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PubMed1988

Development of 4-AP and TEA sensitivities in mammalian myelinated nerve fibers.

1. The sensitivities of mammalian myelinated axons to potassium channel blockers was studied over the course of development using in vitro sucrose gap and intra-axonal recording techniques. 2. Application of 4-aminopyridine (4-AP; 1.0 mM) to young nerves led to a delay in return to base line of the sciatic nerve compound action potential and to a postspike positivity (indicative of hyperpolarization) lasting for tens of milliseconds. These effects were very much attenuated during the course of maturation. 3. Tetraethylammonium chloride (TEA; 10 mM) application alone had little effect on the waveform of the compound action potential at any age. However, the 4-AP-induced postspike positivity was blocked by TEA, Ba/+, and Cs+. This block was observed in Ca2+-free electrolyte solutions containing EGTA (1.0 mM). 4. Immature sciatic nerves (approximately 3 wk postnatal) were incubated in a potassium-free electrolyte solution containing 120 mM CsCl for up to 1 h in an attempt to replace internal potassium with cesium. When the nerves were tested in the sucrose gap chamber using solutions containing 3.0 mM CsCl substituted for KCl, the compound action potential was broadened and a prolonged depolarization appeared, but there was no postspike positivity; the CsCl effect was similar to the combined effects of 4-AP and TEA. 5. Intra-axonal recordings were obtained to study the effects of 4-AP and TEA on individual axons. In the presence of 4-AP a single stimulus led to a burst of action potentials followed by a pronounced afterhyperpolarization (AHP) in sensory fibers. The AHP was blocked by TEA. In motor fibers 4-AP application resulted in action potential broadening with no AHP. 6. Repetitive stimulation (200-500 Hz; 100 ms) was followed by a pronounced AHP in both sensory and motor fibers at all ages studied. This activity-elicited AHP was sensitive to TEA at all ages. 7. The results indicate that 4-AP and TEA sensitivity change over the course of development in rat sciatic nerve. The effects of 4-AP are much more pronounced in immature nerves than in mature nerves, suggesting that 4-AP-sensitive channels become masked as they are covered by myelin during maturation. However, the TEA-sensitive channels, demonstrable after repetitive firing, remain accessible to TEA after myelination. These channels therefore may have a nodal representation.

4-Aminopyridine↗

PubMed2004

Differential response of human ovarian cancer cells to induction of apoptosis by vitamin E Succinate and vitamin E analogue, alpha-TEA.

A vitamin E derivative, vitamin E succinate (VES; RRR-alpha-tocopheryl succinate), and a vitamin E analogue, 2,5,7,8-tetramethyl-2R-(4R,8R,12-trimethyltridecyl)chroman-6-yloxy acetic acid (alpha-TEA), induce human breast, prostate, colon, lung, cervical, and endometrial tumor cells in culture to undergo apoptosis but not normal human mammary epithelial cells, immortalized, nontumorigenic breast cells, or normal human prostate epithelial cells. Human ovarian and cervical cancer cell lines are exceptions, with alpha-TEA exhibiting greater proapoptotic effects. Although both VES and alpha-TEA can induce A2780 and subline A2780/cp70 ovarian cancer cells to undergo DNA synthesis arrest within 24 h of treatment, only alpha-TEA is an effective inducer of apoptosis. VES or alpha-TEA treatment of cp70 cells with 5, 10, or 20 microg/ml for 3 days induced 5, 6, and 19% versus 9, 36, and 71% apoptosis, respectively. Colony formation data provide additional evidence that cp70 cells are more sensitive to growth inhibition by alpha-TEA than VES. Differences in stability of the ester-linked succinate moiety of VES versus the ether-linked acetic acid moiety of alpha-TEA were demonstrated by high-performance liquid chromatography analyses that showed alpha-TEA to remain intact, whereas VES was hydrolyzed to the free phenol, RRR-alpha-tocopherol. Pretreatment of cp70 cells with bis-(p-nitrophenyl) phosphate, an esterase inhibitor, before VES treatment, resulted in increased levels of intact VES and apoptosis. Taken together, these data show alpha-TEA to be a potent and stable proapoptotic agent for human ovarian tumor cells and suggest that endogenous ovarian esterases can hydrolyze the succinate moiety of VES, yielding RRR-alpha-tocopherol, an ineffective apoptotic-inducing agent.

