Cardiovascular effects of coffee: is it a risk factor?

Evaluation of the Caffeine Content in Servings of Popular Coffees in Terms of Its Safe Intake-Can We Drink 3-5 Cups of Coffee per Day, as Experts Advise?

The spreading knowledge of the health benefits of coffee and the development of gastronomy with a wide range of coffees prompt an evaluation of their caffeine content in terms of safe intake. The study analyzed the caffeine content of popular coffees in comparison with recommendations for a safe single dose (200 mg) and daily caffeine intake (400 mg), and guidelines for drinking 3-5 cups of coffee per day. A total of 299 coffee samples from franchise shops and homemade coffees were tested. The "takeaway" coffees had a three times higher mean caffeine content (p < 0.005) compared to homemade coffees. Americano coffee was the "strongest" (143 mg caffeine/serving on average), while coffee prepared by pouring hot water over one teaspoon of ground coffee was the "lightest" (23 mg caffeine/serving on average) (p < 0.05). Over 200 mg of caffeine per serving was found in 4% of samples. Over 400 mg of caffeine would be consumed by people drinking "on the go" 4-5 servings of many types of coffee, except espresso. In this respect, homemade coffees are safer. Therefore, recommendations on drinking coffee should be more practical, and indicate not only the number of cups, but also the "strength" of various types of coffee, in order to avoid the regular intake of high amounts of caffeine.

The association between caffeine exposure during pregnancy and risk of gestational hypertension/preeclampsia: A meta-analysis and systematical review

BACKGROUND

The potential effect of caffeine exposure during pregnancy on gestational hypertension (GH)/preeclampsia has attracted attention but remains unclear.

METHODS

A systematic literature search of PubMed, Embase, and Cochrane Library databases was performed until March 2022. Observational studies assessing the association between caffeine exposure during pregnancy and the risk of GH/preeclampsia were included. The study protocol was registered in PROSPERO: CRD42022322387.

RESULTS

Ten studies involving 114 984 pregnant women (2548 diagnosed with GH and 2473 diagnosed with preeclampsia) were included. Comparing caffeine exposure with noncaffeine exposure, no significant association was found between caffeine exposure during pregnancy and the risk of GH (odds ratio [OR] = 0.99, 95% confidence interval [CI]: 0.90-1.08, p = 0.800) and preeclampsia (OR = 1.13, 95% CI: 0.97-1.31, p = 0.114). Subgroup analyses comparing low to moderate doses with no/lowest doses showed that caffeine exposure during pregnancy was not significant associated with GH (OR = 1.00, p = 0.987) or preeclampsia (OR = 1.03, p = 0.648). Besides, subgroup analyses comparing high doses with no/lowest doses showed that caffeine exposure during pregnancy was not significant associated with GH (OR = 1.06, p = 0.623) or preeclampsia (OR = 1.18, p = 0.192).

CONCLUSION

This study found that caffeine exposure during pregnancy was not significantly associated with the risk of GH/preeclampsia.

Caffeine and rheumatoid arthritis: A complicated relationship

The current ideal goal of rheumatoid arthritis (RA) management is to resolve joint and systemic inflammation by using pharmacological interventions, assuming this will correspondingly lead to overall well-being. Nonetheless, it has emerged that a substantial number of RA patients do not reach optimal disease control. Thus suggesting the holistic management of subjective symptoms might be overlooked. This poses significant medical challenges; hence the proposal of incorporating lifestyle interventions as part of a multidimensional approach. Among these aspects, both patients and physicians perceive the important role of nutrition. This review shall examine how caffeine, one of the most studied bioactive components of the most widely consumed beverages, may potentially interfere with RA management. In particular, the mechanism by which caffeine affects RA pathogenesis, as a trigger for RA onset or flare, including its influence on rheumatic drug metabolism and the most common RA comorbidities and constitutional symptoms are outlined, highlighting important knowledge gaps and unmet research needs.

