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PubMed2005

Model of inhibition of Thermus aquaticus polymerase and Moloney murine leukemia virus reverse transcriptase by tea polyphenols (+)-catechin and (-)-epigallocatechin-3-gallate.

Non-nutritional polyphenolic compounds such as (+)-catechin and (-)-epigallocatechin-3-gallate (EGCG) are known as anticancer chemopreventive agents and have been utilised for medical purposes in form of tea drinking. Documented anticancer properties of these compounds result from their antioxidant effects. However, also direct alteration of an enzyme performance has been reported and deserves more attention. In this paper, a direct effect of catechin and EGCG on the performance of reverse transcription (RT) and/or polymerase chain reaction (PCR) was studied. Both tea polyphenolic compounds were added into real-time RT-PCR reactions and the fluorescence data obtained were fitted with a mathematical model. Several parameters of PCR performance were compared, obtained from the mathematical model for reactions with and without addition of (+)-catechin and EGCG. Addition of EGCG to enzyme reaction seems to inhibit the RT reaction (p < 0.05) and to slow down the DNA polymerase reaction (p < 0.001). Similarly, (+)-catechin inhibited the DNA amplification (p < 0.01) but had no effect on the RT reaction. The effects could be observed in physiological flavanol concentrations ranging from 10(-5) to 10(-8)M.

Animals↗
PubMed2001

Anti-cariogenic properties of tea (Camellia sinensis).

Various components in green and black tea, the beverages made by infusing appropriately processed dried leaves of Camellia sinensis, notably simple catechins, have properties in vitro that suggest an anti-cariogenic activity. These include: a direct bactericidal effect against Streptococcus mutans and S. sobrinus; prevention of bacterial adherence to teeth; inhibition of glucosyl transferase, thus limiting the biosynthesis of sticky glucan; inhibition of human and bacterial amylases. Studies in animal models show that these in-vitro effects can translate into caries prevention. A limited number of clinical trials in man suggest that regular tea drinking may reduce the incidence and severity of caries. If substantiated, this could offer a very economical public health intervention.

Animals↗
PubMed2000

Inhibitory effects of tea catechins and O-methylated derivatives of (-)-epigallocatechin-3-O-gallate on mouse type IV allergy.

The inhibitory effects of tea catechins, the O-methylated derivatives of (-)-epigallocatechin-3-O-gallate (EGCG), and the polyphenol extracts from tea leaves (Camellia sinensis L.) on oxazolone-induced type IV allergy in male ICR mice were investigated. Four major tea catechins and two O-methylated derivatives, (-)-epigallocatechin-3-O-(3-O-methyl)gallate (EGCG3' 'Me) and (-)-epigallocatechin-3-O-(4-O-methyl)gallate (EGCG4' 'Me), showed significant inhibitory effects on mouse type IV allergy after a percutaneous administration at a dose of 0.13 mg/ear. Among tea catechins, the compounds including galloyl moieties, such as EGCG and (-)-epicatechin-3-O-gallate (ECG), showed the strongest inhibitory activities on mouse type IV allergy. The inhibitory activities of EGCG3' 'Me and EGCG4' 'Me were higher than that of EGCG at a dose of 0.05 mg/ear. Polyphenol extract from tea leaves of Benihomare cultivar, which includes EGCG3' 'Me, strongly inhibited mouse type IV allergy after percutaneous administration in comparison with that from Yabukita cultivar, which does not include EGCG3' 'Me, at doses of 0.05 and 0.13 mg/ear. EGCG3' 'Me is thought to contribute, at least in part, to the inhibitory ability of Benihomare tea leaves on mouse type IV allergy. EGCG and the polyphenol extracts from Benihomare and Yabukita tea leaves also inhibited mouse type IV allergy by oral administration at 1 h before the sensitization and at 1 h before the challenge with oxazolone. Therefore, daily intake of tea drinks could have potential to prevent type IV allergy.

Administration, Topical↗
PubMed2006

Black tea--helpful or harmful? A review of the evidence.