Apoptosis↗

PubMed1997

Anti-human immunodeficiency virus activity of oligosaccharides from rooibos tea (Aspalathus linearis) extracts in vitro.

The active substances, acid polysaccharides, were extracted with 1% sodium hydroxide from the leaves of rooibos tea (Aspalathus linearis), Du Zhong Cha (Eucommia ulmoides Oliv.) and Japanese tea leaves (Camellia sinensis var. sinensis). The alkaline extracts of Rooibos tea and Du-Zhong tea leaves, but not Japanese tea leaves suppressed the HIV-induced cytopathicity using HIV (HTLV-III) infected MT-4 cells, having extremely low cytotoxicity: Its 50% effective concentration (EC50) was 12-67 micrograms/mL, white 50% cytotoxic concentration (CC50) was higher than 1.0 mg/mL. The active substances were purified with ethanol precipitation. The substances were composed of 27% of reducing sugar, 46% of neutral sugars and 22% of uronic acid. A LD50 of the alkaline extracts from rooibos tea was higher than 1.2 g/kg body weight. Acid degradated substances composed of disaccharides and trisaccharides, were also suppressed the HIV-induced cytopathicity. From these results, it is probable that acid polysaccharides from rooibos tea were extremely safe, and that HIV infection may be suppressed by daily intake of the alkaline extracts of rooibos tea and Du-Zhong tea.

Anti-HIV Agents↗

PubMed2003

Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial.

BACKGROUND: Tea consumption has been associated with decreased cardiovascular risk, but potential mechanisms of benefit are ill-defined. While epidemiologic studies suggest that drinking multiple cups of tea per day lowers low-density lipoprotein cholesterol (LDL-C), previous trials of tea drinking and administration of green tea extract have failed to show any impact on lipids and lipoproteins in humans. Our objective was to study the impact of a theaflavin-enriched green tea extract on the lipids and lipoproteins of subjects with mild to moderate hypercholesterolemia. METHODS: Double-blind, randomized, placebo-controlled, parallel-group trial set in outpatient clinics in 6 urban hospitals in China. A total of 240 men and women 18 years or older on a low-fat diet with mild to moderate hypercholesterolemia were randomly assigned to receive a daily capsule containing theaflavin-enriched green tea extract (375 mg) or placebo for 12 weeks. Main outcome measures were mean percentage changes in total cholesterol, LDL-C, high-density lipoprotein cholesterol (HDL-C), and triglyceride levels compared with baseline. RESULTS: After 12 weeks, the mean +/- SEM changes from baseline in total cholesterol, LDL-C, HDL-C, and triglyceride levels were -11.3% +/- 0.9% (P =.01), -16.4% +/- 1.1% (P =.01), 2.3% +/- 2.1% (P =.27), and 2.6% +/- 3.5% (P =.47), respectively, in the tea extract group. The mean levels of total cholesterol, LDL-C, HDL-C, and triglycerides did not change significantly in the placebo group. No significant adverse events were observed. CONCLUSION: The theaflavin-enriched green tea extract we studied is an effective adjunct to a low-saturated-fat diet to reduce LDL-C in hypercholesterolemic adults and is well tolerated.

Adult↗

PubMed2006

Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study.