Effect of Antioxidant Addition on Milk Beverage Supplemented with Coffee and Shelf-life Prediction

This study aimed to extend the shelf-life of coffee-containing milk beverage by adding Theobroma cacao (cacao nibs) extract. To prepare the beverage sample containing cacao nibs extract, 0.8% cacao nibs hydrothermal extract was aseptically injected. Qualitative changes in the beverage samples, including antioxidant effect, peroxide value (POV), caffeine content, and sensory parameters were monitored regularly during storage at 10°C, 20°C, and 30°C for 4 wk. The inclusion of cacao nibs extract produced higher antioxidant activity compared to the control. As the storage temperature increased, the POV of all samples increased. Samples with cacao nibs extract generally displayed lower POV than the control. The caffeine content of all samples tended to decrease during storage, with the decrease accentuated by higher storage temperatures. In the shelf-life prediction using the Arrhenius model, the kinetic regressions of the cacao nibs extract-added sample and control were Y POV=1.2212X-2.1141 (r2=0.9713) and Y POV=1.8075X-2.0189 (r2=0.9883), respectively. Finally, the predicted shelf-life of cacao nibs-added group and control to reach the quality limit (20 meq/kg POV) were approximately 18.11 and 12.18 wk, respectively. The results collectively indicate that the addition of cacao nibs extract extends the shelf-life of the coffee-containing milk beverage and heightened the antioxidant effect.

Caffeine induces endothelial tissue factor expression via phosphatidylinositol 3-kinase inhibition

Tissue factor (TF) is the key activator of coagulation and is involved in acute coronary syndromes. Caffeine is often reported to increase cardiovascular risk; however, its effect on cardiovascular morbidity and mortality is controversial. Hence, this study was designed to investigate the impact of caffeine on endothelial TF expression in vitro. Caffeine concentration-dependently enhanced TF protein expression and surface activity in human endothelial cells stimulated by tumour necrosis factor (TNF)-α or thrombin. Caffeine inhibited phosphatidylinositol 3-kinase (PI3K) activity and this effect was comparable to that of the known PI3K inhibitor LY294002. Consistently, treatment of endothelial cells with LY294002 enhanced TNF-α induced TF expression to a similar extent as caffeine, and adenoviral expression of the active PI3K mutant (p110) reversed the effect of both caffeine and LY294002 on TF expression. Caffeine and LY294002 increased DNA binding capacity of the transcription factor nuclear factor κB, whereas the activation pattern of mitogen-activated protein kinases (MAPK) remained unaltered. Luciferase reporter assay revealed a caffeine dependent activation of the TF promoter, and RT-PCR revealed a dose dependent increase in TF mRNA levels when stimulated with caffeine in the presence of TNF-α. In conclusion, caffeine enhances TNF-α-induced endothelial TF protein expression as well as surface activity by inhibition of PI3K signalling. Since the caffeine concentrations applied in the present study are within the plasma range measured in humans, our findings indicate that caffeine enhances the prothrombotic potential of endothelial cells and underscore the importance of PI3K in mediating these effects.

Resting heart rate on the decline: the Tromsø Study 1986-2007

BACKGROUND

We examined secular changes in resting heart rate (RHR) and their relationship with changes in other cardiovascular risk factors in adult men and women over a 22-year period.

METHODS

A single-centre population-based longitudinal study comprised 30,699 men and women aged 30-89 years who participated in at least one of the 1986, 1994, 2001 and 2007 surveys of the Tromsø Study, Tromsø, Norway.

RESULTS

During the study period, the age-adjusted means of RHR declined from 73.4 to 64.7 beats per minute (b.p.m.) in men, and from 78.3 to 66.4 b.p.m. in women. The decline was persistent from one survey to the next and was of similar size in both sexes and for all age groups and birth cohorts. RHR declined gradually over time for different levels of cardiovascular risk factors, and it declined more in those who moved from adverse to favourable values or categories of blood pressure, total and high-density lipoprotein cholesterol, triglycerides, body mass index, smoking and physical activity, and those who started to take blood pressure medication. The strongest predictors of individual decline in RHR were decrease in systolic blood pressure and triglycerides, increase in physical activity, taking blood pressure treatment and smoking cessation.

