title: Acute effects of coffee on endothelial function in healthy subjects Coffee and green tea as a large source of antioxidant polyphenols in the Japanese population. Coffee polyphenol consumption improves postprandial hyperglycemia associated with impaired vascular endothelial function in healthy male adults. Acute Effect of Caffeine on Arterial Stiffness and Aortic Pressure Waveform Smoking and caffeine have a synergistic detrimental effect on aortic stiffness and wave reflections. The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials Acute effects of chlorogenic acid on nitric oxide status, endothelial function, and blood pressure in healthy volunteers: a randomized trial. Impact of acute caffeine ingestion on endothelial function in subjects with and without coronary artery disease. Caffeine increases aortic stiffness in hypertensive patients. Effect of dark chocolate on arterial function in healthy individuals. Effects of hydroxyhydroquinone-reduced coffee on vasoreactivity and blood pressure Dose-dependent effects of decaffeinated coffee on endothelial function in healthy subjects Green coffee bean extract improves human vasoreactivity. Coffee Consumption Increases the Antioxidant Capacity of Plasma and Has No Effect on the Lipid Profile or Vascular Function in Healthy Adults in a Randomized Controlled Trial. Effect of coffee on endothelial function in healthy subjects: the role of caffeine. Effect of caffeine on aortic elastic properties and wave reflection Acute effects of caffeine on blood pressure and wave reflections in healthy subjects: should we consider monitoring central blood pressure? Cardiovascular effects of caffeine in men and women. Coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone improves postprandial endothelial dysfunction in patients with borderline and stage 1 hypertension Acute effects of chlorogenic acids on endothelial function and blood pressure in healthy men and women.
abstract: Background / Objectives : Coffee is the most widely consumed beverage in the world , but its effect on the cardiovascular system has not been fully understood . Coffee contains caffeine and antioxidants , which may influence endothelial function , both of which have not yet been investigated . The objective of this study was to investigate the acute effects of coffee on endothelial function measured by brachial artery flow-mediated dilation (FMD).Subjects/ Methods : A total of 20 ( 10 males and 10 females ) healthy non-obese subjects underwent a double-blind , crossover study . Subjects ingested one cup of caffeinated ( CC ) and one cup of decaffeinated ( DC ) Italian espresso coffee in r and om order at 5- to 7-day intervals . Results : Following CC ingestion , FMD decreased progressively and significantly ( mean±s.e.m . : 0 min , 7.7±0.6 ; 30 min , 6.3±0.7 ; 60 min , 6.0±0.8 % ; ANOVA ( analysis of variance ) , P<0.05 ) , but it did not significantly increase after DC ingestion ( 0 min , 6.9±0.6 ; 30 min , 8.1±0.9 ; 60 min , 8.5±0.9 % ; P=0.115 ) . Similarly , CC significantly increased both systolic and diastolic blood pressure ; this effect was not observed after DC ingestion . Blood glucose concentrations remained unchanged after ingestion of both CC and DC , but insulin ( 0 min , 15.8±0.9 ; 60 min , 15.0±0.8 μU/ml ; P<0.05 ) and C-peptide ( 0 min , 1.25±0.09 ; 60 min , 1.18±0.09 ng/ml ; P<0.01 ) blood concentrations decreased significantly only after CC ingestion . Conclusions : CC acutely induced unfavorable cardiovascular effects , especially on endothelial function . In the fasting state , insulin secretion is also likely reduced after CC ingestion . Future studies will determine whether CC has detrimental clinical ly relevant effects , especially in unhealthy subjects Food and beverages rich in polyphenols with antioxidant activity are highlighted as a potential factor for risk reduction of lifestyle related diseases . This study was conducted to eluci date total polyphenol consumption from beverages in Japanese people .  