Central systolic blood pressure and aortic stiffness response to dietary sodium in young and middle-aged adults

Assessing Sarcocornia as a Salt Substitute: Effects on Lipid Profile and Gelatinase Activity

Sodium, although essential for life, is a key factor in changes in vascular function and cardiovascular disease when consumed in excess. Sarcocornia spp., a halophyte plant with many nutritional benefits, presents itself as a promising substitute for the consumption of purified salt. Matrix metalloproteinases (MMPs) 2 and 9 are widely studied due to their action in physiological processes and as biomarkers at the diagnostic level due to their increased expression in inflammatory processes. This study aimed to evaluate whether replacing salt with Sarcocornia perennis (S. perennis) powder in healthy young people leads to an improvement in biochemical profiles and the attenuation of MMP-2 and MMP-9 activity. In the present study, 30 participants were randomized into a control group that consumed salt and an intervention group that replaced salt with powdered S. perennis. The evaluation of the biochemical parameters was carried out by the spectrophotometry method, and the evaluation of MMP activity was carried out by zymography. A significant decrease was observed in the intervention group in total cholesterol, high-density lipoprotein cholesterol (HDL-c), and creatinine (p-value ≤ 0.05), along with lower but not significantly different mean values of triglycerides. Regarding MMP activity after the intervention, a lower mean value was observed for MMP-9 activity, with there being higher mean values for MMP-2 activity, both with p-values ≥ 0.05. The results confirmed that the consumption of S. perennis is a beneficial choice for health regarding the lipid profile. The evaluation of MMP activity indicated the potential of S. perennis in the regulation of MMP-9 activity in healthy individuals, along with the need for the further study of these proteases in individuals with pathologies.

Higher arterial stiffness and blunted vagal control of the heart in young women with compared to without a clinical diagnosis of PTSD

PURPOSE

Young women are typically thought to be protected from cardiovascular disease (CVD) before menopause. However, posttraumatic stress disorder (PTSD) increases CVD risk in women by up to threefold. Data in predominantly male cohorts point to physiological mechanisms such as vascular and autonomic derangements as contributing to increased CVD risk. The purpose of the study reported here was to determine whether young women diagnosed with PTSD, compared to those without, present with arterial stiffness and impaired autonomic control of the heart.

METHODS

A total of 73 healthy young women, ranging in age from 18 to 40 years, with a history of trauma exposure were included in this study, 32 with and 41 without a clinical PTSD diagnosis. We measured resting pulse wave velocity (PWV), central hemodynamics, augmentation pressure and augmentation index (AI) via pulse wave analysis using applanation tonometry. Heart rate variability was also assessed via peripheral arterial tone.

RESULTS

In comparison to controls, women with PTSD showed higher central arterial pressure (mean ± standard deviation: systolic blood pressure 104 ± 8 vs. 97 ± 8 mmHg, p < 0.001; diastolic blood pressure 72 ± 7 vs. 67 ± 7 mmHg, p = 0.003), PWV (6 ± 0.3 vs. 5 ± 0.6 m/s, p < 0.001) and AI (22 ± 13 vs. 15 ± 12%, p = 0.007) but lower standard deviation of normal-to-normal intervals (SDNN; 44 ± 17 vs. 54 ± 18 ms, p = 0.005) and root mean square of successive differences between normal heartbeats (RMSSD; 37 ± 17 vs. 51 ± 22 ms, p = 0.002).

CONCLUSION

PTSD in young women is associated with higher brachial and central pressures, increased arterial stiffness and blunted parasympathetic control of the heart. These findings illustrate potential mechanisms underlying high risk for CVD in young women with PTSD, suggesting possible treatment targets for this at-risk group.

The damaging duo: Obesity and excess dietary salt contribute to hypertension and cardiovascular disease

Hypertension is a primary risk factor for cardiovascular disease. Cardiovascular disease is the leading cause of death among adults worldwide. In this review, we focus on two of the most critical public health challenges that contribute to hypertension-obesity and excess dietary sodium from salt (i.e., sodium chloride). While the independent effects of these factors have been studied extensively, the interplay of obesity and excess salt overconsumption is not well understood. Here, we discuss both the independent and combined effects of excess obesity and dietary salt given their contributions to vascular dysfunction, autonomic cardiovascular dysregulation, kidney dysfunction, and insulin resistance. We discuss the role of ultra-processed foods-accounting for nearly 60% of energy intake in America-as a major contributor to both obesity and salt overconsumption. We highlight the influence of obesity on elevated blood pressure in the presence of a high-salt diet (i.e., salt sensitivity). Throughout the review, we highlight critical gaps in knowledge that should be filled to inform us of the prevention, management, treatment, and mitigation strategies for addressing these public health challenges.

