Salt intakes around the world: implications for public health

High dietary sodium intake among young children in Vancouver, British Columbia

OBJECTIVE

To determine the intake distribution and food sources of sodium among young children.

METHODS

Dietary intake was determined for 190 children, 16 months to 6 years of age, using a food frequency questionnaire completed by interviewing a parent. Dietary intake of all nutrients, including dietary sodium, was analyzed. The major food sources of sodium were assessed by grouping foods into categories based on Canada's Food Guide, with subsequent subdivision into food type categories.

RESULTS

Dietary sodium intakes were skewed, with a median intake of 2021 mg/d and 5th-95th percentile range of 888-3975 mg/d. The sodium intake of 91.6% of children was above the recommended 1000 or 1200 mg/d for children 1-3 or 3-6 years, respectively, and 85% and 54% had intakes above the tolerable upper limits of 1500 and 1900 mg/d, respectively. The 5 food sources providing the highest amount of sodium were soups, processed/fast foods, dairy products, breads, and processed meats.

CONCLUSION

Children are vulnerable to high sodium intake as a result of their food patterns and the high sodium content of these foods. This report demonstrates that Canadian children have high sodium intakes. Knowledge of feeding practices involving high-sodium foods can assist parents and caregivers in reducing the high sodium intake of young children.

A salt reduction of 50% in bread does not decrease bread consumption or increase sodium intake by the choice of sandwich fillings

Bread is a major contributor to sodium intake in many countries. Reducing the salt (NaCl) content in bread might be an effective way to reduce overall sodium intake. The objectives of this study were to examine the effects of gradually lowering the salt content in brown bread, with and without flavor compensation (KCl and yeast extract), on bread consumption and sodium intake compensation by choice of sandwich fillings. A total of 116 participants (age: 21 ± 3 y; BMI: 22 ± 2 kg/m²) consumed a buffet-style breakfast on weekdays for 4 wk. Participants received either regular bread (control group: n = 39), bread whose salt content was gradually lowered each week by 0, 31, 52, and 67% (reduced group: n = 38), or bread whose salt content was also gradually lowered each week but which was also flavor compensated (compensated group: n = 39). A reduction of up to 52% of salt in bread did not lead to lower consumption of bread compared to the control (P = 0.57), whereas less bread was consumed when salt was reduced by 67% (P = 0.006). When bread was flavor compensated, however, a reduction of 67% did not lead to lower consumption (P = 0.69). Salt reduction in bread (with and without flavor compensation) did not induce sodium intake compensation (P = 0.31). In conclusion, a salt reduction of up to 52% in bread or even up to 67% in flavor-compensated bread neither affected bread consumption nor choice of sandwich fillings.

Body fluid dynamics: back to the future

Pioneering investigations conducted over a half century ago on tonicity, transcapillary fluid exchange, and the distribution of water and solute serve as a foundation for understanding the physiology of body fluid spaces. With passage of time, however, some of these concepts have lost their connectivity to more contemporary information. Here we examine the physical forces determining the compartmentalization of body fluid and its movement across capillary and cell membrane barriers, drawing particular attention to the interstitium operating as a dynamic interface for water and solute distribution rather than as a static reservoir. Newer work now supports an evolving model of body fluid dynamics that integrates exchangeable Na(+) stores and transcapillary dynamics with advances in interstitial matrix biology.

Food sources and correlates of sodium and potassium intakes in Flemish pre-school children

Objective

The aim of the present study was to investigate dietary sources of Na and K intakes among Flemish pre-school children using multiple linear regression analyses.

Design

Three-day estimated diet records were used to assess dietary intakes. The contribution to Na and K intakes of fifty-seven food groups was computed by summing the amount provided by the food group for all individuals divided by the total intake for all individuals.

Setting

A random cluster sampling design at the level of schools, stratified by province and age, was used.

Subjects

A representative sample of 696 Flemish pre-school children aged 2·5–6·5 years was recruited.

