***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Green and black tea polyphenols have been extensively studied as cancer chemopreventive agents . Many in vitro experiments have supported their strong antioxidant activity . Additional in vivo studies are needed to examine the pharmacokinetic relation of absorption and antioxidant activity of tea polyphenols administered in the form of green or black tea or tea extract supplements . OBJECTIVE The purpose of this study was to compare the pharmacokinetic disposition of tea polyphenols and their effect on the antioxidant capacity in plasma 8 h after a bolus consumption of either green tea , black tea , or a green tea extract supplement . DESIGN Thirty healthy subjects were r and omly assigned to 3 different sequences of green tea , black tea , or a green tea extract supplement in a 3 x 3 crossover design with a 1-wk washout period in between treatments . RESULTS Flavanol absorption was enhanced when tea polyphenols were administered as a green tea supplement in capsule form and led to a small but significant increase in plasma antioxidant activity compared with when tea polyphenols were consumed as black tea or green tea . All 3 interventions provided similar amounts of (-)-epigallocatechin-3-gallate . CONCLUSIONS Our observations suggest that green tea extract supplements retain the beneficial effects of green and black tea and may be used in future chemoprevention studies to provide a large dose of tea polyphenols without the side effects of caffeine associated with green and black tea beverages BACKGROUND Increasing coffee intake was inversely associated with risk of type 2 diabetes in population s of European descent ; however , data from high-risk Asian population s are lacking as are data on tea intake in general . OBJECTIVE We investigated the prospect i ve associations between intakes of coffee , black tea , and green tea with the risk of type 2 diabetes in Singaporean Chinese men and women . DESIGN We analyzed data from 36 908 female and male participants in the Singapore Chinese Health Study aged 45 - 74 y in 1993 - 1998 who had multiple diet and lifestyle measures assessed and then were followed up between 1999 and 2004 . We used Cox regression models to investigate the association of baseline coffee and tea intakes with incident type 2 diabetes during follow-up , with adjustment for a number of possible confounding or mediating variables . RESULTS In multivariate models participants reporting > or = 4 cups of coffee/d had a 30 % reduction in risk of diabetes [ relative risk ( RR ) : 0.70 ; 95 % CI : 0.53 , 0.93 ] compared with participants who reported nondaily consumption . Participants reporting > or = 1 cup of black tea/d had a suggestive 14 % reduction in risk of diabetes ( RR : 0.86 ; 95 % CI : 0.74 , 1.00 ) compared with participants who reported 0 cups/d , and we observed no association with green tea . CONCLUSION Regular consumption of coffee and potentially black tea , but not green tea , is associated with lower risk of type 2 diabetes in Asian men and women in Singapore OBJECTIVE : To assess the effect of weight change on the relationship between coffee and tea consumption and diabetes risk . DESIGN : Prospect i ve cohort study , using data from the First National Health and Nutrition Examination Survey Epidemiologic Follow Up Study . Survival analyses were conducted using 301 selfreported cases of diabetes and eight documented diabetes deaths during an 8.4-y follow-up . SUBJECTS : A total of 7006 subjects aged 32–88 y with no reported history of diabetes were included in the study . RESULTS : For all subjects combined , increases in consumption of ground-caffeinated coffee and caffeine at baseline were followed by decreases in diabetes risk during follow-up . There were significant statistical interactions between age and consumption of caffeine ( P=0.02 ) and ground-caffeinated coffee ( P=0.03 ) . Age-stratified analysis showed that the decrease in diabetes risk only applied to ≤60-y-old subjects , for whom the decrease in diabetes risk also obtained for ground-decaffeinated coffee and regular tea . The multivariate hazard ratio ( HR ) and 95 % confidence interval for a 2 cups/day increment in the intake of ground-caffeinated coffee , ground-decaffeinated coffee and regular tea was 0.86 ( 0.75–0.99 ) , 0.58 ( 0.34–0.99 ) and 0.77 ( 0.59–1.00 ) , respectively . The diabetes risk was negatively related to the consumption in a dose – response manner . There were strong statistical interactions between prior weight change and beverage consumption for ≤60-y-old subjects . Further analysis revealed that the decrease in diabetes risk only applied to those who had lost weight , and that there was a positive dose – response relationship between diabetes risk and weight change . For example , the multivariate HR and 95 % confidence interval for > 0 vs 0 cups/day of ground-decaffeinated coffee was 0.17 ( 0.04–0.74 ) , 0.52 ( 0.19–1.42 ) , 0.77 ( 0.30–1.96 ) and 0.91 ( 0.39–2.14 ) for subgroups with weight change of ≤0 , 0–10 , 10–20 and > 20 lbs , respectively . There was no significant association between diabetes risk and consumption of instant-caffeinated coffee , instant-decaffeinated coffee or herbal tea . Caffeine intake appeared to explain some , but not all , of the diabetes-risk reduction and weight change . CONCLUSION : The negative relationship between diabetes risk and consumption of ground coffee and regular tea , observed for all NHEFS subjects , actually only applied to nonelderly adults who had previously lost weight Context Caffeine intake from coffee has been associated with a lower incidence of diabetes . Research ers have not studied the relationship of green tea , a popular beverage in Japan , where the incidence of diabetes is increasing rapidly . Contributions The authors estimated the intake of caffeine-containing beverages in a community-based survey in Japan and measured the 5-year incidence of diabetes . Greater intake of green tea or coffee was associated with a reduced incidence of diabetes . The effect of green tea was largely observed in women , was dose-related , and reflected caffeine intake . Implication s Higher intake of caffeine , whether from coffee or green tea , is associated with a lower incidence of diabetes . The Editors The prevalence of type 2 diabetes has increased worldwide , particularly in Asian countries where it was previously low ( 1 ) . In Japan , population -based studies have shown a 2-fold increase in the prevalence of diabetes during the past 2 decades , from 5 % to 10 % to 10 % to 15 % ( 2 ) . Several cohort studies done in Europe and in the United States reported an association between coffee consumption , a major source of caffeine , and reduced risk for diabetes ( 3 - 7 ) . Although these studies did not show any association between consumption of black tea and the risk for diabetes , they did not examine the effect of green or oolong teas , major sources of caffeine in Asian countries . Consumption of green tea is common in Japan ; 80 % of the population drinks green tea , and the average consumption per capita is 2 cups per day ( 8) . We wanted to determine whether there is a relationship between consumption of green tea and the risk for type 2 diabetes and , if so , whether caffeine fully accounts for this relationship . To examine these questions , we analyzed data from a large cohort study of 19487 middle-aged men and women in 25 communities across Japan . We also examined the effect of age , sex , body mass index ( BMI ) , family history , smoking status , alcohol use , magnesium intake , and physical activity on the association between this mode of caffeine consumption and risk for diabetes . Methods The Japan Collaborative Cohort Study for Evaluation of Cancer Risk ( JACC Study ) started between 1988 and 1990 . A total of 110792 individuals ( 46465 men and 64327 women ) who were 40 to 79 years of age and living in 45 communities across Japan participated in municipal health screening examinations and completed self-administered question naires regarding lifestyle and medical history of cardiovascular disease and cancer ( 9 ) . Informed consent was obtained before the completion of the question naire . Participants from 25 of the 45 communities completed 5-year follow-up surveys . Among 35690 participants ( 15177 men and 20513 women ) who were 40 to 65 years of age at baseline without a history of type 2 diabetes , stroke , coronary heart disease , or cancer , 17413 individuals ( 49 % ; 6727 men and 10686 women ) completed the 5-year follow-up question naire and provided valid responses on tea or coffee consumption