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Results for “Tea drinking”

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At least 127 records · Page 7Linked to original sources
PubMed1995

Cross sectional study of effects of drinking green tea on cardiovascular and liver diseases.

OBJECTIVE: To investigate the association between consumption of green tea and various serum markers in a Japanese population, with special reference to preventive effects of green tea against cardiovascular disease and disorders of the liver. DESIGN: Cross sectional study. SETTING: Yoshimi, Japan. SUBJECTS: 1371 men aged over 40 years resident in Yoshimi and surveyed on their living habits including daily consumption of green tea. Their peripheral blood samples were subjected to several biochemical assays. RESULTS: Increased consumption of green tea was associated with decreased serum concentrations of total cholesterol (P for trend < 0.001) and triglyceride (P for trend = 0.02) and an increased proportion of high density lipoprotein cholesterol together with a decreased proportion of low and very low lipoprotein cholesterols (P for trend = 0.02), which resulted in a decreased atherogenic index (P for trend = 0.02). Moreover, increased consumption of green tea, especially more than 10 cups a day, was related to decreased concentrations of hepatological markers in serum, aspartate aminotransferase (P for trend = 0.06), alanine transferase (P for trend = 0.07), and ferritin (P for trend = 0.02). CONCLUSION: The inverse association between consumption of green tea and various serum markers shows that green tea may act protectively against cardiovascular disease and disorders of the liver.

Adult↗
PubMed2001

Tooth surface pH during drinking of black tea.

OBJECTIVES: To investigate the composition of black tea in terms of its erosive potential. To determine the pH profile at the palatal surface of anterior and posterior sites of the dentition after drinking black tea. METHODS: Tea solution was analysed for its pH and anion composition to provide information on its acid content. A group of ten healthy subjects, aged 21-23 years were monitored for tooth surface pH on the palatal aspects of the maxillary anterior dentition and the maxillary molar dentition after drinking tea using a micro-pH electrode mounted on a vinyl splint. RESULTS: The pH of the tea solution was 4.9 and the major anions detected were oxalate and citrate. Tooth surface pH monitoring indicated that only small decreases in pH of less than 1 pH unit were observed after drinking tea and the minimum mean pH reached was 5.45. Maximum decrease in pH was observed after 20-25 seconds and resting pH levels were restored within approximately 2 minutes after drinking. CONCLUSION: The pH and anion profile of black tea are indicative of low acid composition. The very small pH decreases observed at the tooth surface after drinking tea indicate that it may be safely recommended as a substitute for more acidic drinks as a part of preventive measures for dental erosion.

Adult↗
PubMed2006

Mechanisms of cancer prevention by green and black tea polyphenols.

Drinking green tea is associated with decreased frequency of cancer development. This review outlines the wide range of mechanisms by which epigallocatechin gallate (ECGC) and other green and black tea polyphenols inhibit cancer cell survival. EGCG suppressed androgen receptor expression and signalling via several growth factor receptors. Cell cycle arrest or apoptosis involved caspase activation and altered Bcl-2 family member expression. EGCG inhibited telomerase activity and led to telomere fragmentation. While at high concentrations polyphenols had pro-oxidative activities, at much lower levels, anti-oxidative effects occurred. Nitric oxide production was reduced by EGCG and black tea theaflavins by suppressing inducible nitric oxide synthase via blocking nuclear translocation of the transcription factor nuclear factor-kappaB as a result of decreased IkappaB kinase activity. Polyphenols up- or down-regulated activity of a number of key enzymes, including mitogen-activated protein kinases and protein kinase C, and increased or decreased protein/mRNA levels, including that of cyclins, oncogenes, and tumor suppressor genes. Metastasis was inhibited via effects on urokinase and matrix metalloproteinases. Polyphenols reduced angiogenesis, in part by decreasing vascular endothelial growth factor production and receptor phosphorylation. Recent work demonstrated that EGCG reduced dihydrofolate reductase activity, which would affect nucleic acid and protein synthesis. It also acted as an aryl hydrocarbon receptor an-tagonist by directly binding the receptor's molecular chaperone, heat shock protein 90. In conclusion, green and black tea polyphenols act at numerous points regulating cancer cell growth, survival, and metastasis, including effects at the DNA, RNA, and protein levels.

Animals↗
PubMed1990

Lung cancer risk and mutagenicity of tea.

To study the possible association between drinking tea and lung cancer, epidemiological and experimental materials were collected from the Chinese population in Hong Kong. In a retrospective study of 200 female lung cancer patients and 200 matched controls, all subjects were interviewed concerning their eating habits, smoking histories, and lifetime exposures to environmental pollutants. Analysis of the data demonstrated an adjusted and statistically significant increased lung cancer risk of 2.7 among those who drank green tea. Several brands of tea commonly drank in Hong Kong were assayed for mutagenicity using Ames' assay. Significantly elevated levels of mutagenic activity were found to be present after metabolic activation using cell-free extracts of cecal bacteria from rats. These data suggest that further research is needed to understand the possible consequences to human health of ingestants taken at low doses but long duration over the normal lifespan, and the possible interactive effect between mutagens in tea and other ingestants and inhalants in human cancer etiology.