Results

Mean Na intake was above and mean K intake was largely below the recommendation for children. Bread (22 %) and soup (13 %) were main contributors to Na intake followed by cold meat cuts and other meat products (12 % and 11 %, respectively). Sugared milk drinks, fried potatoes, milk and fruit juices were the main K sources (13 %, 12 %, 11 % and 11 %, respectively). Although Na and K intakes were positively correlated, several food categories showed Na:K intake ratio well above one (water, cheeses, soup, butter/margarine, fast foods and light beverages) whereas others presented a ratio well below one (oil & fat, fruits & juices, potatoes, vegetables and hot beverages).

Conclusions

Flemish pre-school children had too high Na and too low K intakes. The finding that main dietary sources of Na and K are clearly different indicates the feasibility of simultaneously decreasing Na and increasing K intake among children.

24 h-Sodium excretion and hydration status in children and adolescents--results of the DONALD Study

BACKGROUND & AIMS

To describe actual data on intake, sources, age and time trends of urinary sodium excretion and to analyze the potential association between urinary sodium excretion and hydration status respective beverage consumption in a sample of healthy German children and adolescents.

METHODS

Data of 1575 24 h-urine samples and weighed dietary records of 499 children (249 boys) aged 4-18 years of the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study collected in 2003-2009 were analyzed using linear mixed effects regression models. Free water reserve (FWR, measured urine volume (ml/24 h) minus the obligatory urine volume (ml/24 h)) was used as a marker for hydration status.

RESULTS

Urinary sodium excretion was between 1.4 g/day and 3.2 g/day, showing a positive age trend but remained stable during the study period. In girls, there was a significant positive association between salt excretion and FWR (p = 0.04). Per g/MJ urinary sodium excretion, beverage intake increased by 0.05 g/MJ (boys) or 0.08 g/MJ (girls).

CONCLUSION

Hydration status was not affected by salt intake in this sample of healthy children and adolescents in a western life style, due to a compensatory increase in beverage consumption.

Elevated N-terminal pro-brain natriuretic peptide levels predict an enhanced anti-hypertensive and anti-proteinuric benefit of dietary sodium restriction and diuretics, but not angiotensin receptor blockade, in proteinuric renal patients

BACKGROUND

Renin-angiotensin aldosterone system (RAAS) blockade only partly reduces blood pressure, proteinuria and renal and cardiovascular risk in chronic kidney disease (CKD) but often requires sodium targeting [i.e. low sodium diet (LS) and/or diuretics] for optimal efficacy. However, both under- and overtitration of sodium targeting can easily occur. We evaluated whether N-terminal pro-brain natriuretic peptide (NT-proBNP), a biomarker of volume expansion, predicts the benefits of sodium targeting in CKD patients.

METHODS

In a cross-over randomized controlled trial, 33 non-diabetic CKD patients (proteinuria 3.8 ± 0.4 g/24 h, blood pressure 143/86 ± 3/2 mmHg, creatinine clearance 89 ± 5 mL/min) were treated during 6-week periods with placebo, angiotensin receptor blockade (ARB; losartan 100 mg/day) and ARB plus diuretics (losartan 100 mg/day plus hydrochlorothiazide 25 mg/day), combined with LS (93 ± 52 mmol Na(+)/24 h) and regular sodium diet (RS; 193 ± 62 mmol Na(+)/24 h, P < 0.001 versus LS), in random order. As controls, 27 healthy volunteers were studied.

RESULTS

NT-proBNP was elevated in patients during placebo + RS [90 (60-137) versus 35 (27-45) pg/mL in healthy controls, P = 0.001]. NT-proBNP was lowered by LS, ARB and diuretics and was normalized by ARB + diuretic + LS [39 (26-59) pg/mL, P = 0.65 versus controls]. NT-proBNP levels above the upper limit of normal (>125 pg/mL) predicted a larger reduction of blood pressure and proteinuria by LS and diuretics but not by ARB, during all steps of the titration regimen.

CONCLUSIONS

Elevated NT-proBNP levels predict an enhanced anti-hypertensive and anti-proteinuric benefit of sodium targeting, but not RAAS blockade, in proteinuric CKD patients. Importantly, this applies to the untreated condition, as well as to the subsequent treatment steps, consisting of RAAS blockade and even RAAS blockade combined with diuretics. NT-proBNP can be a useful tool to identify CKD patients in whom sodium targeting can improve blood pressure and proteinuria.

