By how much does dietary salt reduction lower blood pressure? III--Analysis of data from trials of salt reduction

Dietary free L-glutamate contributes to maintaining a low sodium intake among Vietnamese

Background

The World Health Organization (WHO) and the Food and Agriculture Organization (FAO) recommend the consumption of less than 2,000 mg of sodium/day to reduce blood pressure and the risk of conditions such as cardiovascular disease and coronary heart disease. The sodium intake among Vietnamese was reported to be 7,200 mg/d or more. Free L-glutamate enhances flavor when it is added to food and improves the taste of sodium-reduced foods.

Objective

This study aims to investigate whether the intake of free L-glutamate-rich seasonings contributes to maintaining a low sodium intake in a cross-over study.

Methods

From a total of 145 subjects, 42 participants were screened for participation in the cross-over design study. Subjects were randomly allocated to the Low free L-glutamate group (Low free L-Gl) and the Normal free L-glutamate group (Normal free L-Gl). Both received a direct educational guideline to reduce sodium intake. The Low free L-Gl group started with a restriction in the variety of free L-glutamate-rich seasonings, and the Normal free L-Gl group had no restriction in the variety of seasonings. Blood pressure was measured at week 0 (baseline), week 2, week 4, and week 6, while body weight, height, urine sodium and potassium excretion, chromogranin-A (CgA pmol/mg protein) from saliva, and free L-glutamate from food were measured at week 0, week 3, and week 6.

Results

In Low free L-Gl, the amount of free L-glutamate in food decreased significantly from baseline to week 6 (p < 0.00), while it did not change in the Normal free L-Gl (p > 0.05). However, the reduction of sodium excretion at week 6 was 22% in Low free L-Gl (5,875 mg/d vs. 4,603 mg/d, p < 0.01) and 46% in Normal free L-Gl (6,107 mg/d vs. 3,277 mg/d, p < 0.00), both lower than the baseline. CgA (pmol/mg protein) did not show any difference between the two groups.

Conclusion

The group with Normal free L-Gl intake showed a 46% reduction in sodium excretion by week 6 compared to the baseline. This suggests that the consumption of L-glutamate-rich seasonings when complemented with direct educational guidelines, can contribute to maintaining a low sodium intake.

Hypertension in an ageing population: Diagnosis, mechanisms, collateral health risks, treatments, and clinical challenges

Ageing population is considerably increasing worldwide, which is considered to reflect an improved quality of life. However, longevity in the human lifespan has increased the burden of late-life illnesses including cancer, neurodegeneration, and cardiovascular dysfunction. Of these, hypertension is the most common condition with huge health risks, with an increased prevalence among the elderly. In this review, we outline the current guidelines for defining hypertension and examine the detailed mechanisms underlying the relationship between hypertension and ageing-related outcomes, including sodium sensitivity, arterial stiffness, endothelial dysfunction, isolated systolic hypertension, white coat effect, and orthostatic hypertension. As hypertension-related collateral health risk increases among the elderly, the available management strategies are necessary to overcome the clinical treatment challenges faced among elderly population. To improve longevity and reduce adverse health effects, potential approaches producing crucial information into new era of medicine should be considered in the prevention and treatment of hypertension among elderly population. This review provides an overview of mechanisms underlying hypertension and its related collateral health risk in elderly population, along with multiple approaches and management strategies to improve the clinical challenges among elderly population.

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.

Hypertensive heart disease: risk factors, complications and mechanisms

Hypertensive heart disease constitutes functional and structural dysfunction and pathogenesis occurring primarily in the left ventricle, the left atrium and the coronary arteries due to chronic uncontrolled hypertension. Hypertensive heart disease is underreported and the mechanisms underlying its correlates and complications are not well elaborated. In this review, we summarize the current understanding of hypertensive heart disease, we discuss in detail the mechanisms associated with development and complications of hypertensive heart disease especially left ventricular hypertrophy, atrial fibrillation, heart failure and coronary artery disease. We also briefly highlight the role of dietary salt, immunity and genetic predisposition in hypertensive heart disease pathogenesis.

Aldosterone Synthase Inhibitors and Dietary Interventions: A Combined Novel Approach for Prevention and Treatment of Cardiovascular Disease

Systemic hypertension (HTN) is the hallmark of cardiovascular disease and the forerunner of heart failure. These associations have been established over decades of research on essential HTN. Advancements in the treatment of patients diagnosed with HTN, consisting of alpha- or beta-adrenergic receptor blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors, thiazide, or aldosterone receptor blockers known as anti-mineralocorticoids, in the presence or absence of low sodium salt diets, often fail to control blood pressure adequately to prevent morbidity and mortality. Low sodium diets have had limited success in controlling HTN because low sodium intake is associated with renin-angiotensin-aldosterone system upregulation. Therefore, upregulating aldosterone secretion, sodium, and water retention which, in turn, moves the blood pressure back toward the range of HTN dictated by the baroreceptor reset value, as a compensatory mechanism, especially in resistant HTN. These impediments to blood pressure control in HTN may have been effectively circumvented by the advent of a new class of drugs known as aldosterone synthase inhibitors, represented by baxdrostat. The mechanism of action of baxdrostat as an aldosterone synthase inhibitor demonstrates the inextricable linkage between sodium and blood pressure regulation. Theoretically, combining a low sodium diet with the activity of this aldosterone synthesis inhibitor should alleviate the adverse effect of renin-angiotensin-aldosterone system upregulation. Aldosterone synthesis inhibition should also decrease the oxidative stress and endothelial dysfunction associated with HTN, causing more endothelial nitric oxide synthesis, release, and vasorelaxation. To the best of our knowledge, this is the first systematic review to summarize evidence-based articles relevant to the use of a novel drug (aldosterone synthase inhibitor) in the treatment of HTN and cardiovascular disease. Making the current database of relevant information on baxdrostat and other aldosterone synthase inhibitors readily available will, no doubt, aid physicians and other medical practitioners in their decision-making about employing aldosterone synthase inhibitors in the treatment of patients.

Altered dietary salt intake for preventing diabetic kidney disease and its progression

BACKGROUND

There is strong evidence that our current consumption of salt is a major factor in the development of increased blood pressure (BP) and that a reduction in our salt intake lowers BP, whether BP levels are normal or raised initially. Effective control of BP in people with diabetes lowers the risk of strokes, heart attacks and heart failure and slows the progression of chronic kidney disease (CKD) in people with diabetes. This is an update of a review first published in 2010.