OBJECTIVE: To consider whether consumption of black tea has a positive or negative impact on health. DESIGN: Databases were searched for relevant epidemiological and clinical studies published between 1990 and 2004. RESULTS: Clear evidence was found for coronary heart disease (CHD), where an intake of > or = 3 cups per day related to risk reduction. The mechanism could involve the antioxidant action of tea polyphenols. While experimental models have suggested that flavonoids attenuated cancer risk, epidemiological studies failed to demonstrate a clear effect for tea, although there is moderate evidence for a slightly positive or no effect of black tea consumption on colorectal cancer. Studies on cancer were limited by sample sizes and insufficient control of confounders. There is moderate evidence suggestive of a positive effect of black tea consumption on bone mineral density although studies were few. There is little evidence to support the effect of tea on dental plaque inhibition but evidence to support the contribution of tea to fluoride intakes and thus theoretical protection against caries. There was no credible evidence that black tea (in amounts typically consumed) was harmful. Normal hydration was consistent with tea consumption when the caffeine content was < 250 mg per cup. A moderate caffeine intake from tea appeared to improve mental performance, although sample sizes were small. There was no evidence that iron status could be harmed by tea drinking unless populations were already at risk from anaemia. CONCLUSIONS: There was sufficient evidence to show risk reduction for CHD at intakes of > or = 3 cups per day and for improved antioxidant status at intakes of one to six cups per day. A maximum intake of eight cups per day would minimise any risk relating to excess caffeine consumption. Black tea generally had a positive effect on health.

Affect↗
PubMed2003

Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses.

Human gammadelta T cells mediate innate immunity to microbes via T cell receptor-dependent recognition of unprocessed antigens with conserved molecular patterns. These nonpeptide alkylamine antigens are shared by tumor cells, bacteria, parasites, and fungi but also by edible plant products such as tea, apples, mushrooms, and wine. Here we show that priming of gammadelta T cells with alkylamine antigens in vitro results in a memory response to these antigens. Such priming results also in a nonmemory response to whole bacteria and to lipopolysaccharide, characterized by IL-12-dependent secretion of IFN-gamma by gammadelta T cells and by gammadelta T cell proliferation. Drinking tea, which contains l-theanine, a precursor of the nonpeptide antigen ethylamine, primed peripheral blood gammadelta T cells to mediate a memory response on reexposure to ethylamine and to secrete IFN-gamma in response to bacteria. This unique combination of innate immune response and immunologic memory shows that gammadelta T cells can function as a bridge between innate and acquired immunity. In addition, these data provide an explanation for the health benefits of tea.

Anti-Bacterial Agents↗
PubMed2001

Are coffee, tea, and total fluid consumption associated with bladder cancer risk? Results from the Netherlands Cohort Study.

OBJECTIVES: Coffee, tea, and fluid consumption have been thought to influence bladder cancer incidence. In a large prospective study, these associations were investigated. METHODS: In 1986, cohort members (55-69 years) completed a questionnaire on cancer risk factors. Follow-up was established by linkage to cancer registries until 1992. The multivariable case-cohort analysis was based on 569 bladder cancer cases and 3,123 subcohort members. RESULTS: The incidence rate ratios (RR) for men consuming <2 cups of coffee/day was 0.89 (95% CI 0.51-1.5) using the median consumption category (4-<5 cups/day) as reference. This RR increased to 1.3 (95% CI 0.94-1.9) for men consuming >7 cups/day, although no clear dose response association was found. The RRs decreased from 1.2 (95% CI 0.56-2.7) for women consuming <2 cups of coffee/day to 0.36 (95% CI 0.18-0.72) for women consuming >5 cups/day compared to the median consumption category (3-<4 cups/day). Men and women who abstained from drinking tea had a RR of 1.3 (95% Cl 0.97-1.8) compared to those consuming 2-<3 cups of tea per day (median consumption category). The RR for men and women comparing highest to lowest quintile of total fluid consumption was 0.87 (95% CI 0.63 1.2). CONCLUSION: The data suggest a possible positive association between coffee consumption and bladder cancer risk in men and a probable inverse association in women. Tea consumption was inversely associated with bladder cancer. Total fluid consumption did not appear to be associated with bladder cancer.

