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Dietary sodium restriction reverses vascular endothelial dysfunction in middle-aged/older adults with moderately elevated systolic blood pressure.

ABSTRACT: This study sought to determine the efficacy of dietary sodium restriction (DSR) for improving vascular endothelial dysfunction in middle-aged/older adults with moderately elevated systolic blood pressure (SBP) (130-159 mm Hg) and the associated physiological mechanisms.Vascular endothelial dysfunction develops with advancing age and elevated SBP, contributing to increased cardiovascular risk. DSR lowers BP, but its effect on vascular endothelial function and mechanisms involved are unknown.Seventeen subjects (11 men and 6 women; mean age, 62 ± 7 years) completed a, randomized crossover study of 4 weeks of both low (DSR) and normal sodium intake. Vascular endothelial function (endothelium-dependent dilation; EDD), nitric oxide (NO)/tetrahydrobiopterin (BH(4)) bioavailability, and oxidative stress-associated mechanisms were assessed following each condition.Urinary sodium excretion was reduced by ? 50% (to 70 ± 30 mmol/day), and conduit (brachial artery flow-mediated dilation [FMD(BA)]) and resistance (forearm blood flow responses to acetylcholine [FBF(ACh)]) artery EDD were 68% and 42% (peak FBF(ACh)) higher following DSR (p < 0.005). Low sodium markedly enhanced NO-mediated EDD (greater ?FBF(ACh) with endothelial NO synthase inhibition) without changing endothelial NO synthase expression/activation (Ser 1177 phosphorylation), restored BH(4) bioactivity (less ?FMD(BA) with acute BH(4)), abolished tonic superoxide suppression of EDD (less ?FMD(BA) and ?FBF(ACh) with ascorbic acid infusion), and increased circulating superoxide dismutase activity (all p < 0.05). These effects were independent of ?SBP. Other subject characteristics/dietary factors and endothelium-independent dilation were unchanged.DSR largely reversed both macro- and microvascular endothelial dysfunction by enhancing NO and BH(4) bioavailability and reducing oxidative stress. Our findings support the emerging concept that DSR induces "vascular protection" beyond that attributable to its BP-lowering effects.

SUBMITTER: Jablonski KL

PROVIDER: S-EPMC3549053 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Dietary sodium restriction reverses vascular endothelial dysfunction in middle-aged/older adults with moderately elevated systolic blood pressure.

Jablonski Kristen L KL Racine Matthew L ML Geolfos Candace J CJ Gates Phillip E PE Chonchol Michel M McQueen Matthew B MB Seals Douglas R DR

Journal of the American College of Cardiology 20121107 3

<h4>Objectives</h4>This study sought to determine the efficacy of dietary sodium restriction (DSR) for improving vascular endothelial dysfunction in middle-aged/older adults with moderately elevated systolic blood pressure (SBP) (130-159 mm Hg) and the associated physiological mechanisms.<h4>Background</h4>Vascular endothelial dysfunction develops with advancing age and elevated SBP, contributing to increased cardiovascular risk. DSR lowers BP, but its effect on vascular endothelial function and ...[more]

PMID: 23141486

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Project description:Aims/hypothesis: Dietary restriction (DR) reduces adiposity and improves metabolism in patients with one or more symptoms of the metabolic syndrome. Nonetheless, it remains elusive whether the benefits of DR in humans are mediated by calorie or nutrient restriction. This study was conducted to identify whether isocaloric dietary protein restriction is sufficient to confer the beneficial effects of dietary restriction in patients with metabolic syndrome. Methods: We performed a prospective, randomized controlled dietary intervention under constant nutritional and medical supervision. A total of 21 individuals diagnosed with the metabolic syndrome was randomly assigned for caloric restriction (CR; n = 11, mean age 49 ± 8.5 years, female 63%; diet of 5,941 ± 686 KJ per day) or isocaloric dietary protein restriction (PR; n = 10, mean age 51.6 ± 8.9 years, female 50%; diet of 8,409 ± 2,360 KJ per day) and followed for 27 days. Results: Like CR, PR promoted weight loss (-6.6%, P= 0.0041) due to reduction in adiposity (-9.9%, P= 0.0007), associated with reductions in blood glucose (-52.7%, P= 0.0002), lipid levels (cholesterol, -35.4%, P= 0.0010; triglycerides, -39.5% P= 0.0022) and blood pressure (systolic, -37.7 P< 0.0001; diastolic, -73.2% P< 0.0001). PR resulted in enrichment of metabolic pathways related to the immune system such as B cell proliferation, lymphocyte proliferation and leukocyte proliferation in subcutaneous adipose tissue. Hence, a reduction in calorie intake or changes in the gut microbiome are not necessary to confer the metabolic benefits of DR. Instead, a reduction in protein intake with a mild increase in carbohydrate intake to maintain the isocaloric balance of the diet is sufficient to improve metabolic control. Conclusions/interpretation: Protein restriction is sufficient to confer almost the same clinical outcomes as calorie restriction without the need for a reduction in calorie intake. The isocaloric characteristic of the PR intervention makes this approach a more attractive and less drastic dietary strategy in clinical settings and has greater potential to be used as adjuvant therapy for people with the metabolic syndrome.