CONTEXT: Green tea polyphenols have been extensively studied as cardiovascular disease and cancer chemopreventive agents in vitro and in animal studies. However, the effects of green tea consumption in humans remain unclear. OBJECTIVE: To investigate the associations between green tea consumption and all-cause and cause-specific mortality. DESIGN, SETTING, AND PARTICIPANTS: The Ohsaki National Health Insurance Cohort Study, a population-based, prospective cohort study initiated in 1994 among 40,530 Japanese adults aged 40 to 79 years without history of stroke, coronary heart disease, or cancer at baseline. Participants were followed up for up to 11 years (1995-2005) for all-cause mortality and for up to 7 years (1995-2001) for cause-specific mortality. MAIN OUTCOME MEASURES: Mortality due to cardiovascular disease, cancer, and all causes. RESULTS: Over 11 years of follow-up (follow-up rate, 86.1%), 4209 participants died, and over 7 years of follow-up (follow-up rate, 89.6%), 892 participants died of cardiovascular disease and 1134 participants died of cancer. Green tea consumption was inversely associated with mortality due to all causes and due to cardiovascular disease. The inverse association with all-cause mortality was stronger in women (P = .03 for interaction with sex). In men, the multivariate hazard ratios of mortality due to all causes associated with different green tea consumption frequencies were 1.00 (reference) for less than 1 cup/d, 0.93 (95% confidence interval [CI], 0.83-1.05) for 1 to 2 cups/d, 0.95 (95% CI, 0.85-1.06) for 3 to 4 cups/d, and 0.88 (95% CI, 0.79-0.98) for 5 or more cups/d, respectively (P = .03 for trend). The corresponding data for women were 1.00, 0.98 (95% CI, 0.84-1.15), 0.82 (95% CI, 0.70-0.95), and 0.77 (95% CI, 0.67-0.89), respectively (P<.001 for trend). The inverse association with cardiovascular disease mortality was stronger than that with all-cause mortality. This inverse association was also stronger in women (P = .08 for interaction with sex). In women, the multivariate hazard ratios of cardiovascular disease mortality across increasing green tea consumption categories were 1.00, 0.84 (95% CI, 0.63-1.12), 0.69 (95% CI, 0.52-0.93), and 0.69 (95% CI, 0.53-0.90), respectively (P = .004 for trend). Among the types of cardiovascular disease mortality, the strongest inverse association was observed for stroke mortality. In contrast, the hazard ratios of cancer mortality were not significantly different from 1.00 in all green tea categories compared with the lowest-consumption category. CONCLUSION: Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer.

Adult↗

PubMed2004

Green tea consumption enhances survival of epithelial ovarian cancer.

Our study investigates whether tea consumption can enhance the survival of patients with epithelial ovarian cancer, a prospective cohort study was conducted in Hangzhou, China. The cohort comprised 254 patients recruited during 1999-2000 with histopathologically confirmed epithelial ovarian cancer and was followed up for a minimum of 3 years. Two hundred forty four (96.1%) of the cohort or their close relatives were traced. The variables examined included their survival time and the frequency and quantity of tea consumed post-diagnosis. The actual number of deaths was obtained and Cox proportional hazards models were used to obtain hazard ratios and associated 95% confidence intervals (CI), adjusting for age at diagnosis, locality, BMI, parity, FIGO stage, histologic grade of differentiation, cytology of ascites, residual tumour and chemotherapeutic status. The survival experience was different between tea drinkers and non-drinkers (p < 0.001). There were 81 (77.9%) of 104 tea-drinkers who survived to the time of interview, compared to only 67 women (47.9%) still alive among the 140 non-drinkers. Compared to non-drinkers, the adjusted hazard ratios were 0.55 (95% CI = 0.34-0.90) for tea-drinkers, 0.43 (95% CI = 0.20-0.92) for consuming at least 1 cup of green tea/day, 0.44 (95% CI = 0.22-0.90) for brewing 1 batch or more of green tea/day, 0.40 (95% CI = 0.18-0.90) for consuming more than 500 g of dried tea leaves/year, and 0.38 (95% CI = 0.15-0.97) for consuming at least 2 g of dried tea leaves/batch. The corresponding dose-response relationships were significant (p < 0.05). We conclude that increasing the consumption of green tea post-diagnosis may enhance epithelial ovarian cancer survival.

Adenocarcinoma, Clear Cell↗

PubMed2005

On-line high-performance liquid chromatography analysis of the antioxidant activity of phenolic compounds in green and black tea.

Teas represent a rich source of dietary antioxidants. This paper describes analysis of the antioxidant potential of individual tea phenolics using an on-line high-performance liquid chromatography (HPLC) method. Tea phenolics from Kenyan green and black teas were identified using liquid chromatography--mass spectrometry (LC-MS(n)) in conjunction with the analysis of their 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS+) radical scavenging ability. Antioxidant potential of flavan-3-ols, caffeoylquinic acids, flavonols, and theaflavins was assessed in comparison to the synthetic vitamin E analogue Trolox. (-)-Epigallocatechin gallate was identified as the most potent antioxidant with a Trolox equivalent antioxidant capacity (TEAC) value of 3.0, contributing approximately 30% of the total antioxidant capacity of green tea. Theaflavins retained antioxidant capacity similar to that of (-)-epicatechin monomers whilst conjugated flavonols did not contribute significantly to the antioxidant capacity of either green or black tea. After HPLC analysis of the antioxidant capacity of phenolics in black tea some 80% of antioxidant activity remained unaccounted for indicating the potential importance of thearubigens as antioxidants in black teas.

