Endothelial Function In Healthy Individuals Research Articles

Effects of photobiomodulation therapy (PBMT) over endothelial function in healthy individuals: a preliminary crossover clinical trial

Photobiomodulation therapy (PBMT) causes stimulatory effects that raise cell metabolism. The study aimed to evaluate the effects of PBMT on the endothelial function of healthy individuals. It was acontrolled, randomized, crossover, triple-blind trial with 22 healthy volunteers (female: 77.3%), aged 25.45years which were randomly divided into three groups. PBMT with gallium-aluminum-arsenide (GaAlAs) diode laser (810nm, continuous-wave mode, 1000 mW, 0.28 cm2) was applied over the radial and ulnar artery regions in two parallel spots: group 1-30J (n = 22, 107J/cm2) per spot; group 2-60J (n = 22, 214J/cm2) per spot; and group 3-placebo (n = 22, sham). The endothelial function was measured before and immediately after PBMT by the flow-mediated dilation technique (%FMD) with high-resolution ultrasound. Statistical analysis was made with ANOVA for repeated measures, the effect size was measured by Cohen's d, and results are presented as mean and standard error (or 95% confidence intervals). A p-value < 0.05 was considered statistically significant. The %FMD increases 10.4% with 60J (mean difference = 0.496mm, 95% CI = 0.42 to 0.57, p < 0.001), 7.3% with 30J (mean difference = 0.518mm, 95% CI = 0.44 to 0.59, p < 0.001), and 4.7% with placebo (mean difference = 0.560mm, 95% CI = 0.48 to 0.63, p < 0.001). We found a small effect size (p = 0.702; d de Cohen = 0.24) without statistical difference between interventions. PBMT with the energy density of 60J and 30J did not improve endothelial function.Trial registration number:NCT03252184 (01/09/2017).

Cocoa flavanol consumption improves lower extremity endothelial function in healthy individuals and people with type 2 diabetes.

Background: diabetes and age are major risk factors for the development of lower extremity peripheral artery disease (PAD). Cocoa flavanol (CF) consumption is associated with lower risk for PAD and improves brachial artery (BA) endothelial function. Objectives: to assess if femoral artery (FA) endothelial function and dermal microcirculation are impaired in individuals with type 2 diabetes mellitus (T2DM) and evaluate the acute effect of CF consumption on FA endothelial function. Methods: in a randomised, controlled, double-blind, cross-over study, 22 individuals (n = 11 healthy, n = 11 T2DM) without cardiovascular disease were recruited. Participants received either 1350 mg CF or placebo capsules on 2 separate days in random order. Endothelial function was measured as flow-mediated dilation (FMD) using ultrasound of the common FA and the BA before and 2 hours after interventions. The cutaneous microvasculature was assessed using optical coherence tomography angiography. Results: baseline FA-FMD and BA-FMD were significantly lower in T2DM (FA: 3.2 ± 1.1% [SD], BA: 4.8 ± 0.8%) compared to healthy (FA: 5.5 ± 0.7%, BA: 6.0 ± 0.8%); each p < 0.001. Whereas in healthy individuals FA-FMD did not significantly differ from BA-FMD (p = 0.144), FA-FMD was significantly lower than BA-FMD in T2DM (p = 0.003) indicating pronounced and additional endothelial dysfunction of lower limb arteries (FA-FMD/BA-FMD: 94 ± 14% [healthy] vs. 68 ± 22% [T2DM], p = 0.007). The baseline FA blood flow rate (0.42 ± 0.23 vs. 0.73 ± 0.35 l min-1, p = 0.037) and microvascular dilation in response to occlusion in hands and feet were significantly lower in T2DM subjects than in healthy ones. CF increased both FA- and BA-FMD at 2 hours, compared to placebo, in both healthy and T2DM subgroups (FA-FMD effect: 2.9 ± 1.4%, BA-FMD effect 3.0 ± 3.5%, each pintervention< 0.001). In parallel, baseline FA blood flow and microvascular diameter significantly increased in feet (3.5 ± 3.5 μm, pintervention< 0.001) but not hands. Systolic blood pressure and pulse wave velocity significantly decreased after CF in both subgroups (-7.2 ± 9.6 mmHg, pintervention = 0.004; -1.3 ± 1.3 m s-1, pintervention = 0.002). Conclusions: individuals with T2DM exhibit decreased endothelial function that is more pronounced in the femoral than in the brachial artery. CFs increase endothelial function not only in the BA but also the FA both in healthy individuals and in those with T2DM who are at increased risk of developing lower extremity PAD and foot ulcers.