CONCLUSION

A considerable decline in RHR has occurred in Tromsø over the past two decades in men and women of all ages. The decline is partly related to changes in several cardiovascular risk factors, and reasons behind this need to be further elucidated. The findings suggest that new definitions of normal RHR may be needed.

Coffee, tea, and caffeine consumption and prevention of late-life cognitive decline and dementia: a systematic review

A prolonged preclinical phase of more than two decades before the onset of dementia suggested that initial brain changes of Alzheimer's disease (AD) and the symptoms of advanced AD may represent a unique continuum. Given the very limited therapeutic value of drugs currently used in the treatment of AD and dementia, preventing or postponing the onset of AD and delaying or slowing its progression are becoming mandatory. Among possible reversible risk factors of dementia and AD, vascular, metabolic, and lifestyle-related factors were associated with the development of dementia and late-life cognitive disorders, opening new avenues for the prevention of these diseases. Among diet-associated factors, coffee is regularly consumed by millions of people around the world and owing to its caffeine content, it is the best known psychoactive stimulant resulting in heightened alertness and arousal and improvement of cognitive performance. Besides its short-term effect, some case-control and cross-sectional and longitudinal population-based studies evaluated the long-term effects on brain function and provided some evidence that coffee, tea, and caffeine consumption or higher plasma caffeine levels may be protective against cognitive impairment/decline and dementia. In particular, several cross-sectional and longitudinal population-based studies suggested a protective effect of coffee, tea, and caffeine use against late-life cognitive impairment/decline, although the association was not found in all cognitive domains investigated and there was a lack of a distinct dose-response association, with a stronger effect among women than men. The findings on the association of coffee, tea, and caffeine consumption or plasma caffeine levels with incident mild cognitive impairment and its progression to dementia were too limited to draw any conclusion. Furthermore, for dementia and AD prevention, some studies with baseline examination in midlife pointed to a lack of association, although other case-control and longitudinal population-based studies with briefer follow-up periods supported favourable effects of coffee, tea, and caffeine consumption against AD. Larger studies with longer follow-up periods should be encouraged, addressing other potential bias and confounding sources, so hopefully opening new ways for diet-related prevention of dementia and AD.

Effect of Caffeine Chronically Consumed During Pregnancy on Adenosine A1 and A2A Receptors Signaling in Both Maternal and Fetal Heart from Wistar Rats

Background: Caffeine is the most widely consumed psychoactive substance in the world, even during pregnancy. Its stimulatory effects are mainly due to antagonism of adenosine actions by blocking adenosine A₁ and A_2A receptors. Previous studies have shown that caffeine can cross the placenta and therefore modulate these receptors not only in the fetal brain but also in the heart. Methods: In the present work, the effect of caffeine chronically consumed during pregnancy on A₁ and A_2A receptors in Wistar rat heart, from both mothers and their fetuses, were studied using radioligand binding, Western-blotting, and adenylyl cyclase activity assays, as well as reverse transcription polymerase chain reaction. Results: Caffeine did not significantly alter A₁R neither at protein nor at gene expression level in both the maternal and fetal heart. On the contrary, A_2AR significantly decreased in the maternal heart, although mRNA was not affected. Gi and Gs proteins were also preserved. Finally, A₁R-mediated inhibition of adenylyl cyclase activity did not change in the maternal heart, but A_2AR mediated stimulation of this enzymatic activity significantly decreased according to the detected loss of this receptor. Conclusions: Opposite to the downregulation and desensitization of the A₁R/AC pathway previously reported in the brain, these results show that this pathway is not affected in rat heart after caffeine exposure during pregnancy. In addition, A_2AR is downregulated and desensitized in the maternal heart, suggesting a differential modulation of these receptor-mediated pathways by caffeine.

