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PubMed2003

Antioxidant effects of tea: evidence from human clinical trials.

Tea remains the most consumed drink in the world after water, well ahead of coffee, beer, wine and carbonated soft drinks. An accumulated number of population studies suggests that consumption of green and black tea beverages may bring positive health effects (1). One hypothesis explaining such effects is that the high levels of flavonoids in tea can protect cells and tissues from oxidative damage by scavenging oxygen-free radicals. Chemically, the flavonoids found in green and black tea are very effective radical scavengers. The tea flavonoids may therefore be active as antioxidants in the digestive tract or in other tissues after uptake. A substantial number of human intervention studies with green and black tea demonstrates a significant increase in plasma antioxidant capacity in humans approximately 1 h after consumption of moderate amounts of tea (1-6 cups/d). There are initial indications that the enhanced blood antioxidant potential leads to reduced oxidative damage to macromolecules such as DNA and lipids. However, the measurement of oxidative damage through biomarkers needs to be further established. In conclusion, tea flavonoids are potent antioxidants that are absorbed from the gut after consumption. Tea consumption consistently leads to a significant increase in the antioxidant capacity of the blood. Beneficial effects of increased antioxidant capacity in the body may be the reduction of oxidative damage to important biomolecules. The scientific support is strongest for the protection of DNA from oxidative damage after black or green tea consumption. However, the quality of the studies now available is insufficient to draw firm conclusions. Therefore, further evidence from human intervention studies is required.

Antioxidants↗

PubMed1999

Consumption of tea modulates the urinary excretion of mutagens in rats treated with IQ. Role of caffeine.

The present study was undertaken to investigate whether the consumption of green tea and black tea influences the excretion of mutagens and promutagens in rats treated orally with the food carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). Rats were maintained on aqueous extracts (2.5%, w/v) of green tea, black tea or decaffeinated black tea as their sole drinking liquid. After 4 weeks, the animals received, by gastric intubation, a single dose of IQ (5 mg/kg), and urine was collected for 48 h. Direct and indirect mutagenicity, in the presence of an activation system derived from Aroclor 1254-treated rats, was determined in the urine samples using the Ames mutagenicity assay. Consumption of green tea and black tea, but not of decaffeinated black tea, markedly decreased the urinary excretion of mutagens and promutagens. In a further study, supplementation of decaffeinated black tea with caffeine suppressed the excretion of mutagens and promutagens in the urine of rats pretreated with IQ. It is concluded that both green tea and black tea modulate the bioactivation and metabolism of IQ, and that caffeine is largely responsible for this effect.

Animals↗

PubMed2000

Green tea consumption and chronic atrophic gastritis: a cross-sectional study in a green tea production village.

Chronic atrophic gastritis (CAG) is well known as a precancerous lesion of the stomach, and Helicobacter pylori (H. pylori) infection increases the risk of CAG. While recent studies have reported that green tea consumption decreases the risk of gastric cancer, there has been no study analyzing the relationship between green tea consumption and the both risks H. pylori infection and CAG. We conducted a cross-sectional study on 636 subjects living in a farming village in Japan to examine the relationship among green tea consumption, H. pylori infection, and CAG. Smoking, alcohol drinking, consumption of four beverages, including green tea, and of five foods were investigated as lifestyle factors that may affect H. pylori infection and CAG. The measurement of H. pylori-IgG antibodies was used to define H. pylori infection, and serum pepsinogens were used to define of CAG. The unconditional logistic regression model was used for analyzing each odds ratio (OR). H. pylori infection was positively associated with the risk of CAG (OR = 3.73; 95% confidence interval [CI], 2.59-5.36). High green tea consumption (more than 10 cups per day) was negatively associated with the risk of CAG, even after adjustment for H. pylori infection and lifestyle factors associated with green tea consumption (OR = 0.63; 95% CI, 0.43-0.93). These results support the hypothesis that high green tea consumption prevents CAG.

Adult↗

PubMed2001

Possible interaction between warfarin and Lycium barbarum L.