Reducing salt intake in the Americas: Pan American Health Organization actions

This article outlines the rationale for reducing dietary salt and some of the Pan American Health Organization actions to facilitate reductions in dietary salt in the Americas. Excessive dietary salt (sodium chloride and other sodium salts) is a major cause of increased blood pressure, which increases risk for stroke, heart disease, and kidney disease. Reduction in salt intake is beneficial for people with hypertension and those with normal blood pressure. The World Health Organization recommends a population salt intake of less than 5 grams/person/day with a Pan American Health Organization expert group recommendation that this be achieved by 2020 in the Americas. In general, the consumption of salt is more than 6 grams/day by age 5 years, with consumption of salt averaging between 9 and 12 grams per day in many countries. Recent salt intake estimates from Brazil (11 grams of salt/day), Argentina (12 grams of salt/day), Chile (9 grams of salt/day) and the United States (8.7 grams of salt/day) confirm that high salt intakes are prevalent in Americas. Sources of dietary salt vary, from 75% of it coming from processed food in developed countries, to 70% coming from discretionary salt added in cooking or at the table in parts of Brazil. The Pan American Health Organization has launched a regionwide initiative called the ?Cardiovascular Disease Prevention Through Dietary Salt Reduction,? led by an expert working group. Working closely with countries, the expert group developed resources to aid policy development through five subgroups: (a) addressing industry engagement and product reformulation; (b) advocacy and communication; (c) surveillance of salt intake, sources of salt in the diet, and knowledge and opinions on salt and health; (d) salt fortification with iodine; and (e) national-level health economic studies on salt reduction.

Moderate dietary sodium restriction added to angiotensin converting enzyme inhibition compared with dual blockade in lowering proteinuria and blood pressure: randomised controlled trial

OBJECTIVE

To compare the effects on proteinuria and blood pressure of addition of dietary sodium restriction or angiotensin receptor blockade at maximum dose, or their combination, in patients with non-diabetic nephropathy receiving background treatment with angiotensin converting enzyme (ACE) inhibition at maximum dose.

DESIGN

Multicentre crossover randomised controlled trial.

SETTING

Outpatient clinics in the Netherlands.

PARTICIPANTS

52 patients with non-diabetic nephropathy.

INTERVENTIONS

All patients were treated during four 6 week periods, in random order, with angiotensin receptor blockade (valsartan 320 mg/day) or placebo, each combined with, consecutively, a low sodium diet (target 50 mmol Na(+)/day) and a regular sodium diet (target 200 mmol Na(+)/day), with a background of ACE inhibition (lisinopril 40 mg/day) during the entire study. The drug interventions were double blind; the dietary interventions were open label.

MAIN OUTCOME MEASURES

The primary outcome measure was proteinuria; the secondary outcome measure was blood pressure.

RESULTS

Mean urinary sodium excretion, a measure of dietary sodium intake, was 106 (SE 5) mmol Na(+)/day during a low sodium diet and 184 (6) mmol Na(+)/day during a regular sodium diet (P<0.001). Geometric mean residual proteinuria was 1.68 (95% confidence interval 1.31 to 2.14) g/day during ACE inhibition plus a regular sodium diet. Addition of angiotensin receptor blockade to ACE inhibition reduced proteinuria to 1.44 (1.07 to 1.93) g/day (P=0.003), addition of a low sodium diet reduced it to 0.85 (0.66 to 1.10) g/day (P<0.001), and addition of angiotensin receptor blockade plus a low sodium diet reduced it to 0.67 (0.50 to 0.91) g/day (P<0.001). The reduction of proteinuria by the addition of a low sodium diet to ACE inhibition (51%, 95% confidence interval 43% to 58%) was significantly larger (P<0.001) than the reduction of proteinuria by the addition of angiotensin receptor blockade to ACE inhibition (21%, (8% to 32%) and was comparable (P=0.009, not significant after Bonferroni correction) to the reduction of proteinuria by the addition of both angiotensin receptor blockade and a low sodium diet to ACE inhibition (62%, 53% to 70%). Mean systolic blood pressure was 134 (3) mm Hg during ACE inhibition plus a regular sodium diet. Mean systolic blood pressure was not significantly altered by the addition of angiotensin receptor blockade (131 (3) mm Hg; P=0.12) but was reduced by the addition of a low sodium diet (123 (2) mm Hg; P<0.001) and angiotensin receptor blockade plus a low sodium diet (121 (3) mm Hg; P<0.001) to ACE inhibition. The reduction of systolic blood pressure by the addition of a low sodium diet (7% (SE 1%)) was significantly larger (P=0.003) than the reduction of systolic blood pressure by the addition of angiotensin receptor blockade (2% (1)) and was similar (P=0.14) to the reduction of systolic blood pressure by the addition of both angiotensin receptor blockade and low sodium diet (9% (1)), to ACE inhibition.

