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PubMed2002

Coffee drinking influences plasma antioxidant capacity in humans.

Coffee and tea are widely consumed beverages, but only tea has been studied for its antioxidant capacity (AC) in vivo. The aim of this study was to compare the capacities of coffee and tea to affect plasma redox homeostasis in humans. The AC of plasma before and after supplementation with 200 mL of beverages (0, 1, and 2 h) was measured by the TRAP and crocin tests. The crocin test detected an increase in plasma AC only in subjects supplemented with coffee (+7% at peak time), whereas the TRAP method showed an increase in plasma AC after consumption of both coffee and tea (+6 and +4%, respectively, at peak time). Both beverages induced a significant increase in plasma uric acid (+5 and +7%, respectively). Uric acid strongly affects the results obtained by the TRAP test and does not affect those obtained by the crocin test. We can thus argue that uric acid is the main component responsible for the plasma AC increase after tea drinking, whereas molecules other than uric acid (probably phenolic compounds) are likely to be responsible for the increase in plasma AC after coffee drinking.

Antioxidants↗
PubMed1992

Association of serum lipoproteins and health-related habits with coffee and tea consumption in free-living subjects examined in the Israeli CORDIS Study.

BACKGROUND: A positive association between coffee consumption and serum cholesterol levels has been demonstrated and recent results indicate that this may be due to a lipid-rich fraction present mainly in boiled coffee. The possible effects of tea consumption are less clear, although evidence has been presented which suggests that tea drinkers have lower cholesterol levels. The associations between serum lipids and lipoproteins and coffee and tea consumption were examined in the Israel CORDIS study. METHODS: Employees of 21 factories were screened for cardiovascular disease risk factors between 1985 and 1987. Detailed data on coffee and tea consumption and serum lipids and lipoproteins were available for 3,858 men and 1,511 women. RESULTS AND CONCLUSIONS: Consumption of five or more cups of coffee per day was reported by 10.1% of men and 8.7% of women, whereas only 3.4% of men and 2.2% of women consumed similar quantities of tea. After controlling for a number of potential confounders, coffee consumption (particularly "mud" coffee) was strongly and positively associated with higher serum total and low-density lipoprotein cholesterol levels in both sexes (consumers of five or more cups per day had cholesterol levels up to 18 mg/dl higher than abstainers) and with high-density lipoprotein cholesterol in women. There was a nonsignificant negative association between tea consumption and serum cholesterol (cholesterol levels about 5 mg/dl more in abstainers than in those consuming five or more cups per day). In general, more negative health-related habits were reported with increased coffee consumption, whereas this relationship was not found for tea drinking. The relatively small percentage of heavy tea drinkers limits the conclusions that one can draw from this study and controlled trials are needed to evaluate possible lipid-lowering effects of tea consumption.

Adult↗
PubMed2002

A rapid effect of caffeinated beverages on two choice reaction time tasks.

Though consumers of tea and coffee can report feeling beneficial subjective effects of consumption virtually immediately, tests for objective effects of caffeine immediately post-consumption have been rare. Two experiments examined caffeine's ability to influence reaction time in choice reaction time tasks, using a dose of caffeine typical of a cup of tea or instant coffee, and testing at short post-consumption delays. Two groups of participants were given 60 mg of caffeine, after overnight abstinence, either in a hot tea drink, or a hot water drink. Two control groups also received hot tea or water, but without caffeine. In Experiment 1, participants were given a keypress task before the drink (baseline), immediately after the drink, and 40 min after the drink. In Experiment 2, a touch-screen test was given either 1, 14, or 27 min post consumption. Caffeine was found to reduce the effect of a distracter on reaction time in the keypress test and to reduce reaction time in a component of the touch-screen task; however, in neither experiment were these effects significantly modulated by post-consumption delay length. Thus, the speed of caffeine's action on psychomotor performance was shown to be on the order of minutes.

Adolescent↗
PubMed1991

Inhibitory effect of Chinese tea on N-nitrosation in vitro and in vivo.