OBJECTIVE: To describe a patient who was stabilized on warfarin and developed an elevated international normalized ratio (INR) after drinking a concentrated Chinese herbal tea. Additionally, to determine the effect of the tea on CYP2C9, the isoenzyme responsible for the metabolism of S-warfarin. CASE SUMMARY: An elevated INR of 4.1 was observed in a 61-year-old Chinese woman, previously stabilized on anticoagulation therapy (INR 2-3). With no changes in her other medications or lifestyle, a review of her dietary habits revealed four days of drinking a concentrated Chinese herbal tea made from Lycium barbarum L. fruits (3-4 glasses daily) prior to her clinic visit Warfarin was withheld for one day and then resumed at a lower weekly dose. She discontinued the tea, while maintaining consistency with medications and dietary habits. A follow-up INR seven days later was 2.4, and seven subsequent INR values were in the 2.0-2.5 range. DISCUSSION: L barbarum L. (family Solanaceae) is a commonly used Chinese herb considered to have a tonic effect on various organs. Any impact of an herbal product on the metabolism of S-warfarin, the enantiomer responsible for most of the anticoagulant activity, could alter the INR values. An herbal-drug interaction was suspected in this case. In vitro evaluation showed inhibition of S-warfarin metabolism by CYP2C9 by the tea of L. barbarum L.; however, the inhibition observed was weak, with a dissociation constant (Ki) value of 3.4 mg/mL, suggesting that the observed interaction may be caused by factors other than the CYP450 system. CONCLUSIONS: There is a potential herbal-drug interaction between warfarin and L. barbarum L., based on an increased INRvalue noted with concurrent use. Thus, combination of L. barbarum L. and warfarin should be avoided. Vigilance is needed with other herbal combinations taken with drugs of narrow therapeutic indices.

Anticoagulants↗

PubMed1991

A comparison of the diets of non-smokers and smokers.

Dietary data, mostly in the form of the frequency of consumption of foods, from the 9003 respondents in the Health and Lifestyle Survey were used to compare lifetime non-smokers with light, heavy and ex-smokers, taking account of age and social class. Non-smokers, of both sexes, were significantly more likely than smokers to consume, frequently, fresh fruit in summer and winter, fruit juice, cooked and canned fruit, salads in summer and winter, breakfast cereals, cakes, biscuits, puddings, pasta, poultry, light desserts and preserves. They were also more likely to choose 'brown' bread, semi- or skimmed milk, low fat or polyunsaturated spread and to eat breakfast. Smokers were likely to consume chips and processed meats frequently, to drink more alcohol, more cups of tea and coffee and take sugar in these beverages. The differences from the non-smokers were more marked in the heavy smokers. Ex-smokers only differed from non-smokers in consuming more alcohol, tea and coffee, and nuts, in consuming cakes and soft drinks less frequently and in being more likely to choose skimmed or semi-skimmed milk. The results extend previous findings, and suggest that the eating patterns of non-smokers are more in line with current dietary recommendations than those of light smokers or, more particularly, heavy smokers.

Adolescent↗

PubMed2004

Smoking, coffee, and pancreatitis.

OBJECTIVES: We studied relationships of cigarette smoking and coffee drinking to risk of pancreatitis. METHODS: This was a cohort study among 129,000 prepaid health plan members who supplied data about demographics and habits in 1978-85. Among 439 persons subsequently hospitalized for pancreatitis, probable etiologic associations were cholelithiasis (168/439 = 38%), alcohol (125/439 = 29%), idiopathic (110/430 = 25%), and miscellaneous (36/439 = 8%). Cox proportional hazards models with seven covariates (including alcohol intake) yielded relative risk estimates for smoking and coffee use. RESULTS: Increasing smoking was strongly related to increased risk of alcohol-associated pancreatitis, less related to idiopathic pancreatitis, and unrelated to gallstone-associated pancreatitis. Relative risks (95% confidence intervals, CI) of one pack per day (vs never) smokers for pancreatitis groups were: alcohol = 4.9 (2.2-11.2, p < 0.001), idiopathic = 3.1 (1.4-7.2, p < 0.01), and gallstone = 1.3 (0.6-3.1). The relationship of smoking to alcohol-associated pancreatitis was consistent in sex and race subsets. Drinking coffee, but not tea, was weakly inversely related to risk only of alcohol-associated pancreatitis, with relative risk (95% CI) per cup per day = 0.85 (0.77-0.95; p= 0.003). Male sex, black ethnicity, and lower-educational attainment were other predictors of alcohol-associated pancreatitis. CONCLUSIONS: Cigarette smoking is an independent risk factor for alcohol-associated and idiopathic pancreatitis. Coffee drinking is associated with reduced risk of alcohol-associated pancreatitis. The data are compatible with the hypotheses that smoking may be toxic to the pancreas or may potentiate other pancreatic toxins while some ingredient in coffee may have a modulating effect.