Antioxidants↗

PubMed2006

Chemoprevention of lung cancer by tea.

Tea is the second only to water as the most consumed beverage in the world. Both green and black teas have been studied for their health benefits for a variety of diseases, particularly cancer. Lung cancer is the predominant cause of cancer mortality in developed countries. Smokers' risk of lung cancer is 20 times that of persons who have never smoked. Epidemiological studies on the cancer-preventive effects of tea produce inconsistent results, which could in part be attributed to the lack of a universal standard for tea preparations. However, most animal studies indicate that tea has strong chemopreventive effects against lung tumorigenesis. The reported mechanisms for chemopreventive activity of green tea are antioxidation, induction of phase II enzymes, inhibition of TNFalpha expression and release, inhibition of cell proliferation, and induction of apoptosis. Cell cycle arrest and apoptosis induced by green tea are probably the two most significant factors. Future studies are needed to determine how green tea affects the genes associated with cell cycle regulation and apoptosis during the mouse lung carcinogenesis process.

Animals↗

PubMed1994

Coffee, tea, and lifestyle.

BACKGROUND: Previous reports have indicated that coffee drinking is associated with an unhealthy lifestyle, compared with tea drinking, which may confound the effect in relation to coronary risk factors. METHODS: In a population sample of 2,400 25- to 64-year-old men and women, associations of lifestyle factors with coffee and tea consumption were analyzed. Lifestyle factors were related to four realms of behavior: smoking, eating, drinking, and physical activity. RESULTS: Overall response rate exceeded 77%. Twenty-two behavioral factors were included in the analysis and controlled for age and sex. Mean daily cigarette consumption, the consumption of main fat sources (meat and sausages) and lemonade drinking increased with coffee and decreased with tea consumption. Conversely, intake of fresh fruits, drinking of juice or mineral water, and physical activity on the way to work decreased with coffee and increased with tea. The strongest associations were between coffee, than tea, and cigarette smoking. Controlling smoking (and physical activity) changed trends mainly with respect to alcoholic drinks. CONCLUSIONS: We conclude that drinking coffee is positively associated with factors that promote coronary heart disease, while drinking tea is associated with a preventive lifestyle. Factors supporting these results were found located in all realms of lifestyle for both for coffee and tea. Therefore, investigations on the health effects of coffee and tea must be carefully controlled for confounding behavioral parameters.

Adult↗

PubMedDate not supplied

Dietary differences with green tea intake among middle-aged Japanese men and women.

BACKGROUND: Although several epidemiologic investigations have suggested a protective role of green tea against cardiovascular diseases and cancer, few studies examined how consumption of green tea was associated with intake of other dietary factors. METHODS: In the winters of 1989-1991, 880 men ages 40-49 years were randomly sampled from the general populations of five Public Health Center districts of Japan. Response rate was 72% (n = 634). A convenience sample of 373 spouses also consented to participate. They were interviewed on the frequency of consumption of green tea and 37 food items. A 3-day weighed food record was collected from a subgroup of the subjects (207 men and 164 women) to calculate daily intake of 22 nutrient variables. Consumption of the foods and nutrients was compared with three levels of green tea intake (< 1, 1-4, and > 4 cups/days) after adjustment for potential confounders. RESULTS: Among men, green tea was associated significantly with consumption of 10 foods (P < 0.05) and at borderline significance with 4 nutrients (P < 0.1). These foods and nutrients included fruits (apple, orange juice), vegetables (green, yellow, and pickled), total lipid, cholesterol, and carotene. Among women, green tea was associated with 6 foods and total energy. CONCLUSION: The results indicate that consumption of green tea is associated with diets that could modify the risks of cardiovascular diseases and cancer, especially among men. When the health effects of green tea are examined by observational epidemiologic studies, potential confounding and effect modification by other dietary factors should be controlled thoroughly.

Adult↗

PubMedDate not supplied

Cancer-preventive effects of drinking green tea among a Japanese population.

