Article

Caffeine Affects Cardiovascular and Neuroendocrine Activation at Work and Home

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

This study investigated the effects of moderate doses of caffeine on ambulatory blood pressure and heart rate, urinary excretion of epinephrine, norepinephrine, and cortisol, and subjective measures of stress during normal activities at work and at home in the evening. Healthy, nonsmoking, habitual coffee drinkers (N = 47) participated in 3 days of ambulatory study. After a day of ad lib caffeine consumption, caffeine (500 mg) and placebo were administered double-blind in counter-balanced order on separate workdays. Ambulatory blood pressure and heart rate were monitored from the start of the workday until bedtime. Urinary excretion of catecholamines and cortisol was assessed during the workday and evening. Caffeine administration significantly raised average ambulatory blood pressure during the workday and evening by 4/3 mm Hg and reduced average heart rate by 2 bpm. Caffeine also increased by 32% the levels of free epinephrine excreted during the workday and the evening. In addition, caffeine amplified the increases in blood pressure and heart rate associated with higher levels of self-reported stress during the activities of the day. Effects were undiminished through the evening until bedtime. Caffeine has significant hemodynamic and humoral effects in habitual coffee drinkers that persist for many hours during the activities of everyday life. Furthermore, caffeine may exaggerate sympathetic adrenal-medullary responses to the stressful events of normal daily life. Repeated daily blood pressure elevations and increases in stress reactivity caused by caffeine consumption could contribute to an increased risk of coronary heart disease in the adult population.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The responsiveness of the HPA axis was particularly obvious in those who consuming moderate doses (300 mg per day) of caffeine but was abolished in those consuming high doses (600 mg/day) of it (Lovallo et al., 2005). Oral caffeine intake by habitual coffee drinkers (300 mg/day) did not affect urinary cortisol excretion (Lane et al., 2002). Alternatively, habitual caffeine consumption can reduce, but not eliminate cortisol secretions in healthy subjects (Lovallo et al., 2005). ...
... Moreover, caffeine in dietary doses (3.3 mg/kg/day) increased adrenocorticotropin and cortisol secretions in humans whether at rest, mental stress or psychomotor task (Michael, 2010). In this respect, caffeine not only activates the stress components and thus elevates glucocorticoid and catecholamine outputs (Lane et at., 2002;al'Absi and Lovallo, 2004), but also lowers the threshold for stress induced cortisol release (Laurent et al., 2000;Eynav, 2017). Benzodiazepines (BZPs) are clinically effective anti-anxiety drugs. ...
... In this field, literature showed obvious controversy. So, oral caffeine intake (300 mg/day) did not affect urinary cortisol excretion (Lane, 1994;Lane et al., 2002). Alternatively, cortisol responses to daily caffeine consumption (300 mg/day) were reduced, but not eliminated, in healthy drinkers (Lovallo et al, 2005). ...
Article
Full-text available
Prednisolone is a glucocorticoid Therapy which induces suppression of the hypothalamo-Pituitary-Adrenocortical (HPA) axis. The beginning of suppression and rate of recovery of HPA axis depend on the dose and duration of prednisolone intake. However, there is a possibility to stimulate or inhibit the recovery of the HPA axis by the simultaneous administration of certain drugs. We investigate the effect of caffeine or diazepam intake on the recovery of suppressed HPA axis function from prednisolone therapy. We included 45 male subjects with minor diseases were divided into three groups. Group (1) 15 patients received orally prednisolone (10 mg/day) at morning beside a suitable placebo for 14 days. Then prednisolone was stopped while the placebo continued for other 10 days. Group (2) 15 patients received orally prednisolone (10 mg/day) combined with caffeine (300 mg/day orally) at morning for 14 days. Then prednisolone was stopped while caffeine intake continued for other 10 days. Group (3) 15 patients received orally prednisolone (10 mg/day) at morning and diazepam (5 mg/day) at night for 14 days. Then prednisolone was stopped while diazepam continued for other 10 days. The HPA axis function was assessed before therapy (basal), after 14 days of the designed therapy (single prednisolone, prednisolone+caffeine or prednizolone+diazepam) and after prednisolone stoppage and maintenances of the respective group on placebo or caffeine or diazepam only for 10 days. Results: In 1st group at the 1st day of recovery from prednisolone therapy, serum cortisol and plasma ACTH levels were significantly decreased from their basal pretreatment levels (P<0.01). After 5 days of prednisolone stoppage, serum cortisol and plasma ACTH concentrations were significantly increased than their 1st day stoppage levels (P<0.01) but still significantly lower than the basal value (P<0.01). At the 10th day after prednisolone cessation the circulating cortisol and ACTH levels were significantly higher than their 5th day levels (P<0.01), the levels almost returned to their basal. In the 2nd group by the end of combined prednisolone+caffeine therapy, endogenous cortisol and ACTH concentrations were significantly lower from their basal values. After 5 days of recovery with maintained caffeine intake only, serum cortisol and plasma ACTH levels increased to their basal levels. Caffeine significantly enhanced the recovery of the prednisolone-suppressed HPA axis. On the other hand, in the 3rd group simultaneous intake of prednisolone with diazepam for 14 days induced significant reduction of both serum cortisol and plasma ACTH concentrations. During the recovery period (10 days) after stopping prednisolone only while diazepam intake was continued, serum cortisol and plasma ACTH concentrations were still significantly decreased than their basal values. Diazepam intake did not significantly enhance the correction of the prednisolone-mediated suppression of the HPA axis. Conclusion: Simultaneous intake of caffeine with prednisolone enhanced recovery of the investigated HPA components (ACTH and cortisol). On the other hand, diazepam intake did not affect significantly prednisolone suppression of the HPA axis and recovery was delayed.
... 26 Increasing urbanization and changing life styles around the world have equally continued to cause the rising incidence. [27][28][29][30] Hypertension is regarded as major public health problem, 31 and has continue to constitute a major threat to the health of adults in particular in sub-Saharan Africa. 32,33 Different researches have put the prevalence to range from 25% to 35% among adults aged 25 to 64 years with an estimated 20 million people being affected in the African Region. ...
... 32,33,39 Studies have estimated the overall prevalence rate of hypertension in Nigeria to be within the range of 1.2-1.8% [34][35][36][37].Environmental and behavioural factors like salt intake, occupation 44 and alcohol intake, cigarette smoking and use of other psychoactive substances, [17][18][19][20][21][22][23]27,28 family size, 39 prolonged period of unemployment and poverty, 45 overcrowding and other life stressors, impaired intrauterine growth 46 and lack of exercise have been implicated in the development of hypertension. ...
... 39 Caffeine, cannabis and cocaine have equally been associated with hypertension. 27,28 From these findings, it became an obvious suggestion development of programs to improve management of hypertension should not only focus on lifestyle variables and their modifications like smoking and alcohol, but most importantly include the assessment and treatment of substance abuse and dependence disorders as well as other psychological morbidity. 27,28,39 Studies have noted the relationship between depression and anxiety symptoms and medical treatment of hypertension. ...
... Experimental studies show that adult ingestion of caffeine increases blood pressure acutely by 5 to 15 mmHg systolic (SBP) and 5 to 10 mmHg diastolic (DBP), with effects in both men and women persisting for up to several hours [47]. Caffeine-induced pressor effects have been found to be additive to the pressor effects of cigarette smoking [22,52,102], to be at least additive (e.g., [20,28,[42][43][44]63,98]) and possibly synergistic (e.g., [1,65]) to the pressor effects of psychosocial stress, and to be of similar magnitude in persons with and without hypertension (e.g., [37]). Source of caffeine has little or no bearing on its pressor effects. ...
... Caffeine's antagonism of adenosine's regulatory functions in the cardiovascular system (e.g., [95]) gives high biological plausibility to concerns that habitual caffeine consumption may pose a threat for cardiovascular health [45,47]. In addition, caffeine has been reported to stimulate neuroendocrine release, especially the catecholamine stress hormones of epinephrine and norepinephrine (e.g., [63]). Given that life stress is a major preventable cause of cardiovascular disease [115,116], caffeine's known pharmacological actions point to possible harmful interactions with everyday stress [46]. ...
... Finally, in addition to examining hemodynamic function at rest, possible additional caffeine-related associations were examined during laboratory-induced hemodynamic stress and recovery from stress. This aspect of the study was intended to shed further light on possible synergy between caffeine consumption and psychosocial stress (e.g., [63]), especially given that these potentially interactive processes have received little attention in studies of young consumers. ...
Article
Objective Most adolescents regularly consume caffeine. Whereas observational studies have suggested that coffee may be cardio-protective, pharmacological experimentation with adults shows that caffeine at dietary doses increases blood pressure, thereby implicating regular caffeine consumption as a potential source of harm for cardiovascular health. The present study was in response to the dearth of caffeine research among younger consumers. It was hypothesised that compared to the consumption of little or no caffeine, adolescents who habitually consume caffeine have overall higher blood pressure and increased vascular resistance. Method Using a quasi-experimental design, continuous measurements of blood pressure, cardiac output, and total peripheral resistance were taken non-invasively from adolescents (n = 333) aged 14–15 years and 18–19 years who reported “low”, “moderate”, or “high” levels of caffeine intake. Measurements were conducted when participants generally had negligible or low systematic caffeine levels while at rest, during stress, and during recovery from stress. Results Whereas habitual caffeine consumption did not predict blood pressure level, higher caffeine intake was associated with modestly increased vascular resistance during all phases of the experiment (i.e., at rest, during stress, and during recovery from stress). Conclusions Present findings are important because they suggest that early exposure to caffeine may lead to persistent increases in vascular resistance, which in turn is an acknowledged risk factor for the development of hypertension. These results highlight the need for further studies of adolescents to determine the robustness of any persistent caffeine-related hemodynamic effects, and the implications such effects could have for long-term cardiovascular health.
... Other cardiovascular processes are related to decreasing cytoplasmic Ca 2þ in the vascular smooth muscle cell (VSMC) through cyclic adenosine monophosphate (cAMP) and the augment of the synthesis of nitric oxide (NO) [70]. Studies have reported that caffeine augments plasmatic levels of stress hormones, including catecholamines (such as adrenaline, noradrenaline, and cortisol) [71,72]. These humoral effects indicate that both the sympathetic-adrenal medullary system as well as the adrenocortical components of the neuroendocrine stress response are activated [71,72]. ...
... Studies have reported that caffeine augments plasmatic levels of stress hormones, including catecholamines (such as adrenaline, noradrenaline, and cortisol) [71,72]. These humoral effects indicate that both the sympathetic-adrenal medullary system as well as the adrenocortical components of the neuroendocrine stress response are activated [71,72]. Caffeine has three main effects on the Renin-Angiotensin-Aldosterone (RAA) axis [73]. ...
... Among the 101 experimental studies, the majority involved a single exposure to caffeine among adults and monitoring heart rate at various times thereafter. Among those, 15 reported an increase in heart rate following ingestion of a single dose (130e560 mg) of caffeine (Astorino et al., 2013;Bunsawat et al., 2015;Buscemi et al., 2009Buscemi et al., , 2011Del Coso et al., 2012;Grasser et al., 2014Grasser et al., , 2015Lane et al., 1998Lane et al., , 2002Miles-Chan et al., 2015;Passmore et al., 1987;Peveler et al., 2016;Stadheim et al., 2013;Steinke et al., 2009;Stubbs and Macdonald, 1995), 19 reported a decrease after 80e350 mg (Addicott et al., 2009;Arciero and Ormsbee, 2009;Awaad et al., 2011;Berry et al., 2003;Domotor et al., 2015;Hajsadeghi et al., 2016;Hartley et al., 2004;Lovallo et al., 1996;Molnar and Somberg, 2015a;Papaioannou et al., 2006;Pincomb et al., 1996;Sung et al., 1994Sung et al., , 1995Temple et al., 2010;Turley and Gerst, 2006;Turley et al., 2007Turley et al., , 2008Vlachopoulos et al., 2003a;Waring et al., 2003) -including all four studies that involved children (Temple et al., 2010;Turley and Gerst, 2006;Turley et al., 2007Turley et al., , 2008) -while the majority (55) reported no significant change in heart rate after 250e570 mg Ammon et al., 1983;Arciero et al., 1998;Astorino et al., 2013;Bak and Grobbee, 1991;Barry et al., 2005;Baum and Weiss, 2001;Blaha et al., 2007;Bonnet et al., 2005;Bortolotti et al., 2014;Brothers et al., 2016;Burr et al., 1989;Buscemi et al., 2010;Chen and Parrish, 2009;Childs and de Wit, 2006;Daniels et al., 1998;Doerner et al., 2015;Donnerstein et al., 1998;Duncan et al., 2013;Engels et al., 1999;Fernandez-Elias et al., 2015;Garcia et al., 2016;Giacomin et al., 2008;Hajsadeghi et al., 2016;Hodgson et al., 1999;Hoffman et al., 2006;Humayun et al., 1997;Kennedy et al., 2008;Kurtz et al., 2013;Lemery et al., 2015;Miles-Chan et al., 2015;Molnar and Somberg, 2015a,b;Mosqueda-Garcia et al., 1990;Nash et al., 2002;Noguchi et al., 2015;Nussberger et al., 1990;Paton et al., 2015;Pettersen et al., 2014;Peveler et al., 2016;Phan and Shah, 2014;Ragsdale et al., 2010;Rashti et al., 2009;Scott et al., 2015;Shah et al., 2016;Shechter et al., 2011;Sondermeijer et al., 2002;Souza et al., 2014;Sudano et al., 2005;Tse et al., 2009;Turley et al., 2007;Umemura et al., 2006;Vlachopoulos et al., 2003bVlachopoulos et al., , 2006Yeragani et al., 2005;Zimmermann-Viehoff et al., 2016). In some cases, the effect on heart rate from caffeine consumption at similar levels may have appeared to be administration-dependent (i.e., pure caffeine; coffee (filtered, boiled, or espresso); energy drink) but it was not consistent. ...