Coffee↗

PubMedDate not supplied

Fluoride concentration and pH of iced tea products.

The objective of this study was to determine the fluoride concentration and pH of 44 iced tea samples and hence to assess the possible role of these beverages as systemic fluoride source as well as their potential cariogenic and erosive character. Ten tea samples were available as a granular instant powder, and 34 as ready-to-drink liquid products. The iced teas contained different types of sugar alone or in combination with maltodextrin, glucose syrup and noncaloric sweeteners. In one product, only acesulfame and aspartame were established. All samples contained lemon juice or citric acid as an additive. The pH ranged from 4.04 to 2.63 and the titrated amount of base to pH 7.0 from 0.75 to 2.39 mmol NaOH/50 ml. The fluoride concentrations measured were <0.6 ppm in 14 products, 0.6-1.0 ppm in 10 products, 1.1-1.5 ppm in 16 products, 1.6-2.0 ppm in 2, and >2.0 ppm in another 2 products. In conclusion, most of the iced teas studied contained considerable fluoride concentrations. If infants ingest larger amounts of them because of their sweet taste, there is a risk of uncontrolled overdosing as a result of additional fluoride intake from other sources at the same time. Furthermore, the majority of the products revealed a highly cariogenic character and finally, all the iced teas appear to be acidic enough to cause dental erosion if these refreshments were excessively consumed from nursing bottles.

Citric Acid↗

PubMed1994

[Occurrence of aluminum in some foodstuffs].

Results of aluminium determinations in breads and biscuits as well as in fish preserves, vegetables, strawberries and teas including fruit-herb teas are presented. Also the percent of extraction of aluminium of various kind of tea leaves into the infusions was determined. The commercially available sample of foods was used for investigation. Aluminium was determined by using two methods: a spectrophotometric extraction method with-hydroxyquinoline and less sensitive AAS method with nitrous oxide-acethylene flame on PU 9100X Philips Spectrometer could with IBM compatible Computer (Hundai) provided with 9178/9X Flame Program Unicam Limited--1991. The sample was at first digested with mixture of concentrated acids (H2SO4 + HNO3 + HClO4) in teflon vessels and then finished in platinum dishes. Solutions of the destroyed samples was kept in polethylene bottles. The methods was checked by recovery tests. In the 8-hydroxyguinoline-extraction-method about 88.5% to 106.5% of the added aluminium was determined and in the AAS method it was of 75% to 100%. The highest level of aluminium was found in the eas: from 445 to 1522 mg/kg (mean 879 mg/kg) and then in herb-fruit teas (consisting of dried herbs and fruits of sloe plum, briar-rose juneberry Aronia etc.) from 45 to 379 mg Al/kg of dry matter. About 29% of the metal was extracted from teas into the infusion. Lower levels was found in breads (0.0-92.0 mg mean 29.95 mg/kg) and in the fish preserves (0.0-57.0 mg mean 18.1 mg AL/kg). Similar levels were also found in 7 kinds of popular vegetables (0.0-100 mg mean 33.3 mg Al/kg). The lowest levels was found in strawberries (0.50-3.0 mg Al/kg). It was calculated that drinking three glasses of tea daily may supply about 2.6 to 3.7% of the provisional tolerable weekly intake dose set by the Joint FAO/WHO Expert Committee. It is concluded that the obtained results are similar to those published by other authors and represents a levels normally encountered in foods, and do not create any risk for human consumption.

