Dose-dependent effects of decaffeinated coffee on endothelial function in healthy subjects

Acute dose-response effect of coffee-derived chlorogenic acids on the human vasculature in healthy volunteers: a randomized controlled trial

BACKGROUND

Epidemiological studies have reported lower risk of cardiovascular disease with moderate coffee consumption. In addition, emerging evidence indicates that consumption of coffee beverages enriched in chlorogenic acids (CGAs) may influence blood pressure and endothelial function, suggesting that the beneficial cardiovascular effect of coffee may relate to its CGA content.

OBJECTIVES

We conducted a double-blind randomized crossover trial to test the effect of acute consumption of a decaffeinated green coffee extract (DGCE), rich in CGAs, on endothelial function in healthy subjects.

METHODS

We compared 3 different doses of DGCE (302, 604, and 906 mg, respectively) with a placebo. Endothelial function was defined as the percentage change in the internal diameter of the brachial artery in response to flow-mediated dilation (%FMD). In addition, we followed the plasma concentration-time profiles of 25 systemic CGA metabolites over 24 h after DGCE consumption and we explored the relation between systemic concentrations of CGAs and the effect on %FMD.

RESULTS

The DGCE formulations containing different amounts of CGAs resulted in dose-proportional increases in overall total polyphenol concentrations. The systemic appearance of total CGAs was biphasic, in agreement with previous results suggesting 2 sites of absorption in the gastrointestinal tract. Compared with the placebo group, a significant FMD increase (>1%) was observed 8.5, 10, and 24 h after consumption of 302 mg DGCE (∼156.4 mg CGAs). The differences with placebo observed in the other 2 groups were not statistically significant. Evaluation of the relation between phenolic exposure and %FMD showed a positive tendency toward a larger effect at higher concentrations and different behavior of CGA metabolites depending on the conjugated chemical position.

CONCLUSIONS

We demonstrated an acute improvement in %FMD over time after ingestion of a DGCE, explained at least partly by the presence in the blood circulation of CGAs and their metabolites. This trial was registered at clinicaltrials.gov as NCT03520452.

Effects of coffee consumption on arterial stiffness and endothelial function: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Endothelial function (EF) and arterial stiffness (AS) are predictors of cardiovascular disease. As previous research concerning the effect of coffee intake on EF and AS was controversial, we conducted a systematic review and meta-analysis to synthesize research.

METHODS

We performed a systematic search in PubMed, Scopus and Web of Science to find clinical trials investigating the effect of coffee intake on EF or AS up to March 2020.Random-effects models were used to estimate the pooled weighted mean difference (WMD) between intervention and control groups for randomized controlled trials (RCTs). Between study heterogeneity was estimated using Cochran's Q and the I ²-inconsistency index. Internal validity of included randomized trials was determined with the Cochrane Collaboration's tool for assessing the risk of bias.

RESULTS

Twenty-three articles were included for qualitative and 11 articles for quantitative synthesis. Meta-analysis of 14 RCTs (nine articles) indicated a positive short-term (postprandial) effect of coffee intake on flow-mediated dilation (FMD) as a measure of EF (WMD: 1.93%[95% CI: 1.10-2.75]; I ²= 97.9%). Meta-analysis of three long-term RCTs(two articles) found no such effect on FMD (WMD: -0.08% [-3.82 to 3.66]; I ²= 61.4%).Most short-term information was from studies at low or unclear risk of bias, while the proportion of long-term information from studies at high risk of bias was considerable.

CONCLUSION

The results from this meta-analysis suggest a beneficial short-term effect of coffee intake on EF as measured by FMD. However, there might be unfavorable effects on AS. Our findings must be interpreted cautiously as the number of studies were low and included studies had a considerable risk of bias.