Total polyphenol ( TP ) contents in beverages were measured using a modified Folin-Ciocalteu method removing the interference of reduced sugars by using reverse-phase column chromatography . A beverage consumption survey was conducted in the Tokyo and Osaka areas in 2004 . R and omly selected male and female subjects ( 10 - 59 years old , n = 8768 ) recorded the amounts and types of all nonalcoholic beverages  consumed in a week . Concentration of TP in coffee , green tea , black tea , Oolong tea , barley tea , fruit juice , tomato/vegetable juice , and cocoa drinks were at 200 , 115 , 96 , 39 , 9 , 34 , 69 , and 62 mg/100 mL , respectively . Total consumption of beverages in a Japanese population was 1.11 + /- 0.51 L/day , and TP contents from beverages was 853 + /- 512 mg/day . Coffee and green tea shared 50 % and 34 % of TP consumption in beverages , respectively , and contribution of each of the other beverages was less than 10 % . TP contents in 20 major vegetables and 5 fruits were 0 - 49 mg and 2 - 55 mg/100 g , respectively . Antioxidant activities , Cu reducing power , and scavenging activities for DPPH and superoxide , of those sample s correlated to the TP contents ( p < 0.001 ) . Beverages , especially coffee , contributed to a large share of the consumption of polyphenols , as antioxidants , in the Japanese diet Epidemiological studies indicate that habitual coffee consumption lowers the risk of diabetes and cardiovascular diseases . Postpr and ial hyperglycemia is a direct and independent risk factor for cardiovascular diseases . We previously demonstrated that coffee polyphenol ingestion increased secretion of Glucagon-like peptide 1 ( GLP-1 ) , which has been shown to exhibit anti-diabetic and cardiovascular effects . We hypothesized coffee polyphenol consumption may improve postpr and ial hyperglycemia and vascular endothelial function by increasing GLP-1 release and /or reducing oxidative stress . To examine this hypothesis , we conducted a r and omized , acute , crossover , intervention study in healthy male adults , measuring blood parameters and flow-mediated dilation ( FMD ) after ingestion of a meal with or without coffee polyphenol extract ( CPE ) .  Nineteen subjects consumed a test meal with either a placebo- or CPE-containing beverage .  Blood biomarkers and FMD were measured at fasting and up to 180 minutes postpr and ially . The CPE beverage led to a significantly lower peak postpr and ial increase in blood glucose and diacron-reactive oxygen metabolite , and significantly higher postpr and ial FMD than the placebo beverage . Postpr and ial blood GLP-1 increase tended to be higher after ingestion of the CPE beverage , compared with placebo . Subclass analysis revealed that the CPE beverage significantly improved postpr and ial blood GLP-1 response and reduced blood glucose increase in the subjects with a lower insulinogenic index . Correlation analysis showed postpr and ial FMD was negatively associated with blood glucose increase after ingestion of the CPE beverage . In conclusion , these results suggest that coffee polyphenol consumption improves postpr and ial hyperglycemia and vascular endothelial function , which is associated with increased GLP-1 secretion and decreased oxidative stress in healthy humans Caffeine acutely increases blood pressure and peripheral vascular resistance , in part because of sympathetic stimulation . Its effects on large artery properties are largely unknown . In a double-blind crossover study , 7 healthy subjects 26±2.6 years of age ( mean±SEM ) were studied for 90 minutes while in the supine position on 2 occasions separated by a week in r and om order after ingestion of 250 mL caffeinated ( 150 mg ) and decaffeinated ( < 2 mg ) coffee . Compared with baseline , arterial stiffness measured by carotid femoral pulse wave velocity increased progressively from 7.2±0.41 to 8.0±0.6 m/s ( P < 0.05 ) at 90 minutes after caffeine intake , an effect that may be independent of changes in blood pressure . In addition , arterial wave reflection , measured by applanation tonometry from the aortic pressure waveform , also increased from −5.7±7.6 % to 5.28%±5.6 ( P < 0.01 ) . No such changes were seen with decaffeinated coffee intake . Although the integral of the brachial systolic and diastolic blood pressure values over the 90 minutes was larger ( P < 0.05 ) after caffeinated than decaffeinated coffee intake , the effect on aortic systolic and diastolic blood pressures was more pronounced ( P < 0.05 ) than on the brachial artery . These results show a significant