OBJECTIVES

To evaluate the effect of altered salt intake on BP and markers of cardiovascular disease and of CKD in people with diabetes.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 31 March 2022 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register were identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of altered salt intake in individuals with type 1 and type 2 diabetes. Studies were included when there was a difference between low and high sodium intakes of at least 34 mmol/day.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies and resolved differences by discussion. We calculated mean effect sizes as mean difference (MD) and 95% confidence intervals (CI) using the random-effects model. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Thirteen RCTs (313 participants), including 21 comparisons (studies), met our inclusion criteria. One RCT (two studies) was added to this review update. Participants included 99 individuals with type 1 diabetes and 214 individuals with type 2 diabetes. Two RCTs (four studies) included some participants with reduced overall kidney function. The remaining studies either reported that participants with reduced glomerular filtration rate (GFR) were excluded from the study or only included participants with microalbuminuria and normal GFR. Five studies used a parallel study design, and 16 used a cross-over design. Studies were at high risk of bias for most criteria. Random sequence generation and allocation concealment were adequate in only three and two studies, respectively. One study was at low risk of bias for blinding of participants and outcome assessment, but no studies were at low risk for selective reporting. Twelve studies reported non-commercial funding sources, three reported conflicts of interest, and eight reported adequate washout between interventions in cross-over studies. The median net reduction in 24-hour urine sodium excretion (24-hour UNa) in seven long-term studies (treatment duration four to 12 weeks) was 76 mmol (range 51 to 124 mmol), and in 10 short-term studies (treatment duration five to seven days) was 187 mmol (range 86 to 337 mmol). Data were only available graphically in four studies. In long-term studies, reduced sodium intake may lower systolic BP (SBP) by 6.15 mm Hg (7 studies: 95% CI -9.27 to -3.03; I² = 12%), diastolic BP (DBP) by 3.41 mm Hg (7 studies: 95% CI -5.56 to -1.27; I² = 41%) and mean arterial pressure (MAP) by 4.60 mm Hg (4 studies: 95% CI -7.26 to -1.94; I² = 28%). In short-term studies, low sodium intake may reduce SBP by 8.43 mm Hg (5 studies: 95% CI -14.37 to -2.48; I² = 88%), DBP by 2.95 mm Hg (5 studies: 95% CI -4.96 to -0.94; I² = 70%) and MAP by 2.37 mm Hg (9 studies: 95% CI -4.75 to -0.01; I² = 65%). There was considerable heterogeneity in most analyses but particularly among short-term studies. All analyses were considered to be of low certainty evidence. SBP, DBP and MAP reductions may not differ between hypertensive and normotensive participants or between individuals with type 1 or type 2 diabetes. In hypertensive participants, SBP, DBP and MAP may be reduced by 6.45, 3.15 and 4.88 mm Hg, respectively, while in normotensive participants, they may be reduced by 8.43, 2.95 and 2.15 mm Hg, respectively (all low certainty evidence). SBP, DBP and MAP may be reduced by 7.35, 3.04 and 4.30 mm Hg, respectively, in participants with type 2 diabetes and by 7.35, 3.20, and 0.08 mm Hg, respectively, in participants with type 1 diabetes (all low certainty evidence). Eight studies provided measures of urinary protein excretion before and after salt restriction; four reported a reduction in urinary albumin excretion with salt restriction. Pooled analyses showed no changes in GFR (12 studies: MD -1.87 mL/min/1.73 m², 95% CI -5.05 to 1.31; I² = 32%) or HbA1c (6 studies: MD -0.62, 95% CI -1.49 to 0.26; I² = 95%) with salt restriction (low certainty evidence). Body weight was reduced in studies lasting one to two weeks but not in studies lasting for longer periods (low certainty evidence). Adverse effects were reported in only one study; 11% and 21% developed postural hypotension on the low-salt diet and the low-salt diet combined with hydrochlorothiazide, respectively.

AUTHORS' CONCLUSIONS

This systematic review shows an important reduction in SBP and DBP in people with diabetes with normal GFR during short periods of salt restriction, similar to that obtained with single drug therapy for hypertension. These data support the international recommendations that people with diabetes with or without hypertension or evidence of kidney disease should reduce salt intake to less than 5 g/day (2 g sodium).

Associations Between the Modified Food Standard Agency Nutrient Profiling System Dietary Index and Cardiovascular Risk Factors in an Elderly Population

Background

Helping consumers to improve the nutritional quality of their diet is a key public health action to prevent cardiovascular diseases (CVDs). The modified version of the Food Standard Agency Nutrient Profiling System Dietary Index (FSAm-NPS DI) underpinning the Nutri-Score front-of-pack label has been used in public health strategies to address the deleterious consequences of poor diets. This study aimed to assess the association between the FSAm-NPS DI and some CVD risk factors including body mass index (BMI), waist circumference, plasma glucose levels, triglyceride levels, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, and diastolic and systolic blood pressure.

Materials and Methods

Dietary intake was assessed at baseline and after 1 year of follow-up using a 143-item validated semi-quantitative food-frequency questionnaire. Dietary indices based on FSAm-NPS applied at an individual level were computed to characterize the diet quality of 5,921 participants aged 55–75 years with overweight/obesity and metabolic syndrome from the PREDIMED-plus cohort. Associations between the FSAm-NPS DI and CVD risk factors were assessed using linear regression models.

Results

Compared to participants with a higher nutritional quality of diet (measured by a lower FSAm-NPS DI at baseline or a decrease in FSAm-NPS DI after 1 year), those participants with a lower nutritional quality of diet (higher FSAm-NPS DI or an increase in score) showed a significant increase in the levels of plasma glucose, triglycerides, diastolic blood pressure, BMI, and waist circumference (β coefficient [95% confidence interval]; P for trend) (1.67 [0.43, 2.90]; <0.001; 6.27 [2.46, 10.09]; <0.001; 0.56 [0.08, 1.05]; 0.001; 0.51 [0.41, 0.60]; <0.001; 1.19 [0.89, 1.50]; <0.001, respectively). No significant associations in relation to changes in HDL and LDL-cholesterol nor with systolic blood pressure were shown.

Conclusion

This prospective cohort study suggests that the consumption of food items with a higher FSAm-NPS DI is associated with increased levels of several major risk factors for CVD including adiposity, fasting plasma glucose, triglycerides, and diastolic blood pressure. However, results must be cautiously interpreted because no significant prospective associations were identified for critical CVD risk factors, such as HDL and LDL-cholesterol, and systolic blood pressure.

Short-term effects of modest salt reduction combined with DASH diet on changing salt eating habits in hypertensive patients with type II diabetes

OBJECTIVE

Excessive salt intake is currently the foremost universal risk factor for controllable chronic disease. This study evaluated the short-term effects of a modest salt intake reduction combined with the Chinese Modified Dietary Approaches to Stop Hypertension (CM-DASH) diet on sodium and potassium intake, mean arterial pressure (MAP), and pulse pressure (PP) in hypertensive patients with type II diabetes.

METHODS

Sixty-one participants were randomized to the intervention group (52% low-sodium salt and DASH) and control group (normal salt and DASH). An 8-week dietary intervention was applied. Daily salt intake, blood pressure (BP), and drug use were recorded every week. Twenty-four-hour urine, casual urine, and blood samples were measured at baseline, the 4th week, and the end of the intervention.

RESULTS

Fifty-nine patients (25 men) completed the entire study. Sodium intake decreased by 1259.66 (792.76, 1726.56)/705.80 (149.21, 1262.39) mg/day after 4 weeks (intervention: P < .001; control: P = .015). Potassium intake increased by 641.14 (73.31, 1208.96)/43.43 (-259.66, 346.53) mg/day (intervention: P = .028); MAP decreased by 9.06 (6.69, 11.43)/7.16 (4.03, 10.28) mmHg (both: P < .001); PP decreased by 7.97 (3.05, 12.88)/5.74 (2.55,8.94) mmHg (intervention: P = .002; control: P = .001) after 8 weeks. However, the difference between the two groups was not statistically significant.

CONCLUSION

Modest salt reduction and the CM-DASH diet for hypertensive patients with type II diabetes can achieve short-term salt reduction effects. The effect on changing salt-eating habits needs to be investigated with an extended follow-up.

The Association of Essential Metals with APOE Genotype in Alzheimer's Disease

BACKGROUND

The major confirmed genetic risk factor for late-onset, sporadic Alzheimer's disease (AD) is variant ɛ4 of apolipoprotein E gene (APOE). It is proposed that ApoE, a protein involved in transport of cholesterol to neurons can cause neurodegeneration in AD through interaction with metals. Previous studies mostly associated copper, iron, zinc, and calcium with ApoE4-mediated toxicity.

OBJECTIVE

To test the association of essential metals with APOE genotype.

METHODS

We compared plasma and cerebrospinal fluid (CSF) levels of copper, zinc, iron, sodium, magnesium, calcium, cobalt, molybdenum, manganese, boron, and chromium, and CSF ferritin levels among AD, mild cognitive impairment (MCI) patients, and healthy controls (HC) with different APOE genotype.

RESULTS

Sodium, copper, and magnesium levels were increased in carriers of ɛ4 allele. Additionally, the increase in sodium, calcium and cobalt plasma levels was observed in carriers of ɛ4/ɛx genotype. The decrease in boron plasma levels was observed in carriers of ɛ4 allele and ɛ4/ɛ4 genotype. Additionally, CSF zinc levels as well as plasma sodium levels were increased in AD patients compared to HC.