Case-Control Studies↗
PubMed1975

The mechanism of the inhibition of iron absorption by tea.

Previous human studies have shown that drinking tea during meals significantly inhibits the absorption of both food iron and medicinal iron. This study provides evidence from experiments with rats that the tannins in the tea are responsible for the inhibition, probably by forming non-absorbable complexes with the iron within the intestinal lumen. The molar ratio of tannin: iron is dependent on the pH, being 1:1 at pH 2,0 2:1 at pH 5,5 and 3:1 at pH 8,0. Since tannins are present in many vegetable foods the formation of such complexes may be a factor in the poor availability for absorption of much food iron.

Chemical Phenomena↗
PubMed2001

[Food habits and oral hygiene of students. Investigation of 150 students in university housing].

The objective of this study is to describe the food intake and the oral hygiene habits of 150 Senegalese students living in a university campus. According to Miller, we realised a four days survey. We noted an increase of sugar drinks; tea is the most consumed drink. The results showed also that the toothbrush as means of oral hygiene supplanted the traditional means such as "cure dents" or water rinse with finger.

Adolescent↗
PubMed2003

Effect of increased tea consumption on oxidative DNA damage among smokers: a randomized controlled study.

Tea drinking has been associated with decreased occurrence of cancer and heart disease. One potential mechanism for these findings is the strong antioxidant effect of tea polyphenols. A phase II randomized controlled tea intervention trial was designed to study the effect of high consumption (4 cups/d) of decaffeinated green or black tea on oxidative DNA damage as measured by urinary 8-hydroxydeoxyguanosine (8-OHdG) among smokers over a 4-mo period. A total of 143 heavy smokers, aged 18-79 y, were randomized to drink either green or black tea or water. Levels of plasma and urinary catechins and urinary 8-OHdG were measured monthly. A total of 133 of 143 smokers completed the 4-mo intervention. Multiple linear regression models were used to estimate the main effects and interaction effect of green and black tea consumption on creatinine-adjusted urinary 8-OHdG, with or without adjustment for potential confounders. Plasma and urinary levels of catechins rose significantly in the green tea group compared with the other two groups. Assessment of urinary 8-OHdG after adjustment for baseline measurements and other potential confounders revealed a highly significant decrease in urinary 8-OHdG (-31%) after 4 mo of drinking decaffeinated green tea (P = 0.002). No change in urinary 8-OHdG was seen among smokers assigned to the black tea group. These data suggest that regular green tea drinking might protect smokers from oxidative damages and could reduce cancer risk or other diseases caused by free radicals associated with smoking.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2006

Coffee, cirrhosis, and transaminase enzymes.

BACKGROUND: A minority of persons at risk develop liver cirrhosis, but knowledge of risk modulators is sparse. Several reports suggest that coffee drinking is associated with lower cirrhosis risk. METHODS: We studied 125,580 multiethnic members of a comprehensive prepaid health care plan without known liver disease who supplied baseline data at voluntary health examinations from 1978 to 1985. Subsequently, through 2001, 330 of them were diagnosed with liver cirrhosis. Review of medical records confirmed the diagnosis of cirrhosis and ascertained probable etiology. The association of coffee drinking with cirrhosis was estimated by Cox proportional hazards models with 7 covariates. We also did a cross-sectional analysis of baseline aspartate aminotransferase and alanine aminotransferase levels, studied by logistic regression. RESULTS: In the cohort study, relative risks of alcoholic cirrhosis (199 subjects) for coffee drinking (vs none) were less than 1 cup per day, 0.7 (95% confidence interval [CI], 0.4-1.1); 1 to 3 cups, 0.6 (95% CI, 0.4-0.8; P<.001); and 4 or more cups, 0.2 (95% CI, 0.1-0.4; P<.001). For 131 subjects with nonalcoholic cirrhosis, relative risks were less than 1 cup, 1.2 (95% CI, 0.6-2.2); 1 to 3 cups, 1.3 (95% CI, 0.8-2.1); and 4 or more cups, 0.7 (95% CI, 0.4-1.3). These relative risks for coffee drinking were consistent in subsets. Tea drinking was unrelated to alcoholic or nonalcoholic cirrhosis. In the cross-sectional analyses, coffee drinking was related to lower prevalence of high aspartate aminotransferase and alanine aminotransferase levels; for example, the odds ratio of 4 or more cups per day (vs none) for a high aspartate aminotransferase level was 0.5 (95% CI, 0.4-0.6; P<.001) and for a high alanine aminotransferase level, 0.6 (95% CI, 0.6-0.7; P<.001), with stronger inverse relations in those who drink large quantities of alcohol. CONCLUSION: These data support the hypothesis that there is an ingredient in coffee that protects against cirrhosis, especially alcoholic cirrhosis.