Aged↗
PubMed2000

Effects of tea catechins on the ERE-regulated estrogenic activity.

Tea catechins exert many biological effects, including anticancer and antibacterial activities. Also, it is reported that some plant flavonoids exhibit estrogenic activity. In this study, we investigated estrogenic or antiestrogenic activities of catechins in HeLa cells transiently transfected with an estrogen response element (ERE)-regulated luciferase reporter and an estrogen receptor (ER) alpha or ERbeta expression vector. Catechins alone did not induce luciferase (luc) activity in either of the ERs. Addition of 17beta-estradiol (E2) plus epicatechin gallate (ECG) or epigallocatechin gallate (EGCG) at 5 x 10(-6) M resulted in significant decreases in the ERalpha-mediated luc activity compared with that of E2 alone. On the contrary, lower concentrations significantly increased the E2-induced luc activity. Similar effects were observed with tamoxifen. The ERbeta-mediated estrogenic activities were stimulated by catechins. In conclusion, some catechins, particularly EGCG, were antiestrogenic for ERalpha at higher doses, and co-estrogenic for ERalpha at lower doses and for ERbeta. The lower doses were found in human plasma after tea-drinking. In addition, some catechins may be antiendocrine disruptors because they suppressed bisphenol A-induced luc activities.

Catechin↗
PubMed2003

Tea intake and risk of colon cancer in African-Americans and whites: North Carolina colon cancer study.

OBJECTIVES: Tea polyphenols have been shown to exhibit anti-cancer activity, but the epidemiological findings are inconsistent. We examined the association between tea consumption and colon cancer in a population-based study in North Carolina. METHODS: The analysis included 630 cases and 1040 controls frequency matched to cases by age, gender, and race. The odds ratios (OR) for tea consumption, adjusted for age and gender, were calculated for African-Americans and Whites and effect modification by race was explored. RESULTS: No association was found between tea consumption and colon cancer overall. Compared to non-consumers, those who consumed <2 servings/day or > or = 2 servings/day had OR = 0.9 (95% CI: 0.7-1.2) and OR = 1.3 (95% CI: 0.9-1.8) respectively. Other risk factors for colorectal cancer (family history of colorectal cancer, exposure to non-steroid anti-inflammatory drugs, meat cooking practices, smoking, physical activity, body mass index, intake of red meat, fruits, vegetables, and alcoholic beverages) did not influence these associations. We did not find any evidence of effect modification by race on either on the multiplicative or additive scale. CONCLUSION: We conclude that, contrary to expectation, tea drinking did not decrease the risk of colon cancer in this study population.

Adult↗
PubMed1993

Gastro-intestinal availability of aluminium from tea.

The in vitro speciation of aluminium (Al) in black tea infusion (pH 4.8) was assessed using 3000, 10,000 and 30,000 Da cut-off ultrafilters, and the effect of adding human gastric juice (pH 2.3) and then raising the pH to 6.5 were also studied. 78% Al in the tea infusion passed through the 3000-Da ultrafilter; this percentage increased to more than 90% with the addition of gastric juice at pH 2.3, but then reduced to approximately 5% when the incubate was adjusted to pH 6.5. The breakdown of tea-derived polyphenols to low molecular weight phenols in vivo was measured using high-resolution 1H nuclear magnetic resonance spectroscopic analysis of ileostomy effluent, but there was no evidence of low molecular weight breakdown products from the polyphenols of ingested tea in this effluent. These results suggest that only a small proportion of Al in tea is potentially available for absorption throughout the small bowel. It may be misleading to estimate systemic Al absorption from tea drinking simply from total urinary aluminium excretion as has been done previously.

Aluminum↗
PubMed1994

Risk-factors for Parkinson's disease: case-control study in the province of Cáceres, Spain.