The gut microbiome drives inter- and intra-individual differences in metabolism of bioactive small molecules

The origin of inter-individual variability in the action of bioactive small molecules from the diet is poorly understood and poses a substantial obstacle to harnessing their potential for attenuating disease risk. Epidemiological studies show that coffee lowers the risk of developing type 2 diabetes, independently of caffeine, but since coffee is a complex matrix, consumption gives rise to different classes of metabolites in vivo which in turn can affect multiple related pathways in disease development. We quantified key urinary coffee phenolic acid metabolites repeated three times in 36 volunteers, and observed the highest inter- and intra-individual variation for metabolites produced by the colonic microbiome. Notably, a urinary phenolic metabolite not requiring the action of the microbiota was positively correlated with fasting plasma insulin. These data highlight the role of the gut microbiota as the main driver of both intra- and inter-individual variation in metabolism of dietary bioactive small molecules.

Role of Polyphenols and Carotenoids in Endothelial Dysfunction: An Overview from Classic to Innovative Biomarkers

Nowadays, the dramatically increased prevalence of metabolic diseases, such as obesity and diabetes mellitus and their related complications, including endothelial dysfunction and cardiovascular disease, represents one of the leading causes of death worldwide. Dietary nutrients together with healthy lifestyles have a crucial role in the endothelium health-promoting effects. From a growing body of evidence, active natural compounds from food, including polyphenols and carotenoids, have attracted particular attention as a complementary therapy on atherosclerosis and cardiovascular disease, as well as preventive approaches through the attenuation of inflammation and oxidative stress. They mainly act as radical scavengers by promoting a variety of biological mechanisms, such as improvements in endothelial function, blood pressure, platelet activity, and insulin sensitivity, and by modulating various known biomarkers. The present review highlights the role of polyphenols and carotenoids in early endothelial dysfunction with attention to their beneficial effect in modulating both classical and recent technologically generated emerging biomarkers. These, alone or in combination, can play an important role in the prediction, diagnosis, and evolution of cardiovascular disease. However, a main challenge is to speed up early and prompt new interventions in order to prevent or slow down disease progression, even with an adequate intake of bioactive compounds. Hence, there is an urgent need of new more validated, appropriate, and reliable diagnostic and therapeutic biomarkers useful to diagnose endothelial dysfunction at an earlier stage.

Increased bioavailability of phenolic acids and enhanced vascular function following intake of feruloyl esterase-processed high fibre bread: A randomized, controlled, single blind, crossover human intervention trial

BACKGROUND & AIMS

Clinical trial data have indicated an association between wholegrain consumption and a reduction in surrogate markers of cardiovascular disease. Phenolics present in wholegrain bound to arabinoxylan fibre may contribute these effects, particularly when released enzymatically from the fiber prior to ingestion. The aim of the present study was therefore to determine whether the intake of high fibre bread containing higher free ferulic acid (FA) levels (enzymatically released during processing) enhances human endothelium-dependent vascular function.

METHODS

A randomized, single masked, controlled, crossover, human intervention study was conducted on 19 healthy men. Individuals consumed either a high fibre flatbread with enzymatically released free FA (14.22 mg), an equivalent standard high fibre bread (2.34 mg), or a white bread control (0.48 mg) and markers of vascular function and plasma phenolic acid concentrations were measured at baseline, 2, 5 and 7 h post consumption.

RESULTS

Significantly increased brachial arterial dilation was observed following consumption of the high free FA ('enzyme-treated') high fibre bread verses both a white bread (2 h: p < 0.05; 5 h: p < 0.01) and a standard high fibre bread (5 h: p < 0.05). Concurrently, significant increases in plasma FA levels were observed, at 2 h (p < 0.01) after consumption of the enzyme-treated bread, relative to control treatments. Blood pressure, heart rate, DVP-SI and DVP-RI were not significantly altered following intake of any of the breads (p > 0.05).

CONCLUSION

Dietary intake of bread, processed enzymatically to release FA from arabinoxylan fiber during production increases the bioavailability of FA, and induces acute endothelium-dependent vasodilation.

CLINICAL TRIAL REGISTRY

NO: NCT03946293. WEBSITE: www.clinicaltrials.gov.

Coffee and Endothelial Function: A Coffee Paradox?