effect of caffeine intake on arterial tone and function and suggest that caffeine acutely increases arterial stiffness OBJECTIVES We investigated the acute and chronic combined effect of cigarette smoking and caffeine intake on aortic stiffness and wave reflections . BACKGROUND We have shown that smoking and caffeine separately increase arterial stiffness . Aortic stiffness and wave reflections are important determinants of the efficient performance of the cardiovascular system and prognosticators of cardiovascular risk . METHODS The acute effects of smoking ( one cigarette ) , caffeine ( 200 mg , equivalent to 2 cups of coffee ) , and smoking plus caffeine were studied in 24 healthy subjects according to a r and omized , placebo- and sham procedure-controlled crossover design . The chronic effect of smoking and caffeine was studied in a population study that enrolled 160 healthy subjects . RESULTS Acute study : there was a significant interaction between caffeine and smoking with regard to pulse-wave velocity ( p < 0.01 ) and augmentation index ( p < 0.05 ) . When smoking followed caffeine intake , pulse-wave velocity and augmentation index increased further by 0.52 m/s and 13.4 % , respectively , reaching a total of 0.85 m/s and 17.4 % , 0.17 m/s and 9.2 % in excess of the mere sum of caffeine effect ( 0.33 m/s and 4 % ) alone and smoking effect alone ( 0.35 m/s and 4.2 % ) . Population study : there was a significant interaction of chronic coffee consumption and smoking regarding pulse-wave velocity ( p < 0.05 ) and augmentation index ( p = 0.001 ) . CONCLUSIONS The present study shows , for the first time , that when smoking and caffeine intake are combined , they interact and exert a synergistic , unfavorable effect on aortic stiffness and wave reflections on both an acute and chronic basis Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more There is mounting evidence that specific dietary polyphenols can enhance vascular health by augmenting nitric oxide . Our aim was to investigate the acute effects of chlorogenic acid , an important dietary phenolic acid present in coffee ( 400 mg , equivalent to 2 cups of coffee ) , on nitric oxide status , endothelial function , and blood pressure .  Healthy men and women ( n = 23 ) were recruited to a r and omized , double-blind , placebo-controlled , crossover trial . Chlorogenic acid result ed in significantly higher plasma concentrations of chlorogenic acid ( P < 0.001 ) . Relative to control , the mean post-treatment systolic blood pressure ( -2.41 mmHg , 95 % CI : -0.03 , -4.78 ; P = 0.05 ) and diastolic blood pressure ( -1.53 mmHg , 95 % CI : -0.05 , -3.01 ; P = 0.04 ) were significantly lower with chlorogenic acid . Markers of nitric oxide status ( P > 0.10 ) and the measure of endothelial function ( P = 0.60 ) were not significantly influenced . Chlorogenic acid can lower blood pressure acutely , an effect that , if sustained , would benefit cardiovascular health Although coffee is a widely used , pharmacologically active beverage , its impact on the cardiovascular system is controversial . To explore the effect of acute caffeine ingestion on brachial artery flow-mediated dilation ( FMD ) in subjects without coronary artery disease ( CAD ; controls ) and patients with CAD , we prospect ively assessed brachial artery FMD in 40 controls and 40 age- and gender-matched patients with documented stable CAD on 2 separate mornings 1 week to 2 weeks apart . After overnight fasting , discontinuation of all medications for ≥12 hours , and absence of caffeine for > 48 hours , participants received capsules with caffeine 200 mg or placebo . One hour after drug ingestion , participants underwent brachial artery FMD and nitroglycerin-mediated dilation ( NTG ) using high-resolution ultrasound . As expected , patients with CAD were more often diabetic , hypertensive , obese , dyslipidemic , and smoked more than controls ( p < 0.01 for all comparisons ) . Aspirin , Clopidogrel , angiotensin-converting enzyme inhibitors , β blockers , and statins  were significantly more common in patients with CAD than in controls ( p < 0.01 for all comparisons ) . At baseline , FMD , but not NTG , was significantly lower in patients with CAD compared to controls . Acute caffeine ingestion significantly increased