[Show abstract][Hide abstract] ABSTRACT: Green tea is known to have various health benefits for humans. However, the effect of green tea consumption on cognitive dysfunction remains to be clinically verified. We conducted a clinical study to investigate the effects of green tea consumption on cognitive dysfunction. Twelve elderly nursing home residents with cognitive dysfunction (Mini-Mental State Examination Japanese version (MMSE-J) score: <28) participated in the study (2 men, 10 women; mean age, 88 years). The participants consumed green tea powder 2 g/day for 3 months. After three months of green tea consumption, the participants' MMSE-J scores were significantly improved (before, 15.3 ± 7.7; after, 17.0 ± 8.2; p = 0.03). This result suggests that green tea consumption may be effective in improving cognitive function or reducing the progression of cognitive dysfunction; however, long-term large-scale controlled studies are needed to further clarify the effect.
[Show abstract][Hide abstract] ABSTRACT: Experimental studies have revealed that green tea catechins and theanine prevent influenza infection, while the clinical evidence has been inconclusive. This study was conducted to determine whether taking green tea catechins and theanine can clinically prevent influenza infection.
A randomized, double-blind, placebo-controlled trial of 200 healthcare workers conducted for 5 months from November 9, 2009 to April 8, 2010 in three healthcare facilities for the elderly in Higashimurayama, Japan.
The catechin/theanine group received capsules including green tea catechins (378 mg/day) and theanine (210 mg/day). The control group received placebo.
The primary outcome was the incidence of clinically defined influenza infection. Secondary outcomes were (1) laboratory-confirmed influenza with viral antigen measured by immunochromatographic assay and (2) the time for which the patient was free from clinically defined influenza infection, i.e., the period between the start of intervention and the first diagnosis of influenza infection, based on clinically defined influenza infection.
Eligible healthcare workers (n = 197) were enrolled and randomly assigned to an intervention; 98 were allocated to receive catechin/theanine capsules and 99 to placebo. The incidence of clinically defined influenza infection was significantly lower in the catechin/theanine group (4 participants; 4.1%) compared with the placebo group (13 participants; 13.1%) (adjusted OR, 0.25; 95% CI, 0.07 to 0.76, P = 0.022). The incidence of laboratory-confirmed influenza infection was also lower in the catechin/theanine group (1 participant; 1.0%) than in the placebo group (5 participants; 5.1%), but this difference was not significant (adjusted OR, 0.17; 95% CI, 0.01 to 1.10; P = 0.112). The time for which the patient was free from clinically defined influenza infection was significantly different between the two groups (adjusted HR, 0.27; 95% CI, 0.09 to 0.84; P = 0.023).
Among healthcare workers for the elderly, taking green tea catechins and theanine may be effective prophylaxis for influenza infection.
ClinicalTrials (NCT): NCT01008020.
BMC Complementary and Alternative Medicine 02/2011; 11:15. · 1.88 Impact Factor
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[Show abstract][Hide abstract] ABSTRACT: Strictinin, which is a member of the ellagitanin family of hydrolyzable tannins, prevented replication of human, duck and swine influenza A viruses (IAVs) in vitro at non-toxic concentrations. The addition of strictinin at the same time as IAV inoculation to MDCK cells inhibited viral replication in a dose-dependent manner. Strictinin showed 50% inhibitory concentrations for IAVs from 0.09±0.021 to 0.28±0.037μM (mean±S.E.M.) by the focus-forming assay. Treatment of MDCK cells with strictinin before and after viral inoculation resulted in no significant antiviral activity. Further studies showed that strictinin inhibited IAV-induced hemifusion. However, strictinin exhibited no inhibitory effect against receptor binding, sialidase activity. Strictinin also showed an antiviral effect on influenza B virus and human parainfluenza virus type-1 in vitro. The results indicate that strictinin is a useful antiviral agent.
Antiviral research 10/2010; 88(1):10-8. · 3.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Epidemiologic and preclinical data support the oral cancer prevention potential of green tea extract (GTE). We randomly assigned patients with high-risk oral premalignant lesions (OPL) to receive GTE at 500, 750, or 1,000 mg/m(2) or placebo thrice daily for 12 weeks, evaluating biomarkers in baseline and 12-week biopsies. The OPL clinical response rate was higher in all GTE arms (n = 28; 50%) versus placebo (n = 11; 18.2%; P = 0.09) but did not reach statistical significance. However, the two higher-dose GTE arms [58.8% (750 and 1,000 mg/m(2)), 36.4% (500 mg/m(2)), and 18.2% (placebo); P = 0.03] had higher responses, suggesting a dose-response effect. GTE treatment also improved histology (21.4% versus 9.1%; P = 0.65), although not statistically significant. GTE was well tolerated, although higher doses increased insomnia/nervousness but produced no grade 4 toxicity. Higher mean baseline stromal vascular endothelial growth factor (VEGF) correlated with a clinical (P = 0.04) but not histologic response. Baseline scores of other biomarkers (epithelial VEGF, p53, Ki-67, cyclin D1, and p16 promoter methylation) were not associated with a response or survival. Baseline p16 promoter methylation (n = 5) was associated with a shorter cancer-free survival. Stromal VEGF and cyclin D1 expression were downregulated in clinically responsive GTE patients and upregulated in nonresponsive patients at 12 weeks (versus at baseline). An extended (median, 27.5 months) follow-up showed a median time to oral cancer of 46.4 months. GTE may suppress OPLs, in part through reducing angiogenic stimulus (stromal VEGF). Higher doses of GTE may improve short-term (12-week) OPL outcome. The present results support longer-term clinical testing of GTE for oral cancer prevention.