... The majority of studies reported no effect on heart rate, while smaller numbers (about the same in each direction) reported increases or decreases following ingestion of caffeine. While some reported consistent outcomes (Grasser et al., 2014Lane et al., 1998Lane et al., , 2002Sung et al., 1994Sung et al., , 1995Turley and Gerst, 2006;Turley et al., 2007Turley et al., , 2008, others reported conflicting outcomes (Arciero et al., 1998;Arciero and Ormsbee, 2009;Astorino et al., 2007Astorino et al., , 2013Grobbee, 1990, 1991;Buscemi et al., 2009Buscemi et al., , 2010Buscemi et al., , 2011James, 1994a,b;James and Gregg, 2004;van Dusseldorp et al., 1989van Dusseldorp et al., , 1991Vlachopoulos et al., 2003aVlachopoulos et al., ,b, 2006. ...
Article
Full-text available
This report evaluates the scientific literature on caffeine with respect to potential cardiovascular outcomes, specifically relative risks of total cardiovascular disease (CVD), coronary heart disease (CHD) and acute myocardial infarction (AMI), effects on arrhythmia, heart failure, sudden cardiac arrest, stroke, blood pressure, hypertension, and other biomarkers of effect, including heart rate, cerebral blood flow, cardiac output, plasma homocysteine levels, serum cholesterol levels, electrocardiogram (EKG) parameters, heart rate variability, endothelial/platelet function and plasma/urine catecholamine levels. Caffeine intake has been associated with a range of reversible and transient physiological effects broadly and cardiovascular effects specifically. This report attempts to understand where the delineations exist in caffeine intake and corresponding cardiovascular effects among various subpopulations. The available literature suggests that cardiovascular effects experienced by caffeine consumers at levels up to 600 mg/day are in most cases mild, transient, and reversible, with no lasting adverse effect. The point at which caffeine intake may cause harm to the cardiovascular system is not readily identifiable in part because data on the effects of daily intakes greater than 600 mg is limited. However, the evidence considered within this review suggests that typical moderate caffeine intake is not associated with increased risks of total cardiovascular disease; arrhythmia; heart failure; blood pressure changes among regular coffee drinkers; or hypertension in baseline populations.
... Hypertension is a non-communicable chronic disease, often requiring long-term treatment. The incidence may be on the increase as a result of increasing urbanisation and changing lifestyles in the world [88][89][90][91][92]. Hypertension is regarded a major public health problem [29], and it is an important threat to the health of adults in sub-Saharan Africa [93, 94]. ...
... A study found that as high as 62% of the total population of hypertensive lived with at least two risk factors, mainly diabetes mellitus and alcohol use. Several other studies both in Nigeria and elsewhere have also implicated diabetes, calcium salt and fat intake from consumption of processed food [91], participating in jobs with minimal activities, obesity [92], consumption of caffeine [89, 108, 109] and alcohol [107], smoking and hypercholesterolemia [110, 111]. A proportion of the diabetic population (20%) suffered from isolated systolic hypertension [106]. ...
... An explanation for these effects is that males have a more sensitive baroreflex than females, as stated by several studies. [24] ...
Article
Full-text available
The most used psychoactive substance globally is caffeine. Recently, the introduction of numerous products containing caffeine, as well as shifts in the consumption of both natural and artificial sources of caffeine, has received the attention of health experts. However, there is a lack of information on the consumption patterns of coffee and caffeinated products in different regions of the Saudi population. Therefore, this review aims to identify gender differences, pharmacological effects and risk of toxicity among caffeine product users in Saudi Arabia. Although there are regulations from the Saudi Food and Drug Authority (SFDA), there have been concerns about excessive caffeine consumption among the youth population. According to the available studies, the prevalence of coffee consumption is high among Saudi females. The extent of caffeine toxicity in Saudi Arabia is not well documented; however, given the widespread use of caffeine in the country, it is possible that instances of caffeine toxicity may arise. It should be emphasized that caffeine toxicity is not common and usually occurs only with extremely high levels of caffeine consumption. This review offers valuable insights into caffeine consumption patterns in Saudi Arabia, which can benefit a range of stakeholders, including scientists, healthcare providers and consumers. To ensure safe caffeine consumption and minimise the risk of negative outcomes arising from insufficient knowledge about its use, there is a need to educate individuals and raise public awareness about caffeine intake.
... An explanation for these effects is that males have a more sensitive baroreflex than females, as stated by several studies. [24] ...
Article
Full-text available
The most used psychoactive substance globally is caffeine. Recently, the introduction of numerous products containing caffeine, as well as shifts in the consumption of both natural and artificial sources of caffeine, has received the attention of health experts. However, there is a lack of information on the consumption patterns of coffee and caffeinated products in different regions of the Saudi population. Therefore, this review aims to identify gender differences, pharmacological effects and risk of toxicity among caffeine product users in Saudi Arabia. Although there are regulations from the Saudi Food and Drug Authority (SFDA), there have been concerns about excessive caffeine consumption among the youth population. According to the available studies, the prevalence of coffee consumption is high among Saudi females. The extent of caffeine toxicity in Saudi Arabia is not well documented; however, given the widespread use of caffeine in the country, it is possible that instances of caffeine toxicity may arise. It should be emphasized that caffeine toxicity is not common and usually occurs only with extremely high levels of caffeine consumption. This review offers valuable insights into caffeine consumption patterns in Saudi Arabia, which can benefit a range of stakeholders, including scientists, healthcare providers and consumers. To ensure safe caffeine consumption and minimise the risk of negative outcomes arising from insufficient knowledge about its use, there is a need to educate individuals and raise public awareness about caffeine intake.
... Accordingly, most studies have demonstrated a fall in CO [15,23,25,27,28]. Exactly where the vasoconstriction occurs is uncertain because nearly all forearm plethysmography studies have shown stable blood flow to skeletal muscle after caffeine consumption [10,11,[29][30][31][32]. More recently, Corti et al. found an approximate 10% increase in MSNA burst rate after both intravenous caffeine and oral coffee, consistent with sympathetic-medicated vasoconstriction in skeletal muscle [14]. ...
Article
Full-text available
Purposes: Habitual coffee drinking is ubiquitous and generally considered to be safe despite its transient hypertensive effect. Our purpose was to determine the role of the sympathetic nervous system in the hypertensive response. Methods: In a single-centre crossover study, medical caregivers were studied after consumption of standard coffee (espresso), water and decaffeinated coffee (decaff) given in random order at least 1 month apart. Plasma caffeine levels, mean arterial pressure, heart rate, total peripheral resistance and muscle sympathetic activity were recorded. Baroreflex activity was assessed using burst incidence and RR interval changes to spontaneous blood pressure fluctuations. Results: A total of 16 subjects (mean [± standard error] age 34.4 ± 2 years; 44% female) were recruited to the study. Three agents were studied in ten subjects, and two agents were studied in six subjects. Over a 120-min period following the consumption of standard coffee, mean (± SE) plasma caffeine levels increased from 2.4 ± 0.8 to 21.0 ± 4 µmol/L and arterial pressure increased to 103 ± 1 mmHg compared to water (101 ± 1 mmHg; p = 0.066) and decaff (100 ± 1 mmHg; p = 0.016). Peripheral resistance in the same period following coffee increased to 120 ± 4% of the baseline level compared to water (107 ± 4; p = 0.01) and decaff (109 ± 4; p = 0.02). Heart rate was lower after both coffee and decaff consumption: 62 ± 1 bpm compared to water (64 bpm; p = 0.01 and p = 0.02, respectively). Cardio-vagal baroreflex activity remained stable after coffee, but sympathetic activity decreased, with burst frequency of 96 ± 3% versus water (106 ± 3%; p = 0.04) and decaff (112 ± 3%; p = 0.001) despite a fall in baroreflex activity from - 2.2 ± 0.1 to - 1.8 ± 0.1 bursts/100 beats/mmHg, compared to water (p = 0.009) and decaff (p = 0.004). Conclusion: The hypertensive response to coffee is secondary to peripheral vasoconstriction but this is not mediated by increased sympathetic nerve activity. These results may explain why habitual coffee drinking is safe.
... Caffeine's main mechanism of action is competitive blockade of the neuromodulator adenosine, with A1 and A2A receptors appearing to be primary targets [5,6]. In addition to influencing functionally important interactions between adenosine and dopamine receptors, caffeine effects include increased neurotransmitter activity in the CNS (anti-somnolent effect), constriction of cerebral and coronary blood vessels, renal diuresis, respiratory bronchodilation, increased secretion of gastrointestinal acid, and increased secretion of the catecholamine stress hormones epinephrine and norepinephrine [5,7]. ...
Article
Full-text available
Background Preventing nicotine use onset among children and youth is an important public health goal. One possible contributor that has received little empirical investigation is caffeine use. The goal of this study was to examine the possible contribution of caffeine to nicotine onset during early adolescence. Methods We used data from the Young Mountaineer Health Study Cohort. Survey data were collected from 1,349 (response rate: 80.7%) 6th grade students (mean age at baseline 11.5 years) in 20 middle schools in West Virginia during the fall of 2020 and spring of 2021. We limited our analyses to students reporting never having used any form of nicotine at baseline. Logistic regression was employed in analyses. Results Approximately 8% of participants reported having used nicotine at least once between baseline and the follow-up, and 4.7% reported solely using electronic nicotine delivery systems (ENDS) and no other forms of nicotine. In multivariable analyses, we controlled for many environmental, social, and behavioral variables known to influence nicotine use such as alcohol use, peer substance use, and perceived access to nicotine. We formulated our main independent variable, caffeine consumption, as continuous deciles. Any nicotine use, as well as ENDS use only at follow-up, were modeled as dependent variables. Caffeine was significantly associated with nicotine use in both models with ORs of 1.15 (1.04–1.27) and 1.13 (1.00–1.28). Conclusions Caffeine consumption among 6th grade non-nicotine users was associated with nicotine use at approximately 6-months follow-up.
... High doses of caffeine consumption can lead to a range of medical and psychiatric effects, typically including anxiety, panic attacks, sleep disorders, and cardiovascular problems. [94] ...
Article
Full-text available
Nootropics, also known as "smart drugs" in modern times, are a group of medicinal substances that positively affect learning and memory. While these substances are more effective when significant impairment is present, they are frequently used by healthy individuals, particularly students, to increase intelligence and improve memory. This review provides a general overview of the most commonly used and well-known classic nootropics, as well as naturally derived botanical nootropics, and their use and procurement by students today.
... Because sleep quality is tied to caffeine intake and DED risk, stratified analyses were conducted, using a Pittsburgh Sleep Quality Index scores $5.5 as a cut-off, in line with past works. 7 Caffeine can be related to stress at work, 37 which could trigger DED. 38 Therefore, stratified analysis based on self-reported stress at work, assessed from the question "In the past year, to what extent did you experience difficulties and stress related to this aspect of your life?/At or with work," was conducted. ...
Article
Full-text available
Purpose: The aim of this study was to determine the association between caffeine intake and dry eye disease (DED) in the large, population-based LifeLines cohort in the Netherlands. Methods: DED was cross-sectionally assessed in 85,302 participants (59% female participants) using the Women's Health Study dry eye questionnaire. Dietary caffeine was calculated from the intake of coffee, tea, cola, and energy drinks. Logistic regression was used to investigate the relationship between DED and caffeine, correcting for demographic variables, smoking status, alcohol intake, and 48 comorbidities of DED. Results: The mean (SD; range) age of participants was 50.7 years (12.4; 18-96), and 50,339 (59%) were female. The mean (SD) caffeine intake was 285 (182) mg/d. After correcting for demographics, body mass index, smoking status, and alcohol intake, higher caffeine intake was associated with a decreased risk of Women's Health Study-defined DED [odds ratio (OR) 0.971 per 100 mg/d, 95% CI, 0.956-0.986, P < 0.0005]. When additionally adjusting for medical comorbidities, no significant effect was observed (OR 0.985, 95% CI, 0.969-1.001, P = 0.06). Caffeine's effect on DED was similar in male and female participants and independent of sleep quality and stress at work. Decaffeinated coffee intake was significantly associated with an increased risk of DED, when adjusted for caffeinated coffee, demographics, alcohol intake, smoking status, and comorbidities (OR 1.046 per cup/d, 95% CI, 1.010-1.084, P = 0.01). None of the beverages were significantly associated with the risk of DED, when correcting for intake of the other caffeinated beverages, demographics, smoking status, alcohol intake, and all comorbidities. Conclusions: Dietary caffeine intake does not seem to be a risk factor for DED in the general population.
... This may be due to the fact that a baseline level was not established before the performance of the experiment. This may have led to unwanted bias in the results; for instance, the consumption of caffeine may have led to differences in HR [95]. ...
Article
Full-text available
Modern surgical education is focused on making use of the available technologies in order to train and assess surgical skill acquisition. Innovative technologies for the automatic, objective assessment of nontechnical skills are currently under research. The main aim of this study is to determine whether personal resourcefulness can be assessed by monitoring parameters that are related to stress and visual attention and whether there is a relation between these and psychomotor skills in surgical education. For this purpose, we implemented an application in order to monitor the electrocardiogram (ECG), galvanic skin response (GSR), gaze and performance of surgeons-in-training while performing a laparoscopic box-trainer task so as to obtain technical and personal resourcefulness’ metrics. Eight surgeons (6 nonexperts and 2 experts) completed the experiment. A total of 22 metrics were calculated (7 technical and 15 related to personal resourcefulness) per subject. The average values of these metrics in the presence of stressors were compared with those in their absence and depending on the participants’ expertise. The results show that both the mean normalized GSR signal and average surgical instrument’s acceleration change significantly when stressors are present. Additionally, the GSR and acceleration were found to be correlated, which indicates that there is a relation between psychomotor skills and personal resourcefulness.
