Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP)

Effects of Exposure to Mixed Organic Solvents on Blood Pressure in Non-Smoking Women Working in a Pharmaceutical Company

Some studies suggest that exposure to industrial solvents can affect blood pressure. The objective of this study was to investigate the effect of a mixture of organic solvents on blood pressure in women working in a pharmaceutical company in Iran. Four hundred and thirty-three women were included in the study. Women working in packing units (group 1) were not exposed to the mixture of organic solvents, women in new laboratory units (group 2) were exposed to the mixture within the permitted range and women working in old laboratory units (group 3) were exposed to the mixture above the permitted limit. We compared systolic and diastolic blood pressures (SBP & DBP) and prevalence of hypertension and pre-hypertension among groups. The results revealed a significant difference in SBP and pre-hypertension (p<0.001) and hypertension (p<0.05) prevalence between the exposed and the control group, but DBP did not differ significantly. Logistic regression analysis showed a significant association between hypertension and exposure to mixed solvents. Odds ratio for hypertension in the group 2 and group 3 (exposed) workers was 2.36 and 3, respectively, compared to controls. Our results suggest that exposure to a mixture of organic solvents may increase SBP and hypertension and pre-hypertension prevalence in drug manufacture workers. Therefore, more attention should be paid to workers that work in such settings by periodically measuring blood pressure and implementing accurate and comprehensive programs to reduce exposure to organic solvents.

[Salt consumption and cardiovascular risk : a plea for salt reduction]

High salt intake over long term is associated with increased incidence of arterial, predominantly systolic, hypertension and increased risk of cardiovascular diseases, e.g., stroke, heart failure, and renal insufficiency. High salt consumption is a vascular risk factor generating aortic stiffness and decreased vascular compliance leading to central blood pressure augmentation, higher cardiac load, and diminished diastolic perfusion. The development of heart failure can be a consequence of this sequelae. Randomized trials show a reduction in blood pressure with lower sodium intake. In long-term clinical trials, a reduction in cardiovascular morbidity and mortality has been demonstrated. Recommendations should emphasize the simultaneous reduction in sodium intake and increase in potassium intake.

Role of dietary therapies in the prevention and treatment of hypertension

Blood pressure naturally rises with increasing age. The rate of change in blood pressure with age is regulated in part by genetic factors, but can also be altered through sustained dietary modification. Dietary approaches to modify blood pressure remain an important part of cardiovascular health promotion, which is especially important given the aging of the general population coupled with the increasing prevalence of obesity and metabolic disturbances. Specific modification of dietary components such as macronutrients and micronutrients could be helpful to lower blood pressure and alter the slope of blood pressure change whereas nutritional supplements are less likely to have a substantial beneficial effect. Population-wide generalizations regarding diet are impractical as individualized strategies are more likely to be successful in facilitating long-term benefits in improving blood-pressure control. Consequently, more effort needs to be focused on evaluating data from large-scale observational and interventional studies and interpreting their information in a clinically relevant manner, which is likely to be helpful for individual patients. Providing education on the relationship between diet and blood pressure from an early age is most likely to produce tangible benefits.

Individualized reduction in dialysate sodium in conventional in-center hemodialysis

Recent studies have focused on the association between dialysate sodium (Na(+)) prescriptions and interdialytic weight gain (IDWG). We report on a case series of 13 patients undergoing conventional, thrice-weekly in-center hemodialysis with an individualized dialysate Na(+) prescription. Individualized dialysate Na(+) was achieved in all patients through a stepwise weekly reduction of the standard dialysate Na(+) prescription (140 mEq/L) by 2-3 mEq/L until reaching a Na(+) gradient of -2 mEq/L (dialysate Na(+) minus average plasma Na(+) over the preceding 3 months). Interdialytic weight gain, with and without indexing to dry weight (IDWG%), blood pressure, and the proportion of treatments with cramps, intradialytic hypotension (drop in systolic blood pressure >30 mmHg) and intradialytic hypotension requiring an intervention were reviewed. At the beginning of the observation period, the pre-hemodialysis (HD) plasma Na(+) concentration ranged from 130 to 141 mEq/L. When switched from the standard to the individualized dialysate Na(+) concentration, IDWG% decreased from 3.4% ± 1.6% to 2.5% ± 1.0% (P = 0.003) with no change in pre- or post-HD systolic or diastolic blood pressures (all P > 0.05). We found no significant change in the proportion of treatments with cramps (6% vs. 13%), intradialytic hypotension (62% vs. 65%), or intradialytic hypotension requiring an intervention (29% vs. 33%). Individualized reduction of dialysate Na(+) reduces IDWG% without significantly increasing the frequency of cramps or hypotension.