The inhibitory effect of 145 samples of Chinese tea on the formation of N-nitrosomorpholine was studied in vitro. The rates of inhibition by green tea, crush, tear, curl (CTC) black tea, brick tea, jasmine tea, Oolong tea, sun-dried tea and black tea were positively correlated with their polyphenol contents. An inhibitory effect of green and black tea on endogenous N-nitrosation was also confirmed in humans. Drinking tea after a meal had a greater effect than drinking it before a meal.

Carcinogens↗
PubMed1993

The inhibitory effect of Chinese tea and its polyphenols on in vitro and in vivo N-nitrosation.

The objective of this study is to evaluate the possible role of Chinese tea as a natural inhibitor of N-nitrosation, and to compare the relative inhibitory potency of various kinds of Chinese tea in vitro and in vivo. Studies on the inhibitory effect of 145 samples of Chinese tea on the formation of N-nitrosomorpholine (NMOR) showed that the inhibitory potency of the 7 types of Chinese tea differed greatly, the average blocking rate of green tea (89.04%, n = 60), crush, tear, and curl (CTC) black tea (86.99%, n = 13), brick tea (85.40%, n = 7), jasmine tea (84.99%, n = 21), Oolong tea (82.37%, n = 9), sun-dried tea (61.99%, n = 13) and Chinese Gongfu black tea (54.98%, n = 22), were positively correlated with their polyphenols contents. The inhibitory effect of green tea and black tea on endogenous N-nitrosation was also confirmed in 3 human volunteer experiments. Drinking tea after meal had a greater effect than drinking it before meal. It is concluded that Chinese tea can exert a relatively strong inhibitory potency for N-Nitroso compounds (NOC) formation both in vitro and in humans, and the active constituents may be related to their polyphenols contents, especially the tea catechin derivatives. The results also demonstrated that the amounts of NMOR formed in vitro depended on the molecular structure of tea catechin derivatives and their molar ratios to nitrite.

Adult↗
PubMed2005

Scale and causes of lead contamination in Chinese tea.

We investigated the scale and causes of Pb contamination in Chinese tea. Lead concentrations in 1,225 tea samples collected nationally between 1999 and 2001 varied from <0.2 to 97.9 mg kg(-1) dry weight (DW), with 32% of the samples exceeding the national maximum permissible concentration (MPC) of 2.0 mg kg(-1) DW and a significant difference between tea types. There was an increasing trend in tea Pb concentration from 1989 to 2000. Proximity to highway and surface dust contamination were found to cause elevated Pb concentrations in tea leaves. Furthermore, Pb concentration in tea leaves correlated significantly and positively with soil extractable Pb, and negatively with soil pH, suggesting that root uptake of Pb from soils also contributed to Pb accumulation in tea. Potential contributions to human Pb intake from drinking tea were small at the median or national MPC Pb values, but considerable at the highest concentration found in the study.

Air Pollutants↗
PubMed1998

Differences in fertility associated with caffeinated beverage consumption.

OBJECTIVES: The effect of caffeine consumption on fertility was examined prospectively in 210 women. METHODS: Women reported on caffeinated beverage consumption and pregnancy status monthly. Odds ratios for becoming pregnant were calculated for both high and moderate vs low consumption. RESULTS: No significant association was found for any of the caffeinated beverages except tea. Drinking one-half cup or more of tea daily approximately doubled the odds of conception per cycle. CONCLUSIONS: These data suggest that caffeine may not be the responsible agent for variation in fertility associated with consumption of the beverages examined.

Adult↗
PubMed2005

Green tea catechin enhances osteogenesis in a bone marrow mesenchymal stem cell line.