Aluminum↗

PubMed2002

Effects of black tea extract on carbon tetrachloride-induced lipid peroxidation in liver, kidneys, and testes of rats.

Previous studies have shown that green tea and black tea have antioxidant effects and chemopreventive activity against chronic disease including some forms of cancer. We have, therefore, examined the effects of an aqueous extract of black tea against carbon tetrachloride-induced lipid peroxidation as determined by the formation of thiobarbituric acid reactive substances in liver, kidneys and testes of rats. A 0.7% black tea extract was used which contained 2 mg of black tea extract solids per mL. Black tea was administered as drinking water for 3, 6, 9 and 12 months before and during carbon tetrachloride (CCl(4)) treatment in female and male rats. Rats were treated with a single oral dose of CCl(4) 1.0 mL/kg. All rats were killed 24 h after CCl(4) treatment. All animals were dosed with CCl(4) at the end of the 3, 6, 9, and 12 month of treatment. Black tea treatment for 75 days produced a decrease in CCl(4)-induced hepatic lipid peroxidation but significant decreases in thiobarbituric acid reactive substances occurred 3 months after treatment in both female and male rats. In liver and kidneys, black tea alone increased lipid peroxidation by 30%-50% in female and male rats. However, black tea decreased CCl(4)-induced lipid peroxidation in liver of female and male rats by approximately 49% and 37%, respectively. Black tea decreased CCl(4)-induced lipid peroxidation in testes by approximately 37% at a dose of 1.0 mL CCl(4)/kg. These results suggest that the protective effects of black tea against CCl(4)-induced lipid peroxidation in liver, kidneys and testes is due at least partly to its antioxidant properties, scavenging CCl(4)-associated free radicals.

Animals↗

PubMed1988

Environmental factors and high risk of esophageal cancer among men in coastal South Carolina.

A case-control study involving interviews of 207 men with esophageal cancer and 422 control subjects or their next of kin was conducted to identify reasons for the unusually high rates of esophageal cancer among men in coastal South Carolina. Tobacco and alcohol, including moonshine, were identified as the major determinants of esophageal cancer risk. Increased risk was also associated with low intake of fresh fruits but not with drinking of local herbal teas. The findings suggest that efforts aimed at reducing tobacco and alcohol use will help to lower the elevated rates of esophageal cancer in coastal South Carolina.

Alcohol Drinking↗

PubMedDate not supplied

Maternal caffeine use before, during and after pregnancy and effects upon offspring.

Prospective information gathered through the course of pregnancy, perinatal measurements, and retrospective data collected postnatally were used to investigate the changing patterns and effects of caffeine use of 286 women participating in the Ottawa Prenatal Prospective Study. Data were collected on maternal use of tea, coffee, caffeinated soft-drinks, chocolate bars and drinks and caffeinated medication. The volume and analysed caffeine concentration of 53 samples of coffee and tea, prepared by subjects as they usually consumed it, were used to examine the predictive potential of the women's subjective description of the beverages. Self-reports of volume and beverage strength were found to be valid predictors; the method of coffee preparation held little predictive power. An algorithm for estimating caffeine intake retrospectively over time was developed. During pregnancy most women continued to consume caffeine but usually at lower intake levels. After pregnancy, caffeine consumption tended to persist at reduced levels for several months and then returned to prepregnancy patterns. Maternal caffeine intake of more than 300 mg daily during pregnancy was associated with lowered birth weight and smaller head circumference of the infant after accounting for maternal nicotine use. No relationship was apparent between maternal caffeine use and the incidence of caesarian sections, breech births, miscarriages or premature births.

Adult↗

PubMed1992

Infant feeding practices among poor families of an urban squatter community.

We studied the types of food, time of introduction, frequency and nutrient intake among 133 infants during the 1st year of life. A 24-hour dietary recall indicated that 42 different types of food, including mothers' milk, were offered directly or in suitable preparations. Breast- and mixed-fed infants were likely to receive more milk feedings than non-breast-fed infants. Sugar and liquids such as tea, fruit juices and soft drinks were introduced at a very early age. The breast-fed babies were offered only teas before the 3rd month. Solid food was offered as early as at 4 months, regardless of breast or bottle feeding. Fe and vitamin A were estimated to be below the recommended dietary allowance in the group that was not receiving breast milk.