... A moderate ingestion of caffeine (100 mg) reveals no decrease in digital blood flow measurement (Knight, Pagkalos, Timmons & Jose, 2015), while higher doses of caffeine can result in an accelerated heart rate, but these effects are not common in people who consume caffeine regularly. In fact, there is evidence that the habitual consumer of caffeine develops a tolerance to its cardiovascular and neuroendocrine effects (Lane, Adcock, Williams & Kuhn, 1990;Lane, Pieper, Phillips-Bute, Bryant & Kuhn, 2002). ...
Article
Full-text available
Coffee is consumed worldwide, but there are different types of espresso blends, each with its unique concentration of caffeine, which can have different effects on the human being. The aim of this study was to understand the effect of the impact of caffeine on the autonomic nervous system, evaluating the physiological changes and subjective responses due to different levels of caffeine intake. A double-blind tasting task consisting of one within-subject factor design (caffeine level: high / double caffeine mixture (blend A) vs single-charge caffeine mixture (blend B) vs low-caffeine mixture (blend c) allowed us to assess participants’ autonomic responses using Heart Rate Variability (HRV) and Pupillary Reactivity (PR). Arousal was also assessed through the Self-Assessment Manikin (SAM). Results revealed statistically significant differences in HRV and PR between coffee blends, showing the blend A,a more pronounced autonomic response that blend C. However, no significant differences were found in arousal level among coffee blends. These results are similar to previous research that pointed out to a discordance between subjective and objective measures when caffeine is consumed.
... A moderate ingestion of caffeine (100 mg) reveals no decrease in digital blood flow measurement (Knight, Pagkalos, Timmons & Jose, 2015), while higher doses of caffeine can result in an accelerated heart rate, but these effects are not common in people who consume caffeine regularly. In fact, there is evidence that the habitual consumer of caffeine develops a tolerance to its cardiovascular and neuroendocrine effects (Lane, Adcock, Williams & Kuhn, 1990;Lane, Pieper, Phillips-Bute, Bryant & Kuhn, 2002). ...
Article
Full-text available
Coffee is consumed worldwide, but there are different types of espresso blends, each with its unique concentration of caffeine, which can have different effects on the human being. The aim of this study was to understand the effect of the impact of caffeine on the autonomic nervous system, evaluating the physiological changes and subjective responses due to different levels of caffeine intake. A double-blind tasting task consisting of one within-subject factor design (caffeine level: high / double caffeine mixture (blend A) vs single-charge caffeine mixture (blend B) vs low-caffeine mixture (blend c) al-lowed us to assess participants’ autonomic responses using Heart Rate Variability (HRV) and Pupillary Reactivity (PR). Arousal was also assessed through the Self-Assessment Manikin (SAM). Results revealed statistically significant differences in HRV and PR between coffee blends, showing the blend A, a more pronounced autonomic response that blend C. However, no significant differences were found in arousal level among coffee blends. These results are similar to previous research that pointed out to a discordance between subjective and objective measures when caffeine is consumed.
... A 1 and A 2A receptors also interact in functionally important ways with dopamine receptors [22,23], with caffeine serving to stimulate secretion of the catecholamine stress hormones of epinephrine and norepinephrine [24]. In turn, elevated catecholamine levels have the potential to increase placental vasoconstriction and fetal heart rate [25], leading to impaired fetal oxygenation [26]. ...
... 15 The sympathetic adrenomedullary and the adrenocorticoid reaction to stress are enhanced: ingested methylxanthines stimulate the sympathetic nervous system, thus augmenting body temperature, systolic pressure, and accelerating heart rate. 16 Further, excess cocoa consumption can also lead to augmented plasmatic renin levels, which influence extracellular volume and, consequently, blood pressure. 17 Recent clinical case reports highlight a possible link between dietary components and heart conduction, thus recognizing excess cocoa-rich foods as a potential substrate for arrhythmias. ...
Article
Full-text available
The interrelation between arrhythmias and lifestyle factors is acknowledged. On the one side, there is a recognized interaction between atrial fibrillation and obesity, hypertension, dyslipidemia and type 2 diabetes mellitus. Saturated fats, excessive added salt, tea, coffee and energy drinks are often deleterious in rhythm disorders. The role of others, such as cocoa-rich foods, is less evident: several authors displayed the beneficial effect of the polyphenols content on numerous cardiovascular risk factors, while little is known about the potential link between diet and incident arrhythmias. Arrhythmias’ most frequent risk factors include aging, hypertension, congenital cardiopathy, heart failure, valvulopathy, thyroid diseases and diabetes. Nevertheless numerous arrhythmias are not related to any of these risk factors: in these cases, immunological, functional and even nutritional mechanisms might be involved in dysrhythmias’ genesis. Aim of this narrative review is to analyze the potential adverse effect of cocoa excessive consumption on cardiac rhythm and its mechanisms and to provide state-of-the-art knowledge on this topic.
... Finally, although caffeine is also a stimulant, its use is not associated with either acquisition, affordability, availability, or legality issues [42,66]. However, with caffeine high-dosage intake a range of medical and psychiatric effects can be observed, most typically including anxiety, panic attacks, sleeping disorders and cardiovascular issues [129]. ...
Article
Full-text available
Introduction: Cognitive enhancers (CEs), also known as "smart drugs", "study aids" or "nootropics" are a cause of concern. Recent research studies investigated the use of CEs being taken as study aids by university students. This manuscript provides an overview of popular CEs, focusing on a range of drugs/substances (e.g., prescription CEs including amphetamine salt mixtures, methylphenidate, modafinil and piracetam; and non-prescription CEs including caffeine, cobalamin (vitamin B12), guarana, pyridoxine (vitamin B6) and vinpocetine) that have emerged as being misused. The diverted non-prescription use of these molecules and the related potential for dependence and/or addiction is being reported. It has been demonstrated that healthy students (i.e., those without any diagnosed mental disorders) are increasingly using drugs such as methylphenidate, a mixture of dextroamphetamine/amphetamine, and modafinil, for the purpose of increasing their alertness, concentration or memory. Aim: To investigate the level of knowledge, perception and impact of the use of a range of CEs within Higher Education Institutions. Methodology: A systematic review was conducted in adherence with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Whilst 1400 studies were identified within this study through a variety of electronic databases (e.g., 520 through PubMed, 490 through Science Direct and 390 through Scopus), 48 papers were deemed relevant and were included in this review. Results: The most popular molecules identified here included the stimulant CEs, e.g., methylphenidate, modafinil, amphetamine salt mixtures and caffeine-related compounds; stimulant CEs' intake was more prevalent among males than females; drugs were largely obtained from friends and family, as well as via the Internet. It is therefore suggested that CEs are increasingly being used among healthy individuals, mainly students without any diagnosed cognitive disorders, to increase their alertness, concentration, or memory, in the belief that these CEs will improve their performance during examinations or when studying. The impact of stimulant CEs may include tolerance, dependence and/or somatic (e.g., cardiovascular; neurological) complications. Discussion: The availability of CEs for non-medical indications in different countries is influenced by a range of factors including legal, social and ethical factors. Considering the risk factors and motivations that encourage university students to use CE drugs, it is essential to raise awareness about CE-related harms, counteract myths regarding "safe" CE use and address cognitive enhancement in an early stage during education as a preventative public health measure.
... The roasted seeds of Coffea sp. are used for coffee extraction. The composition of a coffee beverage basically depends on species, roast, and preparation methods [44][45][46], which vary according to geographic and cultural factors, all affecting the chemical profile. For instance, in Italian coffee shops, the espresso method, in which hot water at high pressure is passed through about 8 g of finely-ground coffee powder producing a serving of 30 mL, is basically the rule. ...
Article
Full-text available
To date, interest in the role of coffee intake in the occurrence and course of age-related neurological and neuropsychiatric disorders has provided an inconclusive effect. Moreover, no study has evaluated mocha coffee consumption in subjects with mild vascular cognitive impairment and late-onset depression. We assessed the association between different quantities of mocha coffee intake over the last year and cognitive and mood performance in a homogeneous sample of 300 non-demented elderly Italian subjects with subcortical ischemic vascular disease. Mini Mental State Examination (MMSE), Stroop Colour-Word Interference Test (Stroop T), 17-items Hamilton Depression Rating Scalfe (HDRS), Activities of Daily Living (ADL), and Instrumental ADL were the outcome measures. MMSE, HDRS, and Stroop T were independently and significantly associated with coffee consumption, i.e., better scores with increasing intake. At the post-hoc analyses, it was found that the group with a moderate intake (two cups/day) had similar values compared to the heavy drinkers (≥three cups/day), with the exception of MMSE. Daily mocha coffee intake was associated with higher cognitive and mood status, with a significant dose-response association even with moderate consumption. This might have translational implications for the identification of modifiable factors for vascular dementia and geriatric depression.
... Moreover, we observed a marked increase in the systolic blood pressure in those patient consuming coffee daily( figure 4).Elevated blood pressure may predate type 2 diabetes [30,31]. The increase in blood pressure due to coffee consumption might be due to its high content of caffeine which has been found to increase blood pressureand heart rate [32,33]. In contrast, we observed a significant decrease in systolic blood pressure in a dose-dependent manner in diabetics who consume green tea daily. ...
Article
Full-text available
Patients Lifestyle such as habitual consumption of certain meals and beverages plays major role in the development of diabetes. There is strong positive association between overall obesity as measured by Body Mass Index (BMI), blood cholesterol, blood pressure and diabetes. Black and green tea and coffee are traditional beverages that are daily consumed by many Libyans. In this study, we studied the relationship between the average daily consumed amount of coffee, green tea, or black tea and fasting blood glucose, cholesterol, blood pressure or Body Mass Index (BMI) as an indicator for obesity in type 2 diabetic patient. Our study included 396 Libyan diabetic patients (292 females and 104 males) with mean age of 49±17 years from Tripoli center of diabetes. This study performed during a period of 2 years. We also included control patients who were coffee or tea non consumer type2 diabetics. The results of this study showed that as the amount of daily consumed coffee, green tea, and black tea increases there is a marked decrease in fasting blood glucose of type 2 diabetics. In addition, a habitual green tea consumption strongly reduces blood cholesterol, blood pressure and BMI while black tea has weaker effect. In contrast, coffee consumption significantly increases blood cholesterol, BMI and blood pressure of diabetics at higher doses.
... 30-32 A 1 and A 2A receptors also interact in functionally important ways with dopamine receptors, 33 34 and caffeine stimulates secretion of the catecholamine stress hormones of epinephrine and norepinephrine. 35 In turn, elevated catecholamine levels have the potential to increase placental vasoconstriction and increase fetal heart rate 36 leading to impaired fetal oxygenation. 37 Furthermore, habitual caffeine consumption leads to physical dependence, indicated by behavioural, physiological and subjective withdrawal effects (caffeine withdrawal syndrome) in response to even brief abstinence. ...
Article
Full-text available
Objectives Caffeine is a habit-forming substance consumed daily by the majority of pregnant women. Accordingly, it is important that women receive sound evidence-based advice about potential caffeine-related harm. This narrative review examines evidence of association between maternal caffeine consumption and negative pregnancy outcomes, and assesses whether current health advice concerning maternal caffeine consumption is soundly based. Methods Database searches using terms linking caffeine and caffeinated beverages to pregnancy outcomes identified 1261 English language peer-reviewed articles. Screening yielded a total of 48 original observational studies and meta-analyses of maternal caffeine consumption published in the past two decades. The articles reported results for one or more of six major categories of negative pregnancy outcomes: miscarriage, stillbirth, low birth weight and/or small for gestational age, preterm birth, childhood acute leukaemia, and childhood overweight and obesity. Results Of 42 separate sets of findings reported in 37 observational studies, 32 indicated significantly increased caffeine-related risk and 10 suggested no or inconclusive associations. Caffeine-related increased risk was reported with moderate to high levels of consistency for all pregnancy outcomes except preterm birth. Of 11 studies reporting 17 meta-analyses, there was unanimity among 14 analyses in finding maternal caffeine consumption to be associated with increased risk for the four outcome categories of miscarriage, stillbirth, low birth weight and/or small for gestational age, and childhood acute leukaemia. The three remaining meta-analyses were also unanimous in reporting absence of a reliable association between maternal caffeine consumption and preterm birth. No meta-analyses were identified for childhood overweight and obesity, although four of five original observational studies reported significant associations linking maternal caffeine consumption to that outcome category. Conclusions The substantial majority finding from observational studies and meta-analyses is that maternal caffeine consumption is reliably associated with major negative pregnancy outcomes. Reported findings were robust to threats from potential confounding and misclassification. Among both observational studies and meta-analyses, there were frequent reports of significant dose–response associations suggestive of causation, and frequent reports of no threshold of consumption below which associations were absent. Consequently, current evidence does not support health advice that assumes 'moderate' caffeine consumption during pregnancy is safe. On the contrary, the cumulative scientific evidence supports pregnant women and women contemplating pregnancy being advised to avoid caffeine.