Effect of dietary salt on regulation of TGF-β in the kidney

Dietary sodium chloride (salt) has long been considered injurious to the kidney by promoting the development of glomerular and tubulointerstitial fibrosis. Endothelial cells throughout the vasculature and glomeruli respond to increased dietary salt intake with increased production of transforming growth factor-β (TGF-β) and nitric oxide. High-salt intake activates large-conductance, voltage- and calcium-activated potassium (BK(Ca)) channels in endothelial cells. Activation of BK(Ca) channels promotes signaling through proline-rich tyrosine kinase-2, cellular-sarcoma (c-Src), Akt (also known as protein kinase B), and mitogen-activated protein kinase pathways that lead to endothelial production of TGF-β and nitric oxide. TGF-β signaling is broadly accepted as a strong stimulator of renal fibrosis. The classic description of TGF-β signaling pathology in renal disease involves signaling through Smad proteins resulting in extracellular matrix deposition and fibrosis. Active TGF-β1 also causes fibrosis by inducing epithelial-mesenchymal transition and apoptosis. By enhancing TGF-β signaling, increased dietary salt intake leads to progressive renal failure from nephron loss and glomerular and tubulointerstitial fibrosis.

Sodium intake and blood pressure in renal transplant recipients

BACKGROUND

Hypertension is common among renal transplant recipients (RTR) and a risk factor for graft failure and mortality. Sodium intake is a well-established determinant of blood pressure (BP) in the general population. However, data in RTR are limited. International guidelines recommend a maximum daily sodium intake of 70 mmol. We investigated sodium intake in RTR as compared to healthy controls and its association with BP.

METHODS

We included 660 RTR (age 53 ± 13 years, 58% male) and 201 healthy controls (age 54 ± 11 years, 46% male). Sodium intake was assessed from 24-h urine collections. The morning after completion of urine collection, BP was measured according to a strict protocol.

RESULTS

Urinary sodium excretion was 156 ± 62 mmol/24 h in RTR and 195 ± 75 in controls (difference: P < 0.001), and 95% of RTR had a urinary sodium excretion >70 mmol/24 h. Systolic BP (SBP) and diastolic BP (DBP) were 136 ± 18 and 82 ± 11 mmHg, respectively. Sodium intake was positively associated with SBP (β = 0.042 mmHg/mmol/24 h, P = 0.002) and DBP (β = 0.023 mmHg/mmol/24 h, P = 0.007), independent of potential confounders.

CONCLUSIONS

Although RTR had a lower sodium intake than healthy controls, their intake still exceeded current guidelines. Reduction of sodium intake to recommended amounts could reduce SBP by 4-5 mmHg. Better control of sodium intake may help to prevent graft failure and mortality due to hypertension among RTR.

[Should we consume less salt?]

There is overwhelming evidence that dietary salt is a major cause of increased blood pressure. There is also a link between a high salt intake and risk of stroke, left ventricular hypertrophy, renal disease, obesity, renal stones and stomach cancer. Reduction of salt intake is efficacious and cost-effective. In developed countries, reduction in salt intake requires the participation of food industry.

Pressure overload

This review discusses cardiac consequences of pressure overload. In response to elevated pressure, the ventricular hypertrophy compensates for the increased wall stress. However, the ventricular hypertrophy involves numerous structural adaptations that may lead to ventricular dysfunction and, eventually, heart failure. Particular emphasis is placed on molecular mechanisms that govern the development of hypertrophy and that may lead to maladaptive structural changes resulting in adverse cardiac events.

Moderation of dietary sodium potentiates the renal and cardiovascular protective effects of angiotensin receptor blockers

Dietary sodium restriction has been shown to enhance the short-term response of blood pressure and albuminuria to angiotensin receptor blockers (ARBs). Whether this also enhances the long-term renal and cardiovascular protective effects of ARBs is unknown. Here we conducted a post-hoc analysis of the RENAAL and IDNT trials to test this in patients with type 2 diabetic nephropathy randomized to ARB or non-renin-angiotensin-aldosterone system (non-RAASi)-based antihypertensive therapy. Treatment effects on renal and cardiovascular outcomes were compared in subgroups based on dietary sodium intake during treatment, measured as the 24-h urinary sodium/creatinine ratio of 1177 patients with available 24-h urinary sodium measurements. ARB compared to non-RAASi-based therapy produced the greatest long-term effects on renal and cardiovascular events in the lowest tertile of sodium intake. Compared to non-RAASi, the trend in risk for renal events was significantly reduced by 43%, not changed, or increased by 37% for each tertile of increased sodium intake, respectively. The trend for cardiovascular events was significantly reduced by 37%, increased by 2% and 25%, respectively. Thus, treatment effects of ARB compared with non-RAASi-based therapy on renal and cardiovascular outcomes were greater in patients with type 2 diabetic nephropathy with lower than higher dietary sodium intake. This underscores the avoidance of excessive sodium intake, particularly in type 2 diabetic patients receiving ARB therapy.