A systematic review and meta-analysis of effect of yoga and meditation on endothelial system

Abstract Background/Introduction Endothelial dysfunction plays an important role in the pathophysiology of cardiovascular diseases and diabetes. Studies reported either an improvement in endothelial function by yoga and meditation or no significant effect. A systematic review and meta-analysis of effect of yoga on endothelial function is not available. Purpose The aim of this systematic review and meta-analysis is to determine the effectiveness of yoga and meditation on endothelial function in healthy subjects or patients of any age or gender. Methods Authors performed a systematic search for relevant research studies as per the PRISMA guidelines. The Pubmed, Scopus, Google Scholar and Cochrane controlled register of trials (CENTRAL) were screened from inception to November 2020. The search strategy was constructed around yoga based techniques, meditation and endothelial function. All the yoga-based interventional studies on endothelial function: controlled, uncontrolled, randomized, non-randomized and cross-over were included for this review. A narrative synthesis and descriptive analysis was done due to diverse methodology of all selected studies. We carried out a formal meta-analysis of controlled trials that assessed flow-mediated dilatation (FMD) which is a gold-standard measure of endothelial function.The quality of the studies was assessed using Cochrane risk of bias (RoB) tool. Results A total of 18 studies were included for review involving 1024 participants. Of these, 10 were RCT, one randomized cross-over study, 4 non-randomized studies and three single-group (before-after) studies. The total duration of yoga intervention ranged from 10 days to 52 weeks. Among the 18 selected studies, yoga training showed a significant favorable change in the measures of endothelial function in 12 studies (involving either healthy individuals or patients with coronary heart disease, myocardial infarction, metabolic syndrome, hypertension, migraine and dysmenorrhea) while 6 studies did not find any significant effect. Among the 15 controlled trials, 7 assessed FMD while the remaining evaluated different biomarkers of endothelial function such as circulating endothelial microparticles, asymmetric dimethyl arginine, nitric oxide or endothelin-1. Hence the results of 7 controlled trials assessing FMD were included for meta-analysis (n=384 participants) which showed a significant increase in brachial FMD by yoga practice (Mean difference = −2.02%, 95% CI: −3.72, −0.32, p=0.02). The heterogeneity between the studies was 76% (τ2=3.31, χ2=25.28) (Fig. 1). Conclusions Yoga and meditation can significantly improve endothelial function in healthy individuals and patients with cardiovascular disease or risk factors. Yoga and meditation can be applied clinically as a lifestyle modality for endothelial protection and cardiovascular prevention and rehabilitation. Funding Acknowledgement Type of funding sources: None.

Impact of proximal and distal cuff inflation on brachial artery endothelial function in healthy individuals.

In this study, we examined whether the decrease in endothelial function associated with short-term exposure to elevated retrograde shear rate (SR), could be prevented when combined with a concurrent drop in transmural pressure in humans. Twenty-five healthy individuals reported to our laboratory on three occasions to complete 30-min experimental conditions, preceded and followed by assessment of endothelial function using flow-mediated dilation (FMD). We used cuff inflation for 30-min to manipulate retrograde SR and transmural pressure in the brachial artery. Subjects underwent, in randomised order: (1) forearm cuff inflation to 60mmHg (distal cuff; causing increase in retrograde SR), (2) upper arm cuff inflation to 60mmHg (proximal cuff; causing increase in retrograde SR + decrease in transmural pressure), and (3) no cuff inflation (Control). The distal and proximal cuff conditions both increased brachial artery retrograde SR (p < 0.001) and oscillatory shear index (p < 0.001). The Control intervention did not alter SR patterns or FMD (p > 0.05). A significant interaction-effect was found for FMD (p < 0.05), with the decrease during distal cuff (from 6.9 ± 2.3% to 6.1 ± 2.5%), being reversed to an increase with proximal cuff (from 6.3 ± 2.0 to 6.9 ± 2.0%). The proximal cuff-related increase in FMD could not be explained by the decrease in antegrade or increase in retrograde shear. This study suggests that a decrease in transmural pressure may ameliorate the decline in endothelial function that occurs following exposure to elevated retrograde shear in healthy individuals.