Green tea has been reported to possess antioxidant, antitumorigenic, and antibacterial qualities that regulate the endocrine system. Previous epidemiological studies found that the bone mineral density (BMD) of postmenopausal women with a habit of tea drinking was higher than that of women without habitual tea consumption. However, the effects of green tea catechins on osteogenic function have rarely been investigated. In this study, we tested (-)-epigallocatechin-3-gallate (EGCG), one of the green tea catechins, on cell proliferation, the mRNA expressions of relevant osteogenic markers, alkaline phosphatase (ALP) activity and mineralization. In a murine bone marrow mesenchymal stem cell line, D1, the mRNA expressions of core binding factors a1 (Cbfa1/Runx2), osterix, osteocalcin, ALP increased after 48 h of EGCG treatment. ALP activity was also significantly augmented upon EGCG treatment for 4 days, 7 days and 14 days. Furthermore, mineralizations assayed by Alizarin Red S and von Kossa stain were enhanced after EGCG treatment for 2-4 weeks in D1 cell cultures. However, a 24-h treatment of EGCG inhibited thymidine incorporation of D1 cells. These results demonstrated that long-term treatment of EGCG increases the expressions of osteogenic genes, elevates ALP activity and eventually stimulates mineralization, in spite of its inhibitory effect on proliferation. This finding suggests that the stimulatory effects of EGCG on osteogenesis of mesenchymal stem cells may be one of the mechanisms that allow tea drinkers to possess higher BMD.

Alkaline Phosphatase↗
PubMed2006

[Older soil contaminations and human biomonitoring--two typical examples].

AIM: A health risk assessment of inhabitants had to be accomplished in two areas of former color production works, which had caused considerable soil contaminations predominantly with arsenic and lead. METHODS: Samples of soil, blood and urine were analysed during orientation and detail investigations according to the German soil protection laws. RESULTS: The soil investigations revealed high contaminations in some parts of the two areas (maximum concentrations 550 mg arsenic/kg and 9100 mg lead/kg in residential topsoil from depths of 0-35 cm). Contrary to these findings, arsenic levels in the urine and lead levels in the blood of most of the residents were lower than the reference values for the common German population (arsenic 15 microg/L, lead 50-90 microg/L). In some cases of elevated biological concentrations, other sources of exposure could be detected like drinking tea from a tea-pot with a lead-containing glaze or drinking water from a highly contaminated garden well; interventional measures resulted in major decreases in the internal loads of these people. CONCLUSIONS: The investigations clearly showed that an exposure via the pathway soil--water--human can be of serious health concern whereas older soil contaminations are seemingly of low relevance with regard to the direct contact of persons during daily life on those areas. Therefore, it is recommended to increase the soil examination values ("Prüfwerte") of the German soil protection laws by a default factor of 2 or 3 in cases of soil contaminations older than 20 years.

Arsenic↗
PubMed2000

[Amounts of selected minerals in green and black teas].

The paper contains the results of 19 minerals (Ca, K, P, Na, Mg, Zn, Fe, Mn, Cu, F, Ni, Co, Cr, Li, Sr, Al, Cd, Hg, Pb) determined in green and black species of market teas. The examined minerals (except phosphorus, fluoride and mercury) were determined by ASA-method using air-acetylene flame (aluminium was determined in the nitrous oxide-acetylene flame). Mercury was determined by cold vapour method. The phosphorus and fluoride was determined by spectrophotometry methods (phosphorus in the form of phosphomolybdate blue and fluoride by use microdiffusion procedure where alizarin-fluoride complex was formed). It has been found that the examined teas are important source of potassium and low source of sodium, assuming a daily intake of 4 glasses of tea infusions. Tea drinking may be advantageous for hypertensive persons. The investigated teas are also important source of other examined minerals especially some microelements. The intake of the toxic metals with tea (Cd, Hg, Pb, Al) is low, from a centesimal to a few percent of the PTWI dose accepted by the FAO/WHO Experts. This paper presents also the first findings of the lithium and stronthium contents of examined tea species--whose physiological role still remains unknown.

Minerals↗
PubMed2004

[FAAS determination of trace elements in tea-leaves using suspension sampling with ultrasonic agitation].

It is known that some minerals and trace elements such as Cu, Fe, Zn and Mn are the necessary elements in human body. The lack of these elements can cause various diseases. Because tea contains all kinds of minerals and trace elements, drinking tea is healthy for people. In order to contrast teas of different sort grades and producing areas the minerals and trace elements in the tea have been determined using suspension sample introduction technique. To determine the content of trace elements in tea-leaves, samples were powdered and sieved after being heated at (80 +/- 2) degerees C for 4 hours. 5 mL 0.15% agar solution was added and mixed thoroughly with the samples by ultrasonic agitation. Then the prepared suspension of sample was directly introduced to FAAS for determination. The results of this method are consistent with those obtained by wet treatment method, and the relative deviation of treatment method is less than +/- 0.96%. The t-test shows that no difference was found. The present method is convenient, rapid and accurate.