High salt intake causes adverse fetal programming--vascular effects beyond blood pressure

BACKGROUND

High salt intake causes hypertension, adverse cardiovascular outcomes and potentially also blood pressure (BP)-independent target organ damage. Excess salt intake in pregnancy is known to affect BP in the offspring. The present study was designed to assess whether high salt intake in pregnancy affects BP and vascular morphology in the offspring.

METHODS

Sprague-Dawley rats were fed a standard rodent diet with low-normal (0.15%) or high (8.0%) salt content during pregnancy and lactation. After weaning at 4 weeks of age, offspring were maintained on the same diet or switched to a high- or low-salt diet, respectively. Vascular geometry was assessed in male offspring at 7 and 12 weeks postnatally.

RESULTS

Up to 12 weeks of age, there was no significant difference in telemetrically measured BP between the groups of offspring. At 12 weeks of age, wall thickness of central (aorta, carotid), muscular (mesenteric) and intrapulmonary arteries was significantly higher in offspring of mothers on a high-salt diet irrespective of the post-weaning diet. This correlated with increased fibrosis of the aortic wall, more intense nitrotyrosine staining as well as elevated levels of marinobufagenin (MBG) and asymmetric dimethyl arginine (ADMA).

CONCLUSIONS

High salt intake in pregnant rats has long-lasting effects on the modeling of central and muscular arteries in the offspring independent of postnatal salt intake and BP. Circulating MBG and ADMA and local oxidative stress correlate with the adverse vascular modeling.

Traditional dietary recommendations for the prevention of cardiovascular disease: do they meet the needs of our patients?

The characteristics of patients with CVD have changed: whereas smoking prevalence declines, obesity and metabolic syndrome are on the rise. Unfortunately, the traditional low-fat diet for the prevention of cardiovascular disease (CVD) still seems to be the “mainstream knowledge” despite contradicting evidence. But lowering LDL-cholesterol by the wrong diet even may be counterproductive, if sd-LDL is raised and HDL is lowered. New insights into the pathophysiology of insulin resistance and its influence on the effects of dietary changes have led to a better approach: (1) the higher a patient's insulin resistance, the more important is the glycemic load of the diet. (2) Fat quality is much more important than fat quantity. (3) The best principle for a reduced calorie intake is not fat counting, but a high volume diet with low energy density, which means fibre rich vegetables and fruits. (4) And finally, satiation and palatability of a diet is very important: there is no success without the patient's compliance. Thus, the best approach to the dietary prevention of CVD is a Mediterranean style low-carb diet represented in the LOGI pyramid. Dietary guidelines for the prevention of CVD should to be revised accordingly.

Salt consumption and cardiovascular, renal, and hypertensive diseases: clinical and mechanistic aspects

PURPOSE OF REVIEW

This review will discuss some relevant and novel studies on the relationship between sodium intake and cardiovascular structure and function, focusing on blood pressure independent effects of salt on the heart, arteries, and kidneys.

RECENT FINDINGS

Several new reports clearly demonstrate the role of high dietary salt in mediating cardiovascular and renal morbidity and mortality including stroke, myocardial infarction, arterial stiffening, heart failure, and renal insufficiency. A number of recent studies also indicate that in addition to increased sodium intake, simultaneous decrease in potassium intake may aggravate adverse cardiovascular and renal manifestations.

SUMMARY

It is now generally accepted that there is a direct positive correlation between dietary salt and arterial pressure. Thus, the beneficial effects of dietary salt reduction are, at least in part, due to a decrease in arterial pressure. Furthermore, the beneficial, pressure-independent effects of sodium restriction on the heart, blood vessels, and kidneys are being increasingly recognized, but not generally appreciated.

Influence of dietary sodium modulation on electrocardiographic voltage criteria for left ventricular hypertrophy in normotensive individuals

OBJECTIVE

Dietary sodium intake and left ventricular hypertrophy (LVH) on electrocardiogram (ECG) are both independent determinants of cardiovascular risk. Prior studies demonstrated that acute dietary sodium modulation significantly altered LVH-specific ECG voltage in hypertensive individuals, thus modifying cardiovascular risk prediction; but whether this phenomenon exists in normotensive individuals is not known. We evaluated the influence of dietary sodium intake on ECG voltage and ECG criteria for LVH in normotensive individuals.

