviewed. Case reports and letters, unpublished studies, posters, and comments were excluded. RESULTS: As per the inclusion criteria, 13 studies were included in the final review. Most studies, including four large prospective studies and one meta-analysis, reported a reduced risk of stone formation for coffee and tea. Caffeine has a diuretic effect and increases the urinary excretion of calcium, but if these losses are compensated for, moderate caffeine intakes may have little or no deleterious effects. Green and Herbal teas infused for short time had low oxalate content compared to black tea. CONCLUSION: There is no evidence that moderate consumption of coffee raises the risk for stone formation in healthy individuals, provided the recommended daily fluid intake is maintained. The currently available literature supports in general a protective role for tea against the stone formation, mainly for green tea. However, heterogeneity of published data and lack of standardization needs to be addressed before final and clear conclusions can be given to patients and to the public in general.

Exogenous abscisic acid induces the lipid and flavonoid metabolism of tea plants under drought stress.

Abscisic acid (ABA) is an important phytohormone responsible for activating drought resistance, but the regulation mechanism of exogenous ABA on tea plants under drought stress was rarely reported. Here, we analyzed the effects of exogenous ABA on genes and metabolites of tea leaves under drought stress using transcriptomic and metabolomic analysis. The results showed that the exogenous ABA significantly induced the metabolic pathways of tea leaves under drought stress, including energy metabolism, amino acid metabolism, lipid metabolism and flavonoids biosynthesis. In which, the exogenous ABA could clearly affect the expression of genes involved in lipid metabolism and flavonoid biosynthesis. Meanwhile, it also increased the contents of flavone, anthocyanins, flavonol, isoflavone of tea leaves under drought stress, including, kaempferitrin, sakuranetin, kaempferol, and decreased the contents of glycerophospholipids, glycerolipids and fatty acids of tea leaves under drought stress. The results suggested that the exogenous ABA could alleviate the damages of tea leaves under drought stress through inducing the expression of the genes and altering the contents of metabolites in response to drought stress. This study will be helpful to understand the mechanism of resilience to abiotic stress in tea plant and provide novel insights into enhancing drought tolerance in the future.

Characterization of CBL-CIPK signaling complexes and their involvement in cold response in tea plant.

Calcineurin B-like (CBL) proteins, a class of Ca2+-binding proteins, play vital roles in calcium signal transduction by interacting specifically with CBL-interacting protein kinases (CIPKs), and these two gene families and their interacting complexes are involved in regulating plant responses to various environmental stimuli. In the present study, eight CBL and 25 CIPK genes were identified in tea plant and divided into four and five subfamilies, respectively. Analysis of the expression of these genes in response to abiotic stresses (mature leaves treated with cold, salinity, and PEG and young shoots treated with cold) revealed that CsCBL1/3/5 and CsCIPK1/4/5/6a/7/8/10b/10c/12/14a/19/23a/24 could be induced by at least two stresses. Under cold stress, CsCBL9 and CsCIPK4/6a/6b/7/11/14b/19/20 were upregulated in both mature leaves and young shoots, CsCBL1/3/5 and CsCIPK1/8/10a/10b/10c/12/14a/23a/24 were induced only in mature leaves, and CsCIPK5/25 were induced only in young shoots. Yeast two-hybrid analysis showed that CsCBL1 could interact with CsCIPK1/10b/12 but not with CsCIPK6a/7/11/14b/20. CsCBL9 was found to interact with CsCIPK1/10b/12/14b but not with CsCIPK6a/7/11/20. These results suggest divergent responses to cold stress regulated by CBL-CIPK complexes between tea plant and Arabidopsis, as well as between mature leaves and young shoots in tea plant. A model of Ca2+-CsCBL-CsCIPK module-mediated abiotic stress signaling in tea plant is proposed.

The effect of green tea supplementation on obesity: A systematic review and dose-response meta-analysis of randomized controlled trials.

The effects of green tea (GT) in obese subjects have been evaluated in different studies, but no consensus has been obtained due to the heterogeneity of the results. The dosage, the type of extract, and the duration of the intervention are the main contributors to the heterogeneity of the results. Therefore, the present systematic review and meta-analysis aimed to evaluate the efficacy and dose-response relationship of GT. Several databases were searched from inception to September 2019 to identify clinical trials that examined the influence of GT supplements on obesity indices in humans. Combined results using the random-effects model indicated that body weight (WMD: -1.78 kg, 95% CI: -2.80, -0.75, p = .001) and body mass index (BMI) (WMD: -0.65 kg/m2 , 95% CI: -1.04, -0.25, p = .001) did change significantly following GT administration. The reduction in waist circumference (WC) after GT consumption was significant in subjects in trials employing GT ≥800 mg/day (WMD: -2.06 cm) and with a treatment duration <12 weeks (WMD: -2.39 cm). Following the dose-response evaluation, GT intake did alter body weight, with a more important reduction when the GT dosage was <500 mg/day and the treatment duration was of 12 weeks. The results of present meta-analysis study support the use of GT for the improvement of obesity indices. Thus, we suggest that the use of GT can be combined with a balanced and healthy diet and regular physical exercise in the management of obese patients.