FMD ( patients with CAD 5.6 ± 5.0 % vs 14.6 ± 5.0 % , controls 8.4 ± 2.9 % vs 18.6 ± 6.8 % , p < 0.001 for all comparisons ) but not NTG ( patients with CAD 13.0 ± 5.2 % vs 13.8 ± 6.1 % , controls 12.9 ± 3.9 % vs 13.9 ± 5.8 % , p = NS for all comparisons ) and significantly decreased high-sensitivity C-reactive protein ( patients with CAD 2.6 ± 1.4 vs 1.4 ± 1.2 mg/L , controls 3.4 ± 3.0 vs 1.2 ± 1.0 mg/L , p < 0.001 for all comparisons ) in the 2 groups compared to placebo . In conclusion , acute caffeine ingestion significantly improved endothelial function assessed by brachial artery FMD in subjects with and without CAD and was associated with lower plasma markers of inflammation BACKGROUND Caffeine is the most widely used pharmacologic substance . Aortic stiffness is an important factor for cardiovascular system performance and a prognosticator of cardiovascular risk . We investigated the effect of caffeine on aortic stiffness in treated hypertensive patients . METHODS We studied the effect of caffeine ( 250 mg ) in 12 treated hypertensive patients according to a r and omized , placebo-controlled  , double-blind , cross-over design during a 3-h period . Aortic stiffness was evaluated by carotid-femoral pulse wave velocity . RESULTS Systolic blood pressure ( BP ) and pulse pressure increased significantly throughout the study ( by 12.3 and 7.4 mm Hg , P = .005 and P < .01 , respectively ) , whereas diastolic BP did not change . Pulse wave velocity increased ( by 0.57 m/sec , P < .05 ) denoting an increase in aortic stiffness . This effect of caffeine lasted throughout the study ( 3 h ) , peaking at 60 min and decreasing progressively thereafter . CONCLUSIONS These results demonstrate , for the first time , that caffeine exerts an acute unfavorable effect on aortic stiffness in treated hypertensive patients . This finding has important implication s for the impact of caffeine consumption on cardiovascular risk in hypertension BACKGROUND Epidemiologic studies suggest that high flavonoid intake confers a benefit on cardiovascular outcome . Endothelial function , arterial stiffness , and wave reflections are important determinants of cardiovascular performance and are predictors of cardiovascular risk . METHODS The effect of flavonoid-rich dark chocolate ( 100 g ) on endothelial function , aortic stiffness , wave reflections , and oxidant status were studied for 3 h in 17 young healthy volunteers according to a r and omized , single-blind , sham procedure-controlled , cross-over protocol .  Flow-mediated dilation ( FMD ) of the brachial artery , aortic augmentation index ( AIx ) , and carotid-femoral pulse wave velocity ( PWV ) were used as measures of endothelial function , wave reflections , and aortic stiffness , respectively . Plasma oxidant status was evaluated with measurement of plasma malondialdehyde ( MDA ) and total antioxidant capacity ( TAC ) . RESULTS Chocolate led to a significant increase in resting and hyperemic brachial artery diameter throughout the study ( maximum increase by 0.15 mm and 0.18 mm , respectively , P < .001 for both ) . The FMD increased significantly at 60 min ( absolute increase 1.43 % , P < .05 ) . The AIx was significantly decreased with chocolate throughout the study ( maximum absolute decrease 7.8 % , P < .001 ) , indicating a decrease in wave reflections , whereas PWV did not change to a significant extent . Plasma MDA and TAC did not change after chocolate , indicating no alterations in plasma oxidant status . CONCLUSIONS Our study shows for the first time that consumption of dark chocolate acutely decreases wave reflections , that it does not affect aortic stiffness , and that it may exert a beneficial effect on endothelial function in healthy adults .  