METHODS

Retrospective evaluation of ECGs of healthy normotensive individuals (n = 39) who were prospectively randomized to a dietary study protocol of 1 week of high-sodium diet (>200 mmol of sodium per day) and 1 week of low-sodium diet (<10 mmol/d) was conducted. Electrocardiogram voltage amplitudes and biochemical assessments were performed at the end of each dietary intervention.

RESULTS

As expected, blood pressure declined and measures of circulating renin-angiotensin-aldosterone system activity rose significantly with low-sodium diet. No significant changes in specific LVH voltage criteria or overall precordial or limb lead ECG voltage amplitudes were detected between diets.

CONCLUSION

Although immediate dietary sodium modulation has been shown to significantly alter LVH-specific ECG voltage and the detection of LVH in hypertensive individuals, dietary sodium intake did not influence ECG voltage in normotensive individuals. Healthy normotensive individuals may exhibit adaptive measures that dampen ECG voltage fluctuations in response to dietary sodium modulation. More specific cardiac imaging studies may provide additional insight into this observation and the influence of dietary sodium in cardiac health.

Short term dietary sodium restriction decreases HDL cholesterol, apolipoprotein A-I and high molecular weight adiponectin in healthy young men: relationships with renal hemodynamics and RAAS activation

BACKGROUND AND AIMS

We aimed to determine the effect of short-term dietary sodium restriction on plasma total cholesterol, LDL-C, HDL-C, triglycerides, apolipoprotein (apo) A-I, apo B and high molecular weight (HMW) adiponectin in non-obese, normotensive young men. Glomerular filtration rate (GFR), effective renal plasma flow (ERPF), plasma renin activity (PRA) and aldosterone were also measured.

METHODS AND RESULTS

Sixty-five men, aged 23 ± 7 years, were randomly studied on a high sodium intake (HS, 228 ± 77 mmol Na+/24 h) and a low sodium intake (LS, 36 ± 27 mmol Na+/24 h), each period lasting 1 week. LS decreased GFR and ERPF and increased PRA and aldosterone (p < 0.0001 for all). LS also induced a decrease in HDL-C (3.8 ± 10.8%), apo A-I (3.7 ± 6.5%) and HMW-adiponectin (13.6 ± 40.5%) (p < 0.05 for all), but plasma total cholesterol, LDL-C, triglycerides and apo B did not significantly change. The changes in HDL-C and apo A-I were correlated negatively to the changes in effective renal plasma flow (p < 0.05), whereas the changes in HMW adiponectin were correlated negatively to the changes in PRA and aldosterone (p < 0.05 for both).

CONCLUSION

Short term sodium restriction modestly decreases HDL-C, apo A-I and HMW-adiponectin in healthy men. Changes in GFR and ERPF and in the renin-angiotensin-aldosterone system as induced by LS may be involved in these responses.

Gene-sodium interaction and blood pressure: findings from genomics research of blood pressure salt sensitivity

High blood pressure (BP) is a complex trait determined by both genetic and environmental factors, as well as the interactions between these factors. Over the past few decades, there has been substantial progress in elucidating the genetic determinants underlying the BP response to sodium intake, or BP salt sensitivity. Research of monogenic BP disorders has highlighted the importance of renal salt handling in BP regulation, implicating genes and biological pathways related to salt sensitivity. Candidate gene studies have contributed important information toward understanding the genomic mechanisms underlying the BP response to salt intake, identifying genes in the renin-angiotensin-aldosterone system, renal sodium channels/transporters, and the endothelial system related to this phenotype. Despite these advancements, genome-wide association studies are still needed to uncover novel mechanisms underlying salt sensitivity, while future sequencing efforts promise the discovery of functional variants related to this complex trait. Delineating the genetic architecture of salt sensitivity will be critical to understanding how genes and dietary sodium interact to influence BP.

Sodium recommendations for special populations and the resulting implications

Based on the most recent Dietary Guidelines for Americans, sodium recommendations are set at 2,300 mg for the general population and 1,500 mg for special populations. However, sodium intake among adults has been shown to be much higher than this; on average 3,436 mg. The Centers for Disease Control and Prevention notes that special populations (those with hypertension, African Americans, and those 40 years of age and older) make up 70% of adults in the United States. Excess sodium in the diet has been shown to contribute to problems such as blood pressure abnormalities, kidney function problems, and congestive heart failure, which account for a large sum of health care costs in the United States. The purpose of this review and accompanying three case studies was to explore if adherence to the sodium recommendations for special populations is feasible. Current literature shows that while a food industry-wide sodium reduction would help reduce overall sodium intake, adherence to low-sodium diets is difficult for the majority of individuals. Three case studies were completed which looked at subjects with a sodium recommendation of 1,500 mg. None of the participants met the recommendation, were aware of their daily sodium intake or knew how much they should be consuming. The snapshot provided by these case studies suggests further research is warranted. Because of the current state of sodium in the American diet, a combination of personal interventions coupled with widespread industry sodium reduction would be the most beneficial way to reduce dietary sodium for most individuals.