Fluctuation in shear rate, with unaltered mean shear rate, improves brachial artery flow-mediated dilation in healthy, young men.

Increase in mean shear stress represents an important and potent hemodynamic stimulus to improve conduit artery endothelial function in humans. No previous study has examined whether fluctuations in shear rate patterns, without altering mean shear stress, impacts conduit artery endothelial function. This study examined the hypothesis that 30-min exposure to fluctuations in shear rate patterns, in the presence of unaltered mean shear rate, improves brachial artery flow-mediated dilation. Fifteen healthy men (27.3 ± 5.0 yr) completed the study. Bilateral brachial artery flow-mediated dilation was assessed before and after unilateral exposure to 30 min of intermittent negative pressure (10 s, -40mmHg; 7 s, 0 mmHg) to induce fluctuation in shear rate, while the contralateral arm was exposed to a resting period. Negative pressure significantly increased shear rate, followed by a decrease in shear rate upon pressure release (both P < 0.001). Across the 30-min intervention, mean shear rate was not different compared with baseline (P = 0.458). A linear mixed model revealed a significant effect of time observed for flow-mediated dilation (P = 0.029), with exploratory post hoc analysis showing an increase in the intervention arm (∆FMD +2.0%, P = 0.008), but not in the contralateral control arm (∆FMD +0.5%, P = 0.664). However, there was no effect for arm (P = 0.619) or interaction effect (P = 0.096). In conclusion, we found that fluctuations in shear patterns, with unaltered mean shear, improves brachial artery flow-mediated dilation. These novel data suggest that fluctuations in shear pattern, even in the absence of altered mean shear, represent a stimulus to acute change in endothelial function in healthy individuals. NEW & NOTEWORTHY Intermittent negative pressure applied to the forearm induced significant fluctuations in antegrade and retrograde shear rate, while mean shear was preserved relative to baseline. Our exploratory study revealed that brachial artery flow-mediated dilation was significantly improved following 30-min exposure to intermittent negative pressure. Fluctuations in blood flow or shear rate, with unaltered mean shear, may have important implications for vascular health; however, further research is required to identify the underlying mechanisms and potential long-term health benefits.

The Effect of the Oral Administration of Leucine on Endothelial Function, Glucose and Insulin Concentrations in Healthy Subjects

The aim of our study was to investigate the potential differential effect of hyperglycaemia and hyperinsulinaemia induced by glucose infusion alone and in combination with leucine consumption on endothelial function in healthy individuals. Ten male volunteers were examined in random order twice. In one visit, they consumed 250 ml water (baseline) and 30 min later glucose was infused iv. In the other visit, they consumed 250 ml water with 25 g of leucine and 30 min later the same amount of glucose was infused. Serum glucose and insulin were measured at baseline and every 10 min after glucose infusion for 1 h. Endothelial function was evaluated by measurement of flow mediated vasodilatation (FMD) at baseline, 10 and 60 min after glucose infusion. In both visits, glucose levels increased to the same degree, whereas insulin response was significantly higher after leucine administration. FMD values declined significantly compared to baseline 10 min after glucose infusion in the control visit (6.9±2.7 vs. 3.2±3.5%, respectively, p=0.006), while no significant change was observed when glucose infusion was followed by leucine consumption. Acute hyperglycaemia impairs endothelial function in healthy male individuals. Leucine administration prevents hyperglycaemia-mediated endothelial dysfunction probably due to enhanced insulin secretion.

A single Mediterranean meal does not impair postprandial flow-mediated dilatation in healthy men with subclinical metabolic dysregulations.