CONCLUSION

These results indicate that the molecular underpinnings of association of essential metals and metalloids with APOE should be further tested and clarified in vivo and in vitro.

Blood Pressure Effects of Sodium Reduction: Dose-Response Meta-Analysis of Experimental Studies

Supplemental Digital Content is available in the text.

Background:

The relationship between dietary sodium intake and blood pressure (BP) has been tested in clinical trials and nonexperimental human studies, indicating a direct association. The exact shape of the dose–response relationship has been difficult to assess in clinical trials because of the lack of random-effects dose–response statistical models that can include 2-arm comparisons.

Methods:

After performing a comprehensive literature search for experimental studies that investigated the BP effects of changes in dietary sodium intake, we conducted a dose–response meta-analysis using the new 1-stage cubic spline mixed-effects model. We included trials with at least 4 weeks of follow-up; 24-hour urinary sodium excretion measurements; sodium manipulation through dietary change or supplementation, or both; and measurements of systolic and diastolic BP at the beginning and end of treatment.

Results:

We identified 85 eligible trials with sodium intake ranging from 0.4 to 7.6 g/d and follow-up from 4 weeks to 36 months. The trials were conducted in participants with hypertension (n=65), without hypertension (n=11), or a combination (n=9). Overall, the pooled data were compatible with an approximately linear relationship between achieved sodium intake and mean systolic as well as diastolic BP, with no indication of a flattening of the curve at either the lowest or highest levels of sodium exposure. Results were similar for participants with or without hypertension, but the former group showed a steeper decrease in BP after sodium reduction. Intervention duration (≥12 weeks versus 4 to 11 weeks), type of study design (parallel or crossover), use of antihypertensive medication, and participants’ sex had little influence on the BP effects of sodium reduction. Additional analyses based on the BP effect of difference in sodium exposure between study arms at the end of the trial confirmed the results on the basis of achieved sodium intake.

Conclusions:

In this dose–response analysis of sodium reduction in clinical trials, we identified an approximately linear relationship between sodium intake and reduction in both systolic and diastolic BP across the entire range of dietary sodium exposure. Although this occurred independently of baseline BP, the effect of sodium reduction on level of BP was more pronounced in participants with a higher BP level.

Salt Consumption and Myocardial Infarction: Is Limited Salt Intake Beneficial?

Introduction: Sodium is an essential mineral that plays a crucial role in the maintenance of normal cellular homeostasis, regulation of fluid and electrolytes, and blood pressure (BP). Due to the presence of sodium in a variety of regularly consumed food products, the deficiency of sodium is extremely unlikely. On the other hand, excess intake of dietary sodium is observed in many populations as it is generally used in most food products. Existing guidelines recommend lowering salt consumption for better cardiovascular health; these dietary sodium intake recommendations are not reassuring as the evolving studies show evidence that there is a higher risk of cardiovascular disease (CVD) with low sodium consumption. The aim of this study was to identify the association between salt consumption and myocardial infarction (MI).

Methods: The National Health and Nutrition Examination Survey (NHANES) data between 2017- 2018 was analyzed to examine the association between sodium intake (use in daily meal preparation) and reported history of MI. Logistic regression was used to assess for significant differences between the groups and calculated odds ratios while adjusting for confounders.

Results: A total of 4626 participants were included in the study, with a mean age of 66 ± 11 years in those with a history of MI (n = 212). Amongst these participants, those with salt consumption "Occasionally used" or "Very often used" were less likely to have suffered from MI than those who "Never used" salt in meal preparation. Multivariable logistic regression was performed to control for confounders. “Occasionally used” compared to “Never used” odds ratio was 0.5227 (95% confidence interval (CI); 0.3053-0.9009 p = 0.0184) and “Very often used” compared to “Never used” odds ratio was 0.5033 (95% CI; 0.2892-0.8799 p = 0.0152).

Conclusion: After adjusting for confounders, the participants that used salt more liberally during meal preparation were less likely to have MI than those who minimally or never used salt in meal preparation.

Effects of the Dietary Approaches to Stop Hypertension Diet and Sodium Reduction on Blood Pressure in Persons With Diabetes

Elevated blood pressure and blood pressure-related morbidity are extraordinarily common in persons with diabetes. The Dietary Approaches to Stop Hypertension dietary pattern and dietary sodium reduction are recommended as lifestyle interventions in individuals with diabetes. However, these recommendations have largely been based on studies conducted in persons without diabetes. In this review, we summarize available evidence from trials that tested the effects of these 2 dietary interventions on blood pressure in people with diabetes. Overall, of the 3 trials (total n=151) that tested the effects of the Dietary Approaches to Stop Hypertension dietary pattern in persons with diabetes, 2 trials documented that the Dietary Approaches to Stop Hypertension dietary pattern lowered blood pressure. While 16 trials (total n=445) tested the effects of sodium reduction in persons with diabetes, results were inconsistent, likely because of design limitations, for example, brief duration, small sample size, and low baseline blood pressure levels, as well as differences in the mode of intervention delivery (behavioral interventions, feeding studies, and sodium supplements). In conclusion, there is a substantial need for additional research on the blood pressure lowering effects of the Dietary Approaches to Stop Hypertension diet and sodium reduction in people with diabetes and hypertension, given the high prevalence of hypertension and the dearth of high-quality trials in this 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.

Salt Reduction to Prevent Hypertension and Cardiovascular Disease: JACC State-of-the-Art Review

There is strong evidence for a causal relationship between salt intake and blood pressure. Randomized trials demonstrate that salt reduction lowers blood pressure in both individuals who are hypertensive and those who are normotensive, additively to antihypertensive treatments. Methodologically robust studies with accurate salt intake assessment have shown that a lower salt intake is associated with a reduced risk of cardiovascular disease, all-cause mortality, and other conditions, such as kidney disease, stomach cancer, and osteoporosis. Multiple complex and interconnected physiological mechanisms are implicated, including fluid homeostasis, hormonal and inflammatory mechanisms, as well as more novel pathways such as the immune response and the gut microbiome. High salt intake is a top dietary risk factor. Salt reduction programs are cost-effective and should be implemented or accelerated in all countries. This review provides an update on the evidence relating salt to health, with a particular focus on blood pressure and cardiovascular disease, as well as the potential mechanisms.

Dietary Influence on Systolic and Diastolic Blood Pressure in the TwinsUK Cohort

Nutrition plays a key role in blood pressure (BP) regulation. Here, we examine associations between nutrient intakes and BP in a large predominantly female population-based cohort. We assessed the correlation between 45 nutrients (from food frequency questionnaires) and systolic BP/diastolic BP (SBP/DBP) in 3889 individuals from TwinsUK not on hypertensive treatments and replicated in an independent subset of monozygotic twins discordant for nutrient intake (17-242 pairs). Results from both analyses were meta-analysed. For significant nutrients, we calculated heritability using structural equation modelling. We identified and replicated 15 nutrients associated with SBP, 9 also being associated with DBP, adjusting for covariates and multiple testing. 14 of those had a heritable component (h2: 27.1-57.6%). Strong associations with SBP were observed for riboflavin (Beta(SE) = -1.49(0.38), P = 1.00 × 10-4) and tryptophan (-0.31(0.01), P = 5 × 10-4), while with DBP for alcohol (0.05(0.07), P = 1.00 × 10-4) and lactose (-0.05(0.0), P = 1.3 × 10-3). Two multivariable nutrient scores, combining independently SBP/DBP-associated nutrients, explained 22% of the variance in SBP and 13.6% of the variance in DBP. Moreover, bivariate heritability analysis suggested that nutrients and BP share some genetic influences. We confirm current understanding and extend the panel of dietary nutrients implicated in BP regulation underscoring the value of nutrient focused dietary research in preventing and managing hypertension.