Top Three Pharmacogenomics and Personalized Medicine Applications at the Nexus of Renal Pathophysiology and Cardiovascular Medicine

Pharmacogenomics is a field with origins in the study of monogenic variations in drug metabolism in the 1950s. Perhaps because of these historical underpinnings, there has been an intensive investigation of 'hepatic pharmacogenes' such as CYP450s and liver drug metabolism using pharmacogenomics approaches over the past five decades. Surprisingly, kidney pathophysiology, attendant diseases and treatment outcomes have been vastly under-studied and under-theorized despite their central importance in maintenance of health, susceptibility to disease and rational personalized therapeutics. Indeed, chronic kidney disease (CKD) represents an increasing public health burden worldwide, both in developed and developing countries. Patients with CKD suffer from high cardiovascular morbidity and mortality, which is mainly attributable to cardiovascular events before reaching end-stage renal disease. In this paper, we focus our analyses on renal function before end-stage renal disease, as seen through the lens of pharmacogenomics and human genomic variation. We herein synthesize the recent evidence linking selected Very Important Pharmacogenes (VIP) to renal function, blood pressure and salt-sensitivity in humans, and ways in which these insights might inform rational personalized therapeutics. Notably, we highlight and present the rationale for three applications that we consider as important and actionable therapeutic and preventive focus areas in renal pharmacogenomics: 1) ACE inhibitors, as a confirmed application, 2) VDR agonists, as a promising application, and 3) moderate dietary salt intake, as a suggested novel application. Additionally, we emphasize the putative contributions of gene-environment interactions, discuss the implications of these findings to treat and prevent hypertension and CKD. Finally, we conclude with a strategic agenda and vision required to accelerate advances in this under-studied field of renal pharmacogenomics with vast significance for global public health.

Non-pharmacological Interventions in Hypertension: A Community-based Cross-over Randomized Controlled Trial

Background:

Hypertension is the most prevalent non-communicable disease causing significant morbidity/mortality through cardiovascular, cerebrovascular, and renal complications.

Objectives:

This community-based study tested the efficacy of non-pharmacological interventions in preventing/controlling hypertension.

Materials and Methods:

This is a cross-over randomized controlled trial (RCT) of the earlier RCT (2007) of non-pharmacological interventions in hypertension, conducted in the urban service area of our Institute. The subjects, prehypertensive and hypertensive young adults (98 subjects: 25, 23, 25, 25 in four groups) were randomly allotted into a group that he/she had not belonged to in the earlier RCT: Control (New Group I), Physical Exercise (NG II)-brisk walking for 50 to 60 minutes, three to four days/week, Salt Intake Reduction (NG III) to at least half of their previous intake, Yoga (NG IV) for 30 to 45 minutes/day, five days/week. Blood pressure was measured before and after eight weeks of intervention. Analysis was by ANOVA with a Games-Howell post hoc test.

Results:

Ninety-four participants (25, 23, 21, 25) completed the study. All three intervention groups showed significant reduction in BP (SBP/DBP mmHg: 5.3/6.0 in NG II, 2.5/2.0 in NG III, and 2.3/2.4 in NG IV, respectively), while the Control Group showed no significant difference. Persistence of significant reduction in BP in the three intervention groups after cross-over confirmed the biological plausibility of these non-pharmacological interventions. This study reconfirmed that physical exercise was more effective than Salt Reduction or Yoga. Salt Reduction, and Yoga were equally effective.

Conclusion:

Physical exercise, salt intake reduction, and yoga are effective non-pharmacological methods for reducing blood pressure in young pre-hypertensive and hypertensive adults.

Lifestyle interventions for hypertension and dyslipidemia among women of reproductive age

INTRODUCTION

Hypertension and dyslipidemia often precede cardiovascular disease. Lifestyle modifications help prevent these conditions, and referrals for women may be possible during reproductive health care visits. However, screening recommendations vary, which may affect screening rates. The objectives of this systematic review were to 1) assess the available literature on the effectiveness of lifestyle interventions, 2) review hypertension and dyslipidemia screening recommendations for consistency, and 3) report prevalence data for hypertension and dyslipidemia screening among women of reproductive age.