BACKGROUND: Laboratory studies have revealed the cancer preventive effects of green tea, so the association between green tea consumption and cancer was examined in a human population. METHODS: The association between green tea consumption and cancer incidence was studied in our prospective cohort study of a Japanese population. We surveyed 8,552 individuals over 40 years of age living in a town in Saitama prefecture on their living habits, including daily consumption of green tea. During the 9 years of follow-up study (71,248.5 person-years), we identified a total of 384 cases of cancer in all sites. RESULTS: We found a negative association between green tea consumption and cancer incidence, especially among females drinking more than 10 cups a day. The slowdown in increase of cancer incidence with age observed among females who consumed more than 10 cups a day is consistent with the finding that increased consumption of green tea is associated with later onset of cancer. Age-standardized average annual incidence rate was significantly lower among females who consumed large amounts of green tea. Relative risk (RR) of cancer incidence was also lower among both females (RR = 0.57, 95% CI = 0.33-0.98) and males (RR = 0.68, 95% CI = 0.39-1.21) in groups with the highest consumption, although the preventive effects did not achieve statistical significance among males, even when stratified by smoking and adjusted for alcohol and dietary variables. CONCLUSION: Our epidemiological study showed that green tea has a potentially preventive effect against cancer among humans.

Adult↗

PubMed1995

[Selenium content of tea from different provinces of the People's Republic of China].

In the People's Republic of China there are wide regions where many people suffer from strong selenium deficiency. In order to elucidate the possibilities to compensate this state of need by the national drink, the selenium contents of 31 tea samples from nine provinces of the PR China were determined by hydride generation atomic absorption spectrometry (HG-AAS). The Se contents of the ten analyzed tea samples from one region with soils containing high selenium amounts range from 83 ng/g to 7530 ng/g. These results are in contrast to the Se contents of the remaining tea samples from other regions, which range from 28 to 573 ng/g. The extractable part of selenium in the tea drink ranges between 7% and 27% without significant difference among different tea samples. The accuracy of Se determination was tested by using one tea standard reference material. The daily consumption of one "Se tea" examined in this study assures that people who suffer from a Se deficiency resume enough of it. Drinking normal quantities of this tea an intoxication by Se is not to be expected.

China↗

PubMed1989

Effect of consumption of green and black tea on the level of various enzymes in rats.

Drinking of both green and black tea as the only liquid ingested resulted in significant decreases in the activity of transketolase in whole blood of rats both before and after the in vitro addition of thiamin diphosphate. Liver transketolase activity was decreased only by green tea. Mucosal transketolase activity was not affected by either type of tea. The activity of lactate dehydrogenase (LDH) was not affected by either type of tea, while whole blood LDH was decreased by both green and black tea. Neither tea had any affect on mucosal alkaline phosphatase, but thiamin diphosphatase activity was decreased by both teas. An increase in liver total thiamin resulted from the drinking of both types of tea.

Alkaline Phosphatase↗

PubMed2004

Green tea supplementation ameliorates insulin resistance and increases glucose transporter IV content in a fructose-fed rat model.

BACKGROUND: Sprague-Dawley rats fed a fructose-rich diet exhibit insulin resistance and hypertension, a pathologic status resembling human type II diabetes mellitus, and are an excellent laboratory animal model for research on insulin action and the development of hypertension. Since green tea has numerous beneficial effects, we tested its effect on fructose-fed rats. AIM: The present study was therefore designed to further evaluate the effects of green tea supplementation on insulin resistance, hypertension, and the glucose transporters I and IV contents in adipose tissue in the fructose-fed rat model. METHODS: The animals were divided into three groups and fed for 12 weeks with standard chow and water (control group), a high fructose diet and water (fructose group), or the same high fructose diet, but with green tea (0.5 g of lyophilized green tea powder dissolved in 100 mL of deionized distilled water) instead of water (fructose/green tea group). During the 12 weeks study period, fresh water or green tea was provided daily at 6:00 PM. Blood pressure was measured twice a week, and an oral glucose tolerance test performed after 12 weeks of diet supplementation. At the end of the experiment, plasma triglyceride (TG), free fatty acid (FFA), glucose, and insulin were assayed. The epididymal fat pads from all rats in the same group were pooled and adipocytes isolated and tested for insulin binding, glucose uptake, and their content of glucose transporters I (GLUT I) and IV (GLUT IV). RESULT: Compared to the control group, the fructose group developed fasting hyperglycemia, hyperinsulinemia, and elevated blood pressure. Insulin-stimulated glucose uptake and insulin binding of adipocytes were significantly reduced, and the glucose transporter IV content of adipocytes also decreased. The fructose/green tea group showed improvement in all of these metabolic defects and in insulin resistance and blood pressure. CONCLUSION: Based on these results, we suggest that the amelioration of insulin resistance by green tea is associated with the increased expression of GLUT IV.