Coffee is a popular beverage throughout the world. Coffee contains various chemical compounds (e.g., caffeine, chlorogenic acids, hydroxyhydroquinone, kahweol, cafestol, and complex chemical mixtures). Caffeine is also the most widely consumed pharmacological substance in the world and is included in various beverages (e.g., coffee, tea, soft drinks, and energy drinks), products containing chocolate, and drugs. The effects of coffee and caffeine on cardiovascular diseases remain controversial. It is well known that there are J-curve-type or U-curve-type associations of coffee consumption with cardiovascular events including myocardial infarction and stroke. However, there is little information on the direct and indirect effects of coffee consumption on endothelial function in humans. It is likely that the coffee paradox or caffeine paradox exists the association of coffee intake with cardiovascular diseases, cardiovascular outcomes, and endothelial function. This review focusses on the effects of coffee and caffeine on endothelial function from molecular mechanisms to clinical perspectives.

TNF-α-induced oxidative stress and endothelial dysfunction in EA.hy926 cells is prevented by mate and green coffee extracts, 5-caffeoylquinic acid and its microbial metabolite, dihydrocaffeic acid

The main phenol in mate and coffee, 5-caffeoylquinic-acid (5-CQA), and its relevant microbial metabolites, dihydrocaffeic (DHCA) and dihydroferulic (DHFA) acids, have shown oxidative-stress protective effects in HepG2 cells. To evaluate possible endothelial-protective effects of the extracts and compounds, endothelial EA.hy926 cells were pre-treated with yerba mate (YME) and green coffee bean (GCBE) phenolic extracts, 5-CQA, DHCA and DHFA and afterwards stressed with tumour-necrosis-factor-alpha (TNF-α). Then oxidative-stress markers and endothelial-nitric-oxide-synthase levels were studied. TNF-α (10 ng/mL, 24 h) depleted reduced glutathione (GSH) and eNOS levels, increased reactive oxygen species (ROS) production, glutathione peroxidase (GPx) and reductase (GR) activities, and protein oxidation (carbonyl groups, CG) in EA.hy926 cells. Pre-treatment with YME, GCBE, 5-CQA, DHCA at certain physiological concentrations, lowered ROS production, recovered depleted GSH, reduced GR and GPx activities, and CG levels, and enhanced eNOS concentration.. YME, GCBE and 5-CQA show antioxidant effects in endothelial cells playing DHCA an important role in such protection; moreover, the extracts, 5-CQA, DHCA and DHFA increased eNOS levels.

Coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone improves postprandial endothelial dysfunction in patients with borderline and stage 1 hypertension

Purpose

The purpose of this study was to evaluate acute effects of coffee with a high content of chlorogenic acids and different hydroxyhydroquinone contents on postprandial endothelial dysfunction.

Methods

This was a single-blind, randomized, placebo-controlled, crossover-within-subject clinical trial. A total of 37 patients with borderline or stage 1 hypertension were randomized to two study groups. The participants consumed a test meal with a single intake of the test coffee. Subjects in the Study 1 group were randomized to single intake of coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone or coffee with a high content of chlorogenic acids and a high content of hydroxyhydroquinone with crossover. Subjects in the Study 2 group were randomized to single intake of coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone or placebo coffee with crossover. Endothelial function assessed by flow-mediated vasodilation and plasma concentration of 8-isoprostanes were measured at baseline and at 1 and 2 h after coffee intake.

Results

Compared with baseline values, single intake of coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone, but not coffee with a high content of chlorogenic acids and high content of hydroxyhydroquinone or placebo coffee, significantly improved postprandial flow-mediated vasodilation and decreased circulating 8-isoprostane levels.

Conclusions

These findings suggest that a single intake of coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone is effective for improving postprandial endothelial dysfunction.

Clinical Trial Registration

URL for Clinical Trial: https://upload.umin.ac.jp; Registration Number for Clinical Trial: UMIN000013283.

How coffee affects metabolic syndrome and its components

Metabolic syndrome, with its increasing prevalence, is becoming a major public health problem throughout the world. Many risk factors including nutrition play a role in the emergence of metabolic syndrome. Of the most-consumed beverages in the world, coffee contains more than 1000 components such as caffeine, chlorogenic acid, diterpenes and trigonelline. It has been proven in many studies that coffee consumption has a positive effect on chronic diseases. In this review, starting from the beneficial effects of coffee on health, the relationship between coffee consumption and metabolic syndrome and its components has been investigated. There are few studies investigating the relationship between coffee and metabolic syndrome, and the existing ones put forward different findings. The factors leading to the differences are thought to stem from coffee variety, the physiological effects of coffee elements, and the nutritional ingredients (such as milk and sugar) added to coffee. It is reported that consumption of coffee in adults up to three cups a day reduces the risk of Type-2 diabetes and metabolic syndrome.

