Effect of salt reduction interventions in lowering blood pressure: A comprehensive systematic review and meta-analysis of controlled clinical trials

Impact of sodium intake on blood pressure, mortality and major cardiovascular events: an umbrella review of systematic reviews and meta-analyses

A plethora of systematic reviews with meta-analyses (SRMAs) evaluating sodium intake on cardiovascular health have been published. However, the quality of the SRMAs, that report absolute estimates of effect for major cardiovascular events and the corresponding certainty of the evidence has not been explicitly summarized. We conducted an umbrella review to assess the strength and validity of associations between lower sodium intake and cardiovascular outcomes. We used a modified, more stringent, version of the AMSTAR 2 instrument and the GRADE approach to assess SRMA methodological quality and evidence certainty, respectively. Across three cardiovascular risk strata, we computed the absolute risk reduction (ARR) for binary outcomes. We included 56 SRMAs. In various cardiovascular risk populations, moderate to high certainty evidence suggested that lower sodium intake reduced systolic blood pressure (BP) by -8.69 to -2.00 mmHg, and had concordant but smaller effects on diastolic BP. Salt substitutes conferred a small but important reduction in all-cause and cardiovascular mortality [ARR 12 fewer per 1000; 9 fewer per 1000; respectively], and had little to no effect on the risk of stroke [ARR 1 fewer per 1000]. Moderate to high certainty evidence suggested that lower sodium intake is probably beneficial for the prevention of major cardiovascular events, especially in low cardiovascular risk populations.

Mental disorders after myocardial infarction: potential mediator role for chemokines in heart-brain interaction?

Acute myocardial infarction (MI) remains one of the leading causes of mortality and morbidity in the global communities. A prevailing topic that has attracted increasing attentions over the past few decades is the so-called heart-brain interaction, in particular following a major traumatic event such as MI. Increased prevalence of depression and other mental disorders has been recognized in cardiac patients after MI, coronary catheterization, or cardiothoracic surgeries. In this review, we focus on the potential pathogenic mechanisms and pre-clinical transcriptomic evidence for identifying potential mediators of post-MI depression. We first summarize the conventional mechanistic understanding that leads to the current clinical management of post-MI depression with the use of selective serotonin reuptake inhibitors (SSRIs) and cognitive behavior and exercise therapies. We further envisage a possible role played by certain chemokines, e.g., Chemokine (C-X-C motif) ligand 12 (CXCL12) and Chemokine (C-C motif) ligand 2 (CCL22), in serving as signaling molecules to connect the MI-induced heart damage to the pro-depressive changes in brain during the post-MI period. Future in-depth investigations into this chemokine hypothesis will be instrumental in developing new chemokine-targeted therapies for better management of the cardiac patients suffering from post-MI depression.

Dissociation of Hypertension and Renal Damage After Cessation of High-Salt Diet in Dahl Rats

BACKGROUND

Every year, thousands of patients with hypertension reduce salt consumption in an effort to control their blood pressure. However, hypertension has a self-sustaining character in a significant part of the population. We hypothesized that chronic hypertension leads to irreversible renal damage that remains after removing the trigger, causing an elevation of the initial blood pressure.

METHODS

Dahl salt-sensitive rat model was used for chronic, continuous observation of blood pressure. Rats were fed a high salt diet to induce hypertension, and then the diet was switched back to normal sodium content.

RESULTS

We found that developed hypertension was irreversible by salt cessation: after a short period of reduction, blood pressure grew even higher than in the high-salt phase. Notably, the self-sustaining phase of hypertension was sensitive to benzamil treatment due to sustaining epithelial sodium channel hyperactivity, as shown with patch-clamp analysis. Glomerular damage and proteinuria were also irreversible. In contrast, some mechanisms, contributing to the development of salt-sensitive hypertension, normalized after salt restriction. Thus, flow cytometry demonstrated that dietary salt reduction in hypertensive animals decreased the number of total CD45+, CD3+CD4+, and CD3+CD8+ cells in renal tissues. Also, we found tubular recovery and improvement of glomerular filtration rate in the postsalt period versus a high-salt diet.