CONCLUSIONS

Dietary sodium restriction to a level recommended in guidelines was more effective than dual blockade for reduction of proteinuria and blood pressure in non-diabetic nephropathy. The findings support the combined endeavours of patients and health professionals to reduce sodium intake. Trial registration Netherlands Trial Register NTR675.

Relation of urinary calcium and magnesium excretion to blood pressure: The International Study Of Macro- And Micro-nutrients And Blood Pressure and The International Cooperative Study On Salt, Other Factors, And Blood Pressure

Data indicate an inverse association between dietary calcium and magnesium intakes and blood pressure (BP); however, much less is known about associations between urinary calcium and magnesium excretion and BP in general populations. The authors assessed the relation of BP to 24-hour excretion of calcium and magnesium in 2 cross-sectional studies. The International Study of Macro- and Micro-Nutrients and Blood Pressure (INTERMAP) comprised 4,679 persons aged 40-59 years from 17 population samples in China, Japan, the United Kingdom, and the United States, and the International Cooperative Study on Salt, Other Factors, and Blood Pressure (INTERSALT) comprised 10,067 persons aged 20-59 years from 52 samples around the world. Timed 24-hour urine collections, BP measurements, and nutrient data from four 24-hour dietary recalls (INTERMAP) were collected. In multiple linear regression analyses, urinary calcium excretion was directly associated with BP. After adjustment for multiple confounders (including weight, height, alcohol intake, calcium intake, urinary sodium level, and urinary potassium intake), systolic BP was 1.9 mm Hg higher per each 4.1 mmol per 24 hours (2 standard deviations) of higher urinary calcium excretion (associations were smaller for diastolic BP) in INTERMAP. Qualitatively similar associations were observed in INTERSALT analyses. Associations between magnesium excretion and BP were small and nonsignificant for most of the models examined. The present data suggest that altered calcium homoeostasis, as exhibited by increased calcium excretion, is associated with higher BP levels.

Low-salt diet increases insulin resistance in healthy subjects

Low-salt (LS) diet activates the renin-angiotensin-aldosterone and sympathetic nervous systems, both of which can increase insulin resistance (IR). We investigated the hypothesis that LS diet is associated with an increase in IR in healthy subjects. Healthy individuals were studied after 7 days of LS diet (urine sodium <20 mmol/d) and 7 days of high-salt (HS) diet (urine sodium >150 mmol/d) in a random order. Insulin resistance was measured after each diet and compared statistically, unadjusted and adjusted for important covariates. One hundred fifty-two healthy men and women, aged 39.1 ± 12.5 years (range, 18-65) and with body mass index of 25.3 ± 4.0 kg/m(2), were included in this study. Mean (SD) homeostasis model assessment index was significantly higher on LS compared with HS diet (2.8 ± 1.6 vs 2.4 ± 1.7, P < .01). Serum aldosterone (21.0 ± 14.3 vs 3.4 ± 1.5 ng/dL, P < .001), 24-hour urine aldosterone (63.0 ± 34.0 vs 9.5 ± 6.5 μg/d, P < .001), and 24-hour urine norepinephrine excretion (78.0 ± 36.7 vs 67.9 ± 39.8 μg/d, P < .05) were higher on LS diet compared with HS diet. Low-salt diet was significantly associated with higher homeostasis model assessment index independent of age, sex, blood pressure, body mass index, serum sodium and potassium, serum angiotensin II, plasma renin activity, serum and urine aldosterone, and urine epinephrine and norepinephrine. Low-salt diet is associated with an increase in IR. The impact of our findings on the pathogenesis of diabetes and cardiovascular disease needs further investigation.