The role of polyphenols in modern nutrition

Polyphenols are found in plant‐based foods and beverages, notably apples, berries, citrus fruit, plums, broccoli, cocoa, tea and coffee and many others. There is substantial epidemiological evidence that a diet high in polyphenol‐rich fruit, vegetables, cocoa and beverages protects against developing cardiovascular disease and type 2 diabetes. The absorption and metabolism of these compounds have been well described and, for many, the gut microbiota play a critical role in absorption; taking into consideration the parent compound and the metabolites from colon bacteria catabolism, more than 80% of a dose can be absorbed and ultimately excreted in the urine. Common polyphenols in the diet are flavanols (cocoa, tea, apples, broad beans), flavanones (hesperidin in citrus fruit), hydroxycinnamates (coffee, many fruits), flavonols (quercetin in onions, apples and tea) and anthocyanins (berries). Many intervention studies, mechanistic in vitro data and epidemiological studies support a role for polyphenols against the development of chronic diseases. For example, flavanols decrease endothelial dysfunction, lower blood pressure and cholesterol, and modulate energy metabolism. Coffee and tea both reduce the risk of developing type 2 diabetes, through action of their constituent polyphenols. Despite extensive research, the exact mechanisms of action of polyphenols in the human body have not been decisively proven, but there is strong evidence that some targets such as nitric oxide metabolism, carbohydrate digestion and oxidative enzymes are important for health benefits. Consumption of polyphenols as healthy dietary components is consistent with the advice to eat five or more portions of fruit and vegetables per day, but it is currently difficult to recommend what ‘doses’ of specific polyphenols should be consumed to derive maximum benefit.

The impact of coffee consumption on blood pressure, cardiovascular disease and diabetes mellitus

INTRODUCTION

Coffee is the most widely consumed beverage, next to water. However, there has been a long-standing controversy regarding its safety on blood pressure (BP) and cardiovascular disease (CVD) and intuitively, physicians dissuaded their patients from coffee drinking. Areas covered: This controversy was, primarily, based on older prospective studies or case reports, which showed a positive association of coffee drinking with the incidence of hypertension and CVD. In contrast to these reports, recent, well controlled, studies have demonstrated either a neutral or beneficial effect of moderate coffee consumption (3-4 cups/day), on BP, CVD, heart failure (HF), cardiac arrhythmias, or diabetes mellitus (DM). For the preparation of this special report, an English language focused search of the Medline database was conducted between 2010 and 2016 on studies with data on effect on the coffee consumption in patients with high BP, CVD, HF, cardiac arrhythmias or DM. Of the 94 abstracts reviewed, 34 pertinent papers were selected, and the findings from these papers together with collateral literature will be discussed in this special report. Expert commentary: Based on the evidence from these studies, coffee consumption in moderation, is safe and is beneficial in both healthy persons as well as patients with high BP, CVD, HF, cardiac arrhythmias or DM. Therefore, coffee restriction is not warranted for these patients, although some caution should be exercised.

From sodium intake restriction to nitrate supplementation: Different measures with converging mechanistic pathways?

Endothelial nitric oxide synthase is at the centre of endothelial physiology producing nitric oxide which dilates blood vessels, inhibits platelet aggregation and smooth muscle cell proliferation and reduces adhesion molecule production. The laminar shear stress is a common test used usually as the flow mediated dilatation test (FMD) which is sensitive to saturated fat, sodium and potassium although with the latter ion it is possible potassium has direct effects on ion channels in the smooth muscle cell as well as the endothelial cell. High blood pressure and blood cholesterol both reduce nitric oxide production, the latter probably by increasing caveolin-1 which binds nitric oxide synthase. Saturated fat reduces nitric oxide by elevating LDL cholesterol and caveolin-1 while insulin stimulates nitric oxide synthase activity by serine phosphorylation. Polyphenols from tea, coffee and cocoa and virgin olive oil enhance FMD and eNOS activity is essential for this activity. Wine polyphenols produce mixed results and it is not clear at present that they are beneficial. Blackberries and other polyphenol-rich fruit also enhance FMD. Dietary nitrate from beetroot and green leafy vegetables is converted to nitrite by salivary microbes and then to nitric oxide and this acts directly on the smooth muscle to lower blood pressure particularly in a low oxygen environment. Dietary nitrate also improves work efficiency and improves flow mediated dilatation.

