The impact of a plant-based diet on indices of cardiovascular health in African Americans: a cross-sectional study.

African-American (AA) individuals are disproportionately affected by cardiovascular diseases. Plant-based diets (PBD) may be cardioprotective in part through their high antioxidant capacity and low inflammatory load. We tested the hypothesis that AA individuals adhering to a 100% PBD would have better vascular health than AA individuals following a typical American diet (TAD). Eighteen AA individuals participated; 9 (24 ± 4 years; 6 females) were following a PBD for 2.4 ± 0.8 years and 9 (21 ± 2 years; 5 females) were following a TAD. Blood lipids and C-reactive protein (CRP) were assessed. Peripheral and central blood pressure (BP) were measured, and vascular function tests included cerebrovascular reactivity to hypercapnia, brachial artery flow-mediated dilation and reactive hyperemia, and local heating-induced cutaneous hyperemia. Total (TC) and low-density lipoprotein (LDL-C) serum cholesterol was lower (TC: 142 ± 30 vs. 174 ± 36 mg/dL; LDL-C: 76 ± 17 vs. 106 ± 33 mg/dL; p < 0.05 and d > 0.80 for both) and serum CRP tended to be lower (0.38 ± 0.18 mg/L vs. 0.96 ± 0.89 mg/L; p = 0.05, d = 0.91) in the PBD cohort. Brachial (b) and central (c) mean arterial BP (MAP) were lower in the PBD cohort (bMAP: 86 ± 5 vs. 91 ± 7 mm Hg; cMAP: 81 ± 5 vs. 87 ± 7 mm Hg; p < 0.05 and d > 0.80 for both). All indices of vascular function were similar between groups (p > 0.05 for all). A PBD was associated with more optimal blood lipid concentrations and decreased peripheral and central BP in AA individuals, but this association was not present in the various indices of vascular function. Registered at ClinicalTrials.gov: NCT05344287.

Young, non-Hispanic Black men and women exhibit divergent peripheral and cerebral vascular reactivity.

NEW FINDINGS: What is the central question of the study? Do peripheral and cerebral vascular function differ between young non-Hispanic Black men and women? What is the main finding and its importance? The non-Hispanic Black women in this study presented greater peripheral conduit artery and cerebrovascular reactivity, yet similar peripheral microvascular function relative to the non-Hispanic Black men. These preliminary findings suggest that young Black women and men possess divergent vascular function, possibly contributing to the unique non-Hispanic Black sex differences in cardiovascular and cerebrovascular diseases. ABSTRACT: In the USA, cardiovascular and cerebrovascular diseases remain more prominent in the non-Hispanic Black (BL) population relative to other racial/ethnic groups. Typically, sex differences emerge in the manifestation of these diseases, though these differences may not fully materialize in the BL population. While numerous mechanisms are implicated, differences in vascular function likely contribute. Research has demonstrated blunted vasodilatation in several vascular regions in BL versus non-Hispanic White individuals, though much of this work did not assess sex differences. Therefore, this study aimed to ascertain if indices of vascular function are different between young BL women (BW) and men (BM). Eleven BW and 15 BM (22 (4) vs. 23 (3) years) participated in this study. Each participant underwent testing for brachial artery flow-mediated dilatation (FMD), post-occlusive reactive hyperaemia and cerebral vasomotor reactivity during rebreathing-induced hypercapnia. BW exhibited greater adjusted FMD than BM (P < 0.05 for all), but similar or lower reactive hyperaemia when assessed as blood velocity (P > 0.39 for all) or blood flow reactivity (P < 0.05 for all), respectively. Across a range of hypercapnia, BW had greater middle cerebral artery blood velocity and cerebrovascular conductance index than BM (P < 0.001 for both). These preliminary data suggest that young BW have greater vascular function relative to young BM, though this was inconsistent across different indices. These findings provide insight into the divergent epidemiological findings between BM and BW. Further research is needed to elucidate possible mechanisms and relate these physiological responses to epidemiological observations.

Contributions of endothelin-1 and l-arginine to blunted cutaneous microvascular function in young, black women.

