Effect of coffee on ambulatory blood pressure in patients with treated hypertension

Effect of Caffeine in Hypertension

Hypertension (HTN) is characterized by an elevated arterial blood pressure with no apparent symptom while proving to be a crucial risk factor for the other underlying disorders such as cardiac failure, atrial fibrillation, stroke and various others, steering to recurrent premature deaths worldwide if left untreated. There are innumerate factors responsible for causing HTN such as age factor, obesity, inheritance, physical inactivity, stress, and unhealthy diet whereas some therapeutics and pharmaceuticals may too trigger this condition notably caffeine. As caffeine is amongst the most widely consumed drinks worldwide and hence an ordeal to cease its use, accordingly this review article in-sighted to raise cognizance specifically towards the action of caffeine affiliated with HTN. Therefore, this review is focused on the risk factors and preventive measures associated with HTN, especially the role of caffeine in inducing HTN as to create social awareness regarding how the excessive habituated caffeine consumption may aggravate this condition.

Bayesian Analysis of Ambulatory Blood Pressure Dynamics with Application to Irregularly Spaced Sparse Data

Ambulatory cardiovascular (CV) measurements provide valuable insights into individuals' health conditions in "real-life," everyday settings. Current methods of modeling ambulatory CV data do not consider the dynamic characteristics of the full data set and their relationships with covariates such as caffeine use and stress. We propose a stochastic differential equation (SDE) in the form of a dual nonlinear Ornstein-Uhlenbeck (OU) model with person-specific covariates to capture the morning surge and nighttime dipping dynamics of ambulatory CV data. To circumvent the data analytic constraint that empirical measurements are typically collected at irregular and much larger time intervals than those evaluated in simulation studies of SDEs, we adopt a Bayesian approach with a regularized Brownian Bridge sampler (RBBS) and an efficient multiresolution (MR) algorithm to fit the proposed SDE. The MR algorithm can produce more efficient MCMC samples that is crucial for valid parameter estimation and inference. Using this model and algorithm to data from the Duke Behavioral Investigation of Hypertension Study, results indicate that age, caffeine intake, gender and race have effects on distinct dynamic characteristics of the participants' CV trajectories.

The effect of coffee on blood pressure and cardiovascular disease in hypertensive individuals: a systematic review and meta-analysis

BACKGROUND

The effect of coffee and caffeine on blood pressure (BP) and cardiovascular disease (CVD) in hypertensive persons is uncertain.

OBJECTIVE

The objective was to summarize the evidence on the acute and longer-term effects of caffeine and coffee intake on BP and on the association between habitual coffee consumption and risk of CVD in hypertensive individuals.

DESIGN

A systematic review and meta-analysis of publications identified in a PubMed and EMBASE search up to 30 April 2011 was undertaken. Data were extracted from controlled trials on the effect of caffeine or coffee intake on BP change and from cohort studies on the association between habitual coffee consumption and CVD.

RESULTS

In 5 trials, the administration of 200-300 mg caffeine produced a mean increase of 8.1 mm Hg (95% CI: 5.7, 10.6 mm Hg) in systolic BP and of 5.7 mm Hg (95% CI: 4.1, 7.4 mm Hg) in diastolic BP. The increase in BP was observed in the first hour after caffeine intake and lasted ≥3 h. In 3 studies of the longer-term effect (2 wk) of coffee, no increase in BP was observed after coffee was compared with a caffeine-free diet or was compared with decaffeinated coffee. Last, 7 cohort studies found no evidence of an association between habitual coffee consumption and a higher risk of CVD.

CONCLUSIONS

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.

Methylxanthines and the kidney

This chapter describes the effects of the natural methylxanthines caffeine and theophylline on kidney function. Theophylline in particular was used traditionally to increase urine out put until more potent diuretics became available in the middle of the last century. The mildly diuretic actions of both methylxanthines are mainly the result of inhibition of tubular fluid reabsorption along the renal proximal tubule. Based upon the use of specific adenosine receptor antagonists and the observation of a complete loss of diuresis in mice with targeted deletion of the A1AR gene, transport inhibition by methylxanthines is mediated mainly by antagonism of adenosine A1 receptors (A1AR) in the proximal tubule. Methylxanthines are weak renal vasodilators, and they act as competitive antagonists against adenosine-induced preglomerular vasoconstriction. Caffeine and theophylline stimulate the secretion of renin by inhibition of adenosine receptors and removal of the general inhibitory brake function of endogenous adenosine. Since enhanced intrarenal adenosine levels lead to reduced glomerular filtration rate in several pathological conditions theophylline has been tested for its therapeutic potential in the renal impairment following administration of nephrotoxic substances such as radiocontrast media, cisplatin, calcineurin inhibitors or following ischemia-reperfusion injury. In experimental animals functional improvements have been observed in all of these conditions, but available clinical data in humans are insufficient to affirm a definite therapeutic efficacy of methylxanthines in the prevention of nephrotoxic or postischemic renal injury.

Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials

PURPOSE

Coffee is a widely consumed beverage and small health effects of substances in coffee may have large public health consequences. It has been suggested that caffeine in coffee increases the risk of hypertension. We performed a meta-analysis of randomized controlled trials of coffee or caffeine and blood pressure (BP).

DATA IDENTIFICATION

BP trials of coffee or caffeine published between January 1966 and January 2003 were identified through literature databases and manual search.

STUDY SELECTION

A total of 16 studies with a randomized, controlled design and at least 7 days of intervention was selected, comprising 25 strata and 1010 subjects.

DATA EXTRACTION

Two persons independently obtained data on sample size, type and duration of intervention, changes in BP and heart rate (HR), and subjects' characteristics for each trial. Meta-analysis was performed using a random-effects model.

RESULTS

A significant rise of 2.04 mmHg [95% confidence interval (CI), 1.10-2.99] in systolic BP and 0.73 mmHg (95% CI, 0.14-1.31) in diastolic BP was found after pooling of coffee and caffeine trials. When coffee trials (n = 18, median intake: 725 ml/day) and caffeine trials (n = 7, median dose: 410 mg/day) were analysed separately, BP elevations appeared to be larger for caffeine [systolic: 4.16 mmHg (2.13-6.20); diastolic: 2.41 mmHg (0.98-3.84)] than for coffee [systolic: 1.22 mmHg (0.52-1.92) and diastolic: 0.49 mmHg (-0.06-1.04)]. Effects on HR were negligible.

CONCLUSIONS

Regular caffeine intake increases BP. When ingested through coffee, however, the blood pressure effect of caffeine is small.

Caffeine tolerance is incomplete: persistent blood pressure responses in the ambulatory setting

BACKGROUND

Caffeine in dietary doses is a well-established pressor agent. Tolerance to this pressor effect occurs in only about half of regular consumers in acute laboratory tests. The clinical significance of this incomplete tolerance depends on whether the pressor effect is maintained throughout the day with repeated intake. Therefore, we examined the ability of a standard dose of caffeine (250 mg x 3) to maintain a blood pressure (BP) elevation during 18 hours of ambulatory BP monitoring (ABPM) after 5 days of regular daily intake of varying background doses.

METHODS

Eighty-five men and women completed a four-week double blind, crossover trial. During each week, subjects consumed capsules totaling 0, 300, or 600 mg/day of caffeine in 3 divided doses. On day 6, they consumed capsules with either 0 or 250 mg at 9:00 am and 1:00 pm, in the laboratory, and again at 6:00 pm during ABPM. Tolerance was defined as a reduction in the diastolic BP response to two challenge doses given in the lab in response to increasing daily intake. Data were analyzed using multivariate repeated measures analysis of variance.

RESULTS

BP responses to caffeine above those found on placebo-placebo (P-P) week were found for both tolerance groups when caffeine was consumed after a week of receiving a placebo. However, only the low tolerance group showed increases, above those found on P-P week, after 300 mg/day in systolic/diastolic BP during the waking hours (mean +/- standard error of the mean = 2.8 +/- 1.1, P = .01/2.2 +/- 0.9, P = .02) and in systolic BP during sleep (2.3 +/- 1, P = .03).

CONCLUSIONS

Persistent elevations in BP occurring on a daily basis in some habitual caffeine consumers may hold clinical significance.

Critical review of dietary caffeine and blood pressure: a relationship that should be taken more seriously

OBJECTIVE

This review aims to determine whether, and to what extent, dietary caffeine may be a risk to cardiovascular health.

METHODS

A critical review of the relevant experimental and epidemiologic literature was conducted, with particular reference to studies of caffeine and blood pressure (BP).