Reducing sodium in foods: the effect on flavor

Sodium is an essential micronutrient and, via salt taste, appetitive. High consumption of sodium is, however, related to negative health effects such as hypertension, cardiovascular diseases and stroke. In industrialized countries, about 75% of sodium in the diet comes from manufactured foods and foods eaten away from home. Reducing sodium in processed foods will be, however, challenging due to sodium's specific functionality in terms of flavor and associated palatability of foods (i.e., increase of saltiness, reduction of bitterness, enhancement of sweetness and other congruent flavors). The current review discusses the sensory role of sodium in food, determinants of salt taste perception and a variety of strategies, such as sodium replacers (i.e., potassium salts) and gradual reduction of sodium, to decrease sodium in processed foods while maintaining palatability.

Drinking Water Salinity and Maternal Health in Coastal Bangladesh: Implications of Climate Change

Background: Drinking water from natural sources in coastal Bangladesh has become contaminated by varying degrees of salinity due to saltwater intrusion from rising sea levels, cyclone and storm surges and upstream withdrawal of freshwater. Objective: Our objective was to estimate salt intake from drinking water sources and examine environmental factors that may explain a seasonal excess of hypertension in pregnancy. Methods: Water salinity data (1998-2000) for Dacope, in rural coastal Bangladesh, were obtained from the Centre for Environment and Geographic Information System. Information on drinking water sources, 24-hour urine samples and blood pressure were obtained from 343 pregnant Dacope women during the dry season (October 2009 - March 2010). The hospital-based prevalence of hypertension in pregnancy was determined for 969 pregnant women (July 2008 - March 2010). Results: Average estimated sodium intakes from drinking water ranged from 5 to 16 g/day in the dry season, compared to 0.6 - 1.2 g/day in the rainy season. Average daily sodium excretion in urine was 3.4 g/day (range 0.4 - 7.7 g/d). Women who drank shallow tubewell water were more likely to have urine sodium > 100 mmol/d than women who drank rainwater (OR=2.05, 95% CI: 1.11 - 3.80). The annual hospital prevalence of hypertension in pregnancy was higher in the dry season (12.2%, 95% CI: 9.5 - 14.8) than the rainy season (5.1%, 95% CI: 2.91 - 7.26). Conclusions: The estimated salt intake from drinking water in this population exceeded recommended limits. The problem of saline intrusion into drinking water has multiple causes and is likely to be exacerbated by climate change induced sea-level rise.

Sodium content of processed foods in the United Kingdom: analysis of 44,000 foods purchased by 21,000 households

BACKGROUND

In the United Kingdom, sodium reduction targets have been set for a large number of processed food categories. Assessment and monitoring are essential to evaluate progress.

OBJECTIVES

Our aim was to determine whether household consumer panel food-purchasing data could be used to assess the sodium content of processed foods. Our further objectives were to estimate the mean sodium content of UK foods by category and undertake analyses weighted by food-purchasing volumes.

DESIGN

Data were obtained for 21,108 British households between October 2008 and September 2009. Purchasing data (product description, product weight, annual purchases) and sodium values (mg/100 g) were collated for all food categories known to be major contributors to sodium intake. Unweighted and weighted mean sodium values were calculated.

RESULTS

Data were available for 44,372 food products. The largest contributors to sodium purchases were table salt (23%), processed meat (18%), bread and bakery products (13%), dairy products (12%), and sauces and spreads (11%). More than one-third of sodium purchased (37%) was accounted for by 5 food categories: bacon, bread, milk, cheese, and sauces. For some food groups (bread and bakery, cereals and cereal products, processed meat), purchase-weighted means were 18-35% higher than unweighted means, suggesting that market leaders have higher sodium contents than the category mean.

CONCLUSION

The targeting of sodium reduction in a small number of food categories and focusing on products sold in the highest volumes could lead to large decreases in sodium available for consumption and therefore to gains in public health.

Dietary salt intake and mortality in patients with type 2 diabetes

OBJECTIVE

Many guidelines recommend that patients with type 2 diabetes should aim to reduce their intake of salt. However, the precise relationship between dietary salt intake and mortality in patients with type 2 diabetes has not been previously explored.