Adipose Tissue↗

PubMed1989

Crude tea extracts decrease the mutagenic activity of N-methyl-N'-nitro-N-nitrosoguanidine in vitro and in intragastric tract of rats.

The effects of tea extracts and their ingredients, catechins and L-ascorbic acid (AsA), on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were examined in vitro and in the stomachs of rats using E. coli WP2 and S. typhimurium TA100. The extracts of green tea and black tea leaves decreased the mutagenic activity of MNNG to E. coli WP2 in vitro in a desmutagenic manner. Catechins such as (-)-epigallocatechin from green tea leaves and the low-molecular-weight tannin fraction isolated from black tea extract with HP-20 resin also exhibited inhibitory effects against the mutagenic activity of MNNG. A desmutagenic effect of AsA on MNNG-induced mutagenicity was observed depending on the dose, though it was complicated. The effects were also demonstrated in the stomachs of rats by assaying the bacterial mutagenic in vitro; the tea extracts previously given orally to rats reduced the mutagenic activity of MNNG remarkably, though simultaneous administration showed less effect. The effectiveness of tea extracts for the decrease of MNNG-induced mutagenesis in vitro and in vivo suggests that the habitual drinking of tea may reduce the tumor-initiating potency of MNNG-type nitrosoureido compounds if they are formed in the stomach.

Animals↗

PubMed1993

Studies on the leaching of fluoride in tea infusions.

In order to assess the levels of fluoride ingestion through intake of tea, studies were conducted with four different brands of tea leaves commonly available in the Indian market. Four most prevalent methods for the preparation of tea with various contact times (2,4,6,8 and 10 min) of tea leaves with water show that: (a) leaching of fluoride is least in case of leaf tea as compared to powdered tea (F levels increasing with decreasing grain size); (b) leaching of fluoride reaches a maximum after a contact of about 6 min; (c) there is no difference between levels of fluoride with or without addition of milk in the English style where tea leaves are not boiled, while for the Indian style, addition of milk and subsequent boiling resulted in reduction of fluoride levels and (d) ingestion of fluoride per cup of tea ranged from 1.55 mg/l to 3.21 mg/l amounting to an intake per day per person of fluoride between 0.3 to 1.9 mg.

Fluorides↗

PubMed2006

The effects of chronic tea intake on platelet activation and inflammation: a double-blind placebo controlled trial.

BACKGROUND: Tea drinking appears to protect against the development of coronary heart disease (CHD), but the mediating pathways are uncertain. We studied the effects of 6 weeks of black tea or placebo on platelet activation, C-reactive protein (CRP), total antioxidant status, and soluble (s) P-Selectin in a randomized double-blind trial. METHODS: Healthy non-smoking men aged 18-55 years were randomized to black tea (N=37) or placebo (N=38) following a 4-week washout period during which they drank no tea, coffee or caffeinated beverages, but consumed caffeinated placebo tea. Bloods were drawn after 6 weeks of treatment. Platelet activation was assessed by measuring leukocyte-platelet aggregates using whole blood flow cytometry. RESULTS: Following treatment, the tea group had fewer monocyte-platelet aggregates (means 5.84 versus 6.60%, P=0.027), neutrophil-platelet aggregates (P=0.017), total leukocyte-platelet aggregates (P=0.027), and lower plasma C-reactive protein (means 0.76 versus 0.97 mg/L, P=0.05) than the placebo group. There were no differences in total antioxidant status or soluble P-Selectin. CONCLUSIONS: Chronic tea consumption reduces platelet activation and plasma C-reactive protein in healthy men. Effects cannot be attributed to observer bias or lifestyle confounders. These effects of tea may contribute to sustained cardiovascular health.

Adolescent↗

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↗