Project description:This study sought to evaluate the impact of sodium restriction on heart failure (HF) outcomes.Although sodium restriction is advised for patients with HF, data on sodium restriction and HF outcomes are inconsistent.We analyzed data from the multihospital HF Adherence and Retention Trial, which enrolled 902 New York Heart Association functional class II/III HF patients and followed them up for a median of 36 months. Sodium intake was serially assessed by a food frequency questionnaire. Based on the mean daily sodium intake prior to the first event of death or HF hospitalization, patients were classified into sodium restricted (<2,500 mg/d) and unrestricted (?2,500 mg/d) groups. Study groups were propensity score matched according to plausible baseline confounders. The primary outcome was a composite of death or HF hospitalization. The secondary outcomes were cardiac death and HF hospitalization.Sodium intake data were available for 833 subjects (145 sodium restricted, 688 sodium unrestricted), of whom 260 were propensity matched into sodium restricted (n = 130) and sodium unrestricted (n = 130) groups. Sodium restriction was associated with significantly higher risk of death or HF hospitalization (42.3% vs. 26.2%; hazard ratio [HR]: 1.85; 95% confidence interval [CI]: 1.21 to 2.84; p = 0.004), derived from an increase in the rate of HF hospitalization (32.3% vs. 20.0%; HR: 1.82; 95% CI: 1.11 to 2.96; p = 0.015) and a nonsignificant increase in the rate of cardiac death (HR: 1.62; 95% CI: 0.70 to 3.73; p = 0.257) and all-cause mortality (p = 0.074). Exploratory subgroup analyses suggested that sodium restriction was associated with increased risk of death or HF hospitalization in patients not receiving angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (HR: 5.78; 95% CI: 1.93 to 17.27; p = 0.002).In symptomatic patients with chronic HF, sodium restriction may have a detrimental impact on outcome. A randomized clinical trial is needed to definitively address the role of sodium restriction in HF management. (A Self-management Intervention for Mild to Moderate Heart Failure [HART]; NCT00018005).

Project description:There are few studies on the mechanism of redox status imbalance and intestinal dysfunction in intrauterine growth restricted (IUGR) newborn piglets. Here, we investigated the mechanism of jejunum dysfunction in weaned piglets with IUGR and the mechanism through which dimethylglycine sodium salt (DMG-Na) supplementation improving the imbalance of their redox status. In this work, a total of 10 normal birth weight (NBW) newborn piglets and 20 IUGR newborn piglets were obtained. After weaning at 21 d, they were assigned to 3 groups (n = 10/group): NBW weaned piglets fed standard basal diets (NBWC); one IUGR weaned piglets fed standard basal diets (IUGRC); another IUGR weaned piglets from the same litter fed standard basal diets plus 0.1% DMG-Na (IUGRD). The piglets in these 3 groups were sacrificed at 49 d of age, and the blood and jejunum samples were collected immediately. The growth performance values in the IUGRC group were lower (P < 0.05) than those in the NBWC group. Jejunum histomorphological parameters, inflammatory cytokines, and digestive enzyme activity as well as serum immunoglobulin were lower (P < 0.05) in the IUGRC group than those in the NBWC group. Compared with these in the NBWC group, the redox status of serum, jejunum, and mitochondria and the expression levels of jejunum redox status-related, cell adhesion-related, and mitochondrial function-related genes and proteins were suppressed in the IUGRC group (P < 0.05). However, compared with those in the IUGRC group, the growth performance values, jejunum histomorphological parameters, inflammatory cytokines, digestive enzyme activity, serum immunoglobulin, redox status of serum, jejunum, and mitochondria, and the expression levels of jejunum redox status-related, cell adhesion-related, and mitochondrial function-related genes and proteins were improved (P < 0.05) in the IUGRD group. In conclusion, dietary DMG-Na supplementation alleviates redox status imbalance and intestinal dysfunction in IUGR weaned piglets mainly by activating the sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptorγcoactivator-1α (PGC1α) pathway, thereby improving their unfavorable body state.

Project description:Background and objectivesMetabolomics is a relatively new field of "-omics" research, focusing on high-throughput identification of small molecular weight metabolites. Diet has both acute and chronic effects on metabolic profiles; however, alterations in response to dietary sodium restriction (DSR) are completely unknown. The goal of this study was to explore changes in urine metabolites in response to DSR, as well as their association with previously reported improvements in vascular function with DSR.Design, setting, participants, & measurementsUsing stored urine samples from a 10-week randomized placebo-controlled crossover study of DSR in 17 middle-aged/older adults (six men and 11 women; mean age 62±8 years) who had moderately elevated systolic BP (130-159 mmHg) and were otherwise healthy, a liquid chromatography/mass spectrometry-based analysis of 289 metabolites was performed. This study identified metabolites that were significantly altered between the typical (153±29 mmol/d) and low (70±29 mmol/d) sodium conditions, as well as their baseline (typical sodium) association with responsiveness to previously reported improvements in vascular endothelial function (brachial artery flow-mediated dilation) and large elastic artery stiffness (aortic pulse wave velocity).ResultsOf the 289 metabolites surveyed, 10 were significantly altered (nine were upregulated and one was downregulated) during the low sodium condition, and eight of these exceeded our prespecified clinically significant threshold of a >40% change. These metabolites were involved in biologic pathways broadly related to cardiovascular risk, nitric oxide production, oxidative stress, osmotic regulation, and metabolism. One metabolite, serine, was independently (positively) associated with previously reported improvements in the primary vascular outcome of brachial artery flow-mediated dilation.ConclusionsThis proof-of-concept study provides the first evidence that DSR is a stimulus that induces significant changes in urinary metabolomic profiles. Moreover, serine was independently associated with corresponding changes in vascular endothelial function after DSR. Larger follow-up studies will be required to confirm and further elucidate the metabolic pathways that are altered in response to DSR.

Dataset Information

Dietary sodium restriction reverses vascular endothelial dysfunction in middle-aged/older adults with moderately elevated systolic blood pressure.

Publications

Dietary sodium restriction reverses vascular endothelial dysfunction in middle-aged/older adults with moderately elevated systolic blood pressure.

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