RESEARCH DESIGN AND METHODS

Six hundred and thirty-eight patients attending a single diabetes clinic were followed in a prospective cohort study. Baseline sodium excretion was estimated from 24-h urinary collections (24hU(Na)). The predictors of all-cause and cardiovascular mortality were determined by Cox regression and competing risk modeling, respectively.

RESULTS

The mean baseline 24hU(Na) was 184 ± 73 mmol/24 h, which remained consistent throughout the follow-up (intraindividual coefficient of variation [CV] 23 ± 11%). Over a median of 9.9 years, there were 175 deaths, 75 (43%) of which were secondary to cardiovascular events. All-cause mortality was inversely associated with 24hU(Na), after adjusting for other baseline risk factors (P < 0.001). For every 100 mmol rise in 24hU(Na), all-cause mortality was 28% lower (95% CI 6-45%, P = 0.02). After adjusting for the competing risk of noncardiovascular death and other predictors, 24hU(Na) was also significantly associated with cardiovascular mortality (sub-hazard ratio 0.65 [95% CI 0.44-0.95]; P = 0.03).

CONCLUSIONS

In patients with type 2 diabetes, lower 24-h urinary sodium excretion was paradoxically associated with increased all-cause and cardiovascular mortality. Interventional studies are necessary to determine if dietary salt has a causative role in determining adverse outcomes in patients with type 2 diabetes and the appropriateness of guidelines advocating salt restriction in this setting.

The increasing pediatric stone disease problem

While once thought to be relatively rare in developed nations, the prevalence of pediatric urolithiasis appears to be increasing, and a number of factors may be contributing to this increase. Many theories are plausible and such theories include the increasing childhood obesity epidemic, a changing sex predilection, climate change, alterations in dietary habits and improving diagnostic modalities. Yet, unlike adult patients, rigorous epidemiologic studies do not exist in pediatric populations. Thus, in the setting of an increasing prevalence of childhood stone disease, improved research is critical to the development of uniform strategies for pediatric urolithiasis management.

Characteristic clinical and biochemical profile of recurrent calcium-oxalate nephrolithiasis in patients with metabolic syndrome

BACKGROUND

Metabolic syndrome is a risk factor for nephrolithiasis. This study was performed to evaluate the clinical and biochemical profile of calcium-oxalate nephrolithiasis in stone formers with metabolic syndrome.

METHODS

A total of 526 recurrent stone formers, 184 of them with metabolic syndrome, and 214 controls were examined on a free diet and after a sodium-restricted diet (sodium intake < 100 mmol/24 h).

RESULTS

On free diet, stone formers with metabolic syndrome showed higher sodium excretion [mean (95% confidence interval), 196 (176-218) vs 160 (150-168) mmol/24 h; P < 0.01] and lower citrate excretion [2.23 (1.99-2.58) vs 2.84 (2.51-3.17) mmol/24 h; P < 0.01] compared to controls, whereas stone formers without metabolic syndrome showed higher calcium and oxalate excretion [5.43 (5.01-5.82) vs 3.58 (2.84-4.19) and 0.34 (0.32-0.36) vs 0.26 (0.20-0.31)m mmol/24 h for calcium and oxalate, respectively; P < 0.01] and lower citrate excretion [2.18 (1.98-2.38) vs 2.84 (2.51-3.17) mmol/24 h; P < 0.01] compared to controls. The ion activity product of urinary calcium-oxalate salts was similar between stone formers with and without metabolic syndrome [1.41 (1.31-1.59) vs 1.40 (1.35-1.45); P > 0.05]. After the test diet, this index was lower in diet-compliant stone formers with metabolic syndrome compared to diet-compliant stone formers without metabolic syndrome [1.15 (1.10-1.21) vs 1.39 (1.31-1.45); P < 0.01].

CONCLUSIONS

The biochemical profiles and responses to the sodium-restricted diet were significantly different between stone formers with metabolic syndrome and those without. Dietary habits play a central role in the pathogenesis of nephrolithiasis in stone formers with metabolic syndrome.