... • Sekundäre Pflanzenstoffe (S. 28) o Theobromin (S. 28) o Catuaba Extrakt (S. 29) o Maca Extrakt (S. 31) o Grüntee Extrakt, entkoffeiniert (S. 32) o Ingwer Extrakt (S. 33) o Magnolia Extrakt (S. 35) o Piperin (S. 37) • Sonstiges/Beschreibung (S. 38) -Produkt 2: Proteinriegel (S. 39) • Inhaltsstoffe (S. 40) o Süßkartoffel-Pulver (S. 40) • Die wichtigsten Nährstoffe im Überblick (S. 41) o Eiklar-Pulver (S. 47) o Allulose (S. 48) o Datteln (S. 48) o Honig (S. 49) o Propolis (S. 51) o Gelee Royal (S. 52) o Flohsamenschalen (S. 53) o Bromelain (S. 54) o Curcuminoide (S. 54) o Piperin (S. 56) o Stevia E960 (S. 56) -Zusammenfassung (S. 58 10,11 Ein häufig behaupteter Zusammenhang zwischen tierischen Produkten (insbesondere Fleisch) und Zivilisationskrankheiten ist, in gesundem Maß, wissenschaftlich nicht haltbar. 12,13,14 Veganer und Vegetarier sollten sich hingegen um ihre Gesundheit bemühen, da eine Mangelsituation häufiger vorkommt als vermutet. ...
Article
Full-text available
Die hier vorgestellten Produkte mit Schwerpunkt Nachhaltigkeit und Evidenz-basierten Inhaltsstoffen (Energy-Drink & Protein-Riegel) erhalten im Verbrauchermarkt aufsteigendes Interesse. Dies liegt unter anderem daran, dass Nahrungsmittel mit gesundheits- und leistungsfördernden Eigenschaften benötigt werden, um der steigenden Anzahl an Krankheiten präventiv entgegenzuwirken. Besonders wichtig ist die adäquate Zufuhr von Proteinen und sekundären Pflanzenstoffe, um langfristig gesund zu bleiben. Im Gegensatz zu anderen bereits bestehenden Unternehmen liegt der Fokus dieses Konzepts auf der wissenschaftlichen Bestätigung zur Wirksamkeit der einzelnen Inhaltsstoffe. Damit soll dem Käufer ein optimales Preis-Leistungsverhältnis, auch in Bezug auf den Geschmack, geboten werden. Zusätzlich steht der Ressourcen-schonende Umgang mit Rohstoffen und Verpackungsmaterialien im Vordergrund, sodass zukunftsfähiges Handeln ermöglicht wird. Gerade in einer Zeit von hohen menschengemachten Umweltbelastungen, wie beispielsweise durch Plastikaufkommen in den Meeren, ist eine moralische Firmenpolitik notwendiger denn je.
... Although we explored changes in BLa and BG concentrations, CAF may also influence various other metabolites (e.g. epinephrine, norepinephrine etc.) [88,89] that might contribute to fluctuations in sport and exercise performance. Moreover, genetic assessments related to caffeine metabolism were not checked across participants which may have influenced the efficacy of CAF pharmacology [90,91]. ...
Article
Full-text available
Caffeine (CAF) has been reported to improve various facets associated with successful soccer play, including gross motor skill performance, endurance capacity and cognition. These benefits are primarily attributed to pharmacological mechanisms. However, evidence assessing CAF's overall effects on soccer performance are sparse with no studies accounting for CAF's potential psychological impact. Therefore, the aim of this study was to assess CAF's psychological vs. pharmacological influence on various facets of simulated soccer performance. Utilising a double-dissociation design, eight male recreational soccer players (age: 22 ± 5 years, body mass: 78 ± 16 kg, height: 178 ± 6 cm) consumed CAF (3 mg/kg/body mass) or placebo (PLA) capsules, 60 minutes prior to performing the Loughborough Intermittent Shuttle Test (LIST) interspersed with a collection of ratings of perceived exertion (RPE), blood glucose and lactate, heart rate and performing the Loughborough Soccer Passing Test (LSPT). Whole-body dynamic reaction time (DRT) was assessed pre-and post-LIST, and endurance capacity (TLIM) post, time-matched LIST. Statistical analysis was performed using IBM SPSS (v24) whilst subjective perceptions were explored using template analysis. Mean TLIM was greatest (p < 0.001) for synergism (given CAF/told CAF) (672 ± 132 s) vs. placebo (given PLA/told PLA) (533 ± 79 s). However, when isolated, TLIM was greater (p = 0.012) for CAF psychology (given PLA/told CAF) (623 ± 117 s) vs. pharmacology (given CAF/told PLA) (578 ± 99 s), potentially, via reduced RPE. Although DRT performance was greater (p = 0.024) post-ingestion (+5 hits) and post-exercise (+7 hits) for pharmacology vs. placebo, psychology and synergism appeared to improve LSPT performance vs. pharmacology. Interestingly, positive perceptions during psychology inhibited LSPT and DRT performance via potential CAF over-reliance, with the opposite occurring following negative perceptions. The benefits associated with CAF expectancies may better suit tasks that entail lesser cognitive-/skill-specific attributes but greater gross motor function and this is likely due to reduced RPE. In isolation, these effects appear greater vs. CAF pharmacology. However, an additive benefit may be observed after combining expectancy with CAF pharmacology (i.e. synergism).
... In this study, we used synthetic fibre swabs (Salivetten® by Sarstedt) as the most convenient, economic, and valid method of saliva collection [67,70]. Since cortisol levels react to physical activity as well as glucose and drug intake [71][72][73][74][75][76][77], we instructed participants to strictly refrain from workout, the consumption of alcohol, caffeine, and nicotine on survey days, as well as eating 30 min and drinking five minutes before taking samples [78]. All saliva samples were collected after sessions, deep-frozen, and analysed in the Heidelberg University Hospital's Steroid Lab. ...
Article
Full-text available
Background Structured peer-led tutorial courses are widespread and indispensable teaching methods that relieve teaching staff and contribute to the development of students’ competencies. Nevertheless, despite high general stress levels in medical students and associated increases in psychopathology, specific knowledge of peer tutors’ additional burdens is very limited. Methods Sixty student near-peer tutors from two structured peer-teaching programmes volunteered to participate. On multiple occasions in three different course sessions, we assessed tutors’ subjective stress, affective state, heart rate variability, and salivary cortisol. Additionally, tutors named everyday and course-specific stressors, which were evaluated by means of content analyses. Results The study participation rate was high (63% of all active tutors). The participating tutors are socially well adapted and resilient individuals. They report a variety of stressors such as time pressure, participant characteristics, teacher role demands, and study requirements, but nevertheless display only moderate psychological and physiological stress that decreases over sessions. Tutors’ negative affect in sessions is low; their positive affect is consistently high for senior as well as novice tutors. Tutors rate their courses’ quality as high and quickly recover after sessions. Conclusions Tutors successfully cope with teaching-associated and everyday life demands. The results corroborate the viability and success of current peer-teaching programmes from the tutors’ perspective. This study is the first to comprehensively quantify tutors’ stress and describe frequent stressors, thus contributing to the development of better peer teaching programmes and tutor qualification training. Electronic supplementary material The online version of this article (10.1186/s12909-019-1521-2) contains supplementary material, which is available to authorized users.
... Caffeine is a mighty stimulant of the cardiovascular system and the effects of one cup of coffee are: increase of both blood pressure and heart rate. The regular consumption of caffeine may contribute to a constant increase in blood pressure, which is a problem for hypertensive people (Lane, et al., 2002). Patients with body mass index (BMI), which is higher or equal to 25, and the girth of waist is over 102cm (for men) and 88cm (for women), must ponder on reducing their weight (Health Canada, 2005). ...
Conference Paper
Full-text available
Abstract:The so-called motivation interviewing is the systematic directing of the patient toward motivation for change. This interviewing includes advices and achieving a feedback, which is aimed at changing the gaps in the patients’ unhealthy behavior in a way, that the motivation could improve and change. The modification of lifestyle is an important aspect of the blood pressure control, and serves as a keystone of global managing of many atherosclerotic risk factors. Patients must be informed with a clear rationale of the necessity of special treatment, which responds to their own model of disease. The nurses’ effectiveness in the initial hypertension management is very well documented in literature. According to the directions given by the nurse, concerning the managing of hypertension, in appropriately selected individuals, some interventions in lifestyle, have the potential to reduce blood pressure rates, to the equivalence of half to one full standard dose of anti-hypertensive medicament. Keywords: interventions, change, hypertension, nurse
... Coffee is a worldwide popular beverage, which has multiple effects on the human body. The ones that have been most frequently documented are those of the central nervous system and the cardiovascular system [18,19]. However, existing evidence on the effect of coffee on the gastrointestinal system, and especially on that of the postoperative bowel, can be considered limited [20,21]. ...
Article
Background: Postoperative ileus prolongs both hospital stay and patients' morbidity, having at the same time a great impact on health care costs. Coffee, a worldwide popular, cheap beverage might have an important effect on the motility of the postoperative bowel. Methods: PubMed, Scopus, and Cochrane Central Register of Controlled Trials were systematically searched. Results: Four studies met the inclusion criteria of our meta-analysis. A total of 341 patients were included. The postoperative administration of coffee significantly reduces the time to first bowel movement, the time to first flatus and the time to tolerance of solid diet. Safe conclusions could not be drawn regarding the additional use of laxatives, the necessity for reinsertion of nasogastric tube or the need for reoperation as all the aforementioned outcomes did not present any statistically significance. None of the complications were attributed to the administration of coffee. Conclusion: The administration of coffee as a postoperative ileus prevention measure can change the way postoperative enhanced recovery is applied. Even though the mechanism of action of coffee is not fully known, currently available literature demonstrates a significant improvement in gastrointestinal motility without having any impact on postoperative morbidity. Studies with higher methodological quality can offer a more careful evaluation of the clinical use of this popular beverage.
... Hal ini terjadi dikarenakan adanya toleransi tubuh terhadap kafein yang dikonsumsi secara teratur setiap hari. Lain halnya apabila kopi dikonsumsi secara berlebihan dalam sehari, karena dapat menyebabkan perubahan hemodinamik diantaranya dapat meningkatkan tekanan darah (Lane, 2002). ...
Article
Full-text available
The existence of bus station can make some problems, one of which is the traffic noise. Traffic noise can induce an increased blood pressure. Therefore, the purpose of this study was to analyzed the relationship between level of traffic noise and increased blood pressure in pedicab drivers around Purabaya bus station. The study was carried out using by cross sectional method. Measurement of traffic noise was carried out around Purabaya bus station Surabaya with Sound Level Meter. Measurement of blood pressure with sphygmomanometer. Sampling method used by simple random sampling with 22 respondents respectively and then total of respondents are 44 respondents. The result of study indicated there was a relationship between the level traffic noise with increased blood pressure (hypertension) (p = 0.034). Another factor related to blood pressure was descendants of the family history (p = 0.002). It was concluded that traffic noise related with increased blood pressure in pedicab drivers. Suggested for the next researcher doing the measurement noise more than a day to get the actual average noise level. In addition, other factors related to the blood pressure should examined to get main factor of hypertension. Keywords: traffic noise, blood pressure, pedicab drivers
... Selain itu, mereka mengonsumsi dengan frekuensi rutin per harinya. Dalam hal ini, Lane (2002), menjelaskan bahwa kafein dalam kopi mampu menghasilkan perubahan haemodinamik diantaranya dapat meningkatkan tekanan darah. Kondisi ini dapat terjadi apabila konsumsi kopi secara teratur setiap hari dalam jumlah yang besar. ...
Article
Full-text available
Noise is a physical exposure that effect to health such as increasing blood pressure. Therefore the aim of this research was to examine the correlation between noise and age toward housewive’s blood pressure. This research applied cross-sectional study with observational comparative method. The population was housewives in Ambengan Surabaya residence with a sample of 53 people, including 29 study and 24 controls selected through cluster sampling. Noise, age, durration of exposure, family history of hypertension, consumption of coffee and salt selected to be independent variables. Noise data measured in the respondent house used Sound Level Meter Merk Kanomax Model 4020. The result of bivariat correlation used chi square showed that there was significant correlation between noise (p (0,002) < α(0.05)) and age (p (0.029) < α(0.05)) to housewive’s blood pressure. It is conclued that noise and age related to housewive’s blood pressure. Government requaired to socialize the damage and health effect of train noise levels to people who lives in residence surround railway and resettlement within < 6 meters from railway into larger land. At last, to ensure the presence of inferential causal temporality, it is required to conduct further study with design of cohort study in a larger sample and correlate variable.
... The influence of coffee consumption (caffeine) on BP may vary, from zero to several mmHg. Longer coffee abstinence may also decrease BP. (2,19,20) Interestingly, caffeine was also found in the sample of non-coffee drinker group, suggesting that subjects have consumed any caffeinecontained meal or drink other than coffee, possibly tea and caffeinated soft drinks. Although being reported harmful, coffee contains beneficial compounds as an antioxidant, including chlorogenic acid, flavonoids, melanoidins and various lipidsoluble compounds such as furans, pyrroles and maltol. ...
Article
Full-text available
BACKGROUND: The association between caffeine with blood pressure (BP) still remains controversial. Caffeine is mainly metabolized by cytochrome-P450 (CYP)1A2 enzyme. Polymorphism of CYP1A2 is known to cause interindividual variation on enzymatic activity, thus affects caffeine metabolism and its effect on cardiovascular (CV) system. METHODS: We conducted a cross-sectional study and recruited 121 Indonesian subjects aged 25-60 years with varying coffee-drinking habits. DNA was extracted from peripheral blood and genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCRRFLP) technique. Blood pressures were measured in the morning prior to the daily activity. Caffeine concentration in blood plasma was measured using high-performance liquid chromatography (HPLC). The differences between variables were analyzed using MannWhitney analysis and the correlations among variables were determined using multivariate logistic regression analysis. RESULTS: This study showed that the frequencies of single nucleotide polymorphisms (SNPs) among Indonesian were 31.8%, 18.2%, 25.2% and 24.8% respectively for CYP1A2*1A, CYP1A2*1B, CYP1A2*1C and CYP1A2*1F alleles. The genotype analysis showed that the subject number of the wild type (*1A/*1A) and the variants were 9.92% and 90.08%. There were no significant differences in term of BP levels among CYP1A2 genotypes and coffee drinking habit groups. CONCLUSIONS: The frequencies of CYP1A2 SNPs in Indonesian are different with frequencies in other populations. Since the association were not statistically significant, CYP1A2 polymorphisms as the predictor of elevated blood pressuare should be investigated further. KEYWORDS: coffee, caffeine, blood pressure, single nucleotide polymorphism, CYP1A2
... Such impairment can also result in the activation of sympathetic adrenal-medullar system. 3 A research investigated that a 100 ml of energy drink contains 80-242 mg of caffeine that is equivalent to consumption of eight cups of strong coffee in a day. 4 The overdose of caffeine can also cause greater risk of toxicity and disturb the overall health structure particularly among youngsters. ...