The Influence of Dietary Interventions on Arterial Stiffness in Overweight and Obese Subjects

Arterial stiffness is often increased in overweight/obese subjects before the development of hypertension. It is also one of the earliest indicators of increased cardiovascular disease risk and can be considered a good predictor of the development of subclinical cardiovascular dysfunction. Arterial stiffness is a significant prognostic factor influencing cardiovascular risk, which dietary habits can modify. Obese patients should use the caloric-restricted diet because it augments aortic distensibility, diminishes pulse wave velocity (PWV), and increases the activity of endothelial nitric oxide synthases. High intake of saturated fatty acids (SFA), trans fats, and cholesterol, typical for the Western diet, impairs endothelial function and raises brachial-ankle PMV. The replacement of SFA with monounsaturated (MUFA) or polyunsaturated fatty acids (PUFA) derived from seafood and plants diminishes the risk of arterial stiffness. The dairy product intake (excluding butter) decreases PWV in the general population. The high-sucrose diet causes toxic hyperglycemia and increases arterial stiffness. Complex carbohydrates with a low glycemic index (including isomaltose) should be recommended to keep vascular health. The high sodium intake (>10 g/day), particularly associated with low potassium consumption, has a deleterious effect on arterial stiffness (↑ baPWV). Since vegetables and fruits are good sources of vitamins and phytochemicals, they should be recommended in patients with high PMV. Thus, the dietary recommendation to prevent arterial stiffness should be similar to the Mediterranean diet, which is rich in dairy products, plant oils, and fish, with a minimal red meat intake and five servings of fruits and vegetables daily.

Dietary sodium and health: How much is too much for those with orthostatic disorders?

High dietary salt (NaCl) increases blood pressure (BP) and can adversely impact multiple target organs including the vasculature, heart, kidneys, brain, autonomic nervous system, skin, eyes, and bone. However, patients with orthostatic disorders are told to increase their NaCl intake to help alleviate symptoms. While there is evidence to support the short-term benefits of increasing NaCl intake in these patients, there are few studies assessing the benefits and side effects of long-term high dietary NaCl. The evidence reviewed suggests that high NaCl can adversely impact multiple target organs, often independent of BP. However, few of these studies have been performed in patients with orthostatic disorders. We conclude that the recommendation to increase dietary NaCl in patients with orthostatic disorders should be done with care, keeping in mind the adverse impact on dietary NaCl in people without orthostatic disorders. Modest, rather than robust, increases in NaCl intake may be sufficient to alleviate symptoms but also minimize any long-term negative effects.

Dietary Reference Intakes of sodium for Koreans: focusing on a new DRI component for chronic disease risk reduction

Sodium is a physiologically essential nutrient, but excessive intake is linked to the increased risk of various chronic diseases, particularly cardiovascular. It is, therefore, necessary to accomplish an evidence-based approach and establish the Korean Dietary Reference Intakes (KDRIs) index, to identify both the nutritional adequacy and health effects of sodium. This review presents the rationale for and the process of revising the KDRIs for sodium and, more importantly, establishing the sodium Chronic Disease Risk Reduction Intake (CDRR) level, which is a new specific set of values for chronic disease risk reduction. To establish the 2020 KDRIs for dietary sodium, the committee conducted a systematic literature review of the intake–response relationships between the selected indicators for sodium levels and human chronic diseases. In this review, 43 studies published from January 2014 to December 2018, using databases of PubMed and Web of Science, were finally included for evaluating the risk of bias and strength of evidence (SoE). We determined that SoE of the relationship between dietary sodium and cardiovascular diseases, cerebrovascular disease, and hypertension, was moderate to strong. However, due to insufficient scientific evidence, we were unable to establish the estimated average requirement and the recommended nutrient intake for dietary sodium. Therefore, the adequate intake of sodium for adults was established to be 1,500 mg/day, whereas the CDRR for dietary sodium was established at 2,300 mg/day for adults. Intake goal for dietary sodium established in the 2015 KDRIs instead of the tolerable upper intake level was not presented in the 2020 KDRIs. For the next revision of the KDRIs, there is a requirement to pursue further studies on nutritional adequacy and toxicity of dietary sodium, and their associations with chronic disease endpoint in the Korean population.

Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride

BACKGROUND

Recent cohort studies show that salt intake below 6 g is associated with increased mortality. These findings have not changed public recommendations to lower salt intake below 6 g, which are based on assumed blood pressure (BP) effects and no side-effects.

OBJECTIVES

To assess the effects of sodium reduction on BP, and on potential side-effects (hormones and lipids) SEARCH METHODS: The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to April 2018 and a top-up search in March 2020: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers regarding further published and unpublished work. The searches had no language restrictions. The top-up search articles are recorded under "awaiting assessment."

SELECTION CRITERIA

Studies randomizing persons to low-sodium and high-sodium diets were included if they evaluated at least one of the outcome parameters (BP, renin, aldosterone, noradrenalin, adrenalin, cholesterol, high-density lipoprotein, low-density lipoprotein and triglyceride,.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected data, which were analysed with Review Manager 5.3. Certainty of evidence was assessed using GRADE.

MAIN RESULTS

Since the first review in 2003 the number of included references has increased from 96 to 195 (174 were in white participants). As a previous study found different BP outcomes in black and white study populations, we stratified the BP outcomes by race. The effect of sodium reduction (from 203 to 65 mmol/day) on BP in white participants was as follows: Normal blood pressure: SBP: mean difference (MD) -1.14 mmHg (95% confidence interval (CI): -1.65 to -0.63), 5982 participants, 95 trials; DBP: MD + 0.01 mmHg (95% CI: -0.37 to 0.39), 6276 participants, 96 trials. Hypertension: SBP: MD -5.71 mmHg (95% CI: -6.67 to -4.74), 3998 participants,88 trials; DBP: MD -2.87 mmHg (95% CI: -3.41 to -2.32), 4032 participants, 89 trials (all high-quality evidence). The largest bias contrast across studies was recorded for the detection bias element. A comparison of detection bias low-risk studies versus high/unclear risk studies showed no differences. The effect of sodium reduction (from 195 to 66 mmol/day) on BP in black participants was as follows: Normal blood pressure: SBP: mean difference (MD) -4.02 mmHg (95% CI:-7.37 to -0.68); DBP: MD -2.01 mmHg (95% CI:-4.37, 0.35), 253 participants, 7 trials. Hypertension: SBP: MD -6.64 mmHg (95% CI:-9.00, -4.27); DBP: MD -2.91 mmHg (95% CI:-4.52, -1.30), 398 participants, 8 trials (low-quality evidence). The effect of sodium reduction (from 217 to 103 mmol/day) on BP in Asian participants was as follows: Normal blood pressure: SBP: mean difference (MD) -1.50 mmHg (95% CI: -3.09, 0.10); DBP: MD -1.06 mmHg (95% CI:-2.53 to 0.41), 950 participants, 5 trials. Hypertension: SBP: MD -7.75 mmHg (95% CI:-11.44, -4.07); DBP: MD -2.68 mmHg (95% CI: -4.21 to -1.15), 254 participants, 8 trials (moderate-low-quality evidence).   During sodium reduction renin increased 1.56 ng/mL/hour (95%CI:1.39, 1.73) in 2904 participants (82 trials); aldosterone increased 104 pg/mL (95%CI:88.4,119.7) in 2506 participants (66 trials); noradrenalin increased 62.3 pg/mL: (95%CI: 41.9, 82.8) in 878 participants (35 trials); adrenalin increased 7.55 pg/mL (95%CI: 0.85, 14.26) in 331 participants (15 trials); cholesterol increased 5.19 mg/dL (95%CI:2.1, 8.3) in 917 participants (27 trials); triglyceride increased 7.10 mg/dL (95%CI: 3.1,11.1) in 712 participants (20 trials); LDL tended to increase 2.46 mg/dl (95%CI: -1, 5.9) in 696 participants (18 trials); HDL was unchanged -0.3 mg/dl (95%CI: -1.66,1.05) in 738 participants (20 trials) (All high-quality evidence except the evidence for adrenalin).