Chlorogenic acid improves ex vivo vessel function and protects endothelial cells against HOCl-induced oxidative damage, via increased production of nitric oxide and induction of Hmox-1

Dietary polyphenols are potential contributors toward improved cardiovascular health. Coffee is one of the richest sources of dietary polyphenols in a coffee-drinking population, the most abundant form being chlorogenic acid (CGA). Endothelial dysfunction is an early and major risk factor for cardiovascular disease. Nitric oxide (NO) is a key factor in regulation of endothelial function. Heme oxygenase-1 (Hmox-1), an inducible isoform of heme oxygenase that is produced in response to stressors such as oxidative stress, may also play a role in vascular protection. The aim of this study was to investigate the effect of CGA on endothelial function with oxidant-induced damage in isolated aortic rings from C57BL mice. We further examine the mechanism by investigating cell viability, activation of eNOS and induction of Hmox-1 in human aortic endothelial cells (HAECs). We found that pretreatment of isolated aortic rings with 10-μM CGA-protected vessels against HOCl-induced endothelial dysfunction (P<0.05). Pretreatment of cultured HAECs with 10-μM CGA increased endothelial cell viability following exposure to HOCl (P<0.05). Moreover, CGA increased NO production in HAECs in a dose-dependent manner, peaking at 6 h (P<0.05). CGA at 5 μM and 10 μM increased eNOS dimerization at 6 h and induced Hmox-1 protein expression at 6 h and 24 h in HAECs. These results are consistent with the cardiovascular protective effects of coffee polyphenols and demonstrate that CGA can protect vessels and cultured endothelial cells against oxidant-induced damage. The mechanism behind the beneficial effect of CGA appears to be in part via increased production of NO and induction of Hmox-1.

Coffee consumption and risk of hypertension in the Polish arm of the HAPIEE cohort study

Background/objectives

Coffee consumption has been hypothesized to be associated with blood pressure, but previous findings are not homogenous. The aim of this study was to evaluate the association between coffee consumption and the risk of developing hypertension.

Subjects/Methods

Data on coffee consumption, blood pressure, and use of anti-hypertensive medicament were derived from 2,725 participants of the Polish arm of the HAPIEE project (Health, Alcohol and Psychosocial factors In Eastern Europe) who were free of hypertension at baseline and followed up for an average of 5 years. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by multivariate logistic regression analyses and stratified for potential confounding factors.

Results

Coffee consumption was related with decreased age, smoking status, and total energy intake. Compared to persons who drink <1 cup coffee per day, systolic blood pressure was significantly associated with coffee consumption and the risk of hypertension was lower for individuals consuming 3-4 cups/day. Despite the analysis stratified by gender showed that the protective effect of coffee consumption on hypertension was significant only in women, the analysis after stratification by smoking status revealed a decreased risk of hypertension in non-smokers drinking 3-4 cups of coffee per day, in both sexes (OR 0.41, 95% CI: 0.21, 0.79 for men and OR 0.54, 95% CI: 0.29, 0.99 for women). Upper category coffee consumption (>4 cups per day) was not related with significant increased risk of hypertension.

Conclusions

Relation between coffee consumption and incidence of hypertension was related to smoking status. Consumption of 3-4 cups of coffee per day decreased risk of hypertension in non-smoking men and women only.

Association of daily coffee and tea consumption and metabolic syndrome: results from the Polish arm of the HAPIEE study

Purpose

The aim of this study was to evaluate whether daily consumption of coffee and tea was associated with components and prevalence of metabolic syndrome (MetS) in the Polish arm of the Health, Alcohol and Psychosocial factors In Eastern Europe cohort study.

Methods

A cross-sectional population-based survey including 8,821 adults (51.4 % female) was conducted in Krakow, Poland. Coffee and tea consumption was evaluated using food frequency questionnaires. MetS was defined according to the International Diabetes Federation definition. Linear and logistic regression models were performed to estimate odds ratios and confidence intervals.

Results

Among high coffee and tea consumers (3 or more cups/day), high prevalence of female gender, young age, medium–high educational and occupational level, high total energy intake, and smoking habit were found. High coffee drinkers had lower BMI, waist circumference, systolic and diastolic blood pressure, triglycerides, and higher HDL cholesterol than those drinking less than 1 cup/day. In contrast, high tea consumers had lower BMI, waist circumference, but not diastolic blood pressure, which was higher than low drinkers. After adjusting for potential confounding factors, both higher coffee and tea consumption were negatively associated with MetS (OR 0.75, 95 % CI 0.66, 0.86 and OR 0.79, 95 % CI 0.67, 0.92, respectively). Among specific components of MetS, high coffee consumption was negatively associated with waist circumference, hypertension, and triglycerides, whereas tea consumption with central obesity and fasting plasma glucose in women, but not in men.

Conclusions

Coffee and tea consumption was negatively associated with MetS and some of its components.

Factors associated with metabolic syndrome in a mediterranean population: role of caffeinated beverages

Background

Intake of caffeinated beverages, such as coffee and tea, has been related to improvements in components of metabolic syndrome (MetS), but studies conducted in the Mediterranean region are scarce. The aim of this study was to evaluate whether or not consumption of a variety of beverages containing caffeine was associated with components of MetS in an Italian population.

Methods

From May 2009 to December 2010, a cross-sectional survey was conducted on 1889 inhabitants living in Sicily, southern Italy. Data regarding demographic characteristics, habitual beverage intake, and adherence to the Mediterranean diet were collected, and clinical information was retrieved from the general practitioners’ computer records.

Results

After adjusting for all covariates, coffee (odds ratio [OR] 0.43, 95% confidence interval [CI] 0.27–0.70) and tea (OR 0.51, 95% CI 0.34–0.78) were associated with MetS, whereas no association was observed between caffeine intake and MetS. Among other factors, age, body mass index, physical activity, current smoking, and adherence to Mediterranean diet were associated with having MetS. Triglycerides were inversely associated with consumption of both espresso coffee and tea. The healthy effects of such beverages were more evident in individuals with unhealthy dietary habits.

Conclusions

Although no direct association between caffeine intake and MetS or its components was observed, coffee and tea consumption was significantly related to reduced odds of MetS.

Habitual consumption of coffee and green tea in relation to serum adipokines: a cross-sectional study

PURPOSE

Coffee and green tea consumption may be associated with circulating adipokines, but data are inconsistent, scarce or lacking. We examined the association of coffee and green tea consumption with serum adiponectin, leptin, visfatin, resistin and plasminogen activator inhibitor-1 (PAI-1) among a Japanese working population.

METHODS

The authors analyzed data (n = 509) from a cross-sectional survey among Japanese workers aged 20-68 years. Serum adipokines were measured using a Luminex suspension bead-based multiplexed array. Coffee and green tea consumption was assessed using a validated diet history questionnaire, and caffeine consumption from these beverages was estimated. Multiple regression analysis was performed with adjustment for potential confounding variables.

RESULTS

Coffee consumption was significantly, inversely associated with leptin and PAI-1 (P for trend = 0.007 and 0.02, respectively); compared with subjects consuming <1 cup per day, those consuming ≥4 cups per day had 13 and 10 % lower means of leptin and PAI-1, respectively. Similar associations were observed for caffeine consumption (P for trend = 0.02 for both leptin and PAI-1). Additionally, we noted a significant positive association between coffee consumption and adiponectin in men (P for trend = 0.046), but not in women (P for trend = 0.43, P for interaction = 0.11). Moreover, there was a positive association between coffee consumption and resistin in current male smokers (P for trend = 0.01), but not in male non-smokers (P for trend = 0.35, P for interaction = 0.11). Green tea consumption was not associated with any adipokine.