Article
Full-text available
Objective To evaluate the consumption, prevalence, side effects and awareness of energy drinks among female university students in Saudi Arabia. Methods A quantitative research design was implied with sample size of 358 female students, recruited from Prince Sattam bin Abdulaziz University. The data, gathered through self-administered questionnaire, was analyzed through SPSS version 20.0 with p value <0.005 deemed statistically significant. Results From the sample of 358 female students, 337 attempted the questionnaire from which 274 students were identified as energy drink consumers. The reasons for increased consumption of energy drinks mainly include giving company to friends (59.4%), better performance in exams (41.2%), and better concentration in studies (39.4%). The most common side effect was headache (32.3%), and the least was identified as allergy (2%). Only 39.4% and 29.9% of students acquired awareness regarding the harmful effects of energy drink consumption during pregnancy and breast feeding respectively. Conclusion A significant proportion of female students at Prince Sattam bin Abdulaziz have reported to consume energy drinks regularly with several adverse effects. The government of Saudi Arabia should take serious initiatives towards organizing effective awareness programs specifically in universities and colleges to control the consumption of energy drinks and educate on the adverse effects.
... We next examined whether the effect of condition remained significant while controlling for gender, habitual caffeine use, perceived stress (PSS), average total sleep time (TST), and positive (PA) and negative (NA) affect. We included gender and caffeine use in the final analyses given their previously observed link to cortisol stress reactivity (Al'Absi et al., 1998;Kirschbaum et al., 1999;Kudielka and Kirschbaum, 2005;Lane et al., 1990;Lane, 2002). We included the remaining covariates in the final analyses given the significant group differences reported above. ...
Article
The hypothalamic-pituitary-adrenal (HPA) axis has been previously identified as one potential mechanism that may explain the link between sleep deprivation and negative health outcomes. However, few studies have examined the direct association between sleep deprivation and HPA-axis functioning, particularly in the context of stress. Therefore, the aim of the current study was to investigate the relationship between acute sleep deprivation and HPA-axis reactivity to a psychosocial stressor. Participants included 40 healthy, young adults between the ages of 18-29. The current protocol included spending two nights in the laboratory. After an adaptation night (night 1), participants were randomized into either a sleep deprivation condition (29 consecutive hours awake) or a control condition (night 2). Following the second night, all participants completed the Trier Social Stress Test (TSST). Salivary cortisol was collected before, during, and after the TSST. Results indicated that there were significant group differences in cortisol stress reactivity. Specifically, compared to participants in the control condition, participants in the sleep deprivation condition had greater baseline (i.e., pre-stress) cortisol, yet a blunted cortisol response to the TSST. Taken together, a combination of elevated baseline cortisol (and its subsequent effect on HPA-axis regulatory processes) and a relative 'ceiling' on the amount of cortisol a laboratory stressor can produce may explain why participants in the sleep deprivation condition demonstrated blunted cortisol responses.
... Coffee is a widely consumed beverage on a daily basis, second only to water in the United Sates [1]. Its consumption, however, has been correlated to the development of cardiovascular events, such as cerebrovascular accident, stroke, coronary diseases [2][3][4], and rise in blood pressure (BP) [5][6][7]. ...
Article
Full-text available
The reduction in blood pressure after the physical exercise practice is called postexercise hypotension (PEH). Previous studies have demonstrated that the ingestion of caffeine at levels corresponding to three doses of coffee eliminates this phenomenon. Thus, we evaluated the influence of different doses of coffee in the PEH in twelve hypertensives, who performed four experimental sessions of aerobic exercise on a cycle ergometer (lasting 40 minutes, with intensity between 60% and 80% of maximum heart rate), followed by the ingestion of one (CAF-1), two (CAF-2), or three (CAF-3) doses of caffeinated coffee, or three doses of decaffeinated coffee (DESC). The blood pressure was measured at rest and at 10-minute intervals during 120 minutes of recovery post exercise. DESC resulted in systolic PEH at all moments of measurement, with averages of -4.1±1.2 mmHg and -1.8±1.3 mmHg on the 1(st) and 2(nd) hours post exercise, respectively. In CAF-1, both systolic hypotensive and hypertensive responses to the exercise were identified, with averages of -1.2±1.7 and 0.5±0.4 mmHg after one and two hours of recovery. Conversely, hypertensive systolic response occurred in all measurements compared rest blood pressure. The 1(st) and 2(nd) hours post exercise was 4.5±1.1 and 6.5+1.1 mmHg in CAF-2 and 5.1+0.9 and 6.5+1.0 mmHg to CAF-3. Diastolic PEH was not found in any of the experimental sessions. Therefore, the ingestion of two and three doses of caffeinated coffee completely blunts the PEH, while one dose results in partial elimination of the PEH.
... 6 Caffeine intake has a well-known disruptive effect on sleep 7 and may exaggerate the sympathetic-adrenal medullary responses to stressful events, negatively affecting resident's quality of life. 8 To date, the epidemiological data on sleep quality in medical trainees are limited and not representative of all nationalities. Psychiatry trainees in Italy are required to perform the same duties and work hours as an attending. ...
Article
Full-text available
Background: Medical residencies are highly demanding and stressful and have been associated with mental and emotional problems. Studies that evaluated this relationship in Italian psychiatry residents are scarce. In this study, we examined sleep quality and its association with perceived stress and caffeinated beverages consumption in Italian psychiatry residents. Methods: Seventy-two PGY1–5 psychiatry residents at two University Hospitals in Italy were asked to complete an anonymous questionnaire. The Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale were used to determine the sleep quality and the level of daytime sleepiness (EDS). In addition, we investigated perceived stress and caffeinated drinks consumption (coffee, tea, soda, energy drinks). Results: Seventy psychiatry residents responded to the survey (97.2% response rate) (M = 34.3%, F = 65.7%; mean age = 30.5 ± 4.2 SD years). 44.3% had poor sleep quality and 15.7% had abnormal EDS. 64.3% reported significant perceived stress. Perceived stress score and coffee consumption were associated with greater likelihood of poor sleep quality. Conclusions: Psychiatry residents have high prevalence of poor sleep quality. Future longitudinal studies are needed to investigate causality and identify appropriate coping strategies and lifestyle changes aimed to improve mental health in psychiatry trainees.
Article
Full-text available
Flow is an intrinsically rewarding state characterised by positive affect and total task absorption. Because cognitive and physical performance are optimal in flow, chemical means to facilitate this state are appealing. Caffeine, a non-selective adenosine receptor antagonist, has been emphasized as a potential flow-inducer. Thus, we review the psychological and biological effects of caffeine that, conceptually, enhance flow. Caffeine may facilitate flow through various effects, including: i) upregulation of dopamine D1/D2 receptor affinity in reward-associated brain areas, leading to greater energetic arousal and ‘wanting’; ii) protection of dopaminergic neurons; iii) increases in norepinephrine release and alertness, which offset sleep-deprivation and hypoarousal; iv) heightening of parasympathetic high frequency heart rate variability, resulting in improved cortical stress appraisal, v) modification of striatal endocannabinoid-CB1 receptor-signalling, leading to enhanced stress tolerance; and vi) changes in brain network activity in favour of executive function and flow. We also discuss the application of caffeine to treat attention deficit hyperactivity disorder and caveats. We hope to inspire studies assessing the use of caffeine to induce flow.
Article
Full-text available
Caffeine is a naturally occurring methylxanthine compound found in various plants, such as coffee beans, tea leaves, and cocoa beans. It is widely consumed worldwide in the form of beverages, dietary supplements, and medications. Caffeine exerts its pharmacological effects primarily through its interaction with adenosine receptors, resulting in widespread physiological and neurological changes. In the field of medicinal chemistry, caffeine has been extensively studied due to its diverse pharmacological actions and potential therapeutic applications. This abstract highlights the key pharmacological actions of caffeine and its relevance in medicinal chemistry research. Caffeine acts as a non-selective antagonist of adenosine receptors, particularly the A1 and A2A subtypes. By inhibiting adenosine binding, caffeine prevents the activation of these receptors, leading to increased neural activity and the release of neurotransmitters such as dopamine and glutamate. This mechanism of action underlies caffeine’s stimulant effects, including increased alertness, reduced fatigue, and improved cognitive function. Caffeine exhibits broncho dilatory effects by acting as a phosphodiesterase inhibitor, primarily targeting phosphodiesterase type 4 (PDE4). Inhibition of PDE4 prevents the breakdown of cyclic adenosine monophosphate (cAMP), leading to smooth muscle relaxation and bronchodilation. This property of caffeine has been utilized in the treatment of asthma and chronic obstructive pulmonary disease (COPD). Furthermore, caffeine possesses diuretic properties by inhibiting the reabsorption of sodium in the renal tubules. This leads to increased water excretion and urine production. The diuretic effects of caffeine have found applications in the management of fluid overload conditions, such as edema and heart failure. Additionally, caffeine has been investigated for its potential anticancer properties. Several studies have shown that caffeine can enhance the cytotoxic effects of certain chemotherapeutic agents, inhibit DNA repair mechanisms, and induce apoptosis in cancer cells. These findings have sparked interest in caffeine as an adjuvant therapy for cancer treatment, although further research is needed to establish its clinical efficacy and safety. In conclusion, caffeine exhibits a wide range of pharmacological actions, making it a versatile compound in medicinal chemistry research. Its interactions with adenosine receptors, phosphodiesterase, and renal tubules contribute to its stimulant, broncho dilatory, diuretic, and potentially anticancer effects. The understanding of caffeine’s pharmacological actions provides valuable insights for the development of novel drugs and therapeutic approaches in various fields of medicine.
Article
Full-text available
Harbor noise intensity remains environmental health issues causing some adverse health effect such as physiological disturbances that can lead to hypertension. This study aimed to explore the risk factors for hypertension among housewife around the harbor. It was a analytical study with cross-sectional approach. There were 90 housewives recruited around harbor Residence they were selected through simple random sampling. Data was collected through interview and blood pressure measurement. Measurement of noise intensity used Sound Level Meter and carried out at ten locations with a radius of every location was 100 meters from the harbor. Data was analyzed by univariate and bivariate using Chi-Square. This study found that the average of noise intensity in 24 hours measurement (LDN) was 57.79 dB(A) which was exceed the threshold limit value for residential area. It showed that 54.4% of housewives who live around harbor Residence got hypertension. According to statistical analysis, there was orrelation between Boom Baru Harbor noise to the risk of hypertension on women who live around harbor Residence (p-value=0.026). Besides that, another factor correlated to hypertension were age (p-value = 0.001) and the distance of house to harbor (p-value = 0.001). this study conclude that the harbor noise intensity was significantly related to hypertension.
Chapter
Full-text available
Plant secondary metabolites (PSMs) are produced in the form of phytochemicals in various plant parts as a natural defense system against attack of various microorganisms and environmental stresses. The role of these compounds is beyond providing protection, as they are linked to many biochemical pathways inside and outside the plants and possess various well-known therapeutic applications. The extraordinary biological activities of plant secondary metabolites lead to their extensive use as an ingredient in medicines and for therapeutic and other culinary purposes since ages. The minimum effective concentration and effect (positive or negative) of plant secondary metabolites on particular metabolic pathways are the concerns which are still under a trial phase. They occur in very minute quantities within the plant cells, while the purity issues have resulted in manufacturing of their chemical derivatives and their industrial applications as well. Environmental, morphogenetic, and genetic factors and ultimately the processing affect the biosynthesis and the concentration of these PSM present. However, the plants are always in contact with changing conditions of light, water, temperature, pH, insect pest infestation, etc. which may adversely affect the accumulation of secondary metabolites. The present chapter has been compiled to give the readers an in-hand information about the plant secondary metabolites with primary objective of their food and functional repute. The overall contents will focus on broad classification of PSMs, various methods adopted for their extraction with their potential advantages and disadvantages, and effect of various methods of food processing on the bioavailability and bioactivity of the PSMs with proposed future research opportunities in their potential therapeutic applications.