Non-Hispanic black (BL) individuals have the greatest prevalence of cardiovascular disease (CVD), relative to other racial/ethnic groups (e.g., non-Hispanic white population; WH), which may be secondary to blunted vascular function. Although women typically present with reduced CVD relative to men of the same racial/ethnic group, the prevalence is similar between BL women and men though the mechanisms differ. This study hypothesized that reduced microvascular function in young, BL women is associated with endothelin-1 (ET-1) overactivity or insufficient l-arginine bioavailability. Nine BL and nine WH women participated (age: 20 ± 2 vs. 22 ± 2 yr). Cutaneous microvascular function was assessed during 39°C local heating, whereas lactated Ringer's (control), BQ-123 (ET-1 receptor type A antagonist), BQ-788 (ET-1 receptor type B antagonist), or l-arginine were infused via intradermal microdialysis to modify cutaneous vascular conductance (CVC). Subsequent infusion of Nω-nitro-l-arginine methyl ester allowed for quantification of the nitric oxide (NO) contribution to vasodilation, whereas combined sodium nitroprusside and 43°C heating allowed for normalization to maximal CVC (%CVCmax). BL women had blunted %CVCmax and NO contribution to dilation during the 39°C plateau (P < 0.027 for both). BQ-123 improved this response through augmented NO-mediated dilation (P < 0.048 for both). BQ-788 and l-arginine did not alter the CVC responses (P > 0.835 for both) or the NO contribution (P > 0.371 for both). Cutaneous microvascular function is reduced in BL women, and ET-1 receptor type A may contribute to this reduced function. Further research is needed to better characterize these mechanisms in young, BL women.NEW & NOTEWORTHY Cardiovascular disease remains a burden in the United States non-Hispanic black (BL) population, although its manifestation through blunted vasodilation in this population is different between men and women. Accordingly, this study determined that reduced microvascular function in young, BL women may be partially controlled by endothelin-1 (ET-1) type A receptors, although neither type B receptors nor insufficient l-arginine bioavailability seems to contribute to this response. Accordingly, further research is needed to better characterize these ET-1 related mechanisms and illuminate other pathways that may contribute to this disparate vascular function in young, BL women.

Blunted hyperemic response to mental stress in young, non-Hispanic black men is not impacted by acute dietary nitrate supplementation.

Non-Hispanic black individuals suffer from an elevated prevalence of hypertension and cardiovascular disease (CVD) relative to other populations. This elevated disease risk is, in large part, related to impaired vascular function, secondary to reduced nitric oxide (NO) bioavailability. Emerging evidence suggests that dietary nitrate supplementation improves several cardiovascular parameters, including vascular function, in part by increased NO bioavailability. However, whether these findings extend to a population of black individuals is unknown. This study tested the hypothesis that forearm blood flow responses in young, non-Hispanic, black (BL) men during a mental stress challenge would be blunted relative to young, non-Hispanic, white (WH) men. We further hypothesized that acute dietary nitrate supplementation would improve this response in BL men. This study comprised two parts (phase 1 and phase 2). Phase 1 investigated the difference in blood flow responses between young, BL, and WH men. In contrast, phase 2 investigated the effect of acute nitrate supplementation on the responses in a subset of the BL men from phase 1. Eleven (nine for phase 2) BL and eight WH men (23 ± 3 vs. 24 ± 4 yr, respectively) participated in this double-blind, placebo-controlled, randomized, crossover study. During each visit, hemodynamic responses during 3 min of mental stress were assessed in the brachial artery using duplex Doppler ultrasound. Phase 1 was completed in one visit, whereas phase 2 was completed over two visits separated by ∼1 wk. During phase 2, data were collected before and 2-h postconsumption of a beverage either high in nitrate content or nitrate depleted. In phase 1, peak forearm blood flow (FBF; P < 0.001), total FBF (P < 0.01), and forearm vascular conductance (FVC; P < 0.001) were blunted in the BL. During phase 2, prebeverage responses were similar to phase 1 and were unaffected following beverage consumption (P > 0.05 vs. prebeverage for all variables). These data indicate that young, BL men have blunted microvascular vasodilatory responses to acute mental stress, which may not be altered following acute nitrate supplementation.NEW & NOTEWORTHY This study tested the hypothesis that non-Hispanic black (BL) men have a blunted forearm hyperemic response to mental stress, which would be augmented following acute nitrate supplementation. The increase in forearm blood flow during mental stress was attenuated in BL men and was not impacted by nitrate supplementation. This supports findings of altered vascular function in this population. This is especially important as BL experience a higher prevalence of stress, which contributes to CVD risk.

Recovery from an acute systemic and central LPS-inflammation challenge is affected by mouse sex and genetic background.

Genetic and sexual factors influence the prevalence and the pathogenesis of many inflammatory disorders. In this study their relevance on the peripheral and central inflammatory status induced by a peripheral injection of lipopolysaccharide (LPS) was evaluated. BALB/c and CD-1 male and female mice were intraperitoneally injected with LPS. Spleens and brains were collected 2 and 72 hours later to study the levels of IL-6, TNF-α and IL-1ß. Percentage of microglia and astrocytes was determined in the cortex and hippocampus. Locomotor activity was registered before and during the 72 hours after LPS-treatment. Two hours after LPS-injection, a peripheral increase of the three cytokines was found. In brains, LPS increased TNF-α only in males with higher levels in CD-1 than BALB/c. IL-1ß increased only in CD-1 males. IL-6 increased in both strains with lower levels in BALB/c females. Peripheral and central levels of cytokines decline 72 hrs after LPS-treatment whilst a significantly increase of Iba-1 expression was detected. A dramatic drop of the locomotor activity was observed immediately after LPS injection. Our results show that acute systemic administration of LPS leads to peripheral and central increase of pro-inflammatory cytokines and microglia activation, in a strain and sex dependent manner.