CONCLUSIONS

Based on earlier publications and current data, poor response to salt restriction is due to the differential contribution of the factors recognized in the developmental phase of hypertension. We suggest that proteinuria or electrolyte transport can be prioritized over therapeutic targets of inflammatory response.

Association between sodium and potassium excretion estimated from spot urine and socioeconomic status among primary school children and their mothers in Okinawa, Japan

Hypertension is the greatest and the most preventable risk factor for cardiovascular disease. Excessive sodium (Na) intake and insufficient potassium (K) intake have been identified as risk factors for hypertension. Socioeconomic status (SES) may be related to diet quality. In Japan, few studies have examined the relationship between urinary Na and K excretion and SES in adults, and there are no studies in children. In 2014, 1944 children (1382 households) in all public elementary schools in Yaese town, Okinawa, Japan were recruited to participate in a study. Casual urine specimens were collected to estimate 24-h urinary Na and K excretion and urinary Na/K ratio. Mother's educational background and household incomes were assessed and used as indicators of SES. A total of 236 pairs of children and their mothers were analyzed in this study. Urinary Na and K excretion were not significantly related to educational levels of mothers and household incomes in children. On the other hand, in mothers, lower household income group had higher 24-h estimated urinary Na excretion and urinary Na/K ratio than other groups. There was no significant difference between urinary excretion and educational levels in mothers. Household income disparities in urinary levels seen in mothers were not seen in children. There may be some factors that moderate the dietary inequalities in children.

Long-Term Effect of Salt Substitution for Cardiovascular Outcomes : A Systematic Review and Meta-analysis

BACKGROUND

Salt substitution is a simple yet increasingly promising strategy to improve cardiovascular outcomes.

PURPOSE

To evaluate the long-term effects of salt substitution on cardiovascular outcomes.

DATA SOURCES

PubMed, EMBASE, Cochrane CENTRAL, and CINAHL searched from inception to 23 August 2023. Trial registries, citation analysis, and hand-search were also done.

STUDY SELECTION

Randomized controlled trials (RCTs) comparing provision of or advice to use a salt substitute with no intervention or use of regular salt among adults for 6 months or longer in total study duration.

DATA EXTRACTION

Two authors independently screened articles, extracted data, and assessed risk of bias. Primary outcomes include mortality, major cardiovascular events (MACE), and adverse events at 6 months or greater. Secondary and post hoc outcomes include blood pressure, cause-specific mortality, and urinary excretion at 6 months or greater. Random-effects meta-analyses were done and certainty of effect estimates were assessed using GRADE (Grading of Recommendations Assessment, Development and Evaluation).

DATA SYNTHESIS

Of the 16 included RCTs, 8 reported on primary outcomes. Most (n = 7 of 8) were done in China or Taiwan, 3 were done in residential facilities, and 7 included populations of older age (average 62 years) and/or with higher-than-average cardiovascular risk. In this population, salt substitute may reduce risk for all-cause mortality (6 RCTs; 27 710 participants; rate ratio [RR], 0.88 [95% CI, 0.82 to 0.93]; low certainty) and cardiovascular mortality (4 RCTs; 25 050 participants; RR, 0.83 [CI, 0.73 to 0.95]; low certainty). Salt substitute may result in a slight reduction in MACE (3 RCTs; 23 215 participants; RR, 0.85 [CI, 0.71 to 1.00]; very low certainty), with very low-certainty evidence of serious adverse events (6 RCTs; 27 995 participants; risk ratio, 1.04 [CI, 0.87 to 1.25]).

LIMITATIONS

The evidence base is dominated by a single, large RCT. Most RCTs were from China or Taiwan and involved participants with higher-than-average cardiovascular risk; therefore, generalizability to other populations is very limited.

CONCLUSION

Salt substitution may reduce all-cause or cardiovascular mortality, but the evidence for reducing cardiovascular events and for not increasing serious adverse events is uncertain, particularly for a Western population. The certainty of evidence is higher among populations at higher cardiovascular risk and/or following a Chinese diet.

PRIMARY FUNDING SOURCE

National Health and Medical Research Council. (PROSPERO: CRD42022327566).