Clinical Laboratory Techniques↗
PubMed2006

[Fluoride content of soft drinks produced in Poland].

Fluoride content of 81 commercial brands of soft drinks and bottled waters were determined using potentiometric method with ion selective electrode. In the beverages produced in the same factory fluoride level were similar. The connection between elevation of fluoride levels and ingredients of investigated products such as juice or cola extract was not found. However, in some samples of ice tea drinks containing the tea extract fluoride levels might have been raised up to 1.28 mg/l. Fluoride contents of beverages from 28 producers ranged from 0.01 to 0.30 mg/l and only from 4 producers up to 0.60 mg/l. The highest level of fluoride (1.39 mg/l) has been determined in one sample of mineral water. In conclusion, ice tea beverages and certain mineral water, made and sold in Poland, may constitute an important source of fluoride in diet. Their consumption, particularly in case of children, must be controlled.

Beverages↗
PubMed1996

Nutrition and esophageal cancer.

Epidemiologic evidence on the relation between nutrition and esophageal cancer is reviewed. Results from ecologic, case-control, cohort, and intervention studies are included. Most of the findings pertain more to squamous cell carcinoma than adenocarcinoma of the esophagus. The protective effect of fruit and vegetable consumption is supported by a large body of evidence, especially from case-control studies. The effects of food groups and nutrients other than fruits and vegetables also have been examined, but the overall evidence is less convincing. Recent intervention studies in high incidence areas in China indicate that micronutrient supplements may have a modest effect in reducing risk, but the generalizability of this result is uncertain. Hot drinks are likely to increase the risk of esophageal cancer. On the other hand, the role of tea drinking, especially the use of green tea, remains to be defined better.

Adenocarcinoma↗
PubMed1979

Tooth staining effects of an alexidine mouthwash.

The primary purpose of this study was to determine the amount of tooth staining produced by an alexidine mouthrinse. One hundred and eighty subjects rinsed twice daily for 1 month with either 15 ml of alexidine (0.035%) or a placebo solution. Prior to the study, the subjects were classified according to their smoking, coffee and tea drinking habits and these factors were subsequently considered in the analysis of the stain scores. Additionally, the effects on staining of a prior prophylaxis and the use of a fluoridated toothpaste during the study were determined. Upon termination of the study, subjects utilizing the active mouthrinse manifested a greater degree of staining than placebo users. The amount and intensity of the stain due to alexidine were not influenced (increased) by smoking, tea or coffee drinking habits. A prior prophylaxis did not reduce the staining propensity of alexidine users. The method of scoring developed can be used to assess the degree of tooth staining induced by antiplaque agents.

Adolescent↗
PubMed2003

[Study on the protective effect of green tea on gastric, liver and esophageal cancers].

OBJECTIVE: To assess the protective effect of drinking green tea on the development of gastric, liver and esophageal cancers. METHODS: A population based study was conducted in Taixing, Jiangsu province, including 206, 204, 218 cases, respectively, and 415 population controls. RESULTS: Green tea decreased the development of gastric cancer risk by 40%. Dose-response relationships were observed between the length of time, concentration and quantity of green tea drinking and its protective effects on gastric cancer. For individuals who drink green tea for more than 250 g per month, the risk of gastric cancer reduced about 60%. Green tea might have protective effect on liver cancer. However, no protective effect of green tea was observed on esophageal cancer. CONCLUSION: Green tea drinking might be a protective factor for gastric cancer. However, the protective effects of green tea on liver and esophageal cancer were not obvious.

Dose-Response Relationship, Drug↗
PubMed1983

Early precursors of pancreatic cancer in college men.