Thesis
As other developing countries, Algeria knows an important increase of cardiovascular diseases resulting from a fast epidemiologic transition. Hypertension is a major risk factor for morbidity and mortality among these cardiovascular diseases. The objectives of the present survey were (i) to estimate the prevalence of hypertension and other cardio vascular risk factors in a sample of adults of EL-Menia oasis in Algerian Sahara and (ii) to study a possible association between hypertension and dietary habits, especially salt intake. Contrary to others oasis of Sahara, El-Menia was characterized by low sodium content in drinking water. We performed a cross-sectional survey. Subjects were selected from people aged 40 years or older by stratified random cluster sampling. Blood pressure (BP) was measured at 3 times on one occasion according to standardized and validated procedures. A case of hypertension was defined as subjects used antihypertensive medication, or as a systolic BP ≥ 140 mm Hg and/or a diastolic BP ≥ 90 mm Hg in the average of the last 2 measures. The blood samples were collected: fasting plasma glucose, total cholesterol, triglycerides and, HDL cholesterol were measured. A questionnaire has been completed by physicians and anthropometric data were recorded for each included subject. Prevalence was expressed on percentage. A Khi-square test was performed to test differences of proportion of multiple variables, and Student’s t-test was performed to evaluate the difference between the mean of two variables. Multiple logistic regression analysis was used to assess significant association between different risk factors to hypertension. P values < 0.05 were regarded as statistically significant. 727 adults were included: 67% are female and 17, 7 % are black subjects. The mean age was 58.5 ± 13.2 years. The prevalence of hypertension was 50.2% (365/727): 51,3% (123/240) of male vs. 49.7% (242/487) of female, without significant differences between genders. Prevalence was significantly higher in black: 62% (80/129) than whites: 47, 9% (285/593), (p<0, 01). Among the 365 subjects diagnosed with hypertension, 58% were not aware of their status. Women and subjects aged of 60 and more years old were more aware of their hypertension than others. The control rate was 20% among 147 (95%) treated hypertensive. Controlled BP was defined as, a systolic BP<140 mm Hg and a diastolic BP<90 mm Hg. There was no association between diet and hypertension in our population. Using multivariate analysis, there was a significant relationship between hypertension and age (OR= 1, 52; CI 95 % = [1.40–1, 65]), skin colour (OR= 2, 23; CI 95 % = [1.39–3,58]),glycaemia (OR= 1,49; CI 95 % = ([1.21 –1,83]) and waist circumference (OR= 1,11; CI 95 % = [1.03–1,19]). Our finding prevalence of arterial hypertension was similar to other age matched studies conducted in north Algeria and worldwide. Our finding prevalence was also similar to another study conducted in other oasis in the Algerian Sahara where the drinking water was characterized by high sodium content. Then, high sodium consumption seems not to be very important in the development of arterial hypertension in these regions. The high prevalence of hypertension shows the need for a model of health care capable of comprehending and integrating effective control and prevention actions. Keywords: Prevalence, Hypertension, Cardiovascular risk factors, Prevention, Control, Diet habits, Salt intake.
Article
Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies was asked to deliver a scientific opinion on the safety of caffeine, providing advice on caffeine intakes, from all dietary sources that do not give rise to concerns about adverse health effects for the general healthy population and subgroups thereof. Possible interactions between caffeine and other constituents of so-called “energy drinks”, alcohol, p-synephrine and physical exercise should also be addressed. Single doses of caffeine up to 200 mg (about 3 mg/kg bw for a 70-kg adult) do not give rise to safety concerns. The same amount does not give rise to safety concerns when consumed < 2 hours prior to intense physical exercise under normal environmental conditions. Other constituents of “energy drinks” at typical concentrations in such beverages (about 300–320, 4 000 and 2 400 mg/L of caffeine, taurine and d-glucurono-γ-lactone, respectively), as well as alcohol at doses up to about 0.65 g/kg bw, would not affect the safety of single doses of caffeine up to 200 mg. Habitual caffeine consumption up to 400 mg per day does not give rise to safety concerns for non-pregnant adults. Habitual caffeine consumption up to 200 mg per day by pregnant women does not give rise to safety concerns for the fetus. Single doses of caffeine and habitual caffeine intakes up to 200 mg consumed by lactating women do not give rise to safety concerns for breastfed infants. For children and adolescents, the information available is insufficient to derive a safe caffeine intake. The Panel considers that caffeine intakes of no concern derived for acute caffeine consumption by adults (3 mg/kg bw per day) may serve as a basis to derive single doses of caffeine and daily caffeine intakes of no concern for these population subgroups.
Chapter
Vasovagal syncope is a common disorder characterized by reflex vasodilatation and bradycardia, resulting in a drop in systemic blood pressure and diminished cerebral perfusion. The episodes are usually provoked by patient- specific triggers, such as intense emotions or prolonged standing, and are self- limiting [1]. Up to half of the normal population experiences at least one episode of syncope during life. The vast majority of these episodes are of vasovagal origin [2,3].
Chapter
Coffee, the most important source of caffeine, is extracted from the fruit of Coffea arabica. The basis of the popularity of all the caffeine-containing beverages has been the ancient belief that these beverages have stimulant and antisoporific actions that elevate mood, decrease fatigue, and increase capacity for work. Caffeine, a methylated xanthine, possesses several pharmacological actions of therapeutic interest: relaxation of smooth muscle, notably bronchial muscle, stimulation of the central nervous system and cardiac muscle, and induction of diuresis. A cup of coffee contains about 85 mg of caffeine and is used as unfiltered (espresso), filtered (“American coffee”), or decaffeinated. The administration of moderate doses of caffeine (500 mg) in healthy, nonsmoking, habitual coffee drinkers significantly raises average ambulatory blood pressure during the working day and evening and reduces average heart rate by 2 bpm [1]. Caffeine also increases by 32% the levels of free epinephrine excreted during the working day and evening. In addition, caffeine amplifies the increase in blood pressure and heart rate associated with higher levels of self-reported stress during the daily activities [1]. Acutely caffeine induces an increase in muscle sympathetic nervous activity and blood pressure in nonhabitual coffee drinkers, whereas habitual coffee drinkers exhibit lack of blood pressure increase despite sympathetic activation [2]. Because decaffeinated coffee also increases blood pressure and muscle sympathetic activity in nonhabitual drinkers, ingredients other than caffeine may be responsible for cardiovascular activation [2]. The consumption of very high doses of unfiltered and filtered coffee increases plasma homocysteine and total cholesterol levels [3].
Article
Objective: Hospitalizations associated with energy drinks have increased in the past decade. Whereas energy drinks are suspected to cause hemodynamic effects, the magnitude of risk remains controversial. We evaluated the effects of acute energy drink consumption on systolic and diastolic blood pressure (SBP and DBP) and heart rate (HR). Data sources: A search in PubMed, Cumulative Index of Nursing and Allied Health Literature, and Cochrane database through December 31, 2015, was performed. Study selection and data extraction: Prospective clinical studies assessing the effects of commercially available energy drinks on BP and HR were included. A weighted mean change from baseline was calculated using the DerSimonian and Laird random-effects model for all end points. Data synthesis: In all, 15 studies were included, encompassing a total of 340, 322, and 340 individuals for SBP, DBP, and HR, respectively. SBP and DBP increased significantly by 4.44 mm Hg (95% CI = 2.71 to 6.17; Cochrane Q P = 0.001) and 2.73 mm Hg (95% CI = 1.52 to 3.95; Cochrane Q P = 0.050), respectively. HR changed nonsignificantly by 0.80 beats per minute (95% CI = -1.26 to 2.87; Cochrane Q P < 0.001). The largest change in SBP was seen with drinks administering ≥200 mg of caffeine (6.44 mm Hg, 95% CI = 4.62 to 8.27). Conclusions: Our results indicate that acute consumption of caffeinated energy drinks significantly raises SBP and DBP. Further investigation of the ingredients in energy drinks and the impact of chronic energy drink consumption is warranted.
Article
Full-text available
To determine the effects on blood pressure of modifying dietary caffeine intake in patients with mild and borderline hypertension by monitoring ambulatory and clinic blood pressure. Four way, randomised, crossover trial of four consecutive two week dietary regimens: normal diet, caffeine free diet alone, caffeine free diet with decaffeinated instant coffee, caffeine free diet with caffeinated instant coffee (instant coffee phases conducted double blind). Hospital hypertension clinic, Scotland. 52 patients (23 men; aged 26-67 years) with untreated borderline or mild hypertension (diastolic blood pressure 90-105 mm Hg) who normally drank a minimum of three cups of coffee daily. Mean ambulatory blood pressure over 24 hours; mean morning, daytime, and night time ambulatory blood pressure; sitting clinic blood pressure at 1700; plasma caffeine concentration at 1700 on the last day of each regimen. Mean 24 hour ambulatory blood pressure was not different between regimens. There was no difference in blood pressure variability between regimens. During the caffeine free diet alone morning ambulatory diastolic blood pressure was higher (2.8 mm Hg) than during the caffeine free diet with caffeinated coffee. Mean sitting clinic systolic blood pressure was higher at 1700 (4.7 mm Hg) with a caffeine free diet than with the caffeine free diet with caffeinated coffee (p less than 0.05). Dietary compliance as assessed by plasma caffeine concentration was excellent. There was no significant correlation between plasma caffeine concentration and blood pressure. Drinking caffeinated instant coffee over a two week period does not adversely influence blood pressure in patients with borderline or mild hypertension; abstinence is of no benefit.
Article
Full-text available
Uncertainty continues to surround the role of habitual caffeine consumption as a cardiovascular risk factor. The present study examined the effects of moderate caffeine intake on 24h blood pressure and heart rate in normotensive men and women. A double-blind, placebo-controlled, crossover design with counterbalancing was used, in which 36 healthy men and women participated in four experimental conditions involving the ingestion of placebo or caffeine three times daily for 6 days, followed by a seventh ('challenge') day of placebo or caffeine ingestion. When caffeine was consumed on the challenge day, blood pressure was found to be elevated immediately after caffeine ingestion and was either unchanged or decreased (hypotensive effect) after a period of abstinence from the drug. Some diminution of the peak pressor effects was found when participants ingested caffeine after habitual use of the drug (6.0/5.2 mmHg) compared with when they had been abstinent before the challenge day (7.7/6.8 mmHg). This diminution in the reaction was comparatively small, however, and pressor effects persisted on caffeine-challenge days even when caffeine was consumed on preceding days. Habitual consumption diminished, but did not eliminate, the pressor effects of caffeine. Considering the almost universal consumption of caffeine beverages, the persistent pressor effects of the drug could have important implications for cardiovascular health.
Chapter
The purpose of this chapter is to provide guidelines for the evaluation of steroid hormone secretion as they relate to cardiovascular function. As aldosterone is covered elsewhere in a discussion of renin—angiotensin—aldosterone secretion (see Atlas, this volume), this chapter will focus on glucocorticoid and gonadal steroids. Parameters relevant to cardiovascular function are emphasized rather than classical endocrinologic methods for assessing adequacy of hormone secretion. This involves somewhat different strategies, as changes in hormone secretion rather than absolute hormone levels are of considerable importance, particularly in understanding the role of behavioral variables in cardiovascular disease.
Article
Longitudinal investigations play an increasingly prominent role in biomedical research. Much of the literature on specifying and fitting linear models for serial measurements uses methods based on the standard multivariate linear model. This article proposes a more flexible approach that permits specification of the expected response as an arbitrary linear function of fixed and time-varying covariates so that mean-value functions can be derived from subject matter considerations rather than methodological constraints. Three families of models for the covariance function are discussed: multivariate, autoregressive, and random effects. Illustrations demonstrate the flexibility and utility of the proposed approach to longitudinal analysis.
Article
The catecholamines norepinephrine (NE), epinephrine (E), and dopamine (DA) are released from nerves and the adrenal into blood, cerebrospinal fluid (CSF), and urine. E is released from the adrenal medulla into the bloodstream where it acts as a hormone by stimulating α- and β-adrenergic receptors. Blood levels of E provide a good guide to adrenomedullary stimulation. A small increase in a resting subject’s blood E levels from a low normal of 20 pg/ml to a high normal of 80 pg/ml is sufficient to alter glucose metabolism. NE is also present in the adrenal, but most blood NE comes from sympathetic nerves. Blood levels of NE in the normal range for a resting, recumbent subject (150–500 pg/ml) have little physiologic effect, but blood levels of 1000 pg/ml cause subtle hemodynamic changes. NE has its major effect following release from sympathetic nerves across a synapse onto adjacent adrenergic receptors. A small fraction of this NE finds its way into the bloodstream. Blood levels of NE correlate with sympathetic nerve activity and double 5 min after one stands from a recumbent posture. Blood levels of the catecholamines are a potentially valuable guide to sympathetic nervous activity. Unfortunately, the use of catecholamine levels as a research tool has sometimes preceded adequate understanding of their chemistry or biology.
Article
The present study examined cardiovascular responses to the combination of caffeine (250mg) and mental arithmetic, cold pressor, and static exercise stressors in 48 healthy males. Subjects were tested in a within-subject, placebo-controlled, double-blind design. Repeated measurements of heart rate finger temperature, respiratory sinus arrhythmia, forearm blood flow, and blood pressure were obtained during a pre-drug resting baseline, a post-drug resting baseline, the three stressor tasks, and a recovery baselin. The primary analyses were 2(Drug) × 5(Period) × 6(Stress Order) MANCOV As using pre-drug baseline values as covariates. Significant period main effects were observed for all measures. Significant drug main effects were observed for blood pressure, finger temperature, respiratory sinus arrhythmia, and forearm blood flow. The significant changes in blood pressure and finger temperature produced by caffeine combined in an additive fashion with the effects produced by the stressors. Significantly greater increases in forearm blood flow and heart rate during mental arithmetic on the caffeine day suggested a potentiation of sympathetic, beta-adrenerigic activity. Questionnaires administered during baseline periods to assess psychological responses to stress and caffeine revealed a potentiation of anxiety and anger responses to stress on the caffeine day.
Article
The effects of caffeine on cardiovascular activity at rest and in response to psychological stress were studied in a group of 30 healthy males who were regular coffee drinkers to replicate caffeine-stress interactions found previously in caffeine-naive subjects. Measures of heart rate, blood pressure, and forearm blood flow were recorded at rest and during the performance of a stressful mental task in two separate sessions. Caffeine (250 mg) or placebo was administered double-blind in a within-subject design. Relative to placebo, caffeine had a pressor effect at rest which persisted during stress and recovery such that blood pressure during stress was higher if caffeine had been consumed. Caffeine also magnified the forearm blood flow and forearm vascular resistance responses to stress, suggestive of a synergistic interaction of caffeine and stress. Analysis of individual difference variables suggested that caffeine effects on the forearm vascular variables were greatest in subjects who were Type B and had a positive family history of hypertension. Results suggest that regular caffeine use does not necessarily lead to tolerance for caffeine-stress interactions and that certain characteristics may be associated with greater sensitivity to caffeine's effects.