METHODS

We conducted a systematic literature search (January 1990-November 2010) for 1) randomized controlled trials on the impact of lifestyle interventions on cardiovascular disease risk factors in women of reproductive age, 2) evidence-based guidelines on hypertension and dyslipidemia screening, and 3) population-based prevalence studies on hypertension or dyslipidemia screening or both.

RESULTS

Twenty-one of 555 retrieved studies (4%) met our inclusion criteria. Lifestyle interventions improved lipid levels in 10 of 18 studies and blood pressure in 4 of 9 studies. Most guidelines recommended hypertension screening at least every 2 years and dyslipidemia screening every 5 years, but recommendations for who should receive dyslipidemia screening varied. One study indicated that 82% of women of reproductive age received hypertension screening during the preceding year. In another study, only 49% of women aged 20 to 45 years received recommended dyslipidemia screening.

CONCLUSION

Lifestyle interventions may offer modest benefits for reducing blood pressure and lipids in this population. Inconsistency among recommendations for dyslipidemia screening may contribute to low screening rates. Future studies should clarify predictors of and barriers to cholesterol screening in this population.

Prevalence, risk factors, and management of prehypertension

Prehypertension remains an important public health challenge all over the world and appropriate treatments should be adopted to prehypertensive group in different degree effectively. This review aimed to assess the prevalence of Prehypertension and provide effective evidence of the benefits of treating prehypertensive patients. The reasonable evaluation and appropriate intervention of prehypertensive remain need further study.

The role of obesity, salt and exercise on blood pressure in children and adolescents

The increasing trends of blood pressure (BP) in children and adolescents pose great concern for the burden of hypertension-related cardiovascular disease. Although primary hypertension in childhood is commonly associated with obesity, it seems that other factors, such as dietary sodium and exercise, also influence BP levels in children and adolescents. Several studies support that sympathetic nervous system imbalance, impairment of the physiological mechanism of pressure natriuresis, hyperinsulinemia and early vascular changes are involved in the mechanisms causing elevated BP in obese children and adolescents. Under the current evidence on the association of salt intake and BP, dietary sodium restriction appears to be a rational step in the prevention of hypertension in genetically predisposed children and adolescents. Finally, interventional studies show that regular aerobic exercise can significantly reduce BP and restore vascular changes in obese with hypertensive pediatric patients. This article aims to summarize previous studies on the role of obesity, salt intake and exercise on BP in children and adolescents.

New evidence relating to the health impact of reducing salt intake

This paper is a Position Statement from an 'ad hoc' Scientific Review Subcommittee of the PAHO/WHO Regional Expert Group on Cardiovascular Disease Prevention through Dietary Salt Reduction. It is produced in response to requests from representatives of countries of the Pan-American Region of WHO needing clarification on two recent publications casting doubts on the appropriateness of population wide policies to reduce salt intake for the prevention of cardiovascular disease. The paper provides a brief background, a critical appraisal of the recent reports and explanations as why the implications have been mis-interpreted. The paper concludes that the benefits of salt reduction are clear and consistent, and reinforces the recommendations outlined by PAHO/WHO and other organizations worldwide for a population reduction in salt intake to prevent strokes, heart attacks and other cardiovascular events.

The effect of intentional weight loss on all-cause mortality in older adults: results of a randomized controlled weight-loss trial

BACKGROUND

Despite the reported benefits, weight loss is not always advised for older adults because some observational studies have associated weight loss with increased mortality. However, the distinction between intentional and unintentional weight loss is difficult to make in an observational context, so the effect of intentional weight loss on mortality may be clarified in the setting of a randomized controlled trial.

OBJECTIVE

The objective was to determine the effect of intentional weight loss on all-cause mortality by using follow-up data from a randomized trial completed in 1995 that included a weight-loss arm.

DESIGN

The Trial of Nonpharmacologic Intervention in the Elderly (TONE) used a 2 × 2 factorial design to determine the effect of dietary weight loss, sodium restriction, or both on blood pressure control in 585 overweight or obese older adults being treated for hypertension (mean ± SD age: 66 ± 4 y; 53% female). All-cause mortality was ascertained by using the Social Security Index and National Death Index through 2006.

RESULTS

The mortality rate of those who were randomly assigned to the weight-loss intervention (n = 291; mean weight loss: 4.4 kg) did not differ significantly from that of those who were not randomly assigned to this group (n = 294; mean weight loss: 0.8 kg). The adjusted HR was 0.82 (95% CI: 0.55, 1.22).

