***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: This study assessed the effects of regular coffee drinking on 24-hour ambulatory blood pressure ( ABP ) in normotensive and hypertensive older men and women . Twenty-two normotensive and 26 hypertensive , nonsmoking men and women , with a mean age of 72.1 years ( range , 54 to 89 years ) , took part in the study . After 2 weeks of a caffeine-free diet , subjects were r and omized to continue with the caffeine-free diet and abstain from caffeine-containing drinks or drink instant coffee ( 5 cups per day , equivalent to 300 mg caffeine per day ) in addition to the caffeine-free diet for a further 2 weeks . Change in systolic and diastolic blood pressures ( SBP , DBP ) determined by 24-hour ambulatory BP monitoring showed significant interactions between coffee drinking and hypertension status . In the hypertensive group , rise in mean 24-hour SBP was greater by 4.8 ( SEM , 1.3 ) mm Hg ( P=0.031 ) and increase in mean 24-hour DBP was higher by 3.0 ( 1.0 ) mm Hg ( P=0.010 ) in coffee drinkers than in abstainers . There were no significant differences between abstainers and coffee drinkers in the normotensive group for 24-hour , daytime , or nighttime SBP or DBP . In older men and women with treated or untreated hypertension , ABP increased in coffee drinkers and decreased in abstainers . Restriction of coffee intake may be beneficial in older hypertensive individuals CONTEXT Caffeine acutely increases blood pressure , but the association between habitual consumption of caffeinated beverages and incident hypertension is uncertain . OBJECTIVE To examine the association between caffeine intake and incident hypertension in women . DESIGN , SETTING , AND PARTICIPANTS Prospect i ve cohort study conducted in the Nurses ' Health Studies ( NHSs ) I and II of 155,594 US women free from physician-diagnosed hypertension followed up over 12 years ( 1990 - 1991 to 2002 - 2003 question naires ) .  Caffeine intake and possible confounders were ascertained from regularly administered question naires . We also tested the associations with types of caffeinated beverages . MAIN OUTCOME MEASURE Incident physician-diagnosed hypertension . RESULTS During follow-up , 19,541 incident cases of physician-diagnosed hypertension were reported in NHS I and 13,536 in NHS II . In both cohorts , no linear association between  caffeine  consumption and risk of incident hypertension was observed after multivariate adjustment ( NHS I , P for trend = .29 ; NHS II , P for trend = .53 ) . Using categorical analysis , an inverse U-shaped association between caffeine consumption and incident hypertension was found . Compared with participants in the lowest quintile of caffeine consumption , those in the third quintile had a 13 % and 12 % increased risk of hypertension , respectively ( 95 % confidence interval in NHS I , 8%-18 % ; in NHS II , 6%-18 % ) . When study ing individual classes of caffeinated beverages , habitual coffee consumption was not associated with increased risk of hypertension . By contrast , consumption of cola beverages was associated with an increased risk of hypertension , independent of whether it was sugared or diet cola ( P for trend < .001 ) . CONCLUSION No linear association between caffeine consumption and incident hypertension was found . Even though habitual coffee consumption was not associated with an increased risk of hypertension , consumption of sugared or diet cola was associated with it . Further research to eluci date the role of cola beverages in hypertension is warranted BACKGROUND Only 2 prospect i ve studies have previously investigated the association between  coffee consumption  and incident hypertension , and the findings are equivocal . OBJECTIVE The objective was to determine the relation between  coffee  consumption and the incidence of antihypertensive drug treatment . DESIGN We prospect ively followed 24 710 Finnish subjects aged 25 - 64 y without a history of antihypertensive drug treatment , coronary heart disease , or stroke at baseline .  