Café e saúde humana: um enfoque nas substâncias presentes na bebida relacionadas às doenças cardiovasculares

O café é a bebida mais consumida no Brasil e no mundo ocidental. O fato de ser uma bebida tão popular, aliado à sua importância econômica, explica o interesse por estudos sobre o café, desde a sua composição até seus efeitos na saúde humana. Dentre as diversas substâncias presentes na composição química do café, além dos nutrientes, destacam-se a cafeína, os diterpenos cafestol e kahweol e os ácidos clorogênicos, o que faz do café uma importante fonte dietética destes compostos. Muitos estudos têm verificado a influência de seus constituintes na saúde, principalmente a cafeína vs a elevação da pressão arterial; o cafestol e o kahweol vs a dislipidemia; e ácidos clorogênicos vs proteção cardiovascular, por suas propriedades antioxidantes. Este artigo tem como objetivo apresentar de forma sucinta a importância da bebida e sua composição química, os mecanismos fisiológicos envolvidos na elevação da pressão arterial e do colesterol sérico atribuíveis ao café, bem como estudos selecionados que verificaram a associação do consumo da bebida com estas doenças cardiovasculares.

Nuclear factor-kappaB/signal transducers and activators of transcription-1-mediated inflammatory responses in lipopolysaccharide-activated macrophages are a major inhibitory target of kahweol, a coffee diterpene

Diterpene kahweol, one of the major components in coffee, has anti-cancer, anti-oxidative, and anti-inflammatory activity. In this study, we explored the molecular mechanism of the anti-inflammatory activity of kahweol. Lipopolysaccharide (LPS)-activated RAW264.7 cells were used to explore the modulatory role of kahweol on nitric oxide (NO) and prostaglandin E(2) (PGE(2)) production and the activation of signaling proteins and transcription factors using immunoblotting and reverse transcription-polymerase chain reaction (RT-PCR). Kahweol diminished both the production of NO and PGE(2) and the mRNA expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2. Interestingly, this compound suppressed the phospho-signal transducers and activators of transcription (STAT)-1 and p65/nuclear factor (NF)-kappaB levels in the nucleus but not c-Jun and c-fos. In conjunction, the phosphorylation of Akt and Janus kinase (JAK)2 also decreased. Therefore, our data suggest that kahweol in coffee may be an anti-inflammatory modulator with NF-kappaB/STAT-1-targeted inhibitory properties in LPS-activated RAW264.7 cells.

Energy beverages: content and safety

Exercise is making a resurgence in many countries, given its benefits for fitness as well as prevention of obesity. This trend has spawned many supplements that purport to aid performance, muscle growth, and recovery. Initially, sports drinks were developed to provide electrolyte and carbohydrate replacement. Subsequently, energy beverages (EBs) containing stimulants and additives have appeared in most gyms and grocery stores and are being used increasingly by "weekend warriors" and those seeking an edge in an endurance event. Long-term exposure to the various components of EBs may result in significant alterations in the cardiovascular system, and the safety of EBs has not been fully established. For this review, we searched the MEDLINE and EMBASE databases from 1976 through May 2010, using the following keywords: energy beverage, energy drink, power drink, exercise, caffeine, red bull, bitter orange, glucose, ginseng, guarana, and taurine. Evidence regarding the effects of EBs is summarized, and practical recommendations are made to help in answering the patient who asks, "Is it safe for me to drink an energy beverage when I exercise?"

Effects of ingesting a commercial thermogenic product on hemodynamic function and energy expenditure at rest in males and females

The purpose of this study was to examine the effects of a commercially available thermogenic product (TP) on resting energy expenditure (REE) and hemodynamic variables in a randomized, double-blind, placebo (PL)-controlled study. Eight male (age: 23.0 +/- 3.70 years, weight: 95.77 +/- 16.44 kg, height: 182.4 +/- 7.87 cm) and 10 female (age: 23.6 +/- 4.81 years, weight: 67.25 +/- 5.74 kg, height: 172.42 +/- 10.31 cm) physically active individuals participated in this study. Participants reported to the laboratory on a 10-h fast and performed baseline testing on REE, heart rate, and blood pressure. Participants were then randomly assigned to ingest 3 capsules of either an experimental TP or a vitamin E PL. Criterion variables were then measured at 1-, 2-, and 3-h post ingestion. Data were analyzed by 2-factor analysis of variance (ANOVA) using SPSS, version 16.0 (SPSS Inc., Chicago, Ill.). Supplementation of the TP resulted in a significant main effect for time (p = 0.040) and for interaction (p < 0.01) in REE when compared with PL. Post hoc analysis revealed that there was no significant difference (p > 0.05) between groups at baseline, but the TP group was significantly higher (p < 0.01) than the PL group at 1-, 2-, and 3-h post, with peak values being achieved at 2-h post time point. The TP group also experienced an overall increase in REE by 17.3%, 19.6%, and 15.3% at the 1-, 2-, and 3-h time points, respectively, over baseline values. Conversely, the PL group experienced a reduction in REE by 2.5%, 1.8%, and 0.3% at the same time points compared with baseline values. There was no significant change in heart rate, systolic blood pressure, or diastolic blood pressure in either group. Taken on a daily basis, a TP may increase overall energy expenditure. Caloric expenditure significantly increased at all 3 time points in the TP group, whereas the PL group experienced no change in energy expenditure.