and history of type 2 diabetes . The data from these 17413 individuals were used for the analyses . The mean age of the nonrespondents was 1 year younger for men ( 52.3 vs. 53.3 years of age ) and did not differ for women ( 53.1 vs. 53.0 years of age ) compared with the respondents . The mean BMI and the prevalence of a BMI of 25.0 kg/m2 or greater did not differ between the respondents and nonrespondents . Mean BMI was 22.7 kg/m2 versus 22.8 kg/m2 for men and 22.8 kg/m2 versus 22.9 kg/m2 for women , respectively ; the prevalence of overweight was 18 % versus 19 % for men and 21 % versus 22 % for women , respectively . The ethical committees at Nagoya University and the University of Tsukuba approved the study . Assessment of Consumption of Tea and Coffee and Caffeine Intake At baseline , consumption of tea and coffee  was assessed by using a self-administered dietary question naire . Participants were asked to state their average consumption of green tea , black tea , oolong tea , and coffee during the previous year . They could select any of 4 frequency responses : less than once a week , about 1 to 2 times a week , about 3 to 4 times a week , and almost every day . Participants who selected the response of almost every day were also asked to state their average consumption of these beverages in number of cups per day . We classified the categories of consumption as less than 1 cup per week , 1 to 6 cups per week , 1 to 2 cups per day , 3 to 5 cups per day , and 6 or more cups per day . The highest 2 or 3 consumption categories were combined for coffee , black tea , and oolong tea because of the small number of participants in these categories . The consumption of decaffeinated coffee or tea  was not recorded because these products were not commercially available in Japan in the early 1990s . The total intake of caffeine was calculated by adding the caffeine content from each specific beverage ( 1 cup for coffee or tea ) and multiplying it by the participant 's weight proportional to the frequency of caffeine use . We estimated the size of the cup for each beverage from a validation study ( 10 ) and the caffeine content per 100 mL of each beverage from the Japan Food Tables ( 11 ) . The estimated caffeine content was 153 mg per cup ( 170 mL ) of coffee , 30 mg per cup ( 200 mL ) of green tea , 51 mg per cup ( 170 mL ) of black tea , and 38 mg per cup ( 190 mL ) of oolong tea . The mean caffeine intake was 229 mg/d for men and 215 mg/d for women .  Relative proportions of caffeine intake by beverage were 46 % from green tea , 44 % to 47 % from coffee , 3 % from black tea , and 4 % to 5 % from oolong tea . For reproducibility , the Spearman correlation coefficients between the 2 question naires , administered 1 year apart for 85 participants ( 8 men and 77 women ) , were 0.79 for green tea , 0.87 for coffee , 0.77 for black tea , and 0.56 for oolong tea ( 10 ) . The validity of the data was confirmed for the 85 participants by comparing the data from the question naire with those from four 3-day dietary records collected approximately 3 to 4 months apart ( 10 ) . The mean frequency of consumption of green tea  was 25.4 cups per week according to the question naire and 30.1 cups per week according to four 1-week dietary records ( Spearman correlation coefficient , 0.47 ) . The respective mean frequencies were 8.0 cups and 7.1 cups per week with a correlation coefficient of 0.79 for coffee , 1.4 cups and 1.6 cups per week with a correlation coefficient of 0.70 for black tea , and 1.8 cups and 1.2 cups per week with a correlation coefficient of 0.55 for oolong tea . When we restricted the data to the 77 women , the results were essentially the same . Assessment of Diabetes Cases Participants who reported having diabetes newly diagnosed by physicians on the 5-year follow-up question naire were considered to have incident diabetes . To examine the validity of self-reporting of diabetes , we compared self-report data with laboratory findings and treatment status in a sample of 1230 men and 1837 women . We considered elevated glucose concentr 
    Output:
    
Similar significant and inverse associations were observed with decaffeinated coffee and tea and risk of incident diabetes .
High intakes of coffee , decaffeinated coffee , and tea are associated with reduced risk of diabetes .