Metabolites and Hypertension: Insights into Hypertension as a Metabolic Disorder: 2019 Harriet Dustan Award

For over 100 years, essential hypertension has been researched from different perspectives ranging from genetics, physiology, and immunology to more recent ones encompassing microbiology (microbiota) as a previously underappreciated field of study contributing to the cause of hypertension. Each field of study in isolation has uniquely contributed to a variety of underlying mechanisms of blood pressure regulation. Even so, clinical management of essential hypertension has remained somewhat static. We, therefore, asked if there are any converging lines of evidence from these individual fields that could be amenable for a better clinical prognosis. Accordingly, here we present converging evidence which support the view that metabolic dysfunction underlies essential hypertension.

The hypotensive effect of salt substitutes in stage 2 hypertension: a systematic review and meta-analysis

Background

Hypertension (HTN) is a ubiquitous risk factor for numerous non-communicable diseases, including cardiovascular disease and stroke. There are currently no wholly effective pharmacological therapies for subjects with HTN. However, salt substitutes have emerged as a potential therapy for the treatment of HTN. The aim of the present study was to assess the effect of salt substitutes on reducing systolic blood pressure (SBP) and diastolic BP (DBP), following a meta-analysis of randomized controlled trials.

Methods

Studies were found via systematic searches of the Pubmed/Medline, Scopus, Ovid, Google Scholar and Cochrane library. Ten studies, comprised of 11 trials and 1119 participants, were included in the meta-analysis.

Results

Pooled weighted mean differences showed significant reductions of SBP (WMD − 8.87 mmHg; 95% CI − 11.19, − 6.55, p < 0.001) and DBP (WMD − 4.04 mmHg; 95% CI − 5.70, − 2.39) with no statistically significant heterogeneity between the 11 included comparisons of SBPs and DBPs. The stratified analysis of trials based on the mean age of participants showed a significant reduction in the mean difference of SBP in both adults (< 65 years old) and elderly (≥65 years old). However, the DBP-lowering effect of salt substitutes was only observed in adult patients (WMD − 4.22 mmHg; 95% CI − 7.85, − 0.58), but not in the elderly subjects.

Conclusions

These findings suggest that salt-substitution strategies could be used for lowering SBP and DBP in patients with stage 2 HTN; providing a nutritional platform for the treatment, amelioration, and prevention of HTN.

Dietary reference values for sodium

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) derived dietary reference values (DRVs) for sodium. Evidence from balance studies on sodium and on the relationship between sodium intake and health outcomes, in particular cardiovascular disease (CVD)-related endpoints and bone health, was reviewed. The data were not sufficient to enable an average requirement (AR) or population reference intake (PRI) to be derived. However, by integrating the available evidence and associated uncertainties, the Panel considers that a sodium intake of 2.0 g/day represents a level of sodium for which there is sufficient confidence in a reduced risk of CVD in the general adult population. In addition, a sodium intake of 2.0 g/day is likely to allow most of the general adult population to maintain sodium balance. Therefore, the Panel considers that 2.0 g sodium/day is a safe and adequate intake for the general EU population of adults. The same value applies to pregnant and lactating women. Sodium intakes that are considered safe and adequate for children are extrapolated from the value for adults, adjusting for their respective energy requirement and including a growth factor, and are as follows: 1.1 g/day for children aged 1-3 years, 1.3 g/day for children aged 4-6 years, 1.7 g/day for children aged 7-10 years and 2.0 g/day for children aged 11-17 years, respectively. For infants aged 7-11 months, an Adequate Intake (AI) of 0.2 g/day is proposed based on upwards extrapolation of the estimated sodium intake in exclusively breast-fed infants aged 0-6 months.

Nonpharmacological interventions for the prevention of hypertension in low- and middle-income countries: a systematic review and meta-analysis

Hypertension is the single biggest cause of various cardiovascular complications and at the same time one of the most preventable phenomena. Low- and middle-income countries (LMICs) are facing increasing prevalence of hypertension which is imposing a huge burden on morbidity, premature mortality, and catastrophic health expenditure. This systematic review searched for the nonpharmacological interventions for prevention of hypertension among normotensive people in LMICs considering the period 1990–2016. This review has been conducted following standard methodology of Cochrane review involving two independent reviewers in screening, quality appraisal, and data extraction. Narrative synthesis of included articles was demonstrated using tables and meta-analysis was conducted to pool the estimates of studies which fulfilled the criteria. Total seven trials were included in the review with 6046 participants from eight LMICs. Two cluster randomized trials were pooled and there was a statistically significant effect (Systolic Blood Pressure: mean difference −2.35 [95% CI: −4.31 to −0.38], Diastolic Blood Pressure: mean difference −2.11 [95% CI: −3.20 to −1.02]) of home based health education in reducing blood pressure. Three individual studies reported reduction of blood pressure as a result of restricted dietary sodium intake. None of the studies was appraised as low risk of bias due to poor methodological quality. Non-pharmacological interventions can play important role in preventing the development of hypertension among normotensive people. Further trials with longer follow-up period and robust methods are recommended for getting stronger evidence on these interventions.

The impact of interventions for the primary prevention of hypertension in Sub-Saharan Africa: A systematic review and meta-analysis

BACKGROUND

The prevalence of hypertension is highest in the African Region with 46% of adults aged 25 and above diagnosed with hypertension, while the lowest prevalence of 35% is found in the Americas. There is sparse evidence on the approaches used to prevent hypertension in Sub-Saharan Africa and the effectiveness of these approaches. It is therefore imperative that a systematic review; which synthesises all the available evidence on the approaches and their impact is conducted to inform public health policy and practice.

OBJECTIVE

To synthesise evidence on the interventions used for the primary prevention of hypertension in Sub-Saharan Africa and to evaluate the effectiveness of these interventions in reducing blood pressure, hypertension prevalence and the risk factors for hypertension.

METHODS AND RESULTS

This systematic review was reported per the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Bibliographic databases were searched on the 4th-17th of January 2018 from 1970 to January 2018 and on the 5th of May 2019 from 1970 to May 2019, for studies focusing on the primary prevention of hypertension in communities in Sub-Saharan Africa. A narrative synthesis was conducted based on study interventions and outcomes. Also, a meta-analysis was carried out using pooled mean differences; using a random effects model of generic inverse variance option in RevMan. A total of 854 studies were identified after deduplication, with thirteen studies meeting the inclusion criteria. Six studies with varying interventions and methodologies observed a significant pooled reduction in systolic blood pressure of -3.3mmHg (95%CI -4.64 to -1.96) and a reduction of -2.26mmHg (95%CI -6.36 to 1.85) in diastolic blood pressure, which was not statistically significant (p = 0.28). Also, moderate to significant heterogeneity was observed (I2 = 68% and 99%) for the systolic and diastolic blood pressure respectively. Intervention and study design accounted for 100% heterogeneity for both systolic and diastolic blood pressure (r2 = 100%).

CONCLUSION

Health promotion and interventions targeting various risk factors of hypertension and, salt consumption restriction interventions have been employed in Sub-Saharan Africa with varying levels of success. We recommend that higher quality studies and a meta-analysis are needed to evaluate the impact of these interventions and to inform public health policy and practice.

Spot urine samples compared with 24-h urine samples for estimating changes in urinary sodium and potassium excretion in the China Salt Substitute and Stroke Study

Background

The capacity of spot urine samples for detecting changes in population sodium and potassium excretion is unclear.

Methods

Changes in urinary sodium and potassium excretion, over a 6-month to 2-year interval, were measured from 24-h urine samples and estimated from spot urine samples using several published methods in 3270 Chinese. Additional estimates were made by multiplying individual spot sodium and potassium concentrations by a single estimated 24-h urine volume derived from external data.

Results

The measured difference in 24-h urinary excretion between intervention and control groups was -0.35 g (95% CI: -0.68 to -0.02; P = 0.039) for sodium and 0.66 g (95% CI: 0.52 to 0.80; P < 0.001) for potassium, based upon 24-h urine samples. The corresponding estimates of sodium differences for the Tanaka (-0.06 g), Kawasaki (-0.09 g), Intersalt without potassium (-0.09 g) and Intersalt with potassium (-0.14 g) equations were all smaller and identified no reduction in sodium excretion (all P > 0.10). The estimates were -0.65 g for sodium and 1.11 g for potassium using individual spot urine concentrations and an externally derived standard urine volume (both P < 0.01).