Cardiovascular risk factors are known to exacerbate high-saturated fatty acid meal (HSFAM)-induced endothelial dysfunction, but the influence of subclinical metabolic dysregulations and the acute impact of a single mixed Mediterranean-type meal (MMM) remains unknown. Thus, this study has the objective to evaluate the metabolic and vascular effect of such meals in healthy subjects with or without subclinical fasting metabolic dysregulations. Twenty-eight healthy males without overt cardiovascular risk factors randomly ingested 1 of 2 isocaloric meals on separate days. Plasma metabolic markers, fatty acid (FA) profile, and endothelial function (flow-mediated dilatation; FMD) were assessed at baseline and 2 and 4 h after meal ingestion. Unsupervised hierarchical clustering identified 2 subgroups of participants (n = 11 and 17) differing by their baseline metabolic profiles. The MMM did not significantly alter postprandial endothelial function in all subjects, irrespective of baseline metabolic parameters. In contrast, the HSFAM induced postprandial endothelial dysfunction (Δ%FMDabsolute = -5.28 ± 2.54, p < 0.01 vs. MMM) in a subgroup of individuals with significantly greater body mass index, fasting insulinemia, and lipid parameters (n = 11). Finally, the postprandial plasma FA profiles were differentially enriched by the HSFAM and MMM, notably with saturated FAs and omega-3 polyunsaturated FAs, respectively. Collectively, our results highlight the detrimental impact of a single HSFAM on endothelial function in healthy individuals displaying subclinical fasting metabolic dysregulations. Such individuals could benefit from MMM, demonstrated herein to be without any acute detriment to endothelial function.

Vasomotor endothelial function in healthy individuals: Association with the types of character

The vascular endothelial vasomotor function has been studied in healthy young subjects as dependent on the type of character accentuation and levels of neuroticism, depression, and anxiety. It has been shown that the types of character accentuation influence the endothelial vasomotor function in healthy men and women. Personality characteristics of a person can be a significant risk factor for diseases where endothelial vasomotor dysfunction is a trigger factor of pathogenesis.

Effects of Acute and Antecedent Hypoglycemia on Endothelial Function and Markers of Atherothrombotic Balance in Healthy Humans.

The aim of this study was to determine the effects of single and repeated episodes of clamped hypoglycemia on fibrinolytic balance, proinflammatory biomarkers, proatherothrombotic mechanisms, and endothelial function. Twenty healthy individuals (12 male and 8 female) were studied during separate 2-day randomized protocols. Day 1 consisted of either two 2-h hyperinsulinemic (812 ± 50 pmol/L)-euglycemic (5 ± 0.1 mmol/L) or hyperinsulinemic (812 ± 50 pmol/L)-hypoglycemic (2.9 ± 0.1 mmol/L) clamps. Day 2 consisted of a single 2-h hyperinsulinemic-hypoglycemic clamp. Two-dimensional Doppler ultrasound was used to determine brachial arterial endothelial function. Plasminogen activator inhibitor 1, vascular cell adhesion molecule-1, intracellular adhesion molecule-1, E-selectin, P-selectin, TAT (thrombin/antithrombin complex), tumor necrosis factor-α, and interleukin-6 responses were increased (P < 0.05) during single or repeated hypoglycemia compared with euglycemia. Endogenous and exogenous nitric oxide (NO)-mediated vasodilation were both impaired by repeated hypoglycemia. Neuroendocrine and autonomic nervous system (ANS) responses were also blunted by repeated hypoglycemia (P < 0.05). In summary, acute moderate hypoglycemia impairs fibrinolytic balance; increases proinflammatory responses, platelet activation, and coagulation biomarkers; and reduces NO-mediated endothelial function in healthy individuals. Repeated episodes of hypoglycemia further impair vascular function by additionally reducing exogenously NO-mediated endothelial function and increasing coagulation biomarkers. We conclude that despite reduced neuroendocrine and ANS responses, antecedent hypoglycemia results in greater endothelial dysfunction and an increased proatherothrombotic state compared with a single acute episode of hypoglycemia.

Impact of eight weeks of repeated ischaemic preconditioning on brachial artery and cutaneous microcirculatory function in healthy males.