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To understand photosynthetic mechanism of tea yield and quality, an experiment was conducted with four different typical habitats, including three intercropping patterns (S1:Osmanthus-Tea, S2:Michelia-Tea, S3:Osmanthus-Michelia-Tea) and a control (CK) at Changsha Agricutural Observation Station of Chinese Academy of Sciences. The photosynthetic physiological and ecological characteristics of tea yield and quality were examined. The results showed that the habitats S1, S2, S3 reduced the leaf temperature (TL), photosynthesis active radiation flux (PAR), net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (gs), as well as the tea polyphenol content. Habitats S1, S2, S3 significantly increased leaf relative humidity (RHS), total amino-acid content of tea, and the yield and quality of tea, with a pattern of S3>S1>S2>CK. The leaves in habitats S1 and S3 could be made into high-grade green tea and famous green tea respectively. Comprehensive indicators showed that habitat S3 is an ideal intercropping pattern for high quality and high yield of tea garden.

Black tea affects obesity by reducing nutrient intake and activating AMP-activated protein kinase in mice.

The effects of certain tea components on the prevention of obesity in humans have been reported recently. However, whether Yinghong NO. 9 black tea consumption has beneficial effects on obesity are not known. Here, we obtained a Yinghong NO. 9 black tea infusion (Y9 BTI) and examined the anti-obesity effects of its oral administration. ICR mice were fed a standard diet supplemented with Y9 BTI at 0.5, 1.0, or 2.0 g/kg body weight for two weeks, and the body weight were recorded. HE staining was used to evaluate the effect of Y9 BTI on mice liver. Western blot analysis was used to detect the expression levels of related proteins in the mice liver and adipose. We found that the body weights of the mice in the control group were significantly higher than those of the mice in the middle and high dose groups. The results of western blot showed that Y9 BTI up-regulated the expression of liver kinase B1 (LKB1) and adenosine monophosphate-activated protein kinase (AMPK) and also increased in AMPK phosphorylation (p-AMPK) and LKB1 phosphorylation (p-LKB1). Y9 BTI significantly down-regulated Fas Cell Surface Death Receptor(FAS) and activated the phosphorylation of acetyl-CoA carboxylase (ACC). Furthermore, Y9 BTI (2.0 g/kg BW) down-regulated the expression of three factors (IL-1ß, Cox-2, and iNOS). Altogether, Y9 BTI supplementation reduced the feed intake of mice and may prevent obesity by inhibiting lipid absorption. These results suggest that Y9 BTI may regulate adipogenic processes through the LKB1/AMPK pathway.

Comparative analysis of the response and gene regulation in cold resistant and susceptible tea plants.

Cold environment is the main constraint for tea plants (Camellia sinensis) distribution and tea farming. We identified two tea cultivars, called var. sinensis cv. Shuchazao (SCZ) with a high cold-tolerance and var. assamica cv. Yinghong9 (YH9) with low cold-tolerance. To better understand the response mechanism of tea plants under cold stress for improving breeding, we compared physiological and biochemical responses, and associated genes expression in response to 7-day and 14-day cold acclimation, followed by 7-day de-acclimation in these two tea cultivars. We found that the low EL50, low Fv/Fm, and high sucrose and raffinose accumulation are responsible for higher cold tolerance in SCZ comparing with YH9. We then measured the expression of 14 key homologous genes, known as involved in these responses in other plants, for each stages of treatment in both cultivars using RT-qPCR. Our results suggested that the increased expression of CsCBF1 and CsDHNs coupling with the accumulation of sucrose play key roles in conferring higher cold resistance in SCZ. Our findings have revealed key genes regulation responsible for cold resistance, which help to understand the cold-resistant mechanisms and guide breeding in tea plants.

Neurobehavioral changes in mice offspring exposed to green tea during fetal and early postnatal development.