Chocolate consumption may exert a protective effect on the cardiovascular system ; further studies are warranted to assess any long-term effects Recent studies suggest that chlorogenic acids , which are the main components of the polyphenol class in coffee , decrease blood pressure , and that hydroxyhydroquinone ( HHQ ) , which is generated by roasting coffee beans , inhibits the antihypertensive effect of chlorogenic acids in brewed coffee . Here , we examined the vasoreactivity and antihypertensive effects of HHQ-reduced coffee in mild hypertension . The study design was a double blind , r and omized , placebo-controlled intervention study , with a 4-week run-in period , followed by an 8-week test beverage ingestion period . The subjects were Japanese men and women with mild hypertension and vascular failure , who were not taking any antihypertensive drugs . During the test beverage ingestion period , the subjects ingested either active or placebo HHQ-reduced coffee ( chlorogenic acids per 184 ml of coffee : active , 300 mg ; and placebo , 0 mg ) daily . Subjects were r and omly divided into two groups : active group ( n=9 ) and placebo group ( n=12 ) . In the active beverage group , endothelium-dependent , flow-mediated vasodilation impairment was significantly ameliorated and systolic blood pressure was significantly decreased from the baseline , but not in the placebo group . There were no test beverage consumption-related changes in other parameters that may influence blood pressure , such as pulse , cardiac output , body weight or 24-h urine volume . Ingestion of the active beverage significantly decreased urinary isoprostane levels , suggesting a reduced oxidative stress . These findings indicate that HHQ-reduced coffee decreased blood pressure in subjects with mild hypertension . The decreased blood pressure was associated with improved vascular endothelial function Background / Objectives : Coffee is known to contain antioxidant substances whose effects may be blunted because of caffeine that may unfavorably affect the cardiovascular system . This study was design ed to investigate the acute dose-dependent effects of decaffeinated coffee ( DC ) on endothelial function measured by the brachial artery flow-mediated dilation (FMD).Subjects/ Methods : A total of 15 ( 8 men and 7 women ) healthy nonobese subjects underwent a single-blind , crossover study . Subjects ingested one and two cups of decaffeinated Italian espresso coffee in r and om order at 5- to 7-day intervals . Results : In the hour following the ingestion of two cups of DC  , FMD increased ( mean±s.e.m . ) : 0 min , 7.4±0.7 % ; 30 min , 8.0±0.6 % ; 60 min , 10.8±0.8 % ; P<0.001 ) as compared to consumption of one cup of DC ( 0 min , 6.9±0.7 % ; 30 min , 8.4±1.2 % ; 60 min , 8.5±1.1 % ; 3 × 2 repeated- measures analysis of variance : P=0.037 for time × treatment effect ) . Blood pressure did not differ between groups , and basal heart rate was lower in the two-cup group at baseline and 60 min . Conclusions : The present study demonstrated a significant acute favorable dose-dependent effect of decaffeinated espresso coffee  on endothelial function . Further studies are needed to investigate the effects of chronic use of DC especially with respect to caffeinated coffee and in subjects with cardiovascular diseases Our previous study revealed the antihypertensive effects of green coffee bean extract ( GCE ) ingestion in spontaneously hypertensive rats . We suggested that this antihypertensive action was due to the fact that GCE contains chlorogenic acid ( CQA ) as a major phenolic compound , and CQA in turn contains ferulic acid as a metabolic component that acts on nitric oxide ( NO ) derived from the vascular endothelium . In this study , the effects of GCE on blood vessels were evaluated in healthy males . The subjects were 20 healthy males with reduced vasodilation responses measured by strain gauge plethysmograms ( SPG ) to ischemic reactive hyperemia . Of the 20 subjects , 10 ( mean age , 37.2 years ) ingested a test drink containing GCE ( CQA : 140 mg/day ) , and the other 10 ( mean age , 34.8 years ) ingested a placebo drink for 4 months . During the ingestion period , SPG , pulse wave velocity ( PWV ) , and serum biochemical parameters were measured , and acceleration plethysmograms ( APG ) were taken . The reactive hyperemia ratio ( RHR ) in the test drink group began to increase after ingestion for 1 month and was significantly higher ( p < 0.05 ) than that in the placebo group after ingestion for 3 months and 4 months . In addition , after ingestion for 4 months , the test drink group showed a significant decrease ( p < 0.01 ) in the plasma total homocysteine level compared with the pre-ingestion level . However , there were no significant differences in PWV or APG between the test drink group