RESULTS

There is extensive evidence that caffeine at dietary doses increases BP. However, concern that the drug may contribute to cardiovascular disease appears to have been dampened by (1) the belief that habitual use leads to the development of tolerance, and (2) confusion regarding relevant epidemiologic findings. When considered comprehensively, findings from experimental and epidemiologic studies converge to show that BP remains reactive to the pressor effects of caffeine in the diet. Overall, the impact of dietary caffeine on population BP levels is likely to be modest, probably in the region of 4/2 mm Hg. At these levels, however, population studies of BP indicate that caffeine use could account for premature deaths in the region of 14% for coronary heart disease and 20% for stroke.

CONCLUSIONS

Current evidence supports the conclusion that the BP-elevating effects of dietary caffeine may be contributing appreciably to population levels of cardiovascular mortality and morbidity. Accordingly, strategies for encouraging reduced dietary levels of caffeine deserve serious consideration.

Effects of coffee on ambulatory blood pressure in older men and women: A randomized controlled trial

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 randomized 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.

The effect of chronic coffee drinking on blood pressure: a meta-analysis of controlled clinical trials

We sought to assess the effect of coffee consumption on blood pressure in humans. Our data sources included a MEDLINE search of the literature published before December 1997, bibliography review, and expert consultation. We selected controlled trials in which coffee consumption was the only difference between the intervention and control groups, mean blood pressure change was reported for each group or period, and treatment lasted for >24 hours. Of 36 studies initially identified, 11 (522 participants) met these inclusion criteria. Information on sample size, study design, participant characteristics (gender, race, age, baseline blood pressure, and antihypertensive medications), and treatment results were abstracted by 3 reviewers using a standardized protocol. Treatment effect of coffee consumption on blood pressure was estimated with the use of a random-effects model. In the 11 trials, median duration was 56 days (range, 14 to 79 days), and median dose of coffee was 5 cups/d. Systolic and diastolic blood pressure increased by 2.4 (range, 1.0 to 3.7) mm Hg and 1.2 (range, 0.4 to 2.1) mm Hg, respectively, with coffee treatment compared with control. Multiple linear regression analysis identified an independent, positive relationship between cups of coffee consumed and subsequent change in systolic blood pressure, independent of age of study participants and study design characteristics. The effect of coffee drinking on systolic and diastolic blood pressure was greater in trials with younger participants. Our findings provide support for a relationship between coffee consumption and higher blood pressure. Trials of coffee cessation of longer duration and in persons with hypertension should be performed.

Caffeine raises blood pressure at work

OBJECTIVE

The study investigated the effects of moderate doses of caffeine on ambulatory blood pressure and heart rate during workday activities.

METHODS

Healthy, nonsmoking, habitual coffee drinkers (N = 21) received daily doses of 100 mg and 500 mg of caffeine on 2 days in a crossover design. Treatment order was random and counterbalanced, and administration was double-blind. Ambulatory monitoring was conducted for 6 to 9 hours during normal workday activities and diary entries were completed at each measurement. Ambulatory data were analyzed for the effects of caffeine dose, controlling for variations in posture, physical activity, and perceived stress.

RESULTS

The average workday blood pressure and heart rate were significantly higher when the higher dose of caffeine was consumed. Controlling for other factors, dose-related differences were 4 mm Hg for systolic and 3 mm Hg for diastolic blood pressure, and were 3 bpm for heart rate.

CONCLUSIONS

Results support earlier evidence that caffeine raises blood pressure at work, and demonstrate that these pressor effects are independent of changes in posture, physical activity, or stress. Daily blood pressure increases associated with caffeine consumption could increase the risk of developing cardiovascular diseases. In addition, caffeine consumption effects might confound ambulatory investigations of the cardiovascular effects of other psychosocial, personality, or health-behavior factors.

Dietary factors in the pathogenesis and treatment of hypertension

Data accumulated from epidemiological observations, intervention trials and studies on experimental animals provide a growing body of evidence of the influence of various dietary components on blood pressure. Dietary sodium, usually taken in the form of sodium chloride (common salt), is positively associated with blood pressure, and in many hypertensive patients reduction in sodium intake lowers blood pressure. On the other hand, in certain patients potassium, calcium and magnesium may be protective electrolytes against hypertension. Dietary fats, especially n-3 polyunsaturated fatty acids, may also influence blood pressure, whereas the possible role of other macronutrients, such as proteins and carbohydrates, or vitamins in the regulation of blood pressure is less well understood. Occasional ingestion of coffee transiently increases blood pressure, but the effects of habitual coffee consumption are controversial. Excessive use of alcohol on a regular basis has been associated with elevated blood pressure. It has also been shown in case reports that large amounts of liquorice lead to the development of hypertension. Thus, with appropriate dietary modifications, it is possible to prevent the development of high blood pressure and to treat hypertensive patients with fewer drugs and with lower doses. In some patients antihypertensive medication may not be at all necessary.

