Effect of black tea consumption on brachial artery flow-mediated dilation and ischaemia–reperfusion in humans

Abstract

Tea consumption is associated with reduced cardiovascular risk. Previous studies found that tea flavonoids work through direct effects on the vasculature, leading to dose-dependent improvements in endothelial function. Cardioprotective effects of regular tea consumption may relate to the prevention of endothelial ischaemia-reperfusion (IR) injury. Therefore, we examined the effect of black tea consumption on endothelial function and the ability of tea to prevent IR injury. In a randomized, crossover study, 20 healthy subjects underwent 7 days of tea consumption (3 cups per day) or abstinence from tea. We examined brachial artery (BA) endothelial function via flow-mediated dilation (FMD), using high resolution echo-Doppler, before and 90 min after tea or hot water consumption. Subsequently, we followed a 20-min ischaemia and 20-min reperfusion protocol of the BA after which we measured FMD to examine the potential of tea consumption to protect against IR injury. Tea consumption resulted in an immediate increase in FMD% (pre-consumption: 5.8 ± 2.5; post-consumption: 7.2 ± 3.2; p < 0.01), whilst no such change occurred after ingestion of hot water. The IR protocol resulted in a significant decrease in FMD (p < 0.005), which was also present after tea consumption (p < 0.001). This decline was accompanied by an increase in the post-IR baseline diameter. In conclusion, these data indicate that tea ingestion improves BA FMD. However, the impact of the IR protocol on FMD was not influenced by tea consumption. Therefore, the cardioprotective association of tea ingestion relates to a direct effect of tea on the endothelium in humans in vivo.

Effects Of Tea Consumption On Measures Of Cardiovascular Disease: A Systematic Review Of Meta-Analysis Studies And Randomised Controlled Trials

“…For black tea those with a higher cardiovascular risk appear to have more benefit [11] with indications from RCTs suggesting that black tea could reduce triglyceride levels, alter body fat distribution and increase fat excretion [6,40,44]. For black tea there is evidence that this can improve FMD and exhibit vascular protective properties that could be of clinical relevance [48,49,53]. Although these effects appear to be modest they could be of importance for cardiovascular health at the population level due to the widespread habitual consumption of tea and high prevalence of cardiovascular risk factors.…”

“…Pang et al [45]; Tang et al [46] Grassi et al [48]; Schreuder et al [49]; Grassi et al [53] Inflammation Meta-analytical evidence looking at tea intake in relation to markers of inflammation is lacking.…”

“…Six RCTs focused on aspects of CV function [48][49][50][51][52][53]. A small 8-day trial providing black tea (150 mg polyphenols) twice daily noted improvements in circulating angiogenic cells (CACs) and flowmediated dilation (FMD), with a maximal response 2 hours after ingestion [48].…”

“…A small 8-day trial providing black tea (150 mg polyphenols) twice daily noted improvements in circulating angiogenic cells (CACs) and flowmediated dilation (FMD), with a maximal response 2 hours after ingestion [48]. A 7-day trial of 20 healthy subjects drinking 3 cups black tea per day also observed improvements in FMD with this appearing to relate to a direct effect of the tea on the endothelium [49]. Similarly, amongst 19 healthy men drinking black tea twice daily over 5 1-week periods showed that the variety of tea providing 800 mg flavonoids significantly improved FMD and reduced peripheral arterial stiffness compared with the control [53].…”

Nutrition and other lifestyle influences on arterial aging

“…The consumption of whey protein and dairy, for instance, is associated with enhanced endothelial function and lower arterial stiffness in middle-aged or older adults (Ballard et al, 2013; Crichton et al, 2012). Similarly, data from controlled trials demonstrate that cocoa products, including dark (not milk) chocolate, improve endothelial function and reduce arterial stiffness (Corti et al, 2009; Heiss et al, 2015), as do fermented dairy, tea and soy (Jauhiainen et al, 2010; Lin et al, 2016; Pase et al, 2011; Schreuder et al, 2014). Besides these well studied foods, accumulating evidence also suggests that consuming olive oil, seeds, whole grains, nuts, legumes and coffee is associated with CVD risk-lowering effects, and this is likely to be mediated in part by preservation of endothelial function and reductions in arterial stiffness (Mozaffarian et al, 2011; Ros and Hu, 2013; Uemura et al, 2013).…”