and the placebo drink group . The improvement in RHR after ingestion of a drink containing GCE suggested an improvement in vasoreactivity by this component BACKGROUND Coffee , a source of antioxidants , has controversial effects on cardiovascular health . OBJECTIVE We evaluated the bioavailability of chlorogenic acids ( CGAs ) in 2 coffees and the effects of their consumption on the plasma antioxidant capacity ( AC ) , the serum lipid profile , and the vascular function in healthy adults . METHODS Thirty-eight men and 37 women with a mean ± SD age of 38.5 ± 9 y and body mass index of 24.1 ± 2.6 kg/m(2 ) were r and omly assigned to 3 groups : a control group that did not consume coffee or a placebo and 2 groups that consumed 400 mL coffee/d for 8 wk containing a medium ( MCCGA ; 420 mg ) or high ( HCCGA ; 780 mg ) CGA content . Both were low in diterpenes ( 0.83 mg/d ) and caffeine ( 193 mg/d ) . Plasma caffeic and ferulic acid concentrations were measured by GC , and the plasma AC was evaluated with use of the ferric-reducing antioxidant power method . The serum lipid profile , nitric oxide ( NO ) plasma metabolites , vascular endothelial function ( flow-mediated dilation ; FMD ) , and blood pressure ( BP ) were evaluated . RESULTS After coffee consumption ( 1 h and 8 wk ) , caffeic and ferulic acid concentrations increased in the coffee-drinking groups , although the values of the 2 groups were significantly different ( P < 0.001 ) ; caffeic and ferulic acid concentrations were undetectable in the control group . At 1 h after consumption , the plasma AC in the control group was significantly lower than the baseline value ( -2 % ) and significantly increased in the MCCGA ( 6 % ) and HCCGA ( 5 % ) groups ( P < 0.05 ) . After 8 wk , no significant differences in the lipid , FMD , BP , or NO plasma metabolite values were observed between the groups . CONCLUSIONS Both coffees , which contained CGAs and were low in diterpenes and caffeine , provided bioavailable CGAs and had a positive acute effect on the plasma AC in healthy adults and no effect on blood lipids or vascular function . The group that did not drink coffee showed no improvement in serum lipid profile , FMD , BP , or NO plasma metabolites . This trial was registered at registroclinico.sld.cu as RPCEC00000168 Coffee is one of the most widely used pharmacologically active beverages . The present study was design ed to evaluate the acute effect of coffee ingestion on endothelial function in healthy individuals , and the potential role of caffeine . We studied 17 healthy young adults ( 28.9+/-3.0 years old ; nine men ) , who were regular non-heavy coffee drinkers . The endothelial performance was estimated by endothelium-dependent FMD ( flow-mediated dilatation ) of the brachial artery before and 30 , 60 , 90 and 120 min after ingestion of a cup of caffeinated coffee ( 80 mg of caffeine ) or the corresponding decaffeinated beverage ( < 2 mg of caffeine ) in two separate sessions , following a r and omized single-blind cross-over design . There was no difference in baseline FMD values between the two sessions [ 7.78 compared with 7.07 % after caffeinated and decaffeinated coffee respectively ; P = NS ( not significant ) ] . Caffeinated coffee led to a decline of FMD ( 7.78 , 2.86 , 2.12 , 4.44 and 4.57 % at baseline , 30 , 60 , 90 and 120 min respectively ; P < 0.001 ) . This adverse effect was focused at 30 ( P = 0.004 ) and 60 min ( P < 0.001 ) . No significant effect on FMD was found with the decaffeinated coffee session ( 7.07 , 6.24 , 5.21 , 7.41 and 5.20 % ; P = NS ) . The composite effect of the type of coffee consumed over time on FMD was significantly different ( P = 0.021 ) . In conclusion , coffee exerts an acute unfavourable effect on the endothelial function  in healthy adults , lasting for at least 1 h after intake . This effect might be attributed to caffeine , given that decaffeinated coffee was not associated with any change in the endothelial performance Objective Caffeine is the most widely used pharmacologically active substance . Aortic elastic properties and arterial wave reflection are important factors for the efficient performance of the cardiovascular system , as well as prognosticators of cardiovascular risk . We investigated the effect of caffeine on