Relationship of plasma renin activity with caffeine intake and physical training in mild hypertensive men. HARVEST Study Group

To study the relationship between plasma renin activity (PRA) and coffee consumption, cigarette smoking, alcohol intake and physical activity habits.

SETTING

The multicentre HARVEST trial, involving 17 Hospital Centres in Northeast Italy.

SUBJECTS

351 borderline to mild hypertensive men (mean age +/- SEM 22.7 +/- 0.47 years), never treated for hypertension.

INTERVENTIONS

Office and 24-hour blood pressure measurement, supine and standing PRA levels, and urinary catecholamines output.

MAIN OUTCOME MEASURES

PRA levels according to coffee intake and physical activity status.

RESULTS

Coffee intake showed a major effect on PRA. Supine PRA levels were 40% higher in the subjects abstaining from coffee (n = 94) than in the coffee drinkers and was similar in the moderate (n = 223) and heavy (n = 34) drinkers. A weaker negative association was found between coffee use and PRA on standing. Office and whole-day blood pressure and heart rate, and urinary catecholamines did not differ according to coffee intake. Supine PRA was lower in the subjects performing regular physical activity than in the inactive subjects. Office and whole-day diastolic blood pressure and heart rate, and urinary norepinephrine were lower in the active than in the sedentary men. No relationship was found between PRA measured either in the supine or the upright posture and tobacco or alcohol use. In a multiple linear regression model supine PRA was negatively correlated with age, coffee consumption and physical activity habits.

CONCLUSIONS

Chronic coffee intake and physical training showed an inverse relationship with PRA in mild hypertensive men, while tobacco and alcohol use were unrelated to PRA.

Effect of coffee and tea drinking on postprandial hypotension in older men and women

1. A postprandial fall in blood pressure (BP) in older men and women increases the risks of falls and impaired cerebral perfusion. Postprandial hypotension has been suggested to be greater in hypertensive subjects, particularly in those on antihypertensive medication. 2. Caffeine, given as tablets or as strong coffee, may attenuate postprandial falls in BP in older subjects, but findings are not consistent. 3. In a randomized controlled intervention in 171 healthy non-smokers over the age of 50 years, we compared the effects of coffee-drinking with abstaining from caffeine in normotensives (NT), untreated hypertensives (UNHT) and subjects on drug treatment for hypertension (TRHT). Tea drinking was a third intervention used only in TRHT. 4. After adjustment for the effects of the initial value on changes in BP, there were no significant differences related to hypertension or to hypertensive agents in the magnitude of postprandial falls in BP. 5. After the intervention, changes in fasting supine and standing systolic BP and heart rate (HR) were not significantly different from controls in NT, UNHT and TRHT, but fasting supine and standing diastolic BP were significantly higher in coffee drinkers in the UNHT group. 6. In normotensive coffee drinkers there was a significant reduction in the postprandial fall in supine systolic BP of 4.1 mmHg (+/- s.e.m. 1.1) and in standing systolic BP of 5.2 +/- 1.6 mmHg. Among untreated hypertensives, abstainers showed a significant attenuation of the postprandial fall in supine, but not standing, systolic BP. Among treated hypertensives who were tea drinkers the postprandial fall decreased for supine systolic BP by 3.8 +/- 1.2 mmHg (P = 0.029) and for standing systolic BP by 5.2 +/- 2.1 mmHg. 7. Both tea and coffee were potentially beneficial in decreasing postprandial falls in systolic BP, but coffee drinking may increase fasting diastolic pressures in untreated hypertensives.

The effects of caffeine on ambulatory blood pressure, heart rate, and mood in coffee drinkers

The present study examined the effects of caffeine, as typically ingested through coffee, on ambulatory systolic and diastolic blood pressure (BP), heart rate, and mood. Normotensive coffee drinkers wore a BP monitor for two 24-hr periods, consuming decaffeinated coffee. Each cup was supplemented with 125 mg caffeine or cornstarch. Systolic and diastolic BPs were elevated on the day caffeine was consumed (maximum, 3.6 and 5.6 mm Hg, respectively), most notably shortly after ingestion. Heart rate was higher overnight following caffeine consumption. Negative Affectivity was also increased by caffeine, but Positive Affectivity and tiredness were unaffected.