BACKGROUND: Green tea extract (GTE) has various health promoting effects on animals and humans. However, the effects of perinatal exposure to GTE on the behavioral aspects of offspring have not been elucidated thus far. GTE was provided for pregnant female mice at concentrations of either 20 or 50 g/L, beginning the day of conception until the third week after delivery, postnatal day 22 (PD 22). Mice pups were subjected to behavioral testing to assess sensory motor reflexes, locomotion, anxiety, and learning on various postnatal days. RESULTS: Perinatal exposure to GTE resulted in a significant reduction in body weight, as well as earlier body hair appearance and opening of the eyes. Sensory motor reflexes exhibited faster responses and significant stimulatory effects in pups exposed to GTE. During the adolescent period, male and female offspring exhibited increased locomotor activity (on PD 22), reduced anxiety and fear (on PD 25), and enhanced memory and learning abilities (on PD 30), all in both GTE treated groups. All blood counts (RBCs, WBCs, Hb, and platelets), and glucose, cholesterol, triglyceride, and low density lipoprotein concentrations were significantly lower in the GTE-treated pups; however, there was no effect on high density lipoprotein levels. CONCLUSION: Our data provide evidence that the high dose of GTE (50 g/L) had higher anxiolytic properties and positive effects on locomotor activities and sensory motor reflexes, as well as learning and memory of the offspring than the low dose of GTE (20 g/L).

Regulation of Anthocyanin Biosynthesis in Purple Leaves of Zijuan Tea (Camellia sinensis var. kitamura).

Plant anthocyanin biosynthesis is well understood, but the regulatory mechanism in purple foliage tea remains unclear. Using isobaric tag for relative and absolute quantification (iTRAQ), 815 differential proteins were identified in the leaves of Zijuan tea, among which 20 were associated with the regulation of anthocyanin metabolism. We found that the abundances of anthocyanin synthesis-related enzymes such as chalcone synthase, chalcone isomerase, dihydroflavonol 4-reductase and anthocyanin synthetase, as well as anthocyanin accumulation-related UDP-glucosyl transferase and ATP-binding cassette (ABC) transporters in the purple leaves were all significantly higher than those in the green leaves. The abundances of the transcription factors bHLH and HY5, regulating anthocyanin biosynthesis at transcriptional level were also obviously higher in purple leaves than those in green leaves. In addition, bifunctional 3-dehydroquinate dehydratase and chorismate mutase in purple leaves were distinctly higher in abundance compared to green leaves, which provided sufficient phenylalanine substrate for anthocyanin synthesis. Furthermore, lignin synthesis was found to be reduced due to the lower abundances of cinnamoyl-CoA reductase 1, peroxidase 15 and laccase-6, which resulted in increase of intermediates flow into anthocyanin synthesis pathway. The physiological data were consistent with proteomic results. These four aspects of biosynthetic regulation contribute to anthocyanin accumulation in purple leaves of Zijuan tea.

Short-term green tea supplementation prevents recognition memory deficits and ameliorates hippocampal oxidative stress induced by different stroke models in rats.

This study investigated the effect of green tea (GT) on short and long term declarative memory and oxidative damage induced by transient ischemia-reperfusion (IR) and intracerebral hemorrhage (ICH) in rats. Male Wistar rats were divided into 8 groups of 10 according the stroke type induced: Sham IR, Sham IR+GT, IR, IR+GT, Sham ICH, Sham ICH+GT, ICH, ICH+GT. Supplementation with GT was initiated 10days before stroke surgery and continuous for 6days after (GT dose 400mg/kg). Short (STM) and long term memory (LTM) we evaluated with object recognition task (OR) and hippocampus were used to evaluate parameters related to oxidative stress (ROS, lipid peroxidation and total antioxidant capacity). The rats subjected to IR and ICH showed STM and LTM deficits and GT intervention prevented it in both stroke models. IR and ICH induced increase on ROS levels in hippocampus. ICH increased the lipid peroxidation in hippocampus and the GT supplementation avoided it. IR induced decrease on total antioxidant capacity and GT prevented it. These results reveal that GT supplementation presents a neuroprotective role, attenuates redox imbalance and might have a beneficial impact on cognitive function after stroke.

The benefits of respective and combined use of green tea polyphenols and ERK inhibitor on the survival and neurologic outcomes in cardiac arrest rats induced by ventricular fibrillation.