Conclusions

The published equations were unable to detect the differences in sodium excretion measured by 24-h urine samples. A method based upon spot urine electrolyte concentrations and a standard urine volume may offer an alternative approach to measuring differences in sodium and potassium excretion between population groups without requiring 24-h urine, but will need further investigation.

Inferred systolic blood pressure levels to switch from lifestyle modifications to antihypertensive medications: a success-rate oriented simulation

Objective: This simulation study attempted to infer the systolic blood pressure (SBP) levels at which subjects with hypertension, health nurses, and primary physicians should switch their preference of their treatment policies from lifestyle modifications to antihypertensive medications in virtual Japanese sample populations. Methods: We assumed that SBP levels were normally distributed and that the incidence rate of cardiovascular disease (IR_CVD, events/year) increased exponentially according to SBP. The total IR_CVD was calculated by the definite integral for the product of the distribution of SBP multiplied by IR_CVD at each SBP level. The success rates were calculated according to SBP and metabolic risk profiles in the two approaches, respectively. We deduced the hypothetical SBP levels by solving differential equations of ∆(IR_CVD)/ ∆(SBP) = 0 using numerical analysis. Results: In the realistic situations where the subjects were not affirmative to antihypertensive medications, the inferred SBP level to switch from lifestyle modifications to antihypertensive medications should be around 150 mmHg. If the subjects are affirmative to antihypertensive medications, the SBP level should be lowered to 140 mm Hg. Conclusion: This success rate-oriented simulation proposes that the SBP level to switch from lifestyle modifications to antihypertensive medications can be modulated according to the behavioral propensity for taking antihypertensive medications.Abbreviations: The following abbreviations are used in this manuscript: CVD: cardiovascular disease; LM: lifestyle modifications; AM: antihypertensive medications; IR_CVD: incidence rate of cardiovascular disease (events/year); SBP: systolic blood pressure; ∆IR_CVD: the improvements in the incidence rate of cardiovascular disease by lifestyle modifications and/or by antihypertensive medications.

Threats to Belonging, Immune Function, and Eating Behavior: an Examination of Sex and Gender Differences

PURPOSE OF REVIEW

The first goal of this review is to discuss the evidence linking belonging threats to immune function and food intake. The second goal is to evaluate whether the links among belonging threats, immune function, and eating behavior differ based on gender.

RECENT FINDINGS

Threats to belonging are linked to elevated herpesvirus antibody titers, dysregulated appetite-relevant hormones, and increased food consumption. Furthermore, these relationships are largely consistent for both men and women. Threats to belonging are also linked to elevated inflammation. However, some studies showed that these effects were stronger among women, others demonstrated that they were stronger among men, and others determined that the links were consistent for men and women. Understanding why belonging threats are inconsistently linked to inflammation across men and women is an important next step. We conclude the review with four concrete recommendations for researchers studying belonging threats, immune function, and eating behavior.

Resistant Hypertension in Adults With Type 1 or 2 Diabetes: A Structured Diagnostic Approach

People with diabetes often have difficulty reaching their blood pressure targets and are labelled as having resistant hypertension. Clinicians often move quickly to screen such people for secondary causes of hypertension; however, such causes are rare, and resistant hypertension usually has other explanations that are significantly more common. By using a structured approach to resistant hypertension, clinicians can assist patients to reach their target blood pressure levels. Step 1 is to determine out-of-office blood pressure measurements using home or ambulatory blood pressure monitors. Step 2 is to determine the level of adherence to prescribed medications. Step 3 is to identify interfering substances. Step 4 is to check that the prescribed medications are synergistic and optimally dosed. Finally, if all other steps fail to get patients to their blood pressure targets, we consider possible secondary causes of hypertension. This approach is particularly useful in helping people with diabetes to reach their blood pressure targets.

Prevalence and Gender-Specific Influencing Factors of Hypertension among Chinese Adults: A Cross-Sectional Survey Study in Nanchang, China

Hypertension has become the leading cause of death worldwide; data on hypertension among Nanchang adults are sparse. The aim of this study was to investigate the prevalence and gender-specific influencing factors of hypertension in adults in Nanchang, China. A cross-sectional survey was conducted with a representative sample of 2722 Chinese residents aged 18 years and above between May and September 2016, with a response rate of 92.4% (2516/2722). A stratified cluster sampling method was adopted in this study. Data on prevalence and influencing factors were obtained from a standard questionnaire and physical measurements. Univariate and multivariate logistic regressions were performed to analyze the influencing factors. The age-standardized prevalence was 19.8% (18.2-21.3) (male: 19.5% (18.0-21.1); female, 20.01% (18.5-21.6)). Factors positively associated with hypertension prevalence were past smoking, diabetes mellitus (DM), and overweight and obesity in both genders. Abdominal obesity and family history of cardiovascular diseases (CVD) were risk factors only in males; sleeping time and consumption of fresh vegetables and fruits were related to the prevalence of hypertension only in females. These findings will form the baseline information for the development of more effective approaches to enhance current prevention and control management of hypertension.

Understanding the Two Faces of Low-Salt Intake

Fierce debate has developed whether low-sodium intake, like high-sodium intake, could be associated with adverse outcome. The debate originates in earlier epidemiological studies associating high-sodium intake with high blood pressure and more recent studies demonstrating a higher cardiovascular event rate with both low- and high-sodium intake. This brings into question whether we entirely understand the consequences of high- and (very) low-sodium intake for the systemic hemodynamics, the kidney function, the vascular wall, the immune system, and the brain. Evolutionarily, sodium retention mechanisms in the context of low dietary sodium provided a survival advantage and are highly conserved, exemplified by the renin-angiotensin system. What is the potential for this sodium-retaining mechanism to cause harm? In this paper, we will consider current views on how a sodium load is handled, visiting aspects including the effect of sodium on the vessel wall, the sympathetic nervous system, the brain renin-angiotensin system, the skin as "third compartment" coupling to vascular endothelial growth factor C, and the kidneys. From these perspectives, several mechanisms can be envisioned whereby a low-sodium diet could potentially cause harm, including the renin-angiotensin system and the sympathetic nervous system. Altogether, the uncertainties preclude a unifying model or practical clinical guidance regarding the effects of a low-sodium diet for an individual. There is a very strong need for fundamental and translational studies to enhance the understanding of the potential adverse consequences of low-salt intake as an initial step to facilitate better clinical guidance.

A Study on Knowledge, Awareness, and Medication Adherence in Patients with Hypertension from a Tertiary Care Centre from Northern Sri Lanka

Objective

To assess the patient's knowledge and awareness about hypertension and adherence to antihypertensive medication among hypertensive patients with validated Morisky questionnaires in a tertiary care centre of northern Sri Lanka.

Methods

A cross-sectional descriptive comparative study was carried out at Teaching Hospital Jaffna, from January 2017 to April 2017. Hypertensive patients were recruited by systematic randomized controlled sampling and interviewed with validated Morisky questionnaires to assess their knowledge about hypertension. Data were analyzed using SPSS (version 21) analytical package.

Results

73 of 303 patients were males. 69.9% of patients had adequate knowledge about hypertension. 40.5% of patients were unaware of their disease status. 75.8% of patients could not recall their blood pressure values at the time of diagnosis. 72.3% of patients were unaware of their values of blood pressure during their last outpatient clinic visit. 48.2% of patients had awareness of target organ damage due to hypertension (kidney, 72, 23.7%; heart, 128, 42.2%; brain, 140, 46.7%; eye, 42, 13.8%). Most of the patients had poor drug compliance. The most common reasons for nonadherence were forgetfulness (70, 23.1%) and interruptions of daily routine (53, 17.5%).