Article
A sensitive and specific procedure for quantifying plasma catecholamines using on-line trace enrichment high performance liquid chromatography with electrochemical detection (HPLC-EC) is described. Plasma catecholamines are off-line extracted using aluminum oxide and then on-line enriched on cation exchange enrichment HPLC columns and back-eluted using a potassium enriched mobile phase for further separation by ion-pair, reverse phase HPLC. The salient features of this method are (1) the on-line combination of distinct HPLC retention mechanisms for enrichment and separation of the catecholamines to yield optimal assay specificity, (2) a lower working limit of detection of 25 pg norepinephrine and epinephrine per milliliter plasma based upon an assayed plasma volume of 1 ml, (3) the generation of calibration curves using standard additions to a ‘like’ matrix, (4) a high daily sample throughput due to the lack of late-eluting chromatographic interferences and (5) use of an optimized aluminum oxide prepurification procedure. The advantages of this method relative to other HPLC-EC assays for plasma norepinephrine and epinephrine are discussed as are the general considerations to be addressed when defining performance characteristics of an assay.
Article
The period of urine collection used to measure excretion of catecholamines varies in epidemiological practice. We set out to compare overnight with 24 hour collection. Twenty-four subjects each collected urine for 24 hours, with the overnight urine being separately collected. The correlation of overnight and 24 hour catecholamines was highest when both measures were standardised for creatinine excretion and when creatinine excretion was adjusted for urine flow rate. The observed correlations were 0.74 for dopamine, 0.81 for noradrenaline and 0.54 for adrenaline. The use of overnight collections may therefore require a sample size up to 1.5 times as large (for noradrenaline) or 3.4 times as large (for adrenaline) to achieve the same power as with 24 hour collections. However, the figures given exaggerate the advantage of 24 hour collections if these incorporate measurement errors that are not present in overnight collections.
Article
Measures of adrenalin, noradrenalin and cortisol excretion and self-reports of various aspects of subjective arousal obtained for 24 female and 24 male university students during five experimental and three baseline conditions were submitted to factor analysis. Two factors were extracted: a “distress factor” with high positive loadings in subjective variables indicative of negative affect and a moderately high positive loading in cortisol excretion; and an “effort factor” with high positive loadings primarily in subjective variables indicative of action-proneness and in adrenalin excretion. The dissociation between pituitary-adrenal and sympathetic-adrenal activity is illustrated by data from (1) a monotonous vigilance task inducing both effort and distress, and a concomitant increase of adrenalin as well as cortisol excretion, and (2) a self-paced reaction time task inducing effort but no distress, and a concomitant increase in adrenalin but decrease in cortisol excretion.
Article
Using a double-blind, randomized, cross-over protocol, we studied the effect of a single dose of oral caffeine on plasma renin activity, catecholamines and cardiovascular control in nine healthy, young, non-coffee drinkers maintained in sodium balance throughout the study period. Caffeine (250 mg) or placebo was administered in a methylxanthine-free beverage to overnight-fasted supine subjects who had had no coffee, tea or cola in the previous three weeks. Caffeine increased plasma renin activity by 57 per cent, plasma norepinephrine by 75 per cent and plasma epinephrine by 207 per cent. Urinary normetanephrine and metanephrine were increased 52 per cent and 100 per cent respectively. Mean blood pressure rose 14/10 mm Hg one hour after caffeine ingestion. There was a slight fall and then a rise in heart rate. Plasma caffeine levels were usually maximal one hour after ingestion but there was considerable individual variation. A 20 per cent increase in respiratory rate correlated well with plasma caffeine levels. Under the conditions of study caffeine was a potent stimulator of plasma renin activity and adrenomedullary secretion. Whether habitual ingestion has similar effects remains to be determined.
Article
The elimination of caffeine from saliva was compared in groups of healthy smokers (n = 13) and nonsmokers (n = 13). Mean caffeine t1/2 in smokers (3.5 hr) was shorter than that in the nonsmokers (6.0 hr). The body clearance of caffeine in the smokers (155 +/- 16 ml . kg-1 . hr-1) was greater than that in the nonsmokers (94 +/- 18 ml . kg-1 . hr-1) (p less than 0.05). No significant difference was noted in the apparent volume of distribution in smokers (720 +/- 67 ml . kg-1) and nonsmokers (610 +/- 80 ml . kg-1). These differences probably reflect the induction of hepatic aryl hydrocarbon hydroxylase (AHH) activity in smokers. The increased clearance of caffeine by smokers may contribute to the higher consumption of coffee reported to occur in this group.
Article
In this review, the importance of smooth muscle cell proliferation as a key event in atherogenesis is emphasized. To convey a better understanding of the factors which can influence smooth muscle cell proliferation, some current information about arterial cell biology was summarized first. Clearly, knowledge concerning the normal characteristics of arterial endothelial and smooth muscle cells must form the basis for any hypothesis concerning the proliferation of smooth muscle cells observed in atherosclerosis. The recognition that smooth muscle proliferation is a sine qua non of atherogenesis is relatively recent. Our ability to focus on this process has been heightened by the development of the 3 hypotheses discussed: the response to injury hypothesis, the monoclonal hypothesis and the clonal selection hypothesis. It should be apparent that the 3 hypotheses are not necessarily mutually exclusive; in fact, in some interesting ways, they are complementary. Each focuses on different aspects of smooth muscle proliferation, and each raises questions that must be seriously considered to better understand the cause and pathogenesis of atherosclerosis. The phenomenon of arterial smooth muscle cell proliferation undoubtedly has much in common with cell proliferation in other tissues. Therefore, fundamental research concerning factors that control cell proliferation will be essential to an understanding of atherogenesis. In addition, research concerning endothelial injury and the response of thrombocytes and arterial cells to this injury will be important, irrespective of what particular hypothesis is proposed. In conclusion, atherosclerosis is a broad category of disease thay may affect different parts of the arterial system in different ways. It may result from endothelial 'injury', which may have different manifestations in different sites in different arteries, but which produces common alterations in the endothelium and the smooth muscle which result in the proliferative smooth muscle response, increased connective tissue formation and lipid deposition that we call atherosclerosis. (131 references)
Article
The associations of diastolic blood pressure (DBP) with stroke and with coronary heart disease (CHD) were investigated in nine major prospective observational studies: total 420,000 individuals, 843 strokes, and 4856 CHD events, 6-25 (mean 10) years of follow-up. The combined results demonstrate positive, continuous, and apparently independent associations, with no significant heterogeneity of effect among different studies. Within the range of DBP studied (about 70-110 mm Hg), there was no evidence of any "threshold" below which lower levels of DBP were not associated with lower risks of stroke and of CHD. Previous analyses have described the uncorrected associations of DBP measured just at "baseline" with subsequent disease rates. But, because of the diluting effects of random fluctuations in DBP, these substantially underestimate the true associations of the usual DBP (ie, an individual's long-term average DBP) with disease. After correction for this "regression dilution" bias, prolonged differences in usual DBP of 5, 7.5, and 10 mm Hg were respectively associated with at least 34%, 46%, and 56% less stroke and at least 21%, 29%, and 37% less CHD. These associations are about 60% greater than in previous uncorrected analyses. (This regression dilution bias is quite general, so analogous corrections to the relations of cholesterol to CHD or of various other risk factors to CHD or to other diseases would likewise increase their estimated strengths.) The DBP results suggest that for the large majority of individuals, whether conventionally "hypertensive" or "normotensive", a lower blood pressure should eventually confer a lower risk of vascular disease.
Article
Caffeine produces an acute increase in blood pressure in the research laboratory, but its effect on the ambulatory blood pressure during normal daily activities is unknown. In 25 normotensive, caffeine-naive subjects, daily administration of 400 mg caffeine produced a small increase (+3/+3 mm Hg, P less than .001) in ambulatory daytime blood pressure on the first day, with values returning to baseline by the third day. The initial rise in blood pressure was associated with a fall in heart rate (-3 beats/min, P less than .02). Readings taken the morning following the first day of caffeine ingestion did not show any persistent effect of caffeine on blood pressure. A 400 mg dose of caffeine causes a small increase in daytime ambulatory blood pressure, but tolerance develops with daily caffeine consumption. Infrequent ingestion of caffeine may cause a transient rise in blood pressure which is unlikely to be harmful to an individual but might influence the diagnosis of hypertension in a patient with a borderline elevated blood pressure.
Article
The effects of a moderate dose of caffeine on cardiovascular and neuroendocrine stress reactivity were examined in 25 healthy male subjects selected as habitual or light consumers of caffeine. Measurements were taken under resting conditions before and after administration of caffeine (3.5 mg/kg) or placebo, during a stressful laboratory task, and in a post-stress recovery period. Caffeine elevated blood pressure and plasma norepinephrine levels at rest, effects which added significantly to the effects of stress. Caffeine potentiated stress-related increases in plasma epinephrine and cortisol stress, more than doubling the responses observed in the control condition. These effects were present in both habitual and light consumers and level of habitual caffeine consumption did not affect their magnitude. Results indicate that caffeine can potentiate both cardiovascular and neuroendocrine stress reactivity and that the habitual use of caffeine is not necessarily associated with the development of tolerance to these effects.
Article
The ambulatory blood pressure and heart rate of twelve healthy volunteers were monitored on two separate days in the participants' work environment. All subjects were studied in a double-blind crossover design while they consumed caffeinated or decaffeinated coffee. We examined them at rest, during a standardized mental arithmetic task, and for 6 h of ambulatory monitoring in their regular work setting (research facility and hospital). On days of drinking caffeinated coffee, both systolic and diastolic blood pressure were consistently elevated at all time points (P less than .0005). In response to the mental arithmetic task, the increase in systolic blood pressure over the resting value was particularly exaggerated on caffeinated coffee (P = .0003). For heart rate, there were no effects from caffeine. The study demonstrates that the blood pressure-elevating effects of caffeine, well-known from laboratory studies, are sufficiently robust to be evident in patients' uncontrolled work environments. It implies the importance of caffeine restriction for hypertensive patients. It also indicates the utility of ambulatory blood pressure techniques in studying the blood pressure effects of various nutritional factors taken ad lib in the real world.
Article
Prerequisite to the use of ambulatory blood pressure monitors in epidemiologic research is demonstration of a satisfactory level of accuracy and precision. Previous evaluations of these devices raise a number of methodological concerns which complicate interpretation of their findings. Also, important issues regarding the precision of blood pressure measurements and the identification of factors associated with measurement inaccuracies remain unaddressed. To assess the accuracy and precision of the Accutracker ambulatory blood pressure monitor, we obtained five serial estimates of resting blood pressure on 120 ambulatory subjects in The Johns Hopkins Medical Institutions in 1987. Two Accutrackers and two manual observers independently recorded blood pressure with the order determined at random. The fourth observer in each sequence obtained a replicate measurement. For both systolic and diastolic blood pressures, the mean difference between Accutracker and manual measurements was less than 3 mmHg for each pairwise comparison. Scatter plots and regression analyses demonstrated that both Accutrackers tended to underestimate high systolic and diastolic blood pressures. In bivariate and multivariate analyses, increased age was significantly associated with underestimation of systolic blood pressures by both Accutrackers. With respect to the precision of blood pressure measurement, no significant differences were present among the four observers. In summary, our data suggest that the Accutracker has satisfactory accuracy and precision, but that accuracy is not uniform across patient subgroups.
Article
The effect of caffeine on blood cortisol levels and blood pressures was examined during rest and in response to a challenging psychomotor task in men with a low versus high risk of essential hypertension. Thirty-four healthy men ages 21-35 years were selected such that 17 were at high risk for hypertension (positive parental history and screening blood pressures of 135/85-155/95 mm Hg) and 17 were at low risk (negative parental history and no pressures above 132/84 mm Hg). Testing consisted of quiet rest (20 minutes); oral placebo (grapefruit juice) or caffeine administration (3.3 mg/kg in grapefruit juice); rest during a postdrug absorption period (40 minutes); work on an unsignalled simple reaction time task (15 minutes); and quiet rest (20 minutes). Blood pressures were recorded at 2-minute intervals, and blood samples were withdrawn via an indwelling catheter at the end of the baseline, drug absorption, task, and recovery periods. The combination of task plus caffeine produced the highest blood pressures in men at risk for hypertension. Cortisol levels were found to be sustained during rest in members of the high risk group after they had consumed caffeine, whereas members of the low risk group showed a modest decline. The high risk subjects also showed a significant rise in cortisol during (+3.7 micrograms/dl) and after (+4.0 micrograms/dl) work on the reaction time task after caffeine consumption.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
Although habitual caffeine users ingest the drug repeatedly throughout each day, the persistence of caffeine's known cardiovascular effects with such repeated use has not been investigated. Blood pressure and heart rate were measured under resting conditions in 10 healthy, male coffee or tea drinkers for 2 hours following a pretreatment dose of caffeine (125 mg) on two separate days after overnight abstinence. Either a second caffeine dose or placebo was administered and measurements continued for 1.5 hours. Compared to placebo, the second dose of caffeine produced significant increases in heart rate and diastolic and mean arterial, but not systolic, blood pressures. The results suggest that the cardiovascular effects of caffeine may persist throughout the day with repeated administration of moderate amounts of caffeine. Habitual caffeine use does not necessarily lead to complete tolerance, which suggests that caffeine's cardiovascular effects could contribute to an increased risk of cardiovascular disease.
