US National Library of MedicineNational Institutes of Health

PLoS One.2014 Jul 31;9(7):e103247. doi: 10.1371/journal.pone.0103247. eCollection 2014.


The effect of blackteaon blood pressure: a systematic review with meta-analysis of randomized controlled trials.


Greyling A,Ras RT,Zock PL,Lorenz M,Hopman MT,Thijssen DH,Draijer R.

Unilever Research & Development Vlaardingen, Vlaardingen, The Netherlands; Department of Physiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.

Unilever Research & Development Vlaardingen, Vlaardingen, The Netherlands; Top Institute Food and Nutrition, Wageningen, The Netherlands.

Department of Cardiology and Angiology, Campus Mitte, Charité - Universitätsmedizin, Berlin, Germany; DZHK (German Centre for Cardiovascular Research), Berlin, Germany.

Department of Physiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.

Department of Physiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom.



Epidemiological evidence has linked consumption of blacktea, produced from Camellia sinensis, with a reduced risk of cardiovascular diseases. However, intervention studies on the effects ofteaconsumption on blood pressure (BP) have reported inconsistent results. Our objective was to conduct a systematic literature review with meta-analysis of controlled human intervention studies examining the effect ofteaconsumption on BP.


We systematically searched Medline, Biosis, Chemical Abstracts and EMBASE databases through July 2013. For inclusion, studies had to meet the following pre-defined criteria: 1) placebo controlled design in human adults, 2) minimum of 1 week blackteaconsumption as the sole intervention, 3) reported effects on systolic BP (SBP) or diastolic BP (DBP) or both. A random effects model was used to calculate the pooled overall effect of blackteaon BP.


Eleven studies (12 intervention arms, 378 subjects, dose of 4-5 cups oftea) met our inclusion criteria. The pooled mean effect of regularteaingestion was -1.8 mmHg (95% CI: -2.8, -0.7; P = 0.0013) for SBP and -1.3 mmHg (95% CI: -1.8, -0.8; P<0.0001) for DBP. In covariate analyses, we found that the method ofteapreparation (teaextract powders versus leaftea), baseline SBP and DBP, and the quality score of the study affected the effect size of theteaintervention (all P<0.05). No evidence of publication bias could be detected.


Our meta-analysis indicates that regular consumption of blackteacan reduce BP. Although the effect is small, such effects could be important for cardiovascular health at population level.

Formerly Archives of Internal Medicine

January 23, 2012, Vol 172, No. 2


Effects of Black Tea on Blood Pressure: A Randomized Controlled Trial

Jonathan M. Hodgson, PhD; Ian B. Puddey, MD; Richard J. Woodman, PhD; Theo P. J. Mulder, PhD; Dagmar Fuchs, PhD; Kirsty Scott, BSc; Kevin D. Croft, PhD


High blood pressure (BP) is a leading risk factor contributing to the global burden of disease. Small changes in BP due to dietary modification may have a significant impact on the prevalence of hypertension and risk of cardiovascular disease.

Tea is a popular beverage worldwide and is usually the major source of population flavonoid intake, often providing more than half of total intake.There is mounting evidence that tea and its flavonoids can make an important contribution to vascular health. However, the effects of regular consumption of black tea on BP remain unclear.

Our objective was to assess the effects of regular black tea consumption (3 cups/d) for 6 months on 24-hour ambulatory BP. We found that black tea consumption resulted in significantly lower systolic BP (SBP) and diastolic BP (DBP).



The American Journal of Cardiology


Black tea increases coronary flow velocity reserve in healthy male subjects.

Columbia University, College of Physicians & Surgeons, Department of Medicine, Division of Cardiology, New York, New York, USA.

OsakaCityUniversityMedicalSchool, Department of Internal Medicine and Cardiology, Osaka, Japan.


Epidemiologic studies suggest that tea consumption decreases the risk for cardiovascular events. However, there has been no clinical report examining the effects of tea consumption on coronary circulation. The purpose of this study was to evaluate the effects of black tea on coronary flow velocity reserve (CFVR) using transthoracic Doppler echocardiography (TTDE). This was a double-blind crossover study of 10 healthy male volunteers conducted to compare the effects of black tea and caffeine on coronary circulation. The coronary flow velocity of the left anterior descending coronary artery was measured at baseline and at hyperemia during adenosine triphosphate infusion by TTDE to determine CFVR. The CFVR ratio was defined as the ratio of CFVR after beverage consumption to CFVR before beverage consumption. All data were divided into 2 groups according to beverage type: group T (black tea) and group C (caffeine). Two-way analysis of variance showed a significant group effect and interaction in CFVR before and after beverage consumption (p = 0.001). CFVR significantly increased after tea consumption in group T (4.5 +/- 0.9 vs 5.2 +/- 0.9, p <0.0001). The CFVR ratio of group T was larger than that of group C (1.18 +/- 0.07 vs 1.04 +/- 0.08, p = 0.002). Acute black tea consumption improves coronary vessel function, as determined by CFVR.





Joseph A. Vita

Tea consumption and cardiovascular disease: effects on endothelial function.


Evans Department of Medicine and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA, USA.


Epidemiological studies suggest that tea consumption is associated with reduced cardiovascular disease risk, but the mechanisms for these observations have remained uncertain. In recent years, it has become apparent that the endothelium plays a central role in the regulation of vascular homeostasis and that endothelial dysfunction contributes to the pathogenesis and clinical expression of cardiovascular disease. This article reviews the evidence that human tea consumption has a beneficial effect on the vascular endothelium and the clinical implications of these findings.



Circulation Journal

Japanese Circulation Society

Sano J, Inami S, Seimiya K, Ohba T, Sakai S, Takano T, Mizuno K.


Effects of green tea intake on the development of coronary artery disease.

Department of Medicine, ChibaHokusohHospital, NipponMedicalSchool, Chiba, Japan.

BACKGROUND: Green tea, a popular beverage in Japan, contains many polyphenolic antioxidants, which might prevent atherosclerosis. This study was designed to determine whether the consumption of green tea is proportionately associated with a decreased incidence of coronary artery disease (CAD) and the cardiovascular and cerebrovascular prognosis. METHODS AND RESULTS: The study group comprised 203 patients who underwent coronary angiography (109 patients with significant coronary stenosis and 94 patients without). Predictors for CAD were analyzed and the patients' cardiovascular and cerebrovascular events were followed. Green tea consumption was significantly higher in patients without CAD than in those with CAD (5.9+/-0.5 vs 3.5+/-0.3 cups/day; p<0.001). An inverse relationship between the intake of green tea and the incidence of CAD was observed (p<0.001). The green tea intake per day was an independent predictor for CAD based on a multivariate logistic regression analysis (odds ratio: 0.84 and 95% confidence interval: 0.76-0.91). In contrast, the green tea intake was not a predictor of cardiovascular and cerebrovascular events based on the Cox proportional hazard model. CONCLUSIONS: Green tea consumption was associated with a lower incidence of CAD in the present study population in Japan. Therefore, the more green tea patients consume, the less likely they are to have CAD.