BACKGROUND: Cerebral injury is a main factor contributing to a high mortality after cardiac arrest (CA)/cardiopulmonary resuscitation (CPR). OBJECTIVE: We sought to evaluate the effect of green tea polyphenols (GTPs) and ERK1/2 inhibitor PD98059 (PD) on the survival and neurologic outcomes after CA/CPR in rats. METHODS: First, rats were subjected to CA after CPR. The rats that restored spontaneous circulation were blindly allocated to the saline group (saline, IV, n = 12), the GTP group (GTPs, 10 mg/kg, IV, n = 12), the PD group (PD, 0.3 mg/kg, IV, n = 12), and the GTPs + PD group (GTPs, 10 mg/kg; PD, 0.3 mg/kg, IV, n = 12). Another 12 rats without experiencing CA and CPR were served as a sham group. Survival and the neurologic deficit score were observed for 72 hours after restoration of spontaneous circulation. Second, same experimental procedures were performed, and in 1 of 5 groups, animals were divided into 4 subgroups further according to the different time points (12, 24, 48, and 72 hours after restoration of spontaneous circulation [ROSC], n = 6/group). Brain tissues were harvested at relative time points for the morphologic evaluation as well as reactive oxygen species (ROS), malonylaldehyde, and superoxide dismutase (SOD) measurement. RESULTS: Green tea polyphenols, PD, and a combination of GTPs and PD used after ROSC alleviated the morphologic changes of the cerebrum. These 3 treatments also decreased the productions of ROS and malonylaldehyde, increased SOD activities in cerebral tissues, and improved the neurologic deficit and survival rates at 12, 24, 48, and 72 hours after ROSC. CONCLUSIONS: Administration of GTPs and PD after ROSC can alleviate cerebral injury, improve the survival and neurologic outcomes via reduction of ROS, and increase of SOD activity in a rat CA/CPR model.

Volatiles emitted from tea plants infested by Ectropis obliqua larvae are attractive to conspecific moths.

Herbivore-induced plant volatiles have been reported to play a role in the host-searching behavior of herbivores. However, next to nothing is known about the effect of volatiles emitted from tea plants infested by Ectropis obliqua larvae on the behavior of conspecific adults. Here, we found that tea plants infested by E. obliqua caterpillars for 24 h were more attractive to both virgin male and female E. obliqua adults than were intact, uninfested tea plants; moreover, mated female E. obliqua moths were more attracted by infested tea plants and preferentially oviposited on these plants, whereas male moths were repelled by infested plants once they had mated. Volatile analysis revealed that the herbivore infestation dramatically increased the emission of volatiles. Among these volatiles, 17 compounds elicited antennal responses from both male and female virginal moths. Using a Y-tube olfactometer, we found that 3 of the 17 chemicals, benzyl alcohol, (Z)-3-hexenyl hexanoate, and (Z)-3-hexenal, were attractive, but two compounds, linalool and benzyl nitril, were repellent to virgin male and female moths. One chemical, (Z)-3-hexenyl acetate, was attractive only to virgin males. Mated females were attracted by three compounds, (Z)-3-hexenyl hexanoate, (Z)-3-hexenyl acetate, and (Z)-3-hexenal; whereas mated males were repelled by (Z)-3-hexenol. The findings provide new insights into the interaction between tea plants and the herbivores, and may help scientists develop new measures with which to control E. obliqua.

Use of temperature and humidity sensors to determine moisture content of oolong tea.

The measurement of tea moisture content is important for processing and storing tea. The moisture content of tea affects the quality and durability of the product. Some electrical devices have been proposed to measure the moisture content of tea leaves but are not practical. Their performance is influenced by material density and packing. The official oven method is time-consuming. In this study, the moisture content of Oolong tea was measured by the equilibrium relative humidity technique. The equilibrium relative humidity, and temperature, of tea materials were measured by using temperature and relative humidity sensors. Sensors were calibrated, and calibration equations were established to improve accuracy. The moisture content was calculated by using an equilibrium moisture content model. The error of the moisture content determined with this method was within 0.5% w.b. at moisture <15% w.b. Uncertainty analysis revealed that the performance of the humidity sensor had a significant effect on the accuracy of moisture determination.

Potential role of green tea catechins in various disease therapies: progress and promise.

Green tea (from the plant Camellia sinensis), a beverage whose consumption started 5000 years ago in China, has important biological and pharmacological properties. The beneficial effects of green tea have been attributed to the presence of phenolic compounds that are powerful anti-oxidants and free iron scavengers. Of all the catechins found in green tea, namely (-)-epicatechin-3-gallate, (-)-epigallocatechin, (-)-epicatechin and (-)-epigallocatechin-3-gallate (EGCG), EGCG is the most abundant and powerful. It is widely believed that green tea may protect against death from all causes, especially cardiovascular diseases (coronary heart disease and stroke) owing to the presence of catechins associated with green tea consumption. Other health benefits include various types of cancer chemoprevention, weight loss and protective effects against neurodegenerative diseases (Alzheimer's disease and Parkinson's disease). Thus far, numerous pharmacological activities regulating disease-specific molecular targets have been reported in vitro for EGCG concentrations in the micromolar range, which are physiologically irrelevant. Although most of the studies have shown benefits with two to three cups of green tea per day, the optimal dose has not yet been established to enable any solid conclusions to be drawn regarding the various health benefits of green tea or its constituents in humans. With Phase I trials providing information on the safety profile and pharmacokinetics of EGCG, the window of opportunity is wider to undertake well-controlled long-term human studies to enable a full understanding of the protective effects of green tea catechins on various parameters in different settings.