CONCLUSIONS

Intentional dietary weight loss was not significantly associated with increased all-cause mortality over 12 y of follow-up in older overweight or obese adults. Additional studies are needed to confirm and extend our findings to older age groups. This trial is registered at clinicaltrials.gov as NCT00000535.

Interactions of genetic variants with physical activity are associated with blood pressure in Chinese: the GenSalt study

BACKGROUND

Blood pressure (BP) homeostasis involves complex interactions among genetic and nongenetic factors, providing major challenges to dissection of the genetic components that influence BP and hypertension. In this study, we examine the effects of interaction of genetic variants with physical activity on BP in a relatively genetically homogenous cohort of rural Chinese villagers.

METHODS

Generalized estimating equations analysis was used to test for associations of systolic blood pressure (SBP) and diastolic blood pressure (DBP) with variants in 24 genes in BP pathways (196 single-nucleotide polymorphisms (SNPs)) among 3,142 Chinese participants divided according to physical activity (active vs. inactive groups).

RESULTS

In the physically active group, two SNPs in NR3C2 were significantly associated with lower SBP, and a SNP in SCNN1B was significantly associated with lower SBP and DBP. In the physically inactive group, a SNP in APLNR was associated with lower SBP, a SNP in GNB3 (guanine nucleotide binding protein, β polypeptide 3) was associated with higher SBP and DBP, and a SNP in BDKRB2 (bradykinin receptor B2) was associated with lower DBP. Cumulative effects in carriers of minor alleles of these SNPs showed reductions of SBP and DBP as large as 8 and 5 mm Hg, respectively, in the active individuals compared to inactive individuals carrying the same number of minor alleles.

CONCLUSIONS

We found that physical activity modifies the effects of genetic variants on BP. However, our results also show that active individuals with specific genotypes always have lower BP than inactive individuals with the same genotypes, demonstrating the overall beneficial effects of physical activity on BP.

Short-term effects of hypertonic saline solution in acute heart failure and long-term effects of a moderate sodium restriction in patients with compensated heart failure with New York Heart Association class III (Class C) (SMAC-HF Study)

INTRODUCTION

Hypertonic saline solution (HSS) and a moderate Na restriction plus high furosemide dose showed beneficial effects in compensated heart failure (HF), in short and long terms. The study was aimed to verify the effects of this combination on hospitalization time, readmissions and mortality in patients in New York Heart Association (NYHA) class III.

METHOD

Chronic ischemic or nonischemic cardiomyopathy uncompensated patients with HF in NYHA III functional class with ejection fraction <40%, serum creatinine <2.5 mg/dL, blood urea nitrogen <60 mg/dL and reduced urinary volume were single-blind randomized in 2 groups: the first group received a 30-minute intravenous infusion of furosemide (250 mg) plus HSS (150 mL) twice daily and a moderate Na restriction (120 mmol); the second group received furosemide intravenous bolus (250 mg) twice a day, without HSS and a low Na diet (80 mmol); both groups received a fluid intake of 1000 mL/d. After discharge, the HSS group continued with 120 mmol Na/d; the second group continued with 80 mmol Na/d.

RESULTS

A total of 1771 patients (881 HSS group and 890 without HSS group) met inclusion criteria: the first group (881 patients), compared with the second (890 patients), showed an increase in diuresis and serum Na levels, a reduction in hospitalization time (3.5 + 1 versus 5.5 + 1 days, P < 0.0001) and, during follow-up (57 + 15 months), a lower rate in readmissions (18.5% versus 34.2%, P < 0.0001) and mortality (12.9% versus 23.8%, P < 0.0001); the second group also showed a significant increase in blood urea nitrogen and serum creatinine.

CONCLUSION

This study suggests that in-hospital HSS administration, combined with moderate Na restriction, reduces hospitalization time and that a moderate sodium diet restriction determines long-term benefit in patients with NYHA class III HF.

Does reducing salt intake increase cardiovascular mortality?

Overwhelming evidence shows that reducing salt intake from 9-12 to 5-6  g/d lowers blood pressure, thereby preventing cardiovascular disease. A recent paper claims that lower salt intake is associated with higher cardiovascular mortality despite lower blood pressure. The study is flawed and cannot refute the evidence for the benefits of salt reduction. The WHO recommends salt reduction as crucial in tackling the global non-communicable-disease crisis. A reduction in population salt intake remains a public-health priority.

Reduced dietary salt for the prevention of cardiovascular disease: a meta-analysis of randomized controlled trials (Cochrane review)

BACKGROUND

Although meta-analyses of randomized controlled trials (RCTs) of salt reduction report a reduction in the level of blood pressure (BP), the effect of reduced dietary salt on cardiovascular disease (CVD) events remains unclear.