Alanine Transaminase↗
PubMed1997

Tea consumption, lipid metabolism, and atherosclerosis.

The use of tea is derived from the Far East and was introduced into Europe, where in some countries tea soon became a favorite drink. Tea accounts for about 43% of all caffeine consumption. Total world caffeine consumption in 1981 was estimated to be approximately 120,000 tons, equivalent to 70 mg a day for each human. There is evidence from in vitro and animal studies, as well as from human investigations, that tea and its main constituents can prevent atherosclerosis to a certain extent. Supplementing tea as beverage instead of coffee might react beneficially with other antiatherosclerotic strategies. Investigations on the hypolipidemic and antiatherosclerotic action of tea, and therefore flavonoid intake, are still in their infancy and further fundamental data from controlled trials are needed to evaluate possible positive effects of tea consumption to prevent or treat atherosclerosis. Brief information on the biological potential of caffeine and flavonoids, as well as on their possible beneficial effects on the atherosclerotic process is documented in this review.

Animals↗
PubMedDate not supplied

Caries preventive effect of wild tea (tsaang-gubat) among school children.

A 3-year study was conducted to determine the effectiveness of wild tea (tsaang-gubat) as a caries preventive agent among schoolchildren in two elementary schools. The experimental group drank one cup of tea daily for 17 months. Tea drink was prepared by boiling for 30 minutes, fresh tea leaves from the school garden. Results showed that wild tea is an effective caries preventive agent. A significant decrease of 75.67% in caries incidence was observed highest in the mesial and occlusal surfaces. Increase in caries incidence in the third year was due to irregular drinking sessions and decrease in fluoride content of tea. Wild tea (tsaang-gubat) drink is acceptable to the pupils even with less sugar, costs cheap and is readily available.

Beverages↗
PubMed2000

Tea intake and squamous cell carcinoma of the skin: influence of type of tea beverages.

Differences in tea drinking habits are likely to vary by populations and could contribute to the inconsistencies found between studies comparing tea consumption and cancer risk. A population-based case-control study was used to evaluate how usual tea consumption patterns of an older population (n = 450) varied with history of squamous cell carcinoma (SCC) of the skin. A detailed tea questionnaire was developed to assess specific tea preparation methods and patterns of drinking. In this southwestern United States population, black tea was the predominant variety of tea consumed. We found no association between the broad definition of any tea consumption and skin SCC. However, the adjusted odds ratios (ORs) for hot and iced black tea intake were 0.63 [95% confidence interval (CI), 0.36-1.10] and 1.02 (95% CI, 0.64-1.63), respectively. Controls were more likely to report usually drinking strong hot tea (OR, 0.74; 95% CI, 0.53-1.03) with increased brewing time (P for trend = 0.03). Adjusting for brewing time, the association between skin SCC and hot black tea consumption suggests a significantly lower risk in consumers of hot tea compared to nonconsumers (OR, 0.33; 95% CI, 0.12-0.87). This is one of the first studies to explore the relation between different types of tea consumption and occurrence of human cancers. Our results show that tea concentration (strength), brewing time, and beverage temperature have major influences on the potential protective effects of hot black tea in relation to skin SCC. Further studies with increased sample sizes are needed to evaluate the interrelationships between preparation techniques, tea type, and other life-style factors.

Adult↗
PubMed2005

[Tea consumption and risk of biliary tract cancers and gallstone disease: a population-based case-control study in Shanghai, China].

OBJECTIVE: To investigate the relationship between tea consumption, biliary tract cancers and gallstone disease. METHODS: A population-based case-control study was conducted in urban Shanghai from 1 June 1997 to 31 May 2001 involving interviews with 627 new cases of biliary tract cancers (including 368 cases of gallbladder cancer, 191 cases of extrahepatic bile duct cancer and 68 cases of cancer of the ampulla of Vater) aged 35 to 74 years and 959 population controls frequency-matched to cases by gender and age in five-year group. 1037 patients of gallstone disease were selected from the same hospital. All subjects were interviewed in person by trained interviewers by use of a structured questionnaire. Unconditional logistic regression analysis was used to calculate adjusted odds ratio (OR) and 95% confidence interval (CI). RESULTS: Compared with tea non-drinkers, current tea consumption was inversely associated with risk of gallbladder cancer, extrahepatic bile duct cancer and gallstone disease among females with OR of 0.57 (95% CI: 0.34-0.96), 0.53 (95% CI: 0.27-1.03) and 0.71 (95% CI: 0.51-0.99), respectively. OR declined with younger age at initiation of tea drinking and with longer duration of tea consumption (P for trend < 0.05). Among males, the corresponding OR were mostly below one, although not statistically significant. CONCLUSION: Tea consumption may decrease the risk of cancers of the gallbladder and extrahepatic bile duct among females. The protective effect appears to be independent of gallstone disease.

Adult↗