Dietary inclusion of tea catechins changes fatty acid composition of muscle in goats.

This study was conducted to examine dietary tea catechins (TC) supplementation on the fatty acid composition of muscle and ruminal bacteria in goats fed a maize stover-based diet. Forty goats, 8 months old (16.2 ± 1.2 kg), were randomly divided into four equal groups (10 animals in each group) and assigned to four experiment diets with TC supplementation at four levels (0, 2,000, 3,000 and 4,000 mg TC/kg feed, namely TC0, TC2000, TC3000 and TC4000, respectively). After a 60-day feeding period, all the goats were slaughtered and sampled. The results showed that dietary TC inclusion increased the average daily gain (ADG), protein content in the semimembranosus muscle and dry matter in the longissimus dorsi muscle (LD). Dietary TC supplementation increased the ratio of n-6 to n-3 fatty acid, the ratio of polyunsaturated fatty acids to saturated fatty acids was higher in TC3000 and TC4000 than in TC0 and TC2000 for LD. The current results implied that dietary inclusion of a suitable TC dose could improve the growth performance and increase the proportions of unsaturated fatty acids in muscle, and the biohydrogenation of ruminal microorganisms might change the profiles of fatty acids in the muscle of growing goats.

Is temperature an effect modifier of the association between green tea intake and gastric cancer risk?

We considered the relationship between green tea and gastric cancer risk in Harbin, Heilongjiang province, Northeast China, an area with high baseline risk of stomach cancer. We used data from a case-control study conducted from 1987 to 1989 among 266 incident cases of stomach cancer and 533 controls admitted to the same hospitals as cases, with non-neoplastic and non-gastric diseases. No association emerged when tea consumption alone was considered: the odds ratio (OR) for green tea consumption was 0.87 (95% CI: 0.60-1.25) for green tea intake > or = 750 g/year versus no intake and 0.99 (95% CI: 0.97-1.02) for an increment of 500 g of tea per year. When tea consumption was classified according to the temperature, however, the OR was 0.19 (95% CI: 0.07-0.49) for lukewarm tea intake > or = 750 g/year and 1.27 (95% CI: 0.85-1.90) for hot tea intake (P value for interaction <0.001) as compared with non-drinkers. The corresponding ORs for an increment of 500 g of tea per year were 0.61 (95% CI: 0.45-0.82) and 1.03 (95% CI: 0.99-1.07) for lukewarm and hot tea, respectively (P value for interaction <0.001). We found an inverse relationship between green tea drinking and gastric cancer risk limited to the intake of lukewarm tea.

Green tea consumption is associated with lower psychological distress in a general population: the Ohsaki Cohort 2006 Study.

BACKGROUND: Although green tea or its constituents might reduce psychological stress, the relation between green tea consumption and psychological distress has not been investigated in a large-scale study. OBJECTIVE: Our aim was to clarify whether green tea consumption is associated with lower psychological distress. DESIGN: We analyzed cross-sectional data for 42,093 Japanese individuals aged > or =40 y from the general population. Information on daily green tea consumption, psychological distress as assessed by the Kessler 6-item psychological distress scale, and other lifestyle factors was collected by using a questionnaire. We used multiple logistic regression analyses adjusted for age, sex, history of disease, body mass index, cigarette smoking, alcohol consumption, time spent walking, dietary factors, social support, and participation in community activities to investigate the relation between green tea consumption and psychological distress. RESULTS: We classified 2774 (6.6%) of the respondents as having psychological distress (Kessler 6-item psychological distress scale > or =13/24). There was an inverse association between green tea consumption and psychological distress in a model adjusted for age and sex. Although the relation was largely attenuated when possible confounding factors were adjusted for, a statistically significant inverse association remained. The odds ratio (with 95% CI) of developing psychological distress among respondents who consumed >/=5 cups of green tea/d was 0.80 (0.70, 0.91) compared with those who consumed <1 cup/d. These relations persisted when respondents were stratified by social support subgroups or by activities in communities. CONCLUSION: Green tea consumption was inversely associated with psychological distress even after adjustment for possible confounding factors.