Animals↗

PubMed1988

Fast profiling of food by analytical pyrolysis.

The analytical application of direct pyrolysis (Py) field ionization (FI)-mass spectrometry (MS) und Curie-point pyrolysis gas chromatography-mass spectrometry (Py-GC/FIMS) to various whole foodstuffs is described for the first time. The former technique yields highly differentiated information from the sample in typically 15 min, namely the molecular weight distribution of released volatiles and pyrolysis products in a single spectrum which, owing to the good reproducibility and high significance of the resulting data, has previously been shown to be suitable for the application of chemometric methods. Such mass spectral peaks are further characterized and assigned by high resolution mass measurement and/or by electron ionization after Curie-point pyrolysis and gas chromatographic separation of the components. In this first report, typical results are presented for ground roasted coffee, rosehip tea, wheatmeal biscuit, chocolate drink powder and milk chocolate. The FI mass spectrum obtained from the latter sample is compared with those obtained using the complementary soft ionization techniques of chemical ionization (CI) and direct chemical ionization (DCI).

Animals↗

PubMed2005

[Effect of tea polyphenols on oxidative metabolism of polymorphonuclear neutrophils in healthy and obese people].

UNLABELLED: Obese people are at high risk for developing diabetes, dyslipidemia, hypertension, and cardiovascular diseases, which lead to an increased risk of mortality. Evidence for the potential role of oxidative stress in various diseases and pathophysiological processes suggests that the dietary intake and the therapeutic use of antioxidants may have positive health effects. The aim of the study was: 1) to investigate the ability of the major tea polyphenols: (-)-epigallocatechin gallate (EGCG), theaflavins (TF) and gallic acid (GA) to protect in vitro human neutrophils from oxidative damage induced by phorbol myristate acetate (PMA), 2) estimation the level of reactive oxygen species (ROS) production in obese patient depending on the red tea Pu-Erh drinking, 3) estimation inflammatory marker: CRP. MATERIAL AND METHODS: We tested 14 obese patients (aged 45+/-12 years, women, BMI=34+/-5.1 kg/m2). The inclusion criteria were based on physical examination, BMI, WHR, and the body composition examination based on bioimpedance method. PMA were isolated and oxidant production, in response to 1 microg/ml PMA, was characterized by the production of hydrogen peroxide, nitric oxide and chemiluminescence intensity. CRP level was assayed by the immunoturbidimetric test in serum. Control group consisted of healthy blood donors. RESULTS: Women consuming red tea revealed alteration in reactive oxygen species generation; the relative decrease of RFT was greater after 5 months than that after 1 month of treatment. A decrease in ROS generation after red tea consumption was accompanied by the decrease of ROS in response to tested compounds in normal cells. EGCG and TF showed similar potency in antioxidative activities. Tea polyphenols were not found to modulate CRP level in obese women. CONCLUSIONS: Tea may thus represent an important source of dietary antioxidants; there is need for more detailed studies to improve our understanding of the role of tea in reducing risk of major disease states.

Adult↗

PubMed2005

Green tea and stomach cancer--a short review of prospective studies.

BACKGROUND: In Japan, green tea has been drunk for a long time. Because it can be drunk casually, many people love drinking it. If such green tea has an effect to prevent stomach cancer, it will be a very convenient way to prevent the disease. METHODS: To examine the association between green tea consumption and the risk of stomach cancer, past epidemiologic studies including JACC Study were reviewed. RESULTS: Among eight case-control studies, five showed risk reduction with a statistically significant difference, and two studies showed risk reduction without a statistically significant difference. The remaining study showed the opposite result. Among six prospective studies regarding stomach cancer, no study showed risk reduction with a statistically significant difference. Four of the six studies showed no relation. In terms of study design, prospective studies, which are considered to be more reliable than case-controlled studies, tend to show no risk reduction. The results of case-control studies and prospective studies present considerably different impressions. CONCLUSIONS: Prospective studies showed no inverse association between the consumption of green tea and the risk of stomach cancer.