AUTHORS' CONCLUSIONS

In white participants, sodium reduction in accordance with the public recommendations resulted in mean arterial pressure (MAP) decrease of about 0.4 mmHg in participants with normal blood pressure and a MAP decrease of about 4 mmHg in participants with hypertension. Weak evidence indicated that these effects may be a little greater in black and Asian participants. The effects of sodium reduction on potential side effects (hormones and lipids) were more consistent than the effect on BP, especially in people with normal BP.

Dietary Sodium Intake and Health Indicators: A Systematic Review of Published Literature between January 2015 and December 2019

As the science surrounding population sodium reduction evolves, monitoring and evaluating new studies on intake and health can help increase our understanding of the associated benefits and risks. Here we describe a systematic review of recent studies on sodium intake and health, examine the risk of bias (ROB) of selected studies, and provide direction for future research. Seven online databases were searched monthly from January 2015 to December 2019. We selected human studies that met specified population, intervention, comparison, outcome, time, setting/study design (PICOTS) criteria and abstracted attributes related to the study population, design, intervention, exposure, and outcomes, and evaluated ROB for the subset of studies on sodium intake and cardiovascular disease risks or indicators. Of 41,601 abstracts reviewed, 231 studies were identified that met the PICOTS criteria and ROB was assessed for 54 studies. One hundred and fifty-seven (68%) studies were observational and 161 (70%) focused on the general population. Five types of sodium interventions and a variety of urinary and dietary measurement methods were used to establish and quantify sodium intake. Five observational studies used multiple 24-h urine collections to assess sodium intake. Evidence mainly focused on cardiovascular-related indicators (48%) but encompassed an assortment of outcomes. Studies varied in ROB domains and 87% of studies evaluated were missing information on ≥1 domains. Two or more studies on each of 12 outcomes (e.g., cognition) not previously included in systematic reviews and 9 new studies at low ROB suggest the need for ongoing or updated systematic reviews of evidence on sodium intake and health. Summarizing evidence from assessments on sodium and health outcomes was limited by the various methods used to measure sodium intake and outcomes, as well as lack of details related to study design and conduct. In line with research recommendations identified by the National Academies of Science, future research is needed to identify and standardize methods for measuring sodium intake.

Effect of remote patient management in peritoneal dialysis on haemodynamic and volume control

AIM

Reduced treatment compliance in patients with peritoneal dialysis facilitates the development of fluid overload and as a result increased blood pressure and vascular stiffness in the long term. We aimed to evaluate blood pressure change and anti-hypertensive needs of patients within 1 year after the changeover to remote monitoring automated peritoneal dialysis (RM-APD) and compare the effect of RM-APD and continuous ambulatory peritoneal dialysis (CAPD) on peripheral and central haemodynamic parameters, volume status of patients and anti-hypertensive drug needs.

METHODS

This was an observational and cross-sectional study. We enrolled 15 patients performing CAPD, 20 patients performing RM-APD, and 38 age, and gender-matched healthy control. We measured pulse wave velocity to assess arterial stiffness, peripheral and central haemodynamic parameters. We measured the volume status of participants via bioimpedance spectroscopy.

RESULTS

The mean excess hydration of patients who underwent CAPD were higher than those who performed RM-APD and healthy control (P = .02). We found that mean diastolic blood pressure, heart rate, central systolic and diastolic blood pressure, and central pulse pressure were significantly different between the RM-APD, CAPD and healthy control (P = .02, P = .05, P = .007, P = .05 and P = .005, respectively). Post hoc analysis of these results showed that the differences between the groups were caused by the healthy control group and the patients with underwent CAPD. Daily anti-hypertensive drug count in patients with performing RM-APD was reduced over time (P < .001).

CONCLUSION

The RM-APD provides better control of peripheral blood pressure and decrease of central haemodynamic parameters via controlling the excess body water.