Conclusion

The knowledge about hypertension among majority of patients was reasonable. But they were unaware of their disease status. The drug compliance among them was poor. Forgetfulness and interruptions of daily routine were common reasons attributed for nonadherence.

Drinking Water Salinity and Raised Blood Pressure: Evidence from a Cohort Study in Coastal Bangladesh

BACKGROUND

Millions of coastal inhabitants in Southeast Asia have been experiencing increasing sodium concentrations in their drinking-water sources, likely partially due to climate change. High (dietary) sodium intake has convincingly been proven to increase risk of hypertension; it remains unknown, however, whether consumption of sodium in drinking water could have similar effects on health.

OBJECTIVES

We present the results of a cohort study in which we assessed the effects of drinking-water sodium (DWS) on blood pressure (BP) in coastal populations in Bangladesh.

METHODS

DWS, BP, and information on personal, lifestyle, and environmental factors were collected from 581 participants. We used generalized linear latent and mixed methods to model the effects of DWS on BP and assessed the associations between changes in DWS and BP when participants experienced changing sodium levels in water, switched from "conventional" ponds or tube wells to alternatives [managed aquifer recharge (MAR) and rainwater harvesting] that aimed to reduce sodium levels, or experienced a combination of these changes.

RESULTS

DWS concentrations were highly associated with BP after adjustments for confounding factors. Furthermore, for each 100 mg/L reduction in sodium in drinking water, systolic/diastolic BP was lower on average by 0.95/0.57 mmHg, and odds of hypertension were lower by 14%. However, MAR did not consistently lower sodium levels.

CONCLUSIONS

DWS is an important source of daily sodium intake in salinity-affected areas and is a risk factor for hypertension. Considering the likely increasing trend in coastal salinity, prompt action is required. Because MAR showed variable effects, alternative technologies for providing reliable, safe, low-sodium fresh water should be developed alongside improvements in MAR and evaluated in "real-life" salinity-affected settings. https://doi.org/10.1289/EHP659.

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

BACKGROUND

In spite of more than 100 years of investigations the question of whether a reduced sodium intake improves health is still unsolved.

OBJECTIVES

To estimate the effects of low sodium intake versus high sodium intake on systolic and diastolic blood pressure (SBP and DBP), plasma or serum levels of renin, aldosterone, catecholamines, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglycerides.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to March 2016: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 3), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also searched the reference lists of relevant articles.

SELECTION CRITERIA

Studies randomising persons to low-sodium and high-sodium diets were included if they evaluated at least one of the above outcome parameters.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected data, which were analysed with Review Manager 5.3.

MAIN RESULTS

A total of 185 studies were included. The average sodium intake was reduced from 201 mmol/day (corresponding to high usual level) to 66 mmol/day (corresponding to the recommended level).The effect of sodium reduction on blood pressure (BP) was as follows: white people with normotension: SBP: mean difference (MD) -1.09 mmHg (95% confidence interval (CI): -1.63 to -0.56; P = 0.0001); 89 studies, 8569 participants; DBP: + 0.03 mmHg (MD 95% CI: -0.37 to 0.43; P = 0.89); 90 studies, 8833 participants. High-quality evidence. Black people with normotension: SBP: MD -4.02 mmHg (95% CI:-7.37 to -0.68; P = 0.002); seven studies, 506 participants; DBP: MD -2.01 mmHg (95% CI:-4.37 to 0.35; P = 0.09); seven studies, 506 participants. Moderate-quality evidence. Asian people with normotension: SBP: MD -0.72 mmHg (95% CI: -3.86 to 2.41; P = 0.65); DBP: MD -1.63 mmHg (95% CI:-3.35 to 0.08; P =0.06); three studies, 393 participants. Moderate-quality evidence.White people with hypertension: SBP: MD -5.51 mmHg (95% CI: -6.45 to -4.57; P < 0.00001); 84 studies, 5925 participants; DBP: MD -2.88 mmHg (95% CI: -3.44 to -2.32; P < 0.00001); 85 studies, 6001 participants. High-quality evidence. Black people with hypertension: SBP MD -6.64 mmHg (95% CI:-9.00 to -4.27; P = 0.00001); eight studies, 619 participants; DBP -2.91 mmHg (95% CI:-4.52, -1.30; P = 0.0004); eight studies, 619 participants. Moderate-quality evidence. Asian people with hypertension: SBP: MD -7.75 mmHg (95% CI:-11,44 to -4.07; P < 0.0001) nine studies, 501 participants; DBP: MD -2.68 mmHg (95% CI: -4.21 to -1.15; P = 0.0006). Moderate-quality evidence.In plasma or serum, there was a significant increase in renin (P < 0.00001), aldosterone (P < 0.00001), noradrenaline (P < 0.00001), adrenaline (P < 0.03), cholesterol (P < 0.0005) and triglyceride (P < 0.0006) with low sodium intake as compared with high sodium intake. All effects were stable in 125 study populations with a sodium intake below 250 mmol/day and a sodium reduction intervention of at least one week.

AUTHORS' CONCLUSIONS

Sodium reduction from an average high usual sodium intake level (201 mmol/day) to an average level of 66 mmol/day, which is below the recommended upper level of 100 mmol/day (5.8 g salt), resulted in a decrease in SBP/DBP of 1/0 mmHg in white participants with normotension and a decrease in SBP/DBP of 5.5/2.9 mmHg in white participants with hypertension. A few studies showed that these effects in black and Asian populations were greater. The effects on hormones and lipids were similar in people with normotension and hypertension. Renin increased 1.60 ng/mL/hour (55%); aldosterone increased 97.81 pg/mL (127%); adrenalin increased 7.55 pg/mL (14%); noradrenalin increased 63.56 pg/mL: (27%); cholesterol increased 5.59 mg/dL (2.9%); triglyceride increased 7.04 mg/dL (6.3%).

A systematic review of economic evaluations of population-based sodium reduction interventions

OBJECTIVE

To summarise evidence describing the cost-effectiveness of population-based interventions targeting sodium reduction.

METHODS

A systematic search of published and grey literature databases and websites was conducted using specified key words. Characteristics of identified economic evaluations were recorded, and included studies were appraised for reporting quality using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist.

RESULTS

Twenty studies met the study inclusion criteria and received a full paper review. Fourteen studies were identified as full economic evaluations in that they included both costs and benefits associated with an intervention measured against a comparator. Most studies were modelling exercises based on scenarios for achieving salt reduction and assumed effects on health outcomes. All 14 studies concluded that their specified intervention(s) targeting reductions in population sodium consumption were cost-effective, and in the majority of cases, were cost saving. Just over half the studies (8/14) were assessed as being of 'excellent' reporting quality, five studies fell into the 'very good' quality category and one into the 'good' category. All of the identified evaluations were based on modelling, whereby inputs for all the key parameters including the effect size were either drawn from published datasets, existing literature or based on expert advice.

CONCLUSION

Despite a clear increase in evaluations of salt reduction programs in recent years, this review identified relatively few economic evaluations of population salt reduction interventions. None of the studies were based on actual implementation of intervention(s) and the associated collection of new empirical data. The studies universally showed that population-based salt reduction strategies are likely to be cost effective or cost saving. However, given the reliance on modelling, there is a need for the effectiveness of new interventions to be evaluated in the field using strong study designs and parallel economic evaluations.

Four and a half years of experience of a clinician born and raised in Fukushima: discrepancy found through dialogues and practices

Many initiatives to measure the internal and external exposures of the residents of Fukushima have been undertaken since the accident at Fukushima Daiichi nuclear power plant. However, residents have had few, if any, opportunities for face-to-face explanations to understand the meaning of such measurements. Although the personal data of tens of thousands of residents were collected, these data were not analysed adequately, and were therefore not used to implement large-scale programmes to manage/reduce exposures. One of the lessons learned from the Fukushima accident is that it is imperative for the government to implement these measures for radiation protection, and to build an effective functioning service for the residents. The author, as a physician from the region, has worked as an explainer/interpreter of exposure dose measurements to individual residents. Another lesson learned from this experience is that local medical and health professionals can contribute to building a public system for radiation protection, by acting as 'liaising officers' to connect residents, the authorities, and experts from outside the region. This paper describes the author's experience and lessons learned in the hope that this information will be useful in the event of a future accident.