Beverages↗

PubMed2002

Effects of tea on preneoplastic lesions and cell cycle regulators in rat liver.

The effects of tea polyphenols and tea pigments on rat liver precancerous lesions and some cell cycle regulators were studied. A modified Solt-Farber model in rats was established by multiple low-dosage of N-nitrosodiethylamine (NDEA) i.p. injections, followed by i.p. CCl(4) injection and partial hepatectomy. Sixty male Wistar rats were randomly divided into four groups: positive control group, two tea-treated groups, and negative control group. Rats in tea-treated groups were given tea polyphenols (0.1%) and tea pigments (0.1%) in drinking fluid during the whole experiment. The number and area of glutathione S-transferase P (GST-P)-positive foci in the rat liver were used as biomarkers of precancerous liver lesions. Western blotting assay was carried out to detect the expression of cyclin D1, CDK4, and P21(WAF1/CIP1) on whole liver extract. At the end of the experiment (56 days), the number and area of GST-P-positive foci in liver increased significantly in carcinogen-administered positive control group, whereas no GST-P-positive foci were found in the negative control group in which animals did not receive carcinogen exposure. The number and area of GST-P-positive foci in tea-treated, carcinogen-exposed groups were significantly reduced as compared with the positive control group. It was also found that the expression of P21(WAF1/CIP1) was significantly induced and the expression of cyclin D1 and CDK4 was significantly inhibited in tea-treated groups. These results suggest that tea polyphenols and tea pigments are effective in preventing the precancerous liver lesions in rats, and modulation of cell cycle by regulating cell cycle regulators may be a possible mechanism.

Animals↗

PubMed1991

Caffeine as a metabolic probe: validation of its use for acetylator phenotyping.

The use of two caffeine metabolite ratios for acetylator phenotyping was validated by demonstrating concordance with two sulfamethazine tests in 178 unrelated healthy subjects. The caffeine metabolites used for this purpose were 5-acetylamino-6-amino-3-methyluracil (AAMU), 1-methylxanthine (1X), and 1-methylurate (1U). The ratio AAMU/(AAMU + 1X + 1U), referred to as molar ratio or N-acetyltransferase, was compared with the ratio AAMU/1X. The results indicated that, for screening purposes, the acetylator phenotype can be determined by analysis of a 6-hour urine sample after a cup of coffee or strong tea or a can of caffeine-containing soft drink. The ratio AAMU/1X is the ratio of choice for the study of subjects in whom variability of xanthine oxidase can be neglected; use of the ratio AAMU/(AAMU + 1X + 1U) appears appropriate for special purposes. Gender, ethnic origin, habitual or moderate consumption of coffee, tea, soft drinks, or ethanol, or cigarette smoking have little if any effect on the caffeine tests for acetylator phenotyping.

Acetylation↗

PubMed1990

[An investigation into the actual condition of the sports drink intake on children].

The purpose of this study was to investigate the actual condition of the sport drink intake on children. We conducted an investigation by means of questionnaires at 3 nursery schools and a day nursery in and around Hiroshima City, and using 505 answers with the comparison between 4 areas. The following results were obtained: 1) Less than 10% of the children often took sport drinks and about 70% of the children sometimes. 2) In response to the question of when taken, 40-50% of answers revealed that the drinks were taken when the children ill and 20-40% of answers were take from home. 3) In response to the question as to why children begin to take the drinks, many parents answered that they were advised by a doctor and a nurse to give their child sport drinks to prevent for dehydration, when their children were ill. This answer accounted for about 60% of the answers to this question. 4) Parents imagined that fruit drinks, carbonated beverages and beverages with lactic acid promoted tooth decay. Also the image of cariogenicity was less than 100% fruit juices, home-made juices, sport drinks, cow milks and water or tea in that order. The results suggest that parents regard sport drinks as beverages which do not promote tooth decay and give their child sport drinks frequency.

Beverages↗