Ischaemic preconditioning has well-established cardiac and vascular protective effects. Short interventions (one week) of daily ischaemic preconditioning episodes improve conduit and microcirculatory function. This study examined whether a longer (eight weeks) and less frequent (three per week) protocol of repeated ischaemic preconditioning improves vascular function. Eighteen males were randomly allocated to either ischaemic preconditioning (22.4 ± 2.3 years, 23.7 ± 3.1 kg/m(2)) or a control intervention (26.0 ± 4.8 years, 26.4 ± 1.9 kg/m(2)). Brachial artery endothelial-dependent (FMD), forearm cutaneous microvascular function and cardiorespiratory fitness were assessed at zero, two and eight weeks. A greater improvement in FMD was evident following ischaemic preconditioning training compared with control at weeks 2 (2.24% (0.40, 4.08); p=0.02) and 8 (1.11% (0.13, 2.10); p=0.03). Repeated ischaemic preconditioning did not change cutaneous microcirculatory function or fitness. These data indicate that a feasible and practical protocol of regular ischaemic preconditioning episodes improves endothelial function in healthy individuals within two weeks, and these effects persist following repeated ischaemic preconditioning for eight weeks.

Modulation of endothelial function by Korean red ginseng (Panax ginseng C.A. Meyer) and its components in healthy individuals: a randomized controlled trial.

Ginseng root and its derivatives remain atop the most widely used medicinal herbs in cardiovascular disease, despite inadequate substantiation of efficacy. We previously reported the potential of Korean red ginseng (KRG) to affect vascular tone by decreasing arterial wave reflection via an unknown mechanism. Given the preclinical link between ginseng intake and vasoactivity related to nitric oxide (NO) production, we sought to directly evaluate the effects of KRG root and its major root components, on an established noninvasive measure of endothelial function. In an acute, randomized, placebo-controlled, double-blind, crossover design, 16 healthy participants (9M:7F, age:30±9y, BMI: 24 kg±3kg/m(2) , systolicBP/diastolicBP: 109±11/66±8mmHg) on four occasions were administered: KRG root (3g), KRG ginsenosides extract, KRG polysaccharides extract, and cornstarch control. Extracted fractions were delivered at doses bioequivalent to those found in 3g of KRG. Flow-mediated vasodilatation (FMD) assessment, preceding a brachial blood pressure measurement, was performed at baseline and at 90 and 180 min posttreatment to assess endothelial function. KRG significantly improved FMD posttreatment. Maximal vasodilatation of Δ2.57±2.8% occurred at 180min compared with control (Δ-0.83±2.7%, P=0.003 for all comparisons). The ginsenoside extract produced a comparable response (Δ1.75±2.6%), but not the polysaccharide fraction (Δ0.10±2.7%). Brachial blood pressure remained unchanged for all treatments (P=0.45). KRG acutely improved endothelial function in healthy individuals, which appears to be attributable to its ginsenoside containing fraction. Our data confirm preclinical data and support the potential for these compounds as targets for therapeutic strategies in disorders involving endothelial dysfunction.

A Comparison of Flow-mediated Dilatation and Peripheral Artery Tonometry for Measurement of Endothelial Function in Healthy Individuals and Patients with Peripheral Arterial Disease

Flow-mediated dilatation (FMD) and peripheral artery tonometry (PAT) are commonly used methods for assessing endothelial function in a research setting but it is unclear how well they correlate. This study aimed to compare and correlate these methods in patients with peripheral arterial disease (PAD) and in healthy individuals. FMD and PAT measurements were obtained as samples of convenience from 26 patients with PAD and 25 healthy subjects. FMD was defined as the percentage increase in the brachial artery diameter after distal occlusion and PAT was measured using the reactive hyperaemia index (RHI). Patients with PAD had a significantly lower FMD than healthy subjects (2.43% vs. 5.80%, p < 0.001). No difference was found in RHI between the two groups. No correlation was found between the FMD and RHI in subjects with PAD (r = 0.284, p = 0.160), in healthy subjects (r = 0.153, p = 0.464) or when both groups were combined (r = 0.174, p = 0.22). The lack of change in RHI in PAD patients suggests that PAT is not a sensitive measure of endothelial function. The lack of correlation suggests that FMD and PAT are not interchangeable. PAT should not be used as a substitute for FMD as a measure of endothelial function.