METHODS

We searched for RCTs with follow-up of at least 6 months that compared dietary salt reduction (restricted salt dietary intervention or advice to reduce salt intake) to control/no intervention in adults, and reported mortality or CVD morbidity data. Outcomes were pooled at end of trial or longest follow-up point.

RESULTS

Seven studies were identified: three in normotensives, two in hypertensives, one in a mixed population of normo- and hypertensives and one in heart failure. Salt reduction was associated with reductions in urinary salt excretion of between 27 and 39 mmol/24 h and reductions in systolic BP between 1 and 4 mm Hg. Relative risks (RRs) for all-cause mortality in normotensives (longest follow-up-RR: 0.90, 95% confidence interval (CI): 0.58-1.40, 79 deaths) and hypertensives (longest follow-up RR 0.96, 0.83-1.11, 565 deaths) showed no strong evidence of any effect of salt reduction CVD morbidity in people with normal BP (longest follow-up: RR 0.71, 0.42-1.20, 200 events) and raised BP at baseline (end of trial: RR 0.84, 0.57-1.23, 93 events) also showed no strong evidence of benefit. Salt restriction increased the risk of all-cause mortality in those with heart failure (end of trial RR 2.59, 1.04-6.44, 21 deaths).We found no information on participant's health-related quality of life.

CONCLUSIONS

Despite collating more event data than previous systematic reviews of RCTs (665 deaths in some 6,250 participants) there is still insufficient power to exclude clinically important effects of reduced dietary salt on mortality or CVD morbidity. Our estimates of benefits from dietary salt restriction are consistent with the predicted small effects on clinical events attributable to the small BP reduction achieved.

Cardioprotective mechanisms of lifestyle modifications and pharmacotherapies on cardiac remodeling and dysfunction in hypertensive heart disease: an overview

The incidence of cardiovascular events in hypertensive patients is clearly related to a left ventricular mass during treatment, and a regression of left ventricular hypertrophy is associated with a better prognosis. This is the case even independently of changes in other risk factors, including blood pressure. Evidence indicates that lifestyle modifications such as dietary salt restriction and weight loss are effective means in preventing the development of hypertension and reducing blood pressure and left ventricular mass in hypertensive patients. Salt restriction may also reduce the long-term risk of cardiovascular events. It has been recognized that the primary targets of current antihypertensive drugs are the renin-angiotensin-aldosterone system, calcium homeostasis, the ionic transport mechanisms in the kidneys, and the sympathetic nervous system. Clinical as well as experimental studies have demonstrated the cardioprotective effects of antihypertensive drugs independently of their blood pressure lowering effects. Hypertension is often complicated by other disease states including diabetes, dyslipidemia, and ischemic heart disease. Some of the drugs used for the treatment of such complications are also shown to produce cardioprotective effects in addition to their original effects. We ought to better understand these pleiotropic effects for the most effective treatments of hypertension and its complications.

Characteristics of sodium sensitivity in Korean populations

Sodium sensitivity (SS) is a variable response of blood pressure (BP) to changes in sodium intake. The present study evaluated the existence and the characteristics of subjects with SS in Koreans. One hundred one subjects with (n = 31, 57.7 ± 9.8 yr) or without hypertension (n = 70, 40.8 ± 16.5 yr) were given a low-sodium dietary approache to stop hypertension (DASH) diet (LSD) for 7 days and a high-sodium DASH diet (HSD) for the following 7 days. The prevalence of SS in the present study population was 27.7% (17.6% in the non-hypertensive subjects and 51.6% in the hypertensive subjects). Analysis of the non-hypertensive subjects showed that systolic BP, diastolic BP, and mean arterial pressure at baseline and after HSD were higher in the subjects with SS than the subjects without SS, and there were no differences after LSD. In the hypertensive subjects, there was no difference in the BP at baseline and after HSD whether or not the subjects had SS. However, the systolic BP of hypertensive subjects with SS was lower than hypertensive subjects without SS after LSD. In the present study population, subjects with SS have distinctive BP features unlike to subjects without SS.

On the local cardiac renin angiotensin system. Basic and clinical implications

In the present review we reevaluated the experimental and clinical evidence that there is a local renin angiotensin system in the heart as well as the presence of a functional intracrine component which is activated during pathological conditions like heart failure and hypertension. The implications of these findings for cardiology were discussed. The novel finding that cell swelling impairs cell coupling and impulse propagation through activation of ionic channels with consequent generation of cardiac arrhythmias and the evidence that AT1 receptors are mechanosensors able to alter the heart function independently of Ang II were discussed. Particular attention was given to the role of salt loading on the activation of a local cardiac renin angiotensin and its consequences.