Tea Consumption and Risk of Type 2 Diabetes: A Meta-Analysis of Cohort Studies

Jing, Yali; Han, Guanjun; Hu, Yun; Bi, Yan; Li, Lirong; Zhu, Dalong

doi:10.1007/s11606-009-0929-5

Cited by 91 publications

(77 citation statements)

References 55 publications

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“…Another study found an association only for green tea, not for black or oolong tea [6]. A recent meta-analysis summarised these studies and concluded that consumption of at least four cups of tea may lower the risk of type 2 diabetes, but a reduced risk was not observed for one to three cups of tea per day [33]. In addition, they were unable to distinguish between black and green tea in this meta-analysis.…”

Section: Discussionmentioning

confidence: 78%

Coffee and tea consumption and risk of type 2 diabetes

et al. 2009

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Aims/hypothesis The aim of this study was to examine the association of consumption of coffee and tea, separately and in total, with risk of type 2 diabetes and which factors mediate these relations. Methods This research was conducted as part of the Dutch Contribution to the European Prospective Investigation into Cancer and Nutrition, which involves a prospective cohort of 40,011 participants with a mean follow-up of 10 years. A validated food-frequency questionnaire was used to assess coffee and tea consumption and other lifestyle and dietary factors. The main outcome was verified incidence of type 2 diabetes. Blood pressure, caffeine, magnesium and potassium were examined as possible mediating factors. Results During follow-up, 918 incident cases of type 2 diabetes were documented. After adjustment for potential confounders, coffee and tea consumption were both inversely associated with type 2 diabetes, with hazard ratios of 0.77 (95% CI 0.63-0.95) for 4.1-6.0 cups of coffee per day (p for trend=0.033) and 0.63 (95% CI: 0.47-0.86) for >5.0 cups of tea per day (p for trend=0.002). Total daily consumption of at least three cups of coffee and/or tea reduced the risk of type 2 diabetes by approximately 42%. Adjusting for blood pressure, magnesium, potassium and caffeine did not attenuate the associations. Conclusions/interpretation Drinking coffee or tea is associated with a lowered risk of type 2 diabetes, which cannot be explained by magnesium, potassium, caffeine or blood pressure effects. Total consumption of at least three cups of coffee or tea per day may lower the risk of type 2 diabetes.

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Section: Discussionmentioning

confidence: 78%

Coffee and tea consumption and risk of type 2 diabetes

et al. 2009

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“…Because tea is the most widely consumed beverage worldwide (Higdon and Frei, 2003), and because numerous epidemiological studies have suggested tea may have a role in reducing risk of diabetes (Greenberg et al, 2005;Song et al, 2005;Iso et al, 2006;Odegaard et al, 2008;Polychronopoulos et al, 2008;Jing et al, 2009;van Dieren et al, 2009), controlled intervention studies are important for defining the potential for tea to maintain healthy glucose metabolism. Oolong tea processing involves fermenting the product more than green tea is fermented, but less than black tea.…”

Section: Discussionmentioning

confidence: 99%

“…As little as one cup of black tea per day was associated with decreased risk of diabetes in a study of 36 908 men and women in the Singapore Chinese Health Study (Odegaard et al, 2008). Jing et al (2009) conducted a meta-analysis that considered many of these studies together and concluded that tea consumption of four or more cups per day 'might have a role in prevention of type 2 diabetes.' In contrast, a number of large survey studies do not support a relationship between tea intake and diabetes risk, including the Health Professionals' Follow-up Study (Salazar-Martinez et al, 2004), the Nurses' Health Study (Salazar-Martinez et al, 2004) and the Nurses' Health Study II (van Dam et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Oolong tea does not improve glucose metabolism in non-diabetic adults

et al. 2010

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Background: Studies of the influence of tea on glucose metabolism have produced inconsistent results, possibly because of the lack of dietary control and/or unclear characterization of tea products. Methods: Therefore, a double-blind crossover study was conducted in which healthy males (n ¼ 19) consumed each of three oolong tea products or a control beverage as part of a controlled diet. Treatment beverages (1.4 l/day) were consumed for 5 days, followed by assessment of fasting plasma glucose, fasting serum insulin and an oral glucose tolerance test. Tea products included oolong tea, oolong tea with added catechins and oolong tea with added oolong tea polyphenols, and control beverages included caffeinated water and unsupplemented water. On the fifth day of each treatment period, treatment beverages were consumed with a standardized meal, and glucose and insulin responses were assessed for 240 min. Results: No significant differences were detected for fasting plasma glucose, fasting serum insulin, incremental plasma glucose area under the concentration time curve (AUC), total plasma glucose AUC or total serum insulin AUC. Conclusions: Neither oolong tea nor oolong tea supplemented with catechins or other polyphenols produced improved glucose metabolism in healthy adult volunteers on the basis of this highly controlled dietary intervention trial.

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“…46 The role of tea (all types included) in the prevention of type 2 diabetes mellitus development has been highlighted in two recent meta-analyses, where consumption of more than 3 to 4 cups per day of tea of any type was associated with reduced subsequent incidence of type 2 diabetes mellitus. 47,48 Green tea acutely increases glucose metabolism and improves oral glucose tolerance test in healthy humans. 49 However, these beneficial effects have not been verified in intervention studies of short-to middle-term green tea consumption.…”

Section: Glucose Metabolismmentioning

confidence: 99%

Role of green tea in reduction of cardiovascular risk factors

Alexopoulos¹,

Vlachopoulos²,

Stefanadis³

2010

NDS

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Tea is widely consumed worldwide. There is accumulating evidence that tea consumption may be associated with reduced cardiovascular risk, an association that could be attributed to its flavonoid content. Green tea, the most common type of tea consumed in Asia, contains a large amount of nonoxidized flavonoids, named catechins. Green tea consumption has been associated with reduced incidence of cardiovascular mortality, stroke, and myocardial infarction. Although there is some inconsistency in the results, large, well-designed observational studies have shown this inverse association. However, the association of green tea with coronary artery disease is less well-established. The protective effect of green tea on cardiovascular events may be mediated by beneficial effects of green tea on various classical and novel cardiovascular risk factors. There is evidence that green tea reduces total and low-density lipoprotein (LDL) cholesterol and oxidized LDL cholesterol, enhances insulin sensitivity, and may prevent development of diabetes mellitus. There is also evidence that green tea reduces oxidative stress and reverses endothelial dysfunction. Its effect on blood pressure and arterial stiffness is confounded by the presence of caffeine, which has pressor and arterial stiffening effects, although this effect is probably counterbalanced by beneficial effects of other constituents in green tea. Green tea acutely increases blood pressure more than its caffeine content; the ingredients responsible for this are not known. On the other hand, green tea has a milder acute effect on arterial stiffness than its caffeine content. Its chronic effect on blood pressure and arterial stiffness may be neutral or even beneficial.

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Tea Consumption and Risk of Type 2 Diabetes: A Meta-Analysis of Cohort Studies

Cited by 91 publications

References 55 publications

Coffee and tea consumption and risk of type 2 diabetes

Coffee and tea consumption and risk of type 2 diabetes

Oolong tea does not improve glucose metabolism in non-diabetic adults

Role of green tea in reduction of cardiovascular risk factors

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