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

Impact of n − 3 fatty acids on endothelial function: results from human interventions studies

Dysfunction of the endothelium plays an integral role in atherogenesis. This review summarizes recent findings on the effects of marine [eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA)] and plant [alpha-linolenic acids (ALA)] n-3 polyunsaturated fatty acids (PUFAs) on endothelial function in healthy individuals and in patients with cardiovascular disease (CVD) risk factors or manifest CVD. We identified 33 intervention trials investigating the effects of n-3 PUFA on fasting and/or postprandial endothelial function. In healthy individuals regular supplementation of EPA/DHA or ALA shows inconsistent results on endothelial function, whereas markers of endothelial function seem to be improved in overweight dyslipidaemic patients and type 2 diabetics. Conflicting results are observed in CVD patients. Reasons for discrepancies between the study results include the health status and age of participants, duration of supplementation, dose and fatty acid composition of the administered n-3 PUFAs as well as methods used to assess endothelial function. In individuals with CVD risk factors including overweight, dyslipidemia and type 2 diabetes n-3 PUFAs may improve endothelial function. However, the evidence for a clinical efficacy is not strong enough to make final recommendations with respect to a specific dose and the duration of supplementation.

The influence of alcohol consumed with a meal on endothelial function in healthy individuals

Alcohol and polyphenols in wine and fruit juices have been strongly implicated in the favourable effects on of these beverages on vascular function. Despite a wealth of information on the metabolic and vascular effects of alcohol and polyphenols, the combined influences of these substances on vascular function, especially when consumed with food, is poorly understood. A study was designed to determine the effects of a phenolic-rich grape juice, with or without alcohol, on vascular endothelial function in the postprandial state. Ten subjects consumed a standard meal with a test drink on three separate occasions. On each occasion, the test drink accompanying the meal was either red grape juice, red grape juice plus alcohol (12% v/v), or water. Endothelial function was measured by flow mediated dilatation (FMD) prior to then 30 and 60 minutes after consuming the meal. Blood samples were taken for the determination of plasma glucose, triacylglycerol (TAG) and non esterified fatty acids (NEFA) at regular intervals. There was a significant effect of the three treatments (P = 0.0026) and time (P = 0.021) on percentage FMD. The meals with the grape juice and grape juice plus alcohol produced similar FMD responses but were both significantly greater than the meal with water. The concentration of plasma glucose, TAG and NEFA were similar after each treatment. Alcohol had no effect on vascular function in the early postprandial phase. These findings provide new evidence to support the potential benefit of non-alcoholic components within alcoholic beverages on vascular function in the fed state.

Muscle sympathetic nerve activity is related to a surrogate marker of endothelial function in healthy individuals.

BackgroundEvidence from animal studies indicates the importance of an interaction between the sympathetic nervous system and the endothelium for cardiovascular regulation. However the interaction between these two systems remains largely unexplored in humans. The aim of this study was to investigate whether directly recorded sympathetic vasoconstrictor outflow is related to a surrogate marker of endothelial function in healthy individuals.Methods and ResultsIn 10 healthy normotensive subjects (3 f/7 m), (age 37±11 yrs), (BMI 24±3 kg/m2) direct recordings of sympathetic action potentials to the muscle vascular bed (MSNA) were performed and endothelial function estimated with the Reactive Hyperaemia- Peripheral Arterial Tonometry (RH-PAT) technique. Blood samples were taken and time spent on leisure-time physical activities was estimated. In all subjects the rate between resting flow and the maximum flow, the Reactive Hyperemic index (RH-PAT index), was within the normal range (1,9–3,3) and MSNA was as expected for age and gender (13–44 burst/minute). RH-PAT index was inversely related to MSNA (r = −0.8, p = 0.005). RH-PAT index and MSNA were reciprocally related to time (h/week) spent on physical activity (p = 0.005 and p = 0.006 respectively) and platelet concentration (PLT) (p = 0.02 and p = 0.004 respectively).ConclusionsOur results show that sympathetic nerve activity is related to a surrogate marker of endothelial function in healthy normotensive individuals, indicating that sympathetic outflow may be modulated by changes in endothelial function. In this study time spent on physical activity is identified as a predictor of sympathetic nerve activity and endothelial function in a group of healthy individuals. The results are of importance in understanding mechanisms underlying sympathetic activation in conditions associated with endothelial dysfunction and emphasise the importance of a daily exercise routine for maintenance of cardiovascular health.