Finding a niche with personalized generics: opportunities from systems-based therapeutic delivery in hypertension

A key principle in earlier eras of drug development was to deliver medicines with clinical benefits for populations. Individual patients frequently did not benefit, or experienced adverse drug reactions, and were at risk of exposure to a prolonged series of treatment trials before effective therapies were found, if available. A personalized medicines approach offers opportunities to select drugs likely to be effective or safer, based on knowledge, for example, of differences in disease-modulating receptors, in drug metabolism, or in drug transporters into cells and across tissue boundaries. This new genetic and phenotypic knowledge allows generics to be revisited and may also help to improve medicine adherence, by reducing predictable adverse effects from unwanted accumulation of a medicine or its metabolites. This review will consider effective population delivery of therapeutics to treat hypertension in order to illustrate the potential and current place of personalizing medicines to improve effective and safe use of therapeutics.

Reversible sympathetic overactivity in hypertensive patients with primary aldosteronism

CONTEXT

Aldosterone has been shown to exert a central sympathoexcitatory action in multiple animal models, but evidence in humans is still lacking.

OBJECTIVES

Our objective was to determine whether hyperaldosteronism causes reversible sympathetic activation in humans.

METHODS

We performed a cross-sectional comparison of muscle sympathetic nerve activity (SNA, intraneural microelectrodes) in 14 hypertensive patients with biochemically proven primary aldosteronism (PA) with 20 patients with essential hypertension (EH) and 18 age-matched normotensive (NT) controls. Seven patients with aldosterone-producing adenoma (APA) were restudied 1 month after unilateral adrenalectomy.

RESULTS

Mean blood pressure values in patients with PA and EH and NT controls was 145 ± 4/88 ± 2, 150 ± 4/90 ± 2, and 119 ± 2/76 ± 2 mm Hg, respectively. The major new findings are 2-fold: 1) baseline SNA was significantly higher in the PA than the NT group (40 ± 3 vs. 30 ± 2 bursts/min, P = 0.014) but similar to the EH group (41 ± 3 bursts/min) and 2) after unilateral adrenalectomy for APA, SNA decreased significantly from 38 ± 5 to 27 ± 4 bursts/min (P = 0.01), plasma aldosterone levels fell from 72.4 ± 20.3 to 11.4 ± 2.3 ng/dl (P < 0.01), and blood pressure decreased from 155 ± 8/94 ± 3 to 117 ± 4/77 ± 2 mm Hg (P < 0.01).

CONCLUSION

These data provide the first evidence in humans that APA is accompanied by reversible sympathetic overactivity, which may contribute to the accelerated hypertensive target organ disease in this condition.

Health promotion behaviors of residents with hypertension in Iwate, Japan and North Carolina, USA

AIM

The aim of this study was to compare the health promotion practises of rural residents in northern Japan (n = 212) to those in south-eastern North Carolina, USA (n = 105), using the Health Promotion Lifestyle II (HPLP) scale.

METHODS

A comparative and descriptive design examined the relationships between health-related behaviors and demographic and physiological variables, and compared cross-cultural patterns.

RESULTS

The Japanese participants scored significantly higher on the total HPLP II score, as well as on the subscales of health responsibility, nutrition, interpersonal support, and stress management. No significant differences were found in the HPLP II subscales for spiritual growth or physical activity between the groups. The subscale scores for both the participants from Japan and the participants from North Carolina were lowest for physical activity. For the participants from North Carolina, the HPLP II subscale scores were highest for spirituality and interpersonal relationships. The predictive factors of variation in the scores of the HPLP II for the participants from North Carolina included being married and not working. No significant demographic predictor was found for the HPLP II scores of the Japanese participants.

CONCLUSIONS

The study's findings add to an increased understanding of the cultural variations in the health-promoting behaviors of persons with hypertension. Providing health promotion strategies for hypertension remains an urgent issue for nurses and other health-care providers in both Japan and North Carolina, USA.

Sources of sodium in Australian children's diets and the effect of the application of sodium targets to food products to reduce sodium intake

The average reported dietary Na intake of children in Australia is high: 2694 mg/d (9-13 years). No data exist describing food sources of Na in Australian children's diets and potential impact of Na reduction targets for processed foods. The aim of the present study was to determine sources of dietary Na in a nationally representative sample of Australian children aged 2-16 years and to assess the impact of application of the UK Food Standards Agency (FSA) Na reduction targets on Na intake. Na intake and use of discretionary salt (note: conversion of salt to Na, 1 g of NaCl (salt) = 390 mