Fat intake impairs the recovery of endothelial function following mental stress in young healthy adults

Introduction

Mental stress has been identified as a trigger of cardiovascular events. A single episode of stress can induce acute impairments in endothelial function in healthy adults. Importantly, during stressful periods, individuals often resort to unhealthy behaviors, such as increased consumption of high-fat foods, which is also known to negatively impact endothelial function. Therefore, this study examined whether consumption of a high-fat meal would further exacerbate the negative effect of mental stress on vascular function.

Methods

In a randomized, counterbalanced, cross- over, postprandial intervention study, 21 healthy males and females ingested a high-fat (56.5 g fat) or a low-fat (11.4 g fat) meal 1.5 h before an 8-min mental stress task (Paced-Auditory-Serial-Addition-Task, PASAT). Plasma triglyceride (TAG) concentration was assessed pre-and post-meal. Forearm blood flow (FBF), blood pressure (BP), and cardiovascular activity were assessed pre-meal at rest and post-meal at rest and during stress. Endothelial function, measured by brachial flow-mediated dilatation (FMD) was assessed pre-meal and 30 and 90 min following mental stress.

Results

Plasma TAG concentration was significantly increased following the high-fat meal compared to the low-fat condition. Mental stress induced similar increases in peripheral vasodilation, BP, and cardiovascular activity, and impaired FMD 30 min post-stress, in both conditions. FMD remained significantly impaired 90 min following stress in the high-fat condition only, suggesting that consumption of fat attenuates the recovery of endothelial function following mental stress.

Discussion

Given the prevalence of fat consumption during stressful periods among young adults, these findings have important implications for dietary choices to protect the vasculature during periods of stress.

A single high-fat Western meal modulates vascular responsiveness to sympathetic activation at rest and during exercise in humans: a randomized controlled trial

A single high-fat Western meal transiently reduces endothelium-dependent vasodilation at rest, but the interaction with sympathetic vasoconstrictor activity during exercise remains unknown. Herein, we tested the hypothesis that a single high-fat Western meal would impair the ability of contracting skeletal muscle to offset vascular responsiveness to sympathetic activation during exercise, termed functional sympatholysis. In 18 (10 females/8 males) healthy young adults, forearm blood flow (Doppler ultrasound) and beat-to-beat arterial pressure (photoplethysmography) were measured during lower-body negative pressure (LBNP; -20 mmHg) applied at rest and simultaneously during low (15% maximum contraction) and moderate (30% maximum contraction)-intensity rhythmic handgrip exercise. The magnitude of sympatholysis was calculated as the difference of LBNP-induced changes in forearm vascular conductance (FVC) between handgrip and rest. Experiments were performed preprandial and 1 h, 2 h, and 3 h after a high- or low-fat meal. In the preprandial state, LBNP decreased resting FVC (Δ-54 ± 10%), and these responses were attenuated during low (Δ-17 ± 7%)- and moderate (Δ-8 ± 6%)-intensity handgrip exercise. Following a high-fat meal, LBNP induced attenuated decreases in resting FVC (3 h postprandial, Δ-47 ± 10%, P = 0.002 vs. preprandial) and blunted attenuation of FVC during low (3 h postprandial, Δ-23 ± 8%, P = 0.001 vs. preprandial)- and moderate (3 h postprandial, Δ-16 ± 6%, P < 0.001 vs. preprandial)-intensity handgrip exercise. The high-fat meal attenuated the magnitude of sympatholysis during low (preprandial, 38 ± 7 vs. 3 h postprandial, 23 ± 8%, P < 0.001)- and moderate (preprandial, 46 ± 11 vs. 3 h postprandial, 31 ± 10%, P < 0.001)-intensity handgrip exercise. The low-fat meal had no impact on these responses. In conclusion, a single high-fat Western meal modulates sympathetic vasoconstriction at rest and during low- and moderate-intensity handgrip exercise in young healthy adults.NEW & NOTEWORTHY We observed that a single high-fat Western meal, but not an isocaloric low-fat meal, attenuated the sympathetic vasoconstriction at rest and the ability of the active skeletal muscle to counteract the vascular responsiveness to sympathetic activation (i.e., functional sympatholysis) during low- and moderate-intensity rhythmic handgrip exercise in healthy young adults. Our findings highlight the potential deleterious vascular effect associated with the consumption of a Western diet.

A single, high-fat meal adversely affects postprandial endothelial function: a systematic review and meta-analysis

BACKGROUND

Endothelial dysfunction is a predictive risk factor for the development of atherosclerosis and is assessed by flow-mediated dilation (FMD). Although it is known that NO-dependent endothelial dysfunction occurs after consuming a high-fat meal, the magnitude of the effect and the factors that affect the response are unquantified.

OBJECTIVES

We conducted a systematic review and meta-analysis exploring the quantitative effects of a single high-fat meal on endothelial function and determined the factors that modify the FMD response.

METHODS

Six databases were systematically searched for original research published up to January 2022. Eligible studies measured fasting and postprandial FMD following consumption of a high-fat meal. Meta-regression was used to analyze the effect of moderator variables.

RESULTS

There were 131 studies included, of which 90 were suitable for quantitative meta-analysis. A high-fat meal challenge transiently caused endothelial dysfunction, decreasing postprandial FMD at 2 hours [-1.02 percentage points (pp); 95% CI: -1.34 to -0.70 pp; P < 0.01; I2 = 93.3%], 3 hours [-1.04 pp; 95% CI: -1.48 to -0.59 pp; P < 0.001; I2 = 84.5%], and 4 hours [-1.19 pp; 95% CI: -1.53 to -0.84 pp; P < 0.01; I2 = 94.6%]. Younger, healthy-weight participants exhibited a greater postprandial reduction in the FMD percentage change than older, heavier, at-risk groups after a high-fat meal ( P < 0.05). The percentage of fat in the meals was inversely associated with the magnitude of postprandial changes in FMD at 3 hours (P < 0.01).

CONCLUSIONS

A single, high-fat meal adversely impacts endothelial function, with the magnitude of the impact on postprandial FMD moderated by the fasting FMD, participant age, BMI, and fat content of the meal. Recommendations are made to standardize the design of future postprandial FMD studies and optimize interpretation of results, as high-fat meals are commonly used in clinical studies as a challenge to assess endothelial function and therapeutics. This trial was registered at PROSPERO as CRD42020187244.

Stress Reactivity as a Contributor to Racial and Socioeconomic Disparities: Rationale and Baseline Results From the Richmond Stress and Sugar Study

OBJECTIVE

There are pronounced racial and socioeconomic disparities in type 2 diabetes. Although "stress" as a general phenomenon is hypothesized to contribute to these disparities, few studies have objective measures of stress reactivity in diverse samples to test hypotheses about purported mechanisms. This study describes the rationale and baseline characteristics of a cohort designed to address the question: how does stress contribute to disparities in diabetes risk?

METHODS

The Richmond Stress and Sugar Study recruited 125 adults at elevated risk of type 2 diabetes using a two-by-two sampling frame wherein non-Hispanic whites and African Americans (AAs) were each recruited from neighborhoods of higher and lower socioeconomic status (SES). Stress reactivity was assessed using the Trier Social Stress Test (TSST) and salivary cortisol. Analyses of variance and multilevel modeling were used to examine how stress reactivity varied both within and across race and neighborhood SES.

RESULTS

The mean (SD) age was 57.4 (7.3) years, 49% were female, 54% were AA or another racial/ethnic minority, and mean hemoglobin A1c level was in the prediabetes range (5.8%; range, 5.50%-5.93%). Living in a lower-SES neighborhood was associated with 16% (95% confidence interval [CI] = -0.04 to 34) higher pre-TSST cortisol, 8.4% (95% CI = -14 to -3) shallower increase in response to the TSST, and 1% (95% CI = 0.3 to 1.7) steeper decline post-TSST than living in the higher neighborhood SES. Post-TSST cortisol decline was 3% greater among AA compared with non-Hispanic whites. Race-by-SES interaction terms were generally small and nonsignificant.

CONCLUSIONS

SES is associated with stress reactivity among adults at high risk of diabetes.

The influence of acute hyperglycaemia on brachial artery flow-mediated dilatation in the early and late follicular phases of the menstrual cycle

NEW FINDINGS

What is the central question of the study? This is the first study to examine the impact of acute hyperglycaemia on endothelial function [flow-mediated dilatation (FMD)] in premenopausal women across the early and late follicular (EF and LF) phases of the menstrual cycle. What is the main finding and its importance? Flow-mediated dilatation was impaired 90 min after glucose ingestion, with no significant difference between phases. This indicates that women are susceptible to acute hyperglycaemia-induced endothelial dysfunction in both the EF and LF phases of the menstrual cycle, despite potentially vasoprotective elevations in estradiol levels during the LF phase.

ABSTRACT

Acute hyperglycaemia transiently impairs endothelial function in healthy men when assessed via flow-mediated dilatation (FMD). However, research in female participants is lacking, and the impact of menstrual phase [early follicular (EF) and late follicular (LF)] on vulnerability to acute hyperglycaemia-induced endothelial dysfunction is unknown. Seventeen healthy, naturally menstruating women [21 ± 1 years old (mean ± SD)] participated in three visits. During two visits (EF_Glucose and LF_Glucose ), brachial artery FMD was assessed before and 60, 90 and 120 min after an oral glucose challenge (75 g glucose). During an additional EF visit, participants ingested 300 ml of water (EF_TimeControl ). Blood glucose and insulin increased 30 min after glucose ingestion (P < 0.001), with no difference between phases. Flow-mediated dilatation did not change in EF_TimeControl (P = 0.748) but was reduced 90 min after glucose ingestion (Pre, 8.5 ± 2.5%; Post90, 6.6 ± 2.4%, P = 0.001; Cohen's d = 0.82), with no difference between phases (main effect of phase, P = 0.506; phase by time interaction, P = 0.391). To account for individual variability in the time course of the impact of hyperglycaemia, the maximal hyperglycaemia-induced impairment in FMD was determined in each participant and compared between phases, revealing no significant phase differences (EF_Glucose , -3.1 ± 2.8%; LF_Glucose , -2.4 ± 2.1%, P = 0.181; d = 0.34). These results indicate that, similar to findings in men, acute hyperglycaemia results in FMD impairment in young women. We did not detect significant protection from acute hyperglycaemia-induced endothelial dysfunction in the LF 'high-oestrogen' phase in this sample, and further research is needed to examine the potential for a protective effect of oestrogen exposure, including oral contraceptive pills and hormone replacement therapy.

The effect of an apple polyphenol extract rich in epicatechin and flavan-3-ol oligomers on brachial artery flow-mediated vasodilatory function in volunteers with elevated blood pressure

BACKGROUND

The primary aim of this study was to test the hypothesis that an orally ingested apple polyphenol extract rich in epicatechin and flavan-3-ol oligomers improves endothelium-dependent brachial artery flow-mediated vasodilatation (FMD) in volunteers with borderline hypertension. The secondary aim of the study was to test whether the investigational product would improve endothelium-independent nitrate-mediated vasodilatation (NMD).

METHODS

This was a single centre, repeated-dose, double-blind, placebo-controlled, crossover study in 60 otherwise healthy subjects (26 men, 34 women; aged 40-65 years) with borderline hypertension (blood pressure 130-139/85-89 mmHg) or unmedicated mild hypertension (blood pressure 140-165/90-95 mmHg). The subjects were randomised to receive placebo or the apple polyphenol extract to provide a daily dose of 100 mg epicatechin for 4 weeks, followed by a four to five-week wash-out period, and then 4 weeks intake of the product that they did not receive during the first treatment period. FMD and NMD of the left brachial artery were investigated with ultrasonography at the start and end of both treatment periods, and the per cent increase of the arterial diameter (FMD% and NMD%) was calculated.