CONCLUSIONS

Higher consumption of coffee and caffeine but not green tea was associated with lower serum levels of leptin and PAI-1 in Japanese adults.

Antithrombotic effects of pyridinium compounds formed from trigonelline upon coffee roasting

Coffee may exert a preventive effect on arterial thrombosis. Trigonelline is one of the most abundant compounds in coffee that undergoes pyrolysis upon roasting of coffee beans. The aim of the present study was to identify pyridinium compounds formed upon trigonelline pyrolysis and coffee roasting and to investigate the effect of three of them, i.e., 1-methylpyridine and 1,3- and 1,4-dimethylpyridine, on experimentally induced arterial thrombosis in rats. 1,3- and 1,4-dimethylpyridine but not 1-methylpyridine inhibited arterial thrombus formation. 1,3-Dimethylpyridine inhibited platelet aggregation and reduced fibrin formation in platelet-rich plasma, whereas 1,4-dimethylpyridine increased the plasma level of 6-keto-PGF1α. 1,4-Dimethylpyridine slightly increased rat tissue plasminogen activator plasma activity. In summary, we demonstrated that pyridinium compounds display mild antithrombotic properties due to stimulation by prostacyclin release (1,4-dimethylpyridine) and inhibition of platelet aggregation (1,3-dimethylpyridine). Those pyridinium compounds may, to some extent, be responsible for the beneficial effects of coffee drinking.

The effect of processing on chlorogenic acid content of commercially available coffee

Chlorogenic acids (CGA) are a class of polyphenols noted for their health benefits. These compounds were identified and quantified, using LC-MS and HPLC, in commercially available coffees which varied in processing conditions. Analysis of ground and instant coffees indicated the presence of caffeoylquinic acids (CQA), feruloylquinic acids (FQA) and dicaffeoylquinic acids (diCQA) in all 18 samples tested. 5-CQA was present at the highest levels, between 25 and 30% of total CGA; subsequent relative quantities were: 4-CQA>3-CQA>5-FQA>4-FQA>diCQA (sum of 3,4, 3,5 and 4,5-diCQA). CGA content varied greatly (27.33-121.25mg/200 ml coffee brew), driven primarily by the degree of coffee bean roasting (a high amount of roasting had a detrimental effect on CGA content). These results highlight the broad range of CGA quantity in commercial coffee and demonstrate that coffee choice is important in delivering optimum CGA intake to consumers.

Dietary (poly)phenolics in human health: structures, bioavailability, and evidence of protective effects against chronic diseases

Human intervention trials have provided evidence for protective effects of various (poly)phenol-rich foods against chronic disease, including cardiovascular disease, neurodegeneration, and cancer. While there are considerable data suggesting benefits of (poly)phenol intake, conclusions regarding their preventive potential remain unresolved due to several limitations in existing studies. Bioactivity investigations using cell lines have made an extensive use of both (poly)phenolic aglycones and sugar conjugates, these being the typical forms that exist in planta, at concentrations in the low-μM-to-mM range. However, after ingestion, dietary (poly)phenolics appear in the circulatory system not as the parent compounds, but as phase II metabolites, and their presence in plasma after dietary intake rarely exceeds nM concentrations. Substantial quantities of both the parent compounds and their metabolites pass to the colon where they are degraded by the action of the local microbiota, giving rise principally to small phenolic acid and aromatic catabolites that are absorbed into the circulatory system. This comprehensive review describes the different groups of compounds that have been reported to be involved in human nutrition, their fate in the body as they pass through the gastrointestinal tract and are absorbed into the circulatory system, the evidence of their impact on human chronic diseases, and the possible mechanisms of action through which (poly)phenol metabolites and catabolites may exert these protective actions. It is concluded that better performed in vivo intervention and in vitro mechanistic studies are needed to fully understand how these molecules interact with human physiological and pathological processes.

Consumption of a boiled Greek type of coffee is associated with improved endothelial function: The Ikaria Study

Objective:

The association of coffee consumption with cardiovascular disease remains controversial. Endothelial function is associated with cardiovascular risk. We examined the association between chronic coffee consumption and endothelium function in elderly inhabitants of the island of Ikaria.