Cancer Prevention Research 11/2009; 2(11):931-41. · 4.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fatigue can be classified as physical and mental depending on the cause. However, in our daily lives, combined fatigue, which is the combination of physical and mental fatigue, is most often experienced. In this study, the effects of (-)-epigallocatechin gallate (EGCg) on combined fatigue were assessed.
To produce an animal model of combined fatigue, rats were kept in a cage filled with water to a height of 1.5 cm for 5 d. To evaluate the extent of fatigue, the rats swam with a load of steel rings that weighed approximately 8% of their body weight and were attached to their tails.
Fatigued rats treated with EGCg (50 or 100 mg/kg intraperitoneally [not for 25 mg/kg]) for 5 d could swim longer than fatigued animals given saline. Although levels of thiobarbituric acid-reactive substances in the plasma, brain, and skeletal muscle were not different between control and fatigued rats, thiobarbituric acid-reactive substance levels were higher in livers of fatigued animals than in livers of control animals. Oral intake of EGCg (50 or 100 mg/kg) for 5 d significantly decreased thiobarbituric acid-reactive substance levels in livers of fatigued animals.
These results suggest that EGCg (50 or 100 mg/kg) is effective for attenuating fatigue. EGCg given orally appears to have an antioxidant effect on the oxidatively damaged liver of fatigued animals.
[Show abstract][Hide abstract] ABSTRACT: Myocarditis is a clinically serious disease. Tea catechins have been shown to reduce inflammation; however the effects of catechins on the development of myocarditis have not been well studied.
To clarify the role of catechins, using an experimental autoimmune myocarditis (EAM) model.
Lewis rats were immunized with porcine cardiac myosin to establish EAM. Tea catechins were administered orally from day 0 to day 21 (Group A, n=12), from day 14 to day 21 (Group B, n=8), or saline (Group C, n=9) daily. Rats were killed on day 21. Echocardiograms indicated that Group A showed significantly improved cardiac function compared to Group C. Pathologically, non-treated EAM hearts showed severe myocardial cell infiltration and fibrosis; however Group A showed significantly less area. Immunohistochemistry revealed enhanced expression of NF-kappaB and ICAM-1 in non-treated EAM hearts, which was suppressed by catechin administration in Group A. mRNA levels of TNF-alpha were decreased and Th2 cytokines were markedly enhanced in Group A compared with the control group. Late catechin administration (Group B) showed limited effects on EAM.
The catechins suppressed ventricular remodelling in EAM; thus catechin treatment might be a promising option for the prevention of EAM myocarditis.
European Journal of Heart Failure 03/2007; 9(2):152-9. · 6.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Tea catechins have many biological functions; these effects are induced by the suppression of several inflammatory factors. However, the effects of catechins on ventricular remodeling after myocardial ischemia have not been well investigated. To test the hypothesis that catechins can attenuate chronic ventricular remodeling after myocardial ischemia, we performed oral administration of catechins into rat myocardial ischemia models. We analyzed the mechanisms using physiological, pathological and molecular examinations. Although severe myocardial fibrosis with enhancement of inflammatory factors were observed in the non-treated ischemia group on day 28, catechins attenuated these changes with suppressed NF-kappaB and matrix metalloproteinases without systemic adverse effects. Catechins are potent for the suppression of chronic ventricular remodeling after myocardial ischemia because they are critically involved in the suppression of several inflammatory genes.
Journal of Molecular and Cellular Cardiology 03/2007; 42(2):432-40. · 5.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Tea catechins have many biological functions; these effects are induced by the suppression of several inflammatory factors. However, effects of catechins on cardiac allograft rejection have not been well investigated.
To test the hypothesis that catechins can attenuate ventricular remodeling and graft arterial diseases (GAD) in cardiac rejection, we orally administered catechins to murine cardiac recipients. We analyzed the mechanisms using immunohistochemistry, RNase protection, gel mobility shift, and cell proliferation assays. Although severe myocardial cell infiltration, fibrosis, and GAD with enhancement of inflammatory factors were observed in untreated class II mismatch allografts at day 60, catechins attenuated these changes with altered Th1/Th2 cytokine balance and suppressed NF-kappaB activation and cell proliferation.
Catechins are potent agents for the suppression of chronic rejection because they are critically involved in the suppression of proinflammatory signaling pathways.