Technology-supported behavior change interventions for reducing sodium intake in adults: a systematic review and meta-analysis

The effects of technology-supported behavior change interventions for reducing sodium intake on health outcomes in adults are inconclusive. Effective intervention characteristics associated with sodium reduction have yet to be identified. A systematic review and meta-analysis were conducted, searching randomized controlled trials (RCTs) published between January 2000 and April 2023 across 5 databases (PROSPERO: CRD42022357905). Meta-analyses using random-effects models were performed on 24-h urinary sodium (24HUNa), systolic blood pressure (SBP), and diastolic blood pressure (DBP). Subgroup analysis and meta-regression of 24HUNa were performed to identify effective intervention characteristics. Eighteen RCTs involving 3505 participants (51.5% female, mean age 51.6 years) were included. Technology-supported behavior change interventions for reducing sodium intake significantly reduced 24HUNa (mean difference [MD] -0.39 gm/24 h, 95% confidence interval [CI] -0.50 to -0.27; I2 = 24%), SBP (MD -2.67 mmHg, 95% CI -4.06 to -1.29; I2 = 40%), and DBP (MD -1.39 mmHg, 95% CI -2.31 to -0.48; I2 = 31%), compared to control conditions. Interventions delivered more frequently (≤weekly) were associated with a significantly larger effect size in 24HUNa reduction compared to less frequent interventions (>weekly). Other intervention characteristics, such as intervention delivery via instant messaging and participant-family dyad involvement, were associated with larger, albeit non-significant, effect sizes in 24HUNa reduction when compared to other subgroups. Technology-supported behavior change interventions aimed at reducing sodium intake were effective in reducing 24HUNa, SBP, and DBP at post-intervention. Effective intervention characteristics identified in this review should be considered to develop sodium intake reduction interventions and tested in future trials, particularly for its long-term effects.

Low-Salt Diet Regulates the Metabolic and Signal Transduction Genomic Fabrics, and Remodels the Cardiac Normal and Chronic Pathological Pathways

Low-salt diet (LSD) is a constant recommendation to hypertensive patients, but the genomic mechanisms through which it improves cardiac pathophysiology are still not fully understood. Our publicly accessible transcriptomic dataset of the left ventricle myocardium of adult male mice subjected to prolonged LSD or normal diet was analyzed from the perspective of the Genomic Fabric Paradigm. We found that LSD shifted the metabolic priorities by increasing the transcription control for fatty acids biosynthesis while decreasing it for steroid hormone biosynthesis. Moreover, LSD remodeled pathways responsible for cardiac muscle contraction (CMC), chronic Chagas (CHA), diabetic (DIA), dilated (DIL), and hypertrophic (HCM) cardiomyopathies, and their interplays with the glycolysis/glucogenesis (GLY), oxidative phosphorylation (OXP), and adrenergic signaling in cardiomyocytes (ASC). For instance, the statistically (p < 0.05) significant coupling between GLY and ASC was reduced by LSD from 13.82% to 2.91% (i.e., -4.75×), and that of ASC with HCM from 10.50% to 2.83% (-3.71×). The substantial up-regulation of the CMC, ASC, and OXP genes, and the significant weakening of the synchronization of the expression of the HCM, CHA, DIA, and DIL genes within their respective fabrics justify the benefits of the LSD recommendation.

Assessing Dietary Salt Intake and Pilot-Testing a Home-Based Intervention to Lower Salt Intake Among Filipino College Students

PURPOSE

To assess the knowledge, attitude, and behaviors related to dietary salt intake and develop a home-based intervention that helps lower salt intake among Filipino college students.

DESIGN

Two-phase program development study utilizing descriptive and quasi-experimental design.

METHODS

Phase 1 determined the knowledge, attitude, and behaviors alongside the frequency of dietary salt intake of a consecutive sample (n = 118). Phase 2 involved the development and pilot-testing of a home-based intervention wherein a random sample (n = 35) selected from Phase 1 joined for pilot-testing. The study was conducted from October - November 2021 and utilized valid and reliable measures to test the knowledge, attitude, and behavior of the participants.

FINDINGS

Initial assessment showed knowledge regarding health risks of high salt intake and positive attitude toward health-promoting behaviors. Post-intervention showed improvement in attitude (p = 0.0004) and behavior (p = 0.001) related to dietary salt intake alongside health literacy (p = 0.036). There was no significant change in knowledge (p = 0.054).