Hydroxyhydroquinone-free coffee: a double-blind, randomized controlled dose-response study of blood pressure

BACKGROUND AND AIM

Coffee is rich in chlorogenic acids (CGA), whose metabolites may have beneficial effects such as anti-hypertensive effects. However, trial results concerning the effects of coffee on blood pressure (BP) are not consistent. A recent study suggested that hydroxyhydroquinone (HHQ), produced by the roasting of green coffee beans, inhibits the effect of CGA. In the present study, the dose-response for CGA in HHQ-free coffee on BP were investigated in mildly hypertensive men and women.

METHODS AND RESULTS

The trial design was a double-blind, randomized controlled trial, with five study groups including, control, zero-dose, low-dose, middle-dose and high-dose. The control beverage was identical to ordinary coffee. The others contained reduced HHQ levels, compared to ordinary coffee, and the CGA were adjusted in target concentration. A total of 203 subjects were randomly allocated. Each subject drank one cup of coffee per day. The study involved a screening and a baseline observation period of 6 weeks and an intervention period of 4 weeks. BP response showed CGA has an anti-hypertensive effect in a dose-dependent manner in HHQ-free coffee, and ordinary coffee showed almost no effect. As a result, a significant correlation between BP change and the three dose-response patterns was observed (p<0.001).

CONCLUSIONS

This study demonstrates a dose-dependent decrease in BP for CGA in HHQ-free coffee.

Tea or coffee? A case study on evidence for dietary advice

The present paper explores the level of evidence required to justify giving dietary advice to the public. There are important practical differences between the development of public health nutrition guidelines and guidelines for clinical practice. While the gold standard for evidence for clinical practice guidelines is a meta-analysis of a number of randomised controlled trials, this is often unrealistic and sometimes unethical for the evaluation of public health nutrition interventions. Hence, epidemiological studies make up the bulk of evidence for nutrition guidelines. Tea and coffee are an interesting case study in relation to this issue. They are two of the most commonly consumed beverages worldwide, yet there is little dietary advice on their use. The evidence for a relationship between coffee or tea consumption and several diseases is discussed. The available studies, predominantly epidemiological, together with animal and in vitro studies, indicate that coffee and tea are both safe beverages. However, tea is the healthier option because it has a possible role in the prevention of several cancers and CVD. While the evidence for such relationships is not strong, the public will continue to drink both tea and coffee, and will continue to ask nutritionists to make recommendations. It is therefore argued that advice should be given on the best available data, as waiting for complete data to become available could have severe consequences for public health.

Acute effects of ingesting Java Fittrade mark energy extreme functional coffee on resting energy expenditure and hemodynamic responses in male and female coffee drinkers

BACKGROUND

The purpose of this study was to examine the effects of a functional coffee beverage containing additional caffeine, green tea extracts, niacin and garcinia cambogia to regular coffee to determine the effects on resting energy expenditure (REE) and hemodynamic variables.