Cardiovascular Research 02/2006; 69(1):272-9. · 5.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Accurate monitoring of tea catechins in biological samples might provide a means of better evaluation of their benefits. The aim of the present study was to develop a rapid method for extracting tea catechins from human plasma samples with a solid-phase extraction technique and to subsequently measure their concentrations using an HPLC system. A human plasma sample spiked with known concentrations of the analyte standards was passed through a Waters Oasis HLB cartridge. After repeated washing, tea catechins were eluted with 70% dimethylformamide containing 0.1% phosphoric acid, and the resulting eluate was injected into an HPLC system. Analytes were separated on a reverse-phase C18 column using an isocratic mobile phase and detected electrochemically. The coefficient of variation for inter- and intraday reproducibility was less than 5.0% and 6.4%, respectively. Linearity was established for the concentration range of 0.01-1.0 microM. The method was successfully applied to measure tea catechin concentrations in the plasma of two healthy subjects who received a single ingestion of a green tea beverage. The proposed method enables the rapid and accurate quantitation of plasma tea catechins and might prove useful for the evaluation of beneficial health effects of tea consumption.
Journal of Agricultural and Food Chemistry 01/2006; 53(26):9885-9. · 3.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The effects of consuming green tea catechins on the development of hyperlipidaemia-induced systemic organ damage have not been well studied; we investigated the effect using low density lipoprotein receptor knockout mice.
Mice were treated with high cholesterol food containing 0.2 or 4% catechins and they were supplemented for 35 weeks. High plasma cholesterol levels, liver and renal dysfunctions were observed in no catechin fed mice, while chow containing catechin suppressed these levels and damages. Severe atherosclerosis of the aorta, fatty liver and renal injury were also shown in the control mice; inflammatory factors were enhanced in these lesions of nontreated mice. The lesions were attenuated with suppression of the inflammatory factors in the chow-contained catechin treatment group.
Dietary consumption of tea catechins attenuated the development of the systemic organ damage; thus, this has a clinical effect against systemic inflammatory diseases.
[Show abstract][Hide abstract] ABSTRACT: Epidemiological surveys suggest that a higher intake of tea may be associated with a lower risk of CHD. There is accumulating evidence that postprandial lipaemia makes a substantial contribution to the incidence of CHD. Our aim was, therefore, to evaluate the effect of tea catechins (major ingredients in green tea) on postprandial lipid responses in human subjects after the consumption of test meals. In a randomized triple-crossover design, nine male subjects with mild or borderline hypertriacylglycerolaemia consumed 10 (control), 224 (moderate dose) and 674 mg (high dose) of the assigned tea catechins three times each along with a standardized light meal consisting of a piece of bread spread with 20 g butter. Plasma lipids were measured in the fasting state and 1, 2, 3, 4 and 6 h after consuming the light meal. Results showed that, compared with the control, moderate and high doses of tea catechins reduced the incremental area under the plasma triacylglycerol curves by 15.1 and 28.7%, respectively. Next, the rapid elevation of remnant-like particle cholesterol was significantly inhibited by a high dose of tea catechins 2 h after consuming the light meal (P<0.01). In the range of tea catechin dosages, no significant differences were observed in the postprandial responses for plasma total cholesterol or NEFA at any time point. In conclusion, this trial demonstrated that tea catechins attenuated the postprandial increase in plasma triacylglycerol levels following a fat load. These results may provide evidence for one of the possible mechanisms involved in lowering the incidence of CVD, and may prove useful in further studies on the beneficial health effects of tea drinking.
British Journal Of Nutrition 05/2005; 93(4):543-7. · 3.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although tea catechins have many biological functions, their effects on cardiac allograft rejection have not been well studied. We used a total allomismatch heart transplant model to test the effects of catechins in cardiac rejection. We have shown that cell infiltration and fibrosis were suppressed in catechin-treated allografts compared with nontreated transplants. However, catechins did not statistically prolong graft survival. We conclude that catechins have a potential to suppress inflammation in cardiac allografts.
[Show abstract][Hide abstract] ABSTRACT: We conducted a high-performance liquid chromatographic analysis of tea for eight catechins (epigallocatechin gallate, epigallocatechin, epicatechin gallate, epicatechin, gallocatechin gallate, gallocatechin, catechin gallate and catechin), caffeine and eight other phenolic compounds (epigallocatechin 3-O- (3″-O-methyl) gallate, epigallocatechin 3,5-di-O-gallate, chlorogenic acid, 3-O-caffeoylquinic acid, 4-O-p-coumaroylquinic acid, 5-O-p-coumaroylquinic acid, coniferin, 1,4,6-tri-O-galloyl-β-d-glucose). Using an octadecylsilyl column and a gradient elution system of water–methanol–ethyl acetate–phosphoric acid, all of these compounds were separated within 40 min. The validity of this method was confirmed by the quantitative measurement of eight catechins and caffeine. The detection limits of these compounds were within the range of 1.4–3.5 ng. All the analyses exhibited good linearity up to 1500 ng, and the accuracies for the analyses were 96–103%.
Journal of Food Composition and Analysis 10/2004; · 2.26 Impact Factor