This case-control study, performed in a mixed rural and urban province, of 74 patients with Parkinson's disease (PD) and 148 unselected age and sex-matched controls, attempted to look possible risk factors for PD. Rural living, well-water drinking, positive family history for PD and postural tremor, were associated to an increased risk for PD, with results regarding exposure to pesticides near to statistical significance. Alcohol-drinking habit in males were associated to a decreased risk for PD, with results regarding cigarette-smoking habit in males near to statistical significance. We did not find association between the risk for PD and the following variables: 1) exposure to industrial toxins; 2) agricultural work; 3) cranial trauma; 4) previous common illnesses including some infections, arterial hypertension, diabetes mellitus, coronary heart disease and thyroid disease; 5) coffee and tea drinking habits.

Aged↗
PubMed1993

Tobacco smoking, alcohol drinking, and cancer of the oral cavity and oropharynx among U.S. veterans.

BACKGROUND: Independent carcinogenic effects of alcohol drinking and tobacco smoking as well as their interaction can be usefully studied in a population of heavy drinkers and smokers. METHODS: A hospital-based case-control study was conducted during 1972 to 1983 in a large Veterans hospital in East Orange, New Jersey. A total of 359 oral cavity-oropharynx cancer cases and 2280 controls were interviewed according to tobacco smoking, use of smokeless tobacco, alcoholic beverage, coffee and tea drinking, race, family origin, religion, and occupation as bartender. RESULTS: Odds ratio of oral cancer increased up to the level of 35 cigarettes per day and 21 whiskey equivalents per day: no further increase was found for higher level of exposure to either factor. A protective effect of quitting smoking was found, but the number of former smokers was small. No difference occurred in oral cancer risk according to type of alcoholic beverage drunk. An interaction effect compatible with a multiplicative model was found between the two exposures. Blacks were at lower risk than whites, and, in the latter group, individuals of Italian origin were at lower risk than individuals from northern or central European countries. CONCLUSIONS: Alcohol drinking and tobacco smoking were responsible for the majority of oral cancer cases in this population of US Veterans.

Adult↗
PubMed1994

Risk factors for renal cell carcinoma in Denmark. I. Role of socioeconomic status, tobacco use, beverages, and family history.

Risk factors for renal cell carcinoma were examined in a population based case-control study in Denmark. A total of 368 cases and 396 age- and gender-matched controls were interviewed in their homes. Increased risk was associated with low socioeconomic status. For men, an increasing risk with decreasing socioeconomic status was seen (odds ratio [OR] = 2.2, 95 percent confidence interval [CI] = 1.0-4.6 for men in the lowest socioeconomic stratum cf the highest). For women, the risk was lower in the highest socioeconomic stratum compared with the rest (OR = 2.4, CI = 0.9-5.9 for the lowest strata cf the highest). Cigarette smoking was a risk factor in men with an OR = 2.3 (CI = 1.1-5.1) for cigarette smokers with a total consumption of more than 40 pack-years compared with nonsmokers. Family history of kidney cancer was associated with an increased risk in both genders (for men, OR = 4.1, CI = 1.1-14.9; for women, OR = 4.8, CI = 1.0-23). Observations were inconsistent regarding coffee and alcohol consumption, and we found no association with tea drinking. The association with socioeconomic status remained after adjustment for other factors.

Adult↗
PubMed1987

Coffee consumption is correlated with serum cholesterol in middle-aged Finnish men and women.

The association between coffee consumption and serum cholesterol was studied in a cross-sectional epidemiological study in Finland where the annual per capita consumption of coffee (13.0 kg) is the highest in the world. Coffee consumption was assessed by a questionnaire in a representative population sample of 4744 men and 4495 women aged 25 to 64 years. Serum total cholesterol and HDL-cholesterol concentrations were determined in fresh sera by the enzymatic method. Data on a large number of potential confounding variables were also collected. In the age group 25 to 44 years, the level of serum total cholesterol increased linearly with increasing coffee consumption in both sexes, but in people aged 45 to 64 the peak level of serum cholesterol was found in those who consumed 4 to 6 cups of coffee per day. In the analysis of covariance controlling for age, body mass index, intake of fat, sugar, and alcohol, smoking, physical activity, and fasting time, the mean level of serum cholesterol of men was lower (p less than 0.001) in those who drank no coffee (5.9 mmol/l) than in those who drank 1 to 3 cups (6.1 mmol/l) or 4 or more cups (6.2 mmol/l) per day. In women, the corresponding mean serum cholesterol values were 5.8 mmol/l, 6.1 mmol/l, and 6.1 mmol/l (p less than 0.05). Serum HDL-cholesterol levels did not vary significantly with coffee consumption. There was a slight inverse association between tea drinking and serum total cholesterol in men (p less than 0.05) but not in women. Although our results suggest a positive association, the impact of coffee drinking on serum cholesterol seems to be minimal. The results also indicate that the possible mechanisms do not include caffeine.