Daily coffee consumption  was assessed by question naires . RESULTS During a mean follow-up period of 13.2 y , 2505 participants started antihypertensive drug treatment . The multivariate-adjusted ( age , sex , study year , education , leisure-time physical activity , smoking , body mass index , high total cholesterol , history of diabetes , and alcohol , tea , fruit , vegetable , sausage , and bread consumption ) hazard ratios for antihypertensive drug treatment associated with the amount of coffee consumed daily ( 0 - 1 , 2 - 3 , 4 - 5 , 6 - 7 , or > or=8 cups ) were 1.00 , 1.29 ( 95 % CI : 1.09 , 1.54 ) , 1.26 ( 95 % CI : 1.06 , 1.49 ) , 1.24 ( 95 % CI : 1.04 , 1.48 ) , and 1.14 ( 95 % CI : 0.94 , 1.37 ) ( P for trend = 0.024 ) , respectively . This trend became marginally significant after additional adjustment for baseline systolic blood pressure ( P for trend = 0.077 ) . CONCLUSIONS The results indicate that coffee drinking seems to increase the risk of antihypertensive drug treatment , and this risk was higher in subjects with low-to-moderate coffee intakes ; however , there was no significantly increased trend in drinkers of approximately 1 cup ( 100 mL)/d or > or=8 cups/d BACKGROUND A high plasma total homocysteine concentration is associated with increased risk of cardiovascular disease . Consumption of unfiltered or filtered coffee raises total homocysteine concentrations in healthy volunteers . The responsible compound , however , is unknown . OBJECTIVE The objective was to determine whether caffeine explains the homocysteine-raising effect of coffee . DESIGN Forty-eight subjects aged 19 - 65 y completed this r and omized crossover study with 3 treatments , each lasting 2 wk . Subjects consumed 6 capsules providing 870 mg caffeine/d ( test treatment ) , 0.9 L paper-filtered coffee providing approximately 870 mg caffeine/d , or 6 placebo capsules . Blood sample s were drawn fasting and 4 h after consumption of 0.45 L coffee or 3 capsules . RESULTS The mean fasting plasma homocysteine concentration after the placebo treatment was 9.6 + /- 3.1 micro mol/L. The caffeine and coffee treatments increased fasting homocysteine by 0.4 micro mol/L ( 95 % CI : 0.1 , 0.7 ; P = 0.04 ) , or 5 % , and by 0.9 micro mol/L ( 95 % CI : 0.6 , 1.2 ; P = 0.0001 ) , or 11 % , respectively , compared with placebo . The increase in homocysteine concentrations 4 h after consumption of 0.45 L coffee relative to consumption of 3 placebo capsules was 19 % ( P = 0.0001 ) . Caffeine treatment had a much weaker acute effect on homocysteine ( 4 % ; P = 0.09 ) . Effects of caffeine were stronger in women than in men , but the effects of coffee did not differ significantly between men and women . CONCLUSIONS Caffeine is partly responsible for the homocysteine-raising effect of coffee . Coffee , but not caffeine , affects homocysteine metabolism within hours after intake , although the effect is still substantial after an overnight fast BACKGROUND Motivated by the possibility that caffeine could ameliorate the effect of postpr and ial hypotension on a high risk of coronary events and mortality in aging , we hypothesized that caffeinated beverage consumption decreases the risk of cardiovascular disease ( CVD ) mortality in the elderly . OBJECTIVE The objective of the study was to use prospect i ve cohort study data to test whether the consumption of caffeinated beverages exhibits this protective effect . DESIGN Cox regression analyses were conducted for 426 CVD deaths that occurred during an 8.8-y follow-up in the prospect i ve first National Health and Nutrition Examination Survey Epidemiologic Follow-up Study . The analysis involved 6594 participants aged 32 - 86 y with no history of CVD at baseline . RESULTS Participants aged > or=65 y with higher caffeinated beverage intake exhibited lower relative risk of CVD and heart disease mortality than did participants with lower caffeinated beverage intake . It was a dose-response protective effect : the relative risk ( 95 % CI ) for heart disease mortality was 1.00 ( referent ) , 0.77 ( 0.54 , 1.10 ) , 0.68 ( 0.49 , 0.94 ) , and 