The Science of Salt: A Systematic Review of Quality Clinical Salt Outcome Studies June 2014 to May 2015

Studies identified from an updated systematic review (from June 2014 to May 2015) on the impact of dietary salt intake on clinical and population health are reviewed. Randomized controlled trials, cohort studies, and meta-analyses of these study types on the effect of sodium intake on blood pressure, or any substantive adverse health outcomes were identified from MEDLINE searches and quality indicators were used to select studies that were relevant to clinical and public health. From 6920 studies identified in the literature search, 144 studies were selected for review, of which only three (n=233,680) met inclusion criteria. Between them, the three studies demonstrated a harmful association between excess dietary salt and all-cause mortality, noncardiovascular and cardiovascular disease mortality, and headache. None of the included studies found harm from lowering dietary salt. The findings of this systematic review are consistent with the large body of research supportive of efforts to reduce population salt intake and congruent with our last annual review from June 2013 to May 2014.

Dietary Sodium Intake in People with Diabetes in Korea: The Korean National Health and Nutrition Examination Survey for 2008 to 2010

BACKGROUND

Diabetics are likely to receive advice from their physicians concerning lifestyle changes. To understand how much sodium is consumed by diabetics in Korea, we compared the average daily sodium intake between diabetics and non-diabetics after controlling for confounding factors.

METHODS

We obtained the sodium intake data for 13,957 individuals who participated in the Korean National Health and Nutrition Examination Survey (KNHANES), 2008 to 2010, which consisted of a health interview and behavioral and nutritional surveys. The KNHANES uses a stratified, multistage, probability-sampling design, and weighting adjustments were conducted to represent the entire population.

RESULTS

Our analysis revealed that, overall, diabetics tended to have lower sodium intake (4,910.2 mg) than healthy individuals (5,188.2 mg). However, both diabetic and healthy individuals reported higher sodium intake than is recommended by the World Health Organization (WHO). Stratified subgroup analyses revealed that the sodium intake (4,314.2 mg) among newly diagnosed diabetics was higher among women when compared to patients with known diabetes (3,812.5 mg, P=0.035). Female diabetics with cardiovascular disease had lower average sodium intake compared to those without cardiovascular disease after adjusting for sex, age, body mass index, and total energy intake (P=0.058). Sodium intake among male diabetics with hypercholesterolemia (P=0.011) and female diabetics with hypertriglyceridemia (P=0.067) tended to be higher than that among those who without dyslipidemia.

CONCLUSION

The average sodium intake of diabetics in Korea was higher than the WHO recommends. Sodium intake in newly diagnosed diabetics was significantly higher than that in non-diabetics and previously diagnosed diabetics among females. Prospective studies are needed to identify the exact sodium intake.

Validation and Assessment of Three Methods to Estimate 24-h Urinary Sodium Excretion from Spot Urine Samples in Chinese Adults

24-h urinary sodium excretion is the gold standard for evaluating dietary sodium intake, but it is often not feasible in large epidemiological studies due to high participant burden and cost. Three methods--Kawasaki, INTERSALT, and Tanaka--have been proposed to estimate 24-h urinary sodium excretion from a spot urine sample, but these methods have not been validated in the general Chinese population. This aim of this study was to assess the validity of three methods for estimating 24-h urinary sodium excretion using spot urine samples against measured 24-h urinary sodium excretion in a Chinese sample population. Data are from a substudy of the Prospective Urban Rural Epidemiology (PURE) study that enrolled 120 participants aged 35 to 70 years and collected their morning fasting urine and 24-h urine specimens. Bias calculations (estimated values minus measured values) and Bland-Altman plots were used to assess the validity of the three estimation methods. 116 participants were included in the final analysis. Mean bias for the Kawasaki method was -740 mg/day (95% CI: -1219, 262 mg/day), and was the lowest among the three methods. Mean bias for the Tanaka method was -2305 mg/day (95% CI: -2735, 1875 mg/day). Mean bias for the INTERSALT method was -2797 mg/day (95% CI: -3245, 2349 mg/day), and was the highest of the three methods. Bland-Altman plots indicated that all three methods underestimated 24-h urinary sodium excretion. The Kawasaki, INTERSALT and Tanaka methods for estimation of 24-h urinary sodium excretion using spot urines all underestimated true 24-h urinary sodium excretion in this sample of Chinese adults. Among the three methods, the Kawasaki method was least biased, but was still relatively inaccurate. A more accurate method is needed to estimate the 24-h urinary sodium excretion from spot urine for assessment of dietary sodium intake in China.

Burden of stroke attributable to selected lifestyle risk factors in rural South Africa

BACKGROUND

Rural South Africa (SA) is undergoing a rapid health transition characterized by increases in non-communicable diseases; stroke in particular. Knowledge of the relative contribution of modifiable risk factors on disease occurrence is needed for public health prevention efforts and community-oriented health promotion. Our aim was to estimate the burden of stroke in rural SA that is attributable to high blood pressure, excess weight and high blood glucose using World Health Organization's comparative risk assessment (CRA) framework.

METHODS

We estimated current exposure distributions of the risk factors in rural SA using 2010 data from the Agincourt health and demographic surveillance system (HDSS). Relative risks of stroke per unit of exposure were obtained from the Global Burden of Disease Study 2010. We used data from the Agincourt HDSS to estimate age-, sex-, and stroke specific deaths and disability adjusted life years (DALYs). We estimated the proportion of the years of life lost (YLL) and DALY loss attributable to the risk factors and incorporate uncertainty intervals into these estimates.

RESULTS

Overall, 38 % of the documented stroke burden was due to high blood pressure (12 % males; 26 % females). This translated to 520 YLL per year (95 % CI: 325-678) and 540 DALYs (CI: 343-717). Excess Body Mass Index (BMI) was calculated as responsible for 20 % of the stroke burden (3.5 % males; 16 % females). This translated to 260 YLLs (CI: 199-330) and 277 DALYs (CI: 211-350). Burden was disproportionately higher in young females when BMI was assessed.

CONCLUSIONS

High blood pressure and excess weight, which both have effective interventions, are responsible for a significant proportion of the stroke burden in rural SA; the burden varies across age and sex sub-groups. The most effective way forward to reduce the stroke burden requires both population wide policies that have an impact across the age spectra and targeted (health promotion/disease prevention) interventions on women and young people.

Prevalence, Awareness, Treatment, Control and Risk Factors Associated with Hypertension among Adults in Southern China, 2013

To investigate the prevalence, awareness, treatment, control of hypertension and their associated factors in southern China. A cross-sectional survey was conducted in 5 cities of urban areas and 5 counties of rural areas in Southern China in 2013, a stratified multistage random sampling method was used to select a representative sample. Recruitment included a total of 19254 participants aged 15 or older. Socio-demographic profiles, examinations were administrated on each subject. Multilevel logistic regression models were used to identify the risk factors of hypertension, awareness, treatment, and control. Overall, the prevalence of hypertension and pre-hypertension are 24.59% and 32.11%, respectively in southern China. Among all the hypertensive patients, 67.43% were aware of their condition, 55.76% took anti-hypertension medication recent two weeks, and 30.79% had their blood pressure controlled. Compared with male, female hypertensive patients had higher rates of hypertension awareness, treatment and control. Age, gender, marital status, living areas, education, BMI, waist circumference, visceral adipose index (VAI), high body fat percentage (BFP) and family hypertension history correlated with the prevalence of hypertension. SBP/DBP increased with VAI and BFP increasing. There is an increasing prevalence of hypertension and high pre-hypertension in the general population in southern China, but levels of awareness, treatment, and control remain relatively low, especially for young and middle-aged population. Innovative strategies including of adopting appropriate anti-hypertensive medication therapy and healthy lifestyles should be taken.