Induced Inflammation Impairs Endothelial Function In Healthy Individuals

Induced Inflammation Impairs Endothelial Function In Healthy Individuals

The acute effect of green tea consumption on endothelial function in healthy individuals

Tea consumption is associated with decreased cardiovascular risk. Flow-mediated dilatation (FMD) of the brachial artery is related to coronary endothelial function and it is an independent predictor of cardiovascular risk. Black tea has a beneficial effect on endothelial function; the effect, however, of green tea on brachial artery reactivity has not been defined yet. We studied 14 healthy individuals (age 30+/-3 years) with no cardiovascular risk factors except from smoking (50%) on three separate occasions on which they took: (a) 6 g of green tea, (b) 125 mg of caffeine (the amount contained in 6 g of tea), or (c) hot water. FMD of the brachial artery was measured before each intervention and 30, 90, and 120 min afterward. High-sensitivity C-reactive protein, interleukins 6 (Il-6) and 1b (Il-1b), total plasma antioxidative capacity, and total plasma oxidative status/stress were measured at baseline and at 120 min after each intervention. Resting and hyperemic brachial artery diameter did not change either with tea or with caffeine. FMD increased significantly with tea (by 3.69%, peak at 30 min, P<0.02), whereas it did not change significantly with caffeine (increase by 1.72%, peak at 30 min, P=NS). Neither tea nor caffeine had any effect on high-sensitivity C-reactive protein, Il-6, Il-1b, total plasma antioxidative capacity, or total plasma oxidative status/stress. Green tea consumption has an acute beneficial effect on endothelial function, assessed with FMD of the brachial artery, in healthy individuals. This may be involved in the beneficial effect of tea on cardiovascular risk.

Effects of Oral Glucose Load on Endothelial Function and on Insulin and Glucose Fluctuations in Healthy Individuals

Background/aims. Postprandial hyperglycemia, an independent risk factor for cardiovascular disease, is accompanied by endothelial dysfunction. We studied the effect of oral glucose load on insulin and glucose fluctuations, and on postprandial endothelial function in healthy individuals in order to better understand and cope with the postprandial state in insulin resistant individuals. Methods. We assessed post-oral glucose load endothelial function (flow mediated dilation), plasma insulin, and blood glucose in 9 healthy subjects. Results. The largest increases in delta FMD values (fasting FMD value subtracted from postprandial FMD value) occurred at 3 hours after both glucose or placebo load, respectively: 4.80 ± 1.41 (P = .009) and 2.34 ± 1.47 (P = .15). Glucose and insulin concentrations achieved maximum peaks at one hour post-glucose load. Conclusion. Oral glucose load does not induce endothelial dysfunction in healthy individuals with mean insulin and glucose values of 5.6 mmol/L and 27.2 mmol/L, respectively, 2 hours after glucose load.

Effect of coffee on endothelial function in healthy subjects: the role of caffeine

Coffee is one of the most widely used pharmacologically active beverages. The present study was designed to evaluate the acute effect of coffee ingestion on endothelial function in healthy individuals, and the potential role of caffeine. We studied 17 healthy young adults (28.9+/-3.0 years old; nine men), who were regular non-heavy coffee drinkers. The endothelial performance was estimated by endothelium-dependent FMD (flow-mediated dilatation) of the brachial artery before and 30, 60, 90 and 120 min after ingestion of a cup of caffeinated coffee (80 mg of caffeine) or the corresponding decaffeinated beverage (< 2 mg of caffeine) in two separate sessions, following a randomized single-blind cross-over design. There was no difference in baseline FMD values between the two sessions [7.78 compared with 7.07% after caffeinated and decaffeinated coffee respectively; P = NS (not significant)]. Caffeinated coffee led to a decline of FMD (7.78, 2.86, 2.12, 4.44 and 4.57% at baseline, 30, 60, 90 and 120 min respectively; P < 0.001). This adverse effect was focused at 30 (P = 0.004) and 60 min (P < 0.001). No significant effect on FMD was found with the decaffeinated coffee session (7.07, 6.24, 5.21, 7.41 and 5.20%; P = NS). The composite effect of the type of coffee consumed over time on FMD was significantly different (P = 0.021). In conclusion, coffee exerts an acute unfavourable effect on the endothelial function in healthy adults, lasting for at least 1 h after intake. This effect might be attributed to caffeine, given that decaffeinated coffee was not associated with any change in the endothelial performance.