aortic elastic properties and wave reflection . Design We studied the effect of caffeine  ( 250 mg ) in 20 healthy subjects according to a r and omized , placebo-controlled , double-blind , cross-over design . Methods Aortic stiffness was evaluated with  carotid-femoral pulse wave velocity and wave reflection with augmentation index of the aortic pressure waveform . Results Pulse wave velocity increased ( by 0.51 m/s , P < 0.001 ) denoting an increase in aortic stiffness . Augmentation index and augmented pressure increased ( by 6.8 % , and by 4.4 mmHg , respectively , P < 0.001 for both ) denoting increased wave reflections . Concurrently , both radial and aortic systolic , diastolic and pulse pressure increased significantly . However , this increase was 20 and 9 % larger for aortic systolic pressure ( at 30 and 60 min , P < 0.001 and P < 0.05 , respectively ) and 56 % larger for aortic pulse pressure ( at 30 min , P < 0.001 ) compared with the corresponding upper limb values . This indicates that peripheral pressure measurements are not an accurate guide for the pressor effect of caffeine in central arteries . Conclusions Caffeine affects unfavorably aortic stiffness and enhances wave reflections . This finding has implication s for the impact of caffeine consumption on cardiovascular risk BACKGROUND Data concerning blood pressure changes , acutely induced by caffeine consumption , are conflicting . Furthermore , limited data exist regarding central hemodynamic response to caffeine ingestion by healthy young subjects . We investigated the acute effect of coffee ( 80 mg of caffeine ) and decaffeinated coffee on peripheral and central hemodynamics , as well as on wave reflections . SUBJECTS For this purpose , 16 healthy volunteers ( eight females and eight males , mean age 29+/-3.2 years ) were investigated . METHODS Repeated measurements were performed at baseline and 30 , 60 , 90 and 120 min after oral administration of each beverage in a double-blind crossover design . Aortic blood pressures , augmentation index ( AI ) and pressure ( AP ) and timing of reflected waves were evaluated by using applanation tonometry and pulse wave analysis . RESULTS Regular coffee increased central systolic ( SBP ) and diastolic pressure ( DBP ) from 96.2+/-9.9 to 101.1+/-10.1 mmHg , p=0.011 and from 72.6+/-9.4 to 76.5+/-9.0 mmHg , p=0.027 , respectively , but no change was observed following consumption of decaffeinated coffee .  Peripheral systolic blood pressure did not change significantly after the administration of either coffee . Augmentation index increased significantly following regular coffee consumption . The change in AI was significantly higher following regular compared to decaffeinated coffee consumption as shown by analysis of variance ( ANOVA ) for repeated measures ( p=0.001 ) . CONCLUSIONS These caffeine effects reveal an unfavourable effect on wave reflections and therefore on left ventricular ( LV ) pulsatile afterload . It also revealed a significant acute effect of caffeine consumption on central hemodynamics which is not observed at peripheral pressures Caffeine increases blood pressure ( BP ) . In men , acute BP elevations after caffeine intake are due to an increase in vascular resistance , with no change in cardiac output . The hemodynamic effects of caffeine have not been studied in women . Accordingly , BP and hemodynamic responses to caffeine were measured in a double-blind trial comparing age-matched men and women at rest and during mental stress .  Caffeine ( 3.3 mg/kg , equivalent to 2 to 3 cups of brewed coffee ) or placebo was given to separate groups of women ( n = 21 and 21 ) and men ( n = 16 and 19 ) ( mean ages 29 and 27 years , respectively ) .  BP , cardiac output , and vascular resistance were observed at rest , during a stressful public-speaking simulation , reading aloud , and recovery . Caffeine caused nearly identical systolic and diastolic BP elevations in women ( 4.5 and 3.3 mm Hg , respectively ) and men ( 4.1 and 3.8 mm Hg , respectively ) . Men given caffeine versus placebo showed the expected elevation in vascular resistance throughout the remainder of the protocol ( p < 0.001 ) , with no difference in cardiac output . In contrast , women responded to caffeine with increases in stroke volume ( p < 0.001 ) and cardiac output ( p < 0.001 ) , with no difference in vascular resistance from women taking placebo .  