Lifestyle Modifications Versus Antihypertensive Medications in Reducing Cardiovascular Events in an Aging Society: A Success Rate-oriented Simulation

Objective It is difficult to compare directly the practical effects of lifestyle modifications and antihypertensive medications on reducing cardiovascular disease (CVD). The purpose of this study was to compare the hypothetical potential of lifestyle modifications with that of antihypertensive medications in reducing CVD in an aging society using a success rate-oriented simulation. Methods We constructed a simulation model for virtual Japanese subpopulations according to sex and age at 10-year intervals from 40 years of age as an example of an aging society. The fractional incidence rate of CVD was calculated as the product of the incidence rate at each systolic blood pressure (SBP) level and the proportion of the SBP frequency distribution in the fractional subpopulations of each SBP. The total incidence rate was calculated by the definite integral of the fractional incidence rate at each SBP level in the sex- and age-specific subpopulations. Results If we consider the effects of lifestyle modifications on metabolic factors and transfer them onto SBP, the reductions in the total incidence rate of CVD were competitive between lifestyle modifications and antihypertensive medications in realistic scenarios. In middle-aged women, the preventive effects of both approaches were limited due to a low incidence rate. In middle-aged men and extremely elderly subjects whose adherence to antihypertensive medications is predicted to be low, lifestyle modifications could be an alternative choice. Conclusion The success rate-oriented simulation suggests that the effectiveness of lifestyle modifications or antihypertensive medications in preventing cardiovascular events largely depends on the baseline incidence rate and sex- and age-specific behavioral factors.

Estimated urinary sodium excretion and risk of heart failure in men and women in the EPIC-Norfolk study

AIMS

Interventional trials provide evidence for a beneficial effect of reduced dietary sodium intake on blood pressure. The association of sodium intake with heart failure which is a long-term complication of hypertension has not been examined.

METHODS AND RESULTS

Hazard ratios [HRs, 95% confidence interval (CI)] of heart failure comparing quintiles of estimated 24 h urinary sodium excretion (USE) were calculated in apparently healthy men (9017) and women (10,840) aged 39–79 participating in the EPIC study in Norfolk. During a mean follow-up of 12.9 years, 1210 incident cases of heart failure occurred. Compared with the reference category (128 mmol/day≤USE≤148 mmol/day), the top quintile (USE≥191 mmol/day) was associated with a significantly increased hazard of heart failure (1.32, 1.07–1.62) in multivariable analysis adjusting for age, sex, body mass index, diabetes, cholesterol, social class, educational level, smoking, physical activity, and alcohol consumption, with a marked attenuation (1.21, 0.98–1.49) when further adjusting for blood pressure. The bottom quintile (USE≤127 mmol/day) was also associated with an increased hazard of heart failure (1.29, 1.04–1.60) in multivariable analysis without relevant attenuation by blood pressure adjustment (1.26, 1.02–1.56), but with substantial attenuation when adjusting for interim ischaemic heart disease and baseline C-reactive protein levels and exclusion of events during the first 2 years (1.18, 0.96–1.47).

CONCLUSION

We demonstrate a U-shaped association between USE and heart failure risk in an apparently healthy middle-aged population. The risk associated with the high range of USE was attenuated after adjustment for blood pressure, whereas the risk associated with the low range of USE was attenuated after adjustment for pre-existing disease processes.

Contributions of risk factors and medical care to cardiovascular mortality trends

Ischaemic heart disease, stroke, and other cardiovascular diseases (CVDs) lead to 17.5 million deaths worldwide per year. Taking into account population ageing, CVD death rates are decreasing steadily both in regions with reliable trend data and globally. The declines in high-income countries and some Latin American countries have been ongoing for decades without slowing. These positive trends have broadly coincided with, and benefited from, declines in smoking and physiological risk factors, such as blood pressure and serum cholesterol levels. These declines have also coincided with, and benefited from, improvements in medical care, including primary prevention, diagnosis, and treatment of acute CVDs, as well as post-hospital care, especially in the past 40 years. These variables, however, explain neither why the decline began when it did, nor the similarities and differences in the start time and rate of the decline between countries and sexes. In Russia and some other former Soviet countries, changes in volume and patterns of alcohol consumption have caused sharp rises in CVD mortality since the early 1990s. An important challenge in reaching firm conclusions about the drivers of these remarkable international trends is the paucity of time-trend data on CVD incidence, risk factors throughout the life-course, and clinical care.

Dietary sodium intake and prediction of cardiovascular events

BACKGROUND/OBJECTIVES

The association of dietary sodium and cardiovascular disease (CVD), as well as the reduction of sodium intake in the prevention of CVD, has been under debate. To study whether sodium consumption has a role as a risk factor for fatal and non-fatal CVD.

SUBJECTS/METHODS

A well-defined population-based cohort of 1045 subjects collected between 1991 and 1993 (mean age 51.4 years) was used with approximately 19 years' follow-up. At the baseline, 716 subjects filled in a 1-week food follow-up diary, which was used to calculate the daily sodium intake (mg/1000 kcal).

RESULTS

The baseline sodium intake correlated significantly with age (rs=0.117, P=0.002), BMI (rs=0.216, P=0.000), waist circumference (rs=0.268, P=0.000), smoking (rs=0.144, P=0.000), alcohol consumption (rs=0.111, P=0.003), systolic blood pressure (rs=0.106, P=0.005) and low-density lipoprotein (LDL) cholesterol (rs=0.081, P=0.033). Those who had cardiovascular events in the follow-up consumed more sodium at the baseline (mean 2010.4 mg/1000 kcal/day, s.d. 435.2, n=101) compared with the subjects without events (mean 1849.9 mg/1000 kcal/day, s.d. 361.2, n=589; t-test; P=0.001). The incidence of cardiovascular events was greater in the highest quartile (22.1%) than in the lower quartiles (first 11.0%, second 9.9% and third 15.6%; X(2); P=0.005). Cox regression analysis showed that sodium intake as a continuous variable predicts CVD events (P=0.031) independently when age, sex, smoking, alcohol consumption, systolic blood pressure, LDL cholesterol and waist circumference were added as covariates. This predictive role is seen especially in the group of subjects on hypertensive medication (P=0.001).

CONCLUSIONS

Dietary sodium intake is a significant independent predictor of cardiovascular events in the study population.

Effects of salt substitutes on blood pressure: a meta-analysis of randomized controlled trials

BACKGROUND

Clinical trials assessing the effects of salt substitutes on blood pressure (BP) have reported mixed results.

OBJECTIVES

A meta-analysis of randomized controlled trials was conducted to evaluate the effect of salt substitutes on BP, including systolic BP (SBP) and diastolic BP (DBP).

DESIGN

Studies were identified via systematic searches of the PubMed, Embase, Cochrane Library, Wanfang Data, and the China National Knowledge Infrastructure databases through December 2013. Random-effects models were used to estimate pooled mean differences in SBP and DBP.

RESULTS

Six cohorts from 5 articles (1 trial enrolled 2 cohorts for independent intervention) consisting of 1974 participants were included. Pooled results showed that salt substitutes had a significant effect on SBP (mean difference: -4.9 mm Hg; 95% CI: -7.3, -2.5 mm Hg; P < 0.001) and DBP (mean difference: -1.5 mm Hg; 95% CI: -2.7, -0.3 mm Hg; P = 0.013). Significant heterogeneity was found for both SBP (I(2) = 76.7%) and DBP (I(2) = 65.8%). The sensitivity analysis indicated that the pooled effects of salt substitutes on SBP and DBP were robust to systematically dropping each trial. Furthermore, no evidence of significant publication bias from funnel plots or Egger's tests (P = 0.17 and 0.22 for SBP and DBP, respectively) was found.

CONCLUSION

This meta-analysis showed that salt-substitution strategies are effective at lowering SBP and DBP, which supports a nutritional approach to preventing hypertension.