0.47 ( 0.32 , 0.69 ) for < 0.5 , 0.5 - 2 , 2 - 4 , and > or=4 servings/d , respectively ( P for trend = 0.003 ) . A similar protective effect was found for caffeine intake in mg/d . The protective effective was found only in participants who were not severely hypertensive . No significant protective effect was found in participants aged < 65 y or in cerebrovascular disease mortality for those aged > or=65 y. CONCLUSION Habitual intake of caffeinated beverages provided protection against the risk of heart disease mortality among elderly participants in this prospect i ve epidemiologic analysis BACKGROUND AND AIM Coffee is rich in chlorogenic acids ( CGA ) , whose metabolites may have beneficial effects such as anti-hypertensive effects . However , trial results concerning the effects of coffee on blood pressure ( BP ) are not consistent . A recent study suggested that hydroxyhydroquinone ( HHQ ) , produced by the roasting of green coffee beans , inhibits the effect of CGA . In the present study , the dose-response for CGA in HHQ-free coffee on BP were investigated in mildly hypertensive men and women . METHODS AND RESULTS The trial design was a double-blind , r and omized controlled trial , with five study groups including , control , zero-dose , low-dose , middle-dose and high-dose . The control beverage was identical to ordinary coffee . The others contained reduced HHQ levels , compared to ordinary coffee , and the CGA were adjusted in target concentration . A total of 203 subjects were r and omly allocated . Each subject drank one cup of coffee per day . The study involved a screening and a baseline observation period of 6 weeks and an intervention period of 4 weeks . BP response showed  CGA  has an anti-hypertensive effect in a dose-dependent manner in HHQ-free coffee , and ordinary coffee showed almost no effect . As a result , a significant correlation between BP change and the three dose-response patterns was observed ( p<0.001 ) . CONCLUSIONS This study demonstrates a dose-dependent decrease in BP for CGA in HHQ-free coffee Background — Data on the association between coffee consumption and  risk of stroke  are sparse . We assessed the association between coffee consumption and the risk of stroke over 24 years of follow-up in women . Methods and Results — We analyzed data from a prospect i ve cohort of 83 076 women in the Nurses ’ Health Study without history of stroke , coronary heart disease , diabetes , or cancer at baseline .  Coffee consumption was assessed first in 1980 and then repeatedly every 2 to 4 years , with follow-up through 2004 . We documented 2280 strokes , of which 426 were hemorrhagic , 1224 were ischemic , and 630 were undetermined . In multivariable Cox regression models with adjustment for age , smoking status , body mass index , physical activity , alcohol intake , menopausal status , hormone replacement therapy , aspirin use , and dietary factors , the relative risks ( RRs ) of stroke across categories of coffee consumption ( < 1 cup per month , 1 per month to 4 per week , 5 to 7 per week , 2 to 3 per day , and ≥4 per day ) were 1 , 0.98 ( 95 % CI , 0.84 to 1.15 ) , 0.88 ( 95 % CI , 0.77 to 1.02 ) , 0.81 ( 95 % CI , 0.70 to 0.95 ) , and 0.80 ( 95 % CI , 0.64 to 0.98 ) ( P for trend=0.003 ) . After further adjustment for high blood pressure , hypercholesterolemia , and type 2 diabetes , the inverse association remained significant . The association was stronger among never and past smokers ( RR for ≥4 cups a day versus < 1 cup a month , 0.57 ; 95 % CI , 0.39 to 0.84 ) than among current smokers ( RR for ≥4 cups a day versus < 1 cup a month , 0.97 ; 95 % CI , 0.63 to 1.48 ) . Other drinks containing caffeine such as tea and caffeinated soft drinks were not associated with stroke . Decaffein 
    Output:
    
In hypertensive individuals , caffeine intake produces an acute increase in BP for ≥3 h. However , current evidence does not support an association between longer-term coffee consumption and increased BP or between habitual coffee consumption and an increased risk of CVD in hypertensive subjects