Adult↗
PubMed2006

Metformin-like effect of Salvia officinalis (common sage): is it useful in diabetes prevention?

Common sage (Salvia officinalis L.) is among the plants that are claimed to be beneficial to diabetic patients, and previous studies have suggested that some of its extracts have hypoglycaemic effects in normal and diabetic animals. In the present study, we aimed to verify the antidiabetic effects of an infusion (tea) of common sage, which is the most common form of this plant consumed. Replacing water with sage tea for 14 d lowered the fasting plasma glucose level in normal mice but had no effect on glucose clearance in response to an intraperitoneal glucose tolerance test. This indicated effects on gluconeogenesis at the level of the liver. Primary cultures of hepatocytes from healthy, sage-tea-drinking rats showed, after stimulation, a high glucose uptake capacity and decreased gluconeogenesis in response to glucagon. Essential oil from sage further increased hepatocyte sensitivity to insulin and inhibited gluconeogenesis. Overall, these effects resemble those of the pharmaceutical drug metformin, a known inhibitor of gluconeogenesis used in the treatment and prevention of type 2 diabetes mellitus. In primary cultures of rat hepatocytes isolated from streptozotocin (STZ)-induced diabetic rats, none of these activities was observed. The present results seem to indicate that sage tea does not possess antidiabetic effects at this level. However, its effects on fasting glucose levels in normal animals and its metformin-like effects on rat hepatocytes suggest that sage may be useful as a food supplement in the prevention of type 2 diabetes mellitus by lowering the plasma glucose of individuals at risk.

Animals↗
PubMed2003

Are smoking and other lifestyle factors associated with female urinary incontinence? The Norwegian EPINCONT Study.

OBJECTIVE: To examine whether modifiable lifestyle factors such as smoking, obesity, physical activity and intake of alcohol or caffeinated drinks were associated with urinary incontinence in women. DESIGN: Cross sectional population-based study. SETTING: The Norwegian Epidemiology of Incontinence in the County of Nord-Trøndelag (EPINCONT) Study is part of a large survey performed in a county in Norway during 1995-1997. POPULATION: Women >/=20 years (n = 34,755, 75% of the invited) attended the first part of the survey and received the questionnaire. There were 27,936 (80% of source population) women who completed the incontinence part of the questionnaire. METHODS: Questionnaire covering several health topics including urinary incontinence was received at a screening station. Logistic regression analysis was used to adjust for confounding and to establish associations with the different outcomes under investigation: any incontinence, severe incontinence and stress, urge and mixed subtypes. MAIN OUTCOME MEASURES: Effect measure were odds ratios with corresponding 95% confidence intervals. RESULTS: Former and current smoking was associated with incontinence, but only for those who smoked more than 20 cigarettes per day. Severe incontinence was weakly associated with smoking regardless of number of cigarettes. The association between increasing body mass index and incontinence was strong and present for all subtypes. Increasing levels of low intensity physical activity had a weak and negative association with incontinence. Tea drinkers were at slightly higher risk for all types of incontinence. We found no important effects of high intensity physical activity, intake of alcohol or coffee. CONCLUSIONS: Several potentially modifiable lifestyle factors are associated with urinary incontinence. Highest odds ratios were found for body mass index, heavy smoking and tea drinking.

Adult↗
PubMed2004

Nocturia in relation to body mass index, smoking and some other life-style factors in women.