Methods:

The analysis was conducted on 142 elderly subjects (aged 66–91 years) of the Ikaria Study. Endothelial function was evaluated by ultrasound measurement of flow-mediated dilation (FMD). Coffee consumption was evaluated based on a food frequency questionnaire and was categorized as ‘low’ (< 200 ml/day), ‘moderate’ (200–450 ml/day), or ‘high’ (> 450 ml/day).

Results:

From the subjects included in the study, 87% consumed a boiled Greek type of coffee. Moreover, 40% had a ‘low’, 48% a ‘moderate’ and 13% a ‘high’ daily coffee consumption. There was a linear increase in FMD according to coffee consumption (‘low’: 4.33 ± 2.51% vs ‘moderate’: 5.39 ± 3.09% vs ‘high’: 6.47 ± 2.72%; p = 0.032). Moreover, subjects consuming mainly a boiled Greek type of coffee had a significantly higher FMD compared with those consuming other types of coffee beverages ( p = 0.035).

Conclusions:

Chronic coffee consumption is associated with improved endothelial function in elderly subjects, providing a new connection between nutrition and vascular health.

Effects of tea and coffee on cardiovascular disease risk

Tea and coffee have been associated with risk of cardiovascular disease (CVD), both positively and negatively. Epidemiological data suggest that black and green tea may reduce the risk of both coronary heart disease and stroke by between 10 and 20%. Experimental and clinical trial data generally indicate either neutral or beneficial effects on risk factors and pathways linked to the development of CVD. Controversy still exists regarding the effects of coffee, where there have been concerns regarding associations with hypercholesterolaemia, hypertension and myocardial infarction. However, long term moderate intake of coffee is not associated with detrimental effects in healthy individuals and may even protect against the risk of developing type 2 diabetes. The detrimental effects of coffee may be associated with the acute pressor effects, most likely due to caffeine at high daily intakes, and lipids from boiled coffee can contribute to raised serum cholesterol. Genetic polymorphisms in enzymes involved in uptake, metabolism and excretion of tea and coffee compounds are also associated with differential biological effects. Potential mechanisms by which tea and coffee phytochemicals can exert effects for CVD protection include the regulation of vascular tone through effects on endothelial function, improved glucose metabolism, increased reverse cholesterol transport and inhibition of foam cell formation, inhibition of oxidative stress, immunomodulation and effects on platelet function (adhesion and activation, aggregation and clotting). The phytochemical compounds in tea and coffee and their metabolites are suggested to influence protective endogenous pathways by modulation of gene-expression. It is not known exactly which compounds are responsible for the suggestive protective effects of tea and coffee. Although many biologically active compounds have been identified with known biological effects, tea and coffee contain many unidentified compounds with potential bioactivity.

Acute effects of coffee on QT interval in healthy subjects

The coronary endothelial function is recognized to have an important role in the physiology of the diastolic ventricular relaxation, a phase of the heart cycle that influences the electrocardiographic QT interval. Endothelial function is investigated in vivo by flow mediated dilation (FMD) in the brachial artery and has proven to be a strong predictor of both coronary endothelial function and cardiovascular events. It has been reported that coffee acutely induces FMD changes. In particular, the brachial artery FMD seems to decrease after caffeinated coffee (CC) and to increase after decaffeinated coffee (DC) ingestion. Since the cardiovascular effects of coffee are still a debated matter, this study aimed at investigating with a randomized, double-blind crossover design, if the QT interval of adult healthy subjects (19 males and 21 females) changes in the hour following CC or DC ingestion. Both systolic and diastolic blood pressure were higher in the hour following the ingestion of CC; the heart rate significantly increased 30 minutes after CC ingestion. A significant increase of the QT duration was observed one hour after DC ingestion (398.9 ± 3.8 vs 405.3 ± 3.7 msec; P < 0.05), not after CC. The QT interval corrected for heart rate did not significantly change following CC or DC ingestion. In conclusion, despite CC and DC previously demonstrated to influence the FMD they do not seem to induce a significant unfavourable acute change of the left ventricular repolarization. Further investigations are required to elucidate the effects of coffee in subjects with cardiovascular diseases.