CONCLUSION

The home-based intervention involving the use of health education materials is successful in improving dietary salt intake patterns.

CLINICAL EVIDENCE

Community health nurses may utilize home-based interventions to help develop health-promoting behaviors among young adults.

The Jamaica Salt Consumption Study Protocol: Sodium Intake; Sodium Content in Restaurant Foods; Knowledge, Attitudes, and Practices; Spot Urine Sodium Validation

Background

Excess dietary salt consumption is a major contributor to hypertension and cardiovascular disease. Public education programs on the dangers of high salt intake, and population level interventions to reduce the salt content in foods are possible strategies to address this problem. In Jamaica, there are limited data on the levels of salt consumption and the population's knowledge and practices with regards to salt consumption. This study therefore aims to obtain baseline data on salt consumption, salt content in foods sold in restaurants, and evaluate knowledge, attitudes, and practices of Jamaicans regarding salt consumption.

Methods

The study is divided into four components. Component 1 will be a secondary analysis of data on urinary sodium from spot urine samples collected as part of a national survey, the Jamaica Health and Lifestyle Survey 2016-2017. Component 2 will be a survey of chain and non-chain restaurants in Jamaica, to estimate the sodium content of foods sold in restaurants. Component 3 is another national survey, this time on a sample 1,200 individuals to obtain data on knowledge, attitudes and practices regarding salt consumption and estimation of urinary sodium excretion. Component 4 is a validation study to assess the level of agreement between spot urine sodium estimates and 24-hour urinary sodium from 120 individuals from Component 3.

Discussion

This study will provide important baseline data on salt consumption in Jamaica and will fulfil the first components of the World Health Organization SHAKE Technical Package for Salt Reduction. The findings will serve as a guide to Jamaica's Ministry of Health and Wellness in the development of a national salt reduction program. Findings will also inform interventions to promote individual and population level sodium reduction strategies as the country seeks to achieve the national target of a 30% reduction in salt consumption by 2025.

Sodium Homeostasis and Hypertension

PURPOSE OF REVIEW

This review aims to summarize and discuss the relationship between sodium homeostasis and hypertension, including emerging concepts of factors outside cardiovascular and renal systems influencing sodium homeostasis and hypertension.

RECENT FINDINGS

Recent studies support the dose-response association between higher sodium and lower potassium intakes and a higher cardiovascular risk in addition to the dose-response relationship between sodium restriction and blood pressure lowering. The growing body of evidence suggests the role of genetic determinants, immune system, and gut microbiota in sodium homeostasis and hypertension. Although higher sodium and lower potassium intakes increase cardiovascular risk, salt restriction is beneficial only to a certain limit. The immune system contributes to hypertension through pro-inflammatory effects. Sodium can affect the gut microbiome and induce pro-inflammatory and immune responses that contribute to salt-sensitive hypertension.

Evaluating the role of salt intake in achieving WHO NCD targets in the Eurasian Economic Union: A PRIME modeling study

The World Health Organization has set clear global targets in reducing non-communicable disease mortality by 2030 in its sustainable development goals. This study models the number of deaths that could be averted if Eurasian Economic Union (EEU) member states met the target of reducing their population's current mean salt intake by 30% to achieve mortality reduction targets. Using the WHO Preventable Risk Integrated ModEl (PRIME), we modelled the mortality impact of reducing salt consumption by 30%, as well as according to WHO recommended levels (5 g/person/day), for the five member states of the EEU. PRIME models the number of averted deaths from reducing salt intake by applying established risk ratios to a given population. The baseline demographic and mortality data that are required to generate these estimates were obtained from the relevant government statistical bodies, and salt intake data were referenced from surveillance studies. Uncertainty intervals were generated using Monte Carlo simulation. If salt consumption was reduced by 30%, we estimate that there would have been 94,150 (95%UI: 47,329 to 137,131) fewer deaths due to cardiovascular disease in the EEU in the baseline year, with males and the elderly being more affected. If the WHO-recommended maximum salt intake of 5 g/day was achieved, a total of 193,155 (95%UI: 98,548 to 272,536) deaths would have been prevented. These findings underline the importance of incorporating effective policy changes to meet targets in reducing NCD mortality by one-third by 2030.