OBJECTIVE: To analyze the relationship of nocturnal micturition to body mass index (BMI), smoking, regular exercise, coffee and tea drinking, parity, and menopausal transition in women. METHODS: A questionnaire study was carried out in 3669 respondents among 6000 women, i.e. 1200 randomly selected from each 5-year age group between 40 and 64 years in the County of Jämtland, Sweden. The questions concerned number of nocturnal voiding episodes, health, childbirths, occurrence of somatic diseases and symptoms, habits and medication. RESULTS: In univariate analyses, body mass index (BMI) > or =30, smoking, lack of regular exercise and menopausal status, but not parity, were associated with an increased number of nocturnal micturition episodes. Nocturia was twice as common in women who drank no evening coffee or tea as in those who drank either of these beverages. In a multiple logistic regression analysis, independent correlates for two or more nocturnal micturition episodes vs. no more than one episode were: smoking 1-15 cigarettes daily vs. no smoking (odds ratio (OR), 1.4; confidence interval (CI), 1.1-1.8), 16 or more cigarettes per day vs. no smoking (OR, 1.8; CI, 1.1-2.8), <5 years after menopause vs. before (OR, 2.0; CI, 1.4-2.7), 5-9 years after vs. before (OR, 2.3; CI, 1.6-3.2) and > or =10 years after vs. before (OR, 3.5; CI, 2.6-4.7), BMI > or =30 vs. <20 (OR, 3.5; CI, 2.6-4.7). BMI in the ranges 20-24.9 and 25-29.9 showed no independent influence on nocturia. CONCLUSIONS: Nocturnal micturition was increased by smoking and raised BMI and decreased by regular exercise, but was not influenced by childbirth.

Adult↗
PubMed1988

First-derivative spectrophotometric and gas-liquid chromatographic determination of caffeine in foods and pharmaceuticals. I. Rapid determination of caffeine in coffee, tea and soft drinks.

A simple and rapid spectrophotometric method is described for the determination of caffeine in coffee, tea and soft drinks. To exclude the irrelevant absorptions, due to the presence of some accompanying naturally occurring ingredients in the analysed multicomponent drinks, the derivative method is found to be superior. Another gas-liquid chromatographic (GLC) procedure for the quantitation of the analeptic agent, in bulk form and in the same drinks, is also investigated. The recovery testing of the proposed methods gives good percentage mean recoveries with relatively low deviations. The results of the methods described are compared with those obtained by direct UV-spectrophotometry as well as by applying an official pharmacopoeial procedure for caffeine.

Beverages↗
PubMed2006

[Surveys of the consumption of nutritional antioxidants in inflammatory bowel diseases].

The redox homeostasis of patients with inflammatory bowel disease is not balanced because of malnutrition and malabsorption. The seriousness of this illness often hinders the intake and use of bioactive agents. We have just a small amount of knowledge about how patients can get access to these important materials. The authors' aim was to edit a questionnaire, which can estimate, with large precision, the amount of fruit and vegetable consumption among a random-chosen group of IBD patients. We also thought that the measuring of tea, fruit-juice and wine consumption is also important in order to see whether the intake of these can help the intake of natural polyphenol, vitamin and trace elements. For this study 50 IBD patients (25 male, 25 female, 35-67 years) and 50 healthy people (35 male, 15 female, 25-47 years) were asked. During the completion of the questionnaire in 8 cases (5 male, 3 female) the provided data could not be accepted, because of inaccuracy. During this study, it became obvious that the intake of polyphenols was not enough if we focus on the average daily consumption of fruits and vegetables. Red wine cannot be considered efficient for replacing polyphenols, because more than the half of patients doesn't drink it at all, or drink it once or twice a month. From the aspect of drinking tea or eating fruits, the situation is much better. The participants' (92 people) consumption of vegetables and fruits is reduced to a small variety, which is not beneficial. Mostly used plants often caused different disorders, and that is why a controlled recommendation of polyphenol, vitamin, trace element and fiber would be favorable.

Adult↗