Men and women have similar BP responses to caffeine , but the BP responses may arise from different hemodynamic mechanisms . Women who consume a dietary dose of caffeine showed an increase in cardiac output , whereas men showed increased vascular resistance Purpose The purpose of this study was to evaluate acute effects of coffee with a high content of chlorogenic acids and different hydroxyhydroquinone contents on postpr and ial endothelial dysfunction . Methods This was a single-blind , r and omized , placebo-controlled , crossover-within-subject clinical trial . A total of 37 patients with borderline or stage 1 hypertension were r and omized to two study groups . The participants consumed a test meal with a single intake of the test coffee . Subjects in the Study 1 group were r and omized to single intake of coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone or coffee with a high content of chlorogenic acids and a high content of hydroxyhydroquinone with crossover . Subjects in the Study 2 group were r and omized to single intake of coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone or placebo coffee with crossover . Endothelial function assessed by flow-mediated vasodilation and plasma concentration of 8-isoprostanes were measured at baseline and at 1 and 2 h after coffee intake . Results Compared with baseline values , single intake of coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone , but not coffee with a high content of chlorogenic acids and high content of hydroxyhydroquinone or placebo coffee , significantly improved postpr and ial flow-mediated vasodilation and decreased circulating 8-isoprostane levels . Conclusions These findings suggest that a single intake of coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone is effective for improving postpr and ial endothelial dysfunction . Clinical Trial Registration URL for Clinical Trial : https://upload.umin.ac.jp ; Registration Number for Clinical Trial : UMIN000013283 Coffee is a rich source of polyphenols , primarily chlorogenic acids ( CGA ) . Certain polyphenols and polyphenol-rich foods and beverages have been shown to improve endothelial function and lower blood pressure ( BP ) . The aim of the present study was to investigate the acute effect of two doses of CGA ( 5-CGA ) on endothelial function and BP . In a cross-over study , 16 healthy men and women received : ( i ) 0 mg purified 5-CGA ( control group ) ; ( ii ) 450 mg purified 5-CGA ; ( iii ) 900 mg purified 5-CGA ; and ( iv ) 200 mg purified (-)-epicatechin ( positive control ) in r and om order one week apart . Peak and continuous mean ( 60 to 240 s post ischaemia ) flow-mediated dilation ( FMD ) was measured at baseline , 1 h and 4 h. BP was measured at baseline and every 30 min to 4 h. Plasma CGA and epicatechin levels were significantly increased at both 1 h and 4 h post their respective treatments . Peak FMD was not significantly altered by either dose of 5-CGA or the epicatechin , relative to control ( p > 0.05 ) . Relative to control , effects on continuous mean FMD response following 450 mg 5-CGA and 900 mg of 5-CGA ( 0.47 ± 0.16 % , p = 0.016 and 0.65 ± 0.16 % , p < 0.001 , respectively ) at 1 h and ( 0.18 ± 0.17 % , p = 0.99 and 0.44 ± 0.16 % , p < 0.05 , respectively ) at 4 h. There was no significant effect of any of the treatments on BP . In conclusion , the present study has found no significant effect of 5-CGA , at 450 and 900 mg , on peak FMD response . However , there were significant improvements in mean post-ischaemic FMD response , particularly at the 1 h time point in this group of healthy individuals
target: Conclusion : The results from this meta- analysis suggest a beneficial short-term effect of coffee intake on EF as measured by FMD .
  Base on systematic review results acute and chronic intake of coffee products may exerts an unfavorable effect on AS .
background: Background : Endothelial function ( EF ) and arterial stiffness ( AS ) are predictors of cardiovascular disease .
  As previous research concerning the effect of coffee intake on EF and AS was controversial , we conducted a systematic review and meta- analysis to synthesize research .