RESULTS

With the apple extract treatment, a significant acute improvement was detected in the mean change of maximum FMD% at the first visit 1.16 (p = 0.04, 95% CI: 0.04; 2.28), last visit 1.37 (p = 0.02, 95% CI: 0.22; 2.52) and for both visits combined 1.29 (p < 0.01, 95% CI: 0.40; 2.18). However, such improvement was not statistically significant when apple extract was compared with placebo. The overall long-term effect of apple extract on FMD% was not different from placebo. No statistically significant differences between the apple extract and placebo treatments were observed for endothelium-independent NMD.

CONCLUSIONS

A significant acute improvement in maximum FMD% with apple extract administration was found. However, superiority of apple extract over placebo was not statistically significant in our study subjects with borderline hypertension or mild hypertension. The study raised no safety concerns regarding the daily administration of an apple polyphenol extract rich in epicatechin.

TRIAL REGISTRATION

The trial is registered at http://clinicaltrials.gov (identifier: NCT01690676 ). Registered 25th May 2012.

The influence of vitamin C on the interaction between acute mental stress and endothelial function

PURPOSE

To determine whether orally administered vitamin C attenuates expected mental stress-induced reductions in brachial artery endothelial function as measured by flow-mediated dilation (FMD).

METHODS

Fifteen men (21 ± 2 years) were given 1000 mg of vitamin C or placebo over two visits in a randomized, double-blinded, within-subject design. Acute mental stress was induced using the Trier Social Stress Test (TSST). Saliva samples for cortisol determination and FMD measures were obtained at baseline, pre-TSST, and 30 and 90-min post-TSST. An additional saliva sample was obtained immediately post-TSST. Cardiovascular stress reactivity was characterized by changes in heart rate (HR) and mean arterial pressure (MAP).

RESULTS

A significant stress response was elicited by the TSST in both conditions [MAP, HR, and salivary cortisol increased (p < 0.001)]. Overall FMD did not differ pre- vs. post-stress (time: p = 0.631) and there was no effect of vitamin C (condition: p = 0.792) (interaction between time and condition, p = 0.573). However, there was a correlation between cortisol reactivity and changes in FMD from pre- to post-stress in the placebo condition (r ² = 0.66, p < 0.001) that was abolished in the vitamin C condition (r ² = 0.02, p = 0.612).

CONCLUSION

Acute mental stress did not impair endothelial function, and vitamin C disrupted the relationship between cortisol reactivity and changes in FMD post-stress. This suggests that acute mental stress does not universally impair endothelial function and that reactive oxygen species signaling may influence the interaction between FMD and stress responses.

Evidence that meal fat content does not impact hemodynamic reactivity to or recovery from repeated mental stress tasks

The magnitude (reactivity) and duration (recovery) of hemodynamic stress responses are predictive of cardiovascular risk, and fat intake has been shown to enhance hemodynamic reactivity to psychological stress tasks. The objective of this study was to determine the impact of a high-fat meal (HFM) on the magnitude and stability of hemodynamic stress reactivity and recovery. This was assessed by: (i) the peak changes from baseline to during stress for heart rate (HR); mean, systolic, and diastolic blood pressure; cardiac output; and total peripheral resistance; and (ii) the residual arousal in hemodynamic parameters at 2 points post-stress ("early" and "late" recovery). On different days, 10 healthy males (aged 23.2 ± 3.3 years) consumed either a HFM (54 g fat) or low-fat meal (LFM; 0 g fat) (∼1000 calories each), followed by 4 hourly 10-min stress tasks (mental arithmetic and speech tasks). Pre-stress (baseline) parameters did not differ between HFM and LFM conditions (all P > 0.05). Plasma triglycerides were greater following the HFM versus the LFM (P = 0.023). No reactivity or recovery parameters differed between meals (all P > 0.05). Stress reactivity and recovery parameters were stable over the 4 stress tasks (main effects of time, all P > 0.05), with the exception of HR (P < 0.05). Contrary to previous reports, meal fat content did not impact hemodynamic reactivity to laboratory stressors. These data also provide the first evidence that meal fat content does not impact hemodynamic recovery from repeated mental stress tasks.