Article
The effects of caffeine on cardiovascular responses to a mental arithmetic task were assessed using a between-subjects, double-blind design. Thirty-six male undergraduates were randomly assigned to either a placebo group or a group which received 250mg of caffeine. Repeated measurements of systolic and diastolic blood pressure (SBP, DBP), heart rate (HR), digital blood volume pulse (DBVP), and finger pulse transit time (FPTT) were obtained during a predrug baseline, a postdrug resting period, and a mental arithmetic task. Significant Period (i.e., stress) effects were observed on all measures, except DBVP which revealed a marginally significant Period effect. Significant main effects of Drug were observed on DBP and DBVP. There were no significant Drug x Period interactions. These results indicate that the increases in DBP and the decreases in DBVP produced by caffeine were additive with effects produced by stress.
Article
Caffeine use during exposure to mental stress is an extremely common occurrence. Because both have been shown to alter blood pressure (BP) and its underlying hemodynamic mechanisms, the potential exists for additive or even synergistic effects. Changes in heart rate, BP and noninvasive thoracic impedance measures of left ventricular function were examined in young men (ages 20 to 36) at rest and during a demanding behavioral task performed 40 minutes after predosing with caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee) or placebo in a double-blind crossover design. All subjects were healthy young men without history of cardiovascular disease, regular use of nicotine, recreational or prescription drugs or caffeine intolerance. Caffeine abstinence was required for 12 hours before each test session. Systolic and diastolic BP were elevated by both caffeine and the behavioral task alone (p less than 0.01 for each); when combined, caffeine's pressor effects were additive to those of the behavioral task. However, caffeine's pressor effect was produced by different mechanisms depending on the behavioral state. Caffeine increased systemic vascular resistance (p less than 0.01) under resting conditions, but it enhanced cardiac output (p less than 0.01) during behavioral arousal associated with the task. The combined influence of caffeine and the task increased the number of men in whom peak systolic BP reached hypertensive levels, and also synergistically increased cardiac minute work (p less than 0.01) and the rate-pressure product estimate of myocardial oxygen demand (p less than 0.05). Implications of these findings are discussed for long standing theoretical disputes regarding caffeine, its health consequences, and for methodologic issues in behavioral and clinical studies.
Article
Systolic (SBP) and diastolic (DBP) blood pressure levels generated by a new noninvasive ambulatory monitor, the Accutracker 102, were compared in the laboratory with intra-arterial pressure levels in 12 normotensive men, and with stethoscopic auscultatory determinations in 27 normotensive and hypertensive men and women over a wide range of within-subject pressure variations. In 11 subjects, its performance was also compared with another ambulatory monitor, the Spacelabs Model 5200. Highly positive correlations with both the intra-arterial (median r=+.90 for SBP, +.92 for DBP) and the stethoscopic standards (median r=+.93 for SBP, +.88 for DBP) were obtained using Accutracker's automatic readings (digital readout), while slightly higher correlations were obtained with hand-scoring of recorded data. The Spacelabs BP monitor also yielded readings that were highly correlated with stethoscopic readings (median r=+.83 for SBP, +.77 for DBP), although in 3 of the 11 subjects the Accutracker correlations were substantially higher than the Spacelabs correlations. Despite their generally good tracking of changes in pressure, both ambulatory monitors yielded absolute values in many subjects that differed by 5 mmHg or more from stethoscopic levels. The Accutracker's SBP levels were consistently too high and its DBP levels were occasionally too low, while Spacelabs' SBP and DBP values were too high and too low with equal frequency. However, mean deviation scores for each patient calculated from 5 concurrent ambulatory monitor and stethoscopic readings were shown to yield relatively stable correction factors for use when comparison with clinical standards is desired.
Article
The purpose of this study was to examine the variability of 24-hour urinary and serum creatinine levels and creatinine clearance in normal subjects and to develop nomograms for assessing the adequacy of 24-hour urine collections. The data were from a longitudinal research program examining biochemical, hormonal, and hemodynamic parameters in normal subjects. Bloods and 24-hour urine specimens were collected at yearly intervals from 144 people over 9 years, and from an additional 110 over 4 years. The subjects were originally distributed equally by sex, race (black, white), blood pressure (three groups within the normal range), and age (three groups). Men had 33% higher urine creatinines per weight than females (P less than 0.001). Because they only had 8% higher creatinine clearance per weight they also exhibited 21% higher serum creatinine. Blacks had 5% higher urine creatinine per weight than whites, perhaps reflecting greater muscle mass, but their serum creatinines were not different from those of whites, reflecting a 5% higher creatinine clearance by weight than whites (P less than 0.01). Interestingly, older black men (age greater than 60 years) had 12% lower urine creatinine/weight than younger black men (P less than 0.001). They also had 13% lower creatinine clearance by weight, resulting in no net difference in serum creatinine. The intraindividual variability in urine creatinine excretion averaged 15% and did not differ between blacks and whites and men and women. The within individual variability in serum creatinine and creatinine clearance averaged 14 and 20%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
Caffeine (3.3 mg/kg) was tested against a placebo in 20 male medical students during periods of low (no exams) versus high (final exams) work stress. On each of 8 test days, heart rate and blood pressure were measured at baseline and over a 40-min postdrug interval; immediately afterward, blood was drawn to test plasma cortisol and serum lipid concentrations. Exams increased heart rate (p less than .005) and systolic blood pressure (p less than .02). Caffeine decreased heart rate (p less than .0001) and increased systolic blood pressure (p less than .005), diastolic blood pressure (p less than .0001), plasma cortisol levels (p less than .01), and serum cholesterol levels (p less than .02). Caffeine effects were additive with those of exams, and together they increased the number of men showing systolic blood pressures in the borderline hypertensive range. Thus, caffeine use during periods of increased occupational stress may enhance the cumulative stress response.
Article
The mechanisms by which caffeine typically elevates blood pressure (BP) in humans have not been previously examined using a placebo-controlled design. Accordingly, oral caffeine (3.3 mg/kg body weight, equivalent to 2 to 3 cups of coffee) was given on 2 days and a placebo was given on 1 day to 15 healthy young men using a double-blind, crossover procedure. All 3 test sessions were held during a week of caffeine abstinence. Multiple measurements were made on subjects at rest (baseline values) and over a 45-minute interval after ingestion of caffeine for BP, heart rate, systolic time intervals and thoracic impedance measures of ventricular function. Baseline measurements were highly reliable for each subject across all sessions and yielded means for placebo vs caffeine days that were not different. Caffeine increased systolic and diastolic BP (p less than 0.01) and decreased heart rate (p less than 0.05). The pressor effect was due to progressively increased systemic vascular resistance and resulted in greater stroke work (p less than 0.01). There was no indication that caffeine increased cardiac output or contractility. These actions of caffeine were replicable when each caffeine day was tested separately against the placebo day. These results suggest that caffeine use by persons with cardiovascular diseases should be examined to determine whether caffeine's enhancement of vascular resistance may contribute to systematic hypertension and/or create excessive demands for cardiac work.
Article
The effect of chronic (greater than 3 months) administration of low-dose oestrogen-containing (less than 50 micrograms oestrogen) oral contraceptives (OCS) on the pharmacokinetics of caffeine has been examined in a treated females matched with 9 non-smoking, drug-free, healthy control females of similar age, weight and ethnic origin. Each subject received 162 mg caffeine base orally after an overnight fast. OCS subjects had a prolonged elimination half-life of caffeine, (mean 7.88 h vs 5.37 h in the controls). This was the result of marked impairment of the plasma clearance of caffeine (1.05 vs 1.75 ml/min/kg, respectively) with no change in apparent volume of distribution (0.685 in OCS vs 0.7501/kg in the control group). The absorption parameters determined were peak plasma caffeine concentration (3.99 vs 4.09 micrograms/ml) and time to peak concentration after drug administration (1.52 vs 0.79), which was moderately prolonged in OCS users. Thus, caffeine clearance, previously reported to be a specific marker of cytochrome P-448 activity in man, is decreased by chronic OCS use. This suggests that OCS may cause significant impairment of this enzyme activity as assessed in vivo. With chronic caffeine consumption, OCS users are predicted to have an increased steady-state plasma caffeine concentration as compared to non-OCS users.
Article
The effects of caffeine on cardiovascular activity at rest and during psychological stress were examined in 33 healthy male college students who did not normally ingest caffeinated products. Caffeine (250 mg) and placebo were administered double-blind in separate sessions. Heart rate, blood pressure, and forearm blood flow and vascular resistance were assessed at rest and during the stressful, competitive performance of a mental arithmetic task. Comparisons of caffeine and placebo sessions revealed that caffeine elevated resting blood pressure 4–6 mmHg, an effect which added to the elevation produced by stress. Caffeine did not affect resting forearm blood flow but potentiated the forearm blood flow response to stress and led to higher levels of flow during stress. No caffeine effects appeared in heart rate or in task performance. Family history of hypertension and Type A behavior were examined as potential modulating factors of caffeine effects but results were generally negative. These results suggest possible mechanisms through which caffeine could enhance the pathogenic effects of stress on the cardiovascular system.
Article
: Caffeine and psychologic stress have similar physiologic effects. Moderate doses of caffeine were found to elevate blood pressure in healthy, young males during periods of rest and stress. Blood pressure during stress was also significantly higher after caffeine had been consumed. The elevation of blood pressure due to caffeine appears to add to that elicited by stress. The implications of these results for prevention and treatment of cardiovascular disease are discussed. Copyright (C) 1983 by American Psychosomatic Society
Article
Acute caffeine in subjects who do not normally ingest methylxanthines leads to increases in blood pressure, heart rate, plasma epinephrine, plasma norepinephrine, plasma renin activity, and urinary catecholamines. Using a double-blind design, the effects of chronic caffeine administration on these same variables were assessed. Near complete tolerance, in terms of both humoral and hemodynamic variables, developed over the first 1-4 d of caffeine. No long-term effects of caffeine on blood pressure, heart rate, plasma renin activity, plasma catecholamines, or urinary catecholamines could be demonstrated. Discontinuation of caffeine ingestion after 7 d of administration did not result in a detectable withdrawal phenomenon relating to any of the variables assessed.
Article
The effect of OCS on the disposition and elimination of caffeine was examined. Caffeine (250 mg) was administered orally to 13 healthy males, nine healthy females taking no OCS, and nine healthy females on OCS. The t1/2 (beta) was significantly prolonged in women on OCS (10.7 +/- 3.0 hr vs. 6.2 +/- 1.6) (p less than 0.001) as compared to women taking no OCS. Women on OCS had a significantly lower total plasma clearance (0.79 +/- 0.21 ml/min/kg vs. 1.3 +/- 0.35) and free clearance (1.12 +/- 0.28 ml/min/kg vs. 1.97 +/- 0.57) that women not taking OCS. Volumes of distribution and plasma binding were similar in both groups of females. When women taking no OCS were compared with men, all pharmacokinetic parameters were similar except for volume of distribution, which was significantly larger in the women (p less than 0.05). We conclude that OCS impair the elimination of caffeine.
Article
Type A and Type B university students of both sexes performed a choice-reaction task that was designed to allow each subject at his/her preferred pace and to maintain control over the stimulus rate throughout a period of sustained work. Type As selected faster stimulus rates, and coped more effectively with their total work load than did Type Bs with their lesser load. The superior achievement of the Type A group was not reflected in self-reports of subjective arousal, not in physiological arousal indices, e.g. heart rate, and catecholamine and cortisol excretion. Comparison between sexes (Type A and Type B persons) showed that males reported exerting significantly more effort than females and, accordingly, secreted significantly more adrenaline. A common charcteristic of all groups was the dissociation between sympathetic-adrenal and pituitary-adrenal arousal, catecholamine output increasing and cortisol output decreasing in response to the achievement demands. The rise in catecholamine output was interpreted in terms of the mobilization of effort induced by the task, and the decrease of cortisol in terms of the high level of personal control in performing the task.
Article
The inherent variability of blood pressure means that the accuracy of a small number of clinic readings in estimating the true blood pressure is limited. In many patients, a clinic visit provokes an increase in blood pressure such that they may be misclassified as being hypertensive (white coat hypertension). This applies to about 20% of hypertensives. Ambulatory monitoring has the potential to overcome these limitations. The white coat effect may still occur in patients taking antihypertensive medications, although in some cases medication may lower the clinic pressure without affecting the ambulatory pressure. The diurnal rhythm of blood pressure is another major source of variability and is influenced by both extrinsic and intrinsic factors. Its pathologic significance is unclear. Antihypertensive medication generally lowers the set point of blood pressure but has relatively little effect on variability.
Article
Caffeine is known to raise blood pressure (BP). We examined a single oral dose of caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee) on BP in 18 hypertensive (HTN) and 12 age-matched, normotensive (NT) men for 3 h. Systolic BPs were significantly higher after caffeine for both groups (P < .001) for the entire 3 h. The HTN group showed persistent elevation in diastolic BP for 3 h, whereas the increment of diastolic BP became smaller in the NT group 90 min after caffeine ingestion. Our results suggest that caffeine consumption may affect both diagnosis and treatment of hypertension and abstinence from caffeine may be beneficial, especially for hypertensive individuals.
Article
The effect of caffeine on neuroendocrine stress responses in the workplace was studied in 14 habitual coffee drinkers. Urinary catecholamine and cortisol levels were measured on 2 study days, in a 4-hour interval from morning until noon, while participants performed their normal work-related activities. Caffeine (300 mg) or placebo was administered blind at the beginning of study intervals, after overnight caffeine abstinence. Retrospective mood and symptom ratings were collected at the end of each morning. Caffeine elevated urinary epinephrine levels during work by 37% but did not affect norepinephrine or cortisol levels. Subjective reports suggest that caffeine abstinence was associated with symptoms of caffeine withdrawal by the end of the morning. Effects included higher ratings of sleepiness, lethargy, and headache and a reduced desire to socialize. Results suggest caffeine may increase the activity of the sympathetic adrenal-medullary system during everyday activities in the work environment. This action may potentiate psychophysiological responses elicited by occupational stressors.