METHODS

Subjects included five male (26 +/- 2.1 y, 97.16 +/- 10.05 kg, 183.89 +/- 6.60 cm) and five female (28.8 +/- 5.3 y, 142.2 +/- 12.6 lbs) regular coffee drinkers. Subjects fasted for 10 hours and were assessed for 1 hour prior (PRE) and 3 hours following 1.5 cups of coffee ingestion [JavaFittrade mark Energy Extreme (JF) ~400 mg total caffeine; Folgers (F) ~200 mg total caffeine] in a double-blind, crossover design. REE, resting heart rate (RHR), and systolic (SBP) and diastolic (DBP) blood pressure was assessed at PRE and 1, 2, and 3-hours post coffee ingestion. Data were analyzed by three-factor repeated measures ANOVA (p < 0.05).

RESULTS

JF trial resulted in a significant main effect for REE (p < 0.01), SBP (p < 0.01), RER (p < 0.01), and VO2 (p < 0.01) compared to F, with no difference between trials on the RHR and DBP variables. A significant interaction for trial and time point (p < 0.05) was observed for the variable REE. The JF trial resulted in a significant overall mean increase in REE of 14.4% (males = 12.1%, females = 17.9%) over the observation period (p < 0.05), while the F trial produced an overall decrease in REE of 5.7%. SBP was significantly higher in the JF trial; however, there was no significant increase from PRE to 3-hours post.

CONCLUSION

Results from this study suggest that JavaFittrade mark Energy Extreme coffee is more effective than Folgers regular caffeinated coffee at increasing REE in regular coffee drinkers for up to 3 hours following ingestion without any adverse hemodynamic effects.

Brewing controversies: Darwinian perspective on the adaptive and maladaptive effects of caffeine and ethanol as dietary autonomic modulators

Ethanol and caffeine are two of the oldest human drugs. Their pervasive integration into the modern human diet may reflect behavioral attempts to correct maladaptations induced by evolutionary displacement of the autonomic system. The dietary adoption of caffeine may parallel the emergence of cognition as an independent basis of competition. Enhancement of the cognitive ability to gather and process information likely evolved as a valuable adjunct to physical behavior in prehistoric fight-or-flight encounters. Caffeine effectively exploits this pre-existing association between adrenergic activity and cognitive readiness, leading to its use in the modern environment where success in competition increasingly depends on cognitive, rather than physical, prowess. Ethanol may have emerged as a dietary means to buffer the maladaptive chronic sympathetic activation and fear response associated with stressful lifestyles and the social phobias associated with the dissolution of kin networks. We explore the health implications of ethanol and caffeine use, with particular attention to their acute and chronic effects on the autonomic axis. The putative protective effects of ethanol in surviving major trauma or reducing inflammation and heart disease may relate to tempering the behavioral and cardiovascular consequences of catastrophic or chronic sympathetic activation. Acute or chronic abuse of ethanol manifests paradoxical pro-adrenergic effects such as tremors and insomnia that may partly represent compensatory responses. Compensatory remodeling may also explain why confirmation of detrimental effects related to caffeine-induced sympathetic activation has proven elusive; indeed, paradoxical pro-vagal benefits may eventually be recognized. Ethanol and caffeine are potential agents that may beneficially expand the dynamic range of the autonomic system. In an environment where the Darwinian value of knowledge has increasingly supplanted that of physical traits, the consumption of caffeine and alcohol may represent both a cause and an effect of modern human evolution.

Chronic intake of caffeine during gestation down regulates metabotropic glutamate receptors in maternal and fetal rat heart

Caffeine is the most widely consumed substance in the world which antagonizes adenosine effects. Adenosine acting through A(1) receptors inhibits glutamate release which binds to metabotropic glutamate receptors (mGluRs). Recently, we have shown that maternal caffeine intake during gestation causes down-regulation of A(1) and metabotropic glutamate receptors in the brain of both rat mothers and fetuses. In the present work we provide evidence that caffeine also affects receptors in hearts, causing a decrease in mGluRs from both maternal and fetal hearts. A decrease in G(q/11) and PLC beta(1) proteins level was also observed in both tissues. However, phospholipase C activity was only affected in fetal heart, being significantly decreased. These results suggest an in vivo cross-talk mechanism between adenosine and glutamate receptors in peripheral tissues. Therefore, special attention should be paid to caffeine ingestion during gestation.