From college data on 50,000 male former students, the records of 126 men who died of pancreatic cancer in a 16-50 yr follow-up period were compared with those of 504 surviving classmates with respect to physical and social characteristics. Return mail questionnaires received from 30,000 surviving alumni in 1962 or 1966 also were reviewed for characteristics that might predict altered risk of pancreatic cancer. Strong positive associations were found for cigarette smoking as reported both during college (p less than 0.001) and at time of questionnaire return (p = 0.03). Smoking 10 or more cigarettes per day during college corresponded to a relative risk of 2.6 with 95% confidence limits 1.5 to 4.6, and a positive smoking history at questionnaire return yielded a relative risk of 2.4 (1.1-5.1). No association was found for collegiate coffee drinking, either before or after adjustment for cigarette smoking. The relative risk for coffee drinking adjusted for smoking was 1.1 (0.7-1.8). In contrast, collegiate tea consumption was associated with a reduction in pancreatic cancer risk. The relative risk for tea drinking adjusted for smoking was 0.5 (0.3-0.9). Men who at college physical examination complained of occasional abdominal pain or discomfort had increased relative risk of pancreatic cancer (3.1 : 1.1-9.0) in the follow-up period.

Adolescent↗
PubMed2001

Tea consumption and the risk of colorectal cancer in Sweden.

The association between tea drinking and colorectal cancer risk remains unclear. The evidence for black tea is sparse but may indicate an increased risk with regular use. Because black tea is a common beverage in many populations, the significant twofold increased risk of colon cancer recently reported from a large prospective cohort of male Finnish smokers is disconcerting. Using Cox proportional hazards models to estimate relative risks, we examined this association in a large, population-based prospective cohort study in Sweden. During an average 9.6 years of follow-up of our cohort of 61,463 women (588,270 person-yr), we observed 460 incident cases of colorectal cancer (291 colon, 159 rectal, and 10 with both colon and rectal cancer). We observed no association between tea consumption and combined colorectal cancers in age- or multivariate-adjusted models. With the use of collapsed exposure categories, the multivariate-adjusted relative risk for the highest exposure (> or = cups/day) compared with the lowest (never or seldom) was 0.97 (95% confidence interval = 0.63-1.48, p for trend = 0.34). Examining the association by cancer subsite, we observed no association between tea consumption and proximal, distal, or combined colon cancers. We did, however, observe a nonsignificant positive association with rectal cancers, which became stronger and statistically significant among women > or = 65 years of age at baseline. Our data do not support the strong, dose-dependent positive association with colon cancer found in the Finnish study.

Age Factors↗
PubMed2001

Reproducibility and relative validity of a questionnaire to assess intake of black tea polyphenols in epidemiological studies.

Epidemiological studies suggest that tea drinking may reduce the risk of cardiovascular diseases and cancers. Although tea is an important source of antioxidant phytochemicals, variation in preparation techniques may translate to variation in antioxidant capacity. However, most large-scale epidemiological studies use regular food frequency questionnaires to estimate tea intake, and nationally available nutrient analysis databases do not include levels of black tea polyphenols. The Arizona Tea Questionnaire (ATQ) was designed as a tool for collecting more complete dietary tea consumption information, and a database was developed after analyzing 40 black tea samples (brewed, instant, and sun tea) for polyphenols. This study assesses the reliability and relative validity of the ATQ and polyphenol database. Relative validity of estimates of black tea consumption was tested by comparing the ATQ with the traditional Arizona Food Frequency Questionnaire and four days of food records. The ATQ was tested for reproducibility of estimates of black (hot and iced) tea consumption and levels of black tea polyphenol intake. Correlations between two measures of intake taken 2 months apart ranged from 0.72 for black hot tea to 0.86 for black sun tea. Mean intakes (range) of total flavonoids for black tea consumers were 80.8 (3.0-588.0) mg/day at the first ATQ and 102.4 (4.5-802.3) mg/day at the second ATQ (r = 0.83, P < 0.001). The ATQ provided highly reproducible estimates of both total tea consumption and individual tea polyphenol intake. This instrument may be a useful tool in studies of the associations between tea consumption, tea polyphenols intake, and risk for chronic disease.

Adult↗