Antioxidant cocktail following a high-sodium meal does not affect vascular function in young, healthy adult humans: a randomized controlled crossover trial

Chronic high sodium intake is a risk factor for cardiovascular disease as it impairs vascular function through an increase in oxidative stress. The objective of this study was to investigate the acute effects of a high-sodium meal (HSM) and antioxidant (AO) cocktail on vascular function. We hypothesized that a HSM would impair endothelial function, and increase arterial stiffness and wave reflection, while ingestion of the AO cocktail would mitigate this response. Healthy adults ingested either an AO cocktail (vitamin C, E, alpha-lipoic acid) or placebo (PLA) followed by a HSM (1500 mg) in a randomized crossover blinded design. Blood pressure (BP), endothelial function (flow-mediated dilation; FMD) and measures of arterial stiffness (pulse wave velocity; PWV) and wave reflection (augmentation index; AIx) were made at baseline and 30, 60, 90, and 120 min after meal consumption. Forty-one participants (20M/21W; 24 ± 1 years; BMI 23.4 ± 0.4 kg/m²) completed the study. Mean BP increased at 120 min relative to 60 min (60 min: 79 ± 1; 120 min: 81 ± 1 mmHg; time effect P = .01) but was not different between treatments (treatment × time interaction P = .32). AIx decreased from baseline (time effect P < .001) but was not different between treatments (treatment × time interaction P = .31). PWV (treatment × time interaction, P = .91) and FMD (treatment × time interaction P = .65) were also not different between treatments. In conclusion, a HSM does not acutely impair vascular function suggesting young healthy adults can withstand the acute impact of sodium on the vasculature and therefore, the AO cocktail is not necessary to mitigate the response.

The Impact of High Dietary Sodium Consumption on Blood Pressure Variability in Healthy, Young Adults

BACKGROUND

High sodium (Na+) intake augments blood pressure variability (BPV) in normotensive rodents, without changes in resting blood pressure (BP). Augmented BPV is associated with end-organ damage and cardiovascular morbidity. It is unknown if changes in dietary Na+ influence BPV in humans. We tested the hypothesis that high Na+ feeding would augment BPV in healthy adults.

METHODS

Twenty-one participants (10 F/11 M; 26 ± 5 years; BP: 113 ± 11/62 ± 7 mm Hg) underwent a randomized, controlled feeding study that consisted of 10 days of low (2.6 g/day), medium (6.0 g/day), and high (18.0 g/day) salt diets. On the ninth day of each diet, 24-h urine samples were collected and BPV was calculated from 24-h ambulatory BP monitoring. On the tenth day, in-laboratory beat-to-beat BPV was calculated during 10 min of rest. Serum electrolytes were assessed. We calculated average real variability (ARV) and standard deviation (SD) as metrics of BPV. As a secondary analysis, we calculated central BPV from the 24-h ambulatory BP monitoring.

RESULTS

24-h urinary Na+ excretion (low = 41 ± 24, medium = 97 ± 43, high = 265 ± 92 mmol/24 h, P < 0.01) and serum Na+ (low = 140.0 ± 2.1, medium = 140.7 ± 2.7, high = 141.7 ± 2.5 mmol/l, P = 0.009) increased with greater salt intake. 24-h ambulatory ARV (systolic BP ARV: low = 9.5 ± 1.7, medium = 9.5 ± 1.2, high = 10.0 ± 1.9 mm Hg, P = 0.37) and beat-to-beat ARV (systolic BP ARV: low = 2.1 ± 0.6, medium = 2.0 ± 0.4, high = 2.2 ± 0.8 mm Hg, P = 0.46) were not different. 24-h ambulatory SD (systolic BP: P = 0.29) and beat-to-beat SD (systolic BP: P = 0.47) were not different. There was a trend for a main effect of the diet (P = 0.08) for 24-h ambulatory central systolic BPV.

CONCLUSIONS

Ten days of high sodium feeding does not augment peripheral BPV in healthy, adults.

CLINICAL TRIALS REGISTRATION

NCT02881515.

Effect of dietary salt restriction on central blood pressure: A systematic review and meta-analysis of the intervention studies

Central blood pressure (cBP) is highly associated with cardiovascular risk. Although reduction of salt intake leads to lower peripheral blood pressure (BP), the studies on cBP provided inconsistent results. Therefore, we performed a systematic review and a meta-analysis of the available intervention trials of salt reduction on cBP values to reach definitive conclusions. A systematic search of the online databases available (up to December 2018) was conducted including the intervention trials that reported non-invasively assessed cBP changes after two different salt intake regimens. For each study, the mean difference and 95% confidence intervals were pooled using a random-effect model. Sensitivity, heterogeneity, publication bias, subgroup, and meta-regression analyses were performed. Fourteen studies met the pre-defined inclusion criteria and provided 17 cohorts with 457 participants with 1-13 weeks of intervention time. In the pooled analysis, salt restriction was associated with a significant reduction in augmentation index (9.3%) as well as central systolic BP and central pulse pressure. There was a significant heterogeneity among studies (I²  = 70%), but no evidence of publication bias. Peripheral BP changes seemed to partially interfere on the relationship between salt restriction and cBP. The results of this meta-analysis indicate that dietary salt restriction reduces cBP. This effect seems to be, at least in part, independent of the changes in peripheral BP.

Salt Loading Blunts Central and Peripheral Postexercise Hypotension

INTRODUCTION

High salt intake is a widespread cardiovascular risk factor with systemic effects. These effects include an expansion of plasma volume, which may interfere with postexercise hypotension (PEH). However, the effects of high salt intake on central and peripheral indices of PEH remain unknown. We tested the hypothesis that high salt intake would attenuate central and peripheral PEH.

METHODS

Nineteen healthy adults (7 female/12 male; age, 25 ± 4 yr; body mass index, 23.3 ± 2.2 kg·m; V[Combining Dot Above]O2peak, 41.6 ± 8.7 mL·min·kg; systolic blood pressure (BP), 112 ± 9 mm Hg; diastolic BP, 65 ± 9 mm Hg) participated in this double-blind, randomized, placebo-controlled crossover study. Participants were asked to maintain a 2300 mg·d sodium diet for 10 d on two occasions separated by ≥2 wk. Total salt intake was manipulated via ingestion of capsules containing either table salt (3900 mg·d) or placebo (dextrose) during each diet. On the 10th day, participants completed 50 min of cycling at 60% V[Combining Dot Above]O2peak. A subset of participants (n = 8) completed 60 min of seated rest (sham trial). Beat-to-beat BP was measured in-laboratory for 60 min after exercise via finger photoplethysmography. Brachial and central BPs were measured for 24 h after exercise via ambulatory BP monitor.

RESULTS

Ten days of high salt intake increased urinary sodium excretion (134 ± 70 (dextrose) vs 284 ± 74 mmol per 24 h (salt), P < 0.001), expanded plasma volume (7.2% ± 10.8%), and abolished PEH during in-laboratory BP monitoring (main effect of diet, P < 0.001). Ambulatory systolic BPs were higher for 12 h after exercise during the salt and sham trials compared with the dextrose trial (average change, 3.6 ± 2.1 mm Hg (dextrose), 9.9 ± 1.4 mm Hg (salt), 9.8 ± 2.5 mm Hg (sham); P = 0.01). Ambulatory central systolic BP was also higher during the salt trial compared with dextrose trial.

CONCLUSION

High salt intake attenuates peripheral and central PEH, potentially reducing the beneficial cardiovascular effects of acute aerobic exercise.

Arterial Stiffness and Central Hemodynamics are Associated with Low Diurnal Urinary Sodium Excretion

BACKGROUND

Excessive salt intake is an important determinant of cardiovascular (CV) health, impacting arterial stiffness and central blood pressure. However, sodium exhibits several patterns of excretion in urine during day- and night-time, which could differently affect CV risk. Here, we sought to explore the relationship between the day:night urinary sodium excretion ratio and arterial stiffness and central hemodynamics in the general population.

METHODS

Cross-sectional analysis in 1062 subjects. Arterial stiffness (pulse-wave velocity, PWV), central blood pressure (central systolic blood pressure, cSBP; central diastolic blood pressure, cDBP), and other hemodynamic parameters were noninvasively assessed. Day- and night-time urinary sodium were separately detected. Analyses were performed according to the day:night urinary sodium excretion ratio tertiles (T1-T3).

RESULTS

Low day-time excretors (T1) showed significantly higher values of arterial stiffness when compared with high day-time excretors (T3) (cf-PWV 7.6 ± 1.9 vs 6.9 ± 1.5 m/sec; p ≤ 0.001), and higher central BP parameters (cSBP: 111.6 ± 12.1 vs 109.0 ± 11.1 mmHg, p ≤ 0.001; cDBP, 76.9 ± 9.2 vs 75.1 ± 9.3 mmHg, p ≤ 0.001). In multivariate linear-regression models (β, CI), the day:night ratio of sodium excretion was significantly associated with arterial stiffness (cf-PWV -0.386, -0.559, -0.213, p ≤ 0.001) and with central hemodynamic parameters (cSBP -1.655, -2.800, -0.510; p ≤ 0.001; cDBP -1.319, -2.218, -0.420, p ≤ 0.001). Associations persisted after controlling for multiple confounding factors. In logistic-regression models, the risk of increased arterial stiffness was significantly reduced as the day:night ratio of urinary sodium excretion increased (OR 0.40, 95% CI 0.25-0.65, p ≤ 0.001).

CONCLUSION

The individual, intra-daily pattern of urinary sodium excretion, characterised by low daytime excretion, is associated with increased arterial stiffness and central blood pressure. Further studies are advocated to clarify the clinical utility of assessing the daily pattern of sodium excretion.

Current Data on Dietary Sodium, Arterial Structure and Function in Humans: A Systematic Review

Background: Subclinical arterial damage (SAD) (arteriosclerosis, arterial remodeling and atheromatosis) pre-exists decades before cardiovascular disease (CVD) onset. Worldwide, sodium (Na) intake is almost double international recommendations and has been linked with CVD and death, although in a J-shape manner. Studies regarding dietary Na and major types of SAD may provide pathophysiological insight into the association between Na and CVD. Objectives: Systematic review of data derived from observational and interventional studies in humans, investigating the association between dietary Na with (i) atheromatosis (arterial plaques); (ii) arteriosclerosis (various biomarkers of arterial stiffness); (iii) arterial remodeling (intima–media thickening and arterial lumen diameters). Data sources: Applying the PRISMA criteria, the PubMed and Scopus databases were used. Results: 36 studies were included: 27 examining arteriosclerosis, four arteriosclerosis and arterial remodeling, three arterial remodeling, and two arterial remodeling and atheromatosis. Conclusions: (i) Although several studies exist, the evidence does not clearly support a clinically meaningful and direct (independent from blood pressure) effect of Na on arterial wall stiffening; (ii) data regarding the association of dietary Na with arterial remodeling are limited, mostly suggesting a positive trend between dietary Na and arterial hypertrophy but still inconclusive; (iii) as regards to atheromatosis, data are scarce and the available studies present high heterogeneity. Further state-of-the-art interventional studies must address the remaining controversies.

Moving the Needle on Hypertension: What Knowledge Is Needed?

This review highlights the gaps in knowledge and methodological challenges discussed during the Experimental Biology 2019 expert panel session titled "Moving the Needle on Hypertension: What Knowledge Is Needed?" Hypertension is a critical public health burden. Despite a demonstrated benefit of blood pressure reduction on measures of hypertension-related morbidity and mortality, rates for successful blood pressure control remain low. Dietary sodium reduction has been shown to reduce both systolic blood pressure by approximately 3.2 mm Hg and diastolic blood pressure by 2.3 mm Hg, depending on baseline blood pressure and degree of sodium reduction. The updated Dietary Reference Intakes for adults released by the National Academies of Sciences, Engineering, and Medicine include a Chronic Disease Risk Reduction sodium intake level of 2300 mg/d, highlighting the importance of dietary sodium intake in reducing elevated blood pressure and indicating that reducing intakes to this level is expected to reduce blood pressure and risk of cardiovascular disease. The average US daily sodium intake of 3400 mg/d is well above the Chronic Disease Risk Reduction of 2300 mg/d, suggesting that dietary sodium reduction has the potential to significantly improve public health. Although the National Academies of Sciences, Engineering, and Medicine report presents intake recommendations based on a systematic, comprehensive, and thorough evaluation of the evidence, several challenges to moving the needle on hypertension remain. Success will require a more advanced understanding of sodium and potassium physiology, as well as development of the tools needed to effectively address existing research gaps and reduce barriers to sodium intake reduction.

Effects of dietary salt restriction on home blood pressure in diabetic patients with excessive salt intake: a pilot study

The aim of the present study was to examine whether dietary salt restriction guidance is beneficial for dietary salt restriction and lowering of home blood pressure in patients with diabetes with excessive salt intake. We performed an intervention trial of 37 people with type 2 diabetes and excessive salt intake. National registered dietitians provided dietary salt restriction guidance to each patient at the start of the study. All participants were instructed to perform triplicate morning and evening home blood pressure measurements using home blood pressure telemonitoring system. Daily salt intake at 2 months and 6 months was significantly lower than that at baseline; the difference was 0.8 [95% confidence interval (CI): 0.2–1.4, p = 0.009] g and 0.7 (95% CI: 0.1–1.3, p = 0.009) g, respectively. Morning systolic blood pressure at 2 months and 6 months was significantly lower than that at baseline; the difference was 2.7 (95% CI: 0.2–5.1, p = 0.034) mmHg and 5.8 (95% CI: 0.5–11.1, p = 0.034) mmHg, respectively. This intervention study revealed, for the first time, that dietary salt restriction guidance provided by a national registered dietitian is beneficial for reducing daily salt intake and home blood pressure in people with diabetes with excessive salt intake.

N-acetyl-l-cysteine exacerbates kidney dysfunction caused by a chronic high-sodium diet in renal ischemia and reperfusion rats

AIMS

To investigate the effect of long-term N-acetyl-l-cysteine (NAC) treatment in Wistar rats subjected to renal ischemia and reperfusion (IR) and a chronic high‑sodium diet (HSD).

MAIN METHODS

Adult male Wistar rats received an HSD (8.0% NaCl) or a normal‑sodium diet (NSD; 1.3% NaCl) and NAC (600 mg/L) or normal drinking water starting at 8 weeks of age. At 11 weeks of age, the rats from both diet and NAC or water treatment groups underwent renal IR or Sham surgery and were followed for 10 weeks. The study consisted of six animal groups: NSD + Sham + water; NSD + IR + water; NSD + IR + NAC; HSD + Sham + water; HSD + IR + water; and HSD + IR + NAC.

KEY FINDINGS

Tail blood pressure (tBP) increased with IR and NAC treatment in the NSD group but not in the HSD group. The serum creatinine level was higher after NAC treatment in both diet groups, and creatinine clearance was decreased in only the HSD + IR + NAC group. Albuminuria increased in the HSD + IR + water group and decreased in the HSD + IR + NAC group. Kidney mass was increased in the HSD + IR group and decreased with NAC treatment. Renal fibrosis was prevented with NAC treatment and cardiac fibrosis was decreased with NAC treatment in the HSD + IR group.

SIGNIFICANCE

NAC treatment promoted structural improvements, such as decreased albuminuria and fibrosis, in the kidney and heart. However, NAC could not recover kidney function or blood pressure from the effects of IR associated with an HSD. Therefore, in general, long-term NAC treatment is not effective and is deleterious to recovery of function after kidney injury.

Sex differences in mechanisms of arterial stiffness

Arterial stiffness progressively increases with aging and is an independent predictor of cardiovascular disease (CVD) risk. Evidence supports that there are sex differences in the time course of aging-related arterial stiffness and the associated CVD risk, which increases disproportionately in postmenopausal women. The association between arterial stiffness and mortality is almost twofold higher in women versus men. The differential clinical characteristics of the development of arterial stiffness between men and women indicate the involvement of sex-specific mechanisms. This review summarizes the current literature on sex differences in vascular stiffness induced by aging, obesity, hypertension, and sex-specific risk factors as well as the impact of hormonal status, diet, and exercise on vascular stiffness in males and females. An understanding of the mechanisms driving sex differences in vascular stiffness has the potential to identify novel sex-specific therapies to lessen CVD risk, the leading cause of death in males and females. LINKED ARTICLES: This article is part of a themed section on The Importance of Sex Differences in Pharmacology Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.21/issuetoc.

The Influence of Dietary Salt Beyond Blood Pressure

PURPOSE OF REVIEW

Excess sodium from dietary salt (NaCl) is linked to elevations in blood pressure (BP). However, salt sensitivity of BP varies widely between individuals and there are data suggesting that salt adversely affects target organs, irrespective of BP.

RECENT FINDINGS

High dietary salt has been shown to adversely affect the vasculature, heart, kidneys, skin, brain, and bone. Common mediators of the target organ dysfunction include heightened inflammation and oxidative stress. These physiological alterations may contribute to disease development over time. Despite the adverse effects of salt on BP and several organ systems, there is controversy surrounding lower salt intakes and cardiovascular outcomes. Our goal here is to review the physiology contributing to BP-independent effects of salt and address the controversy around lower salt intakes and cardiovascular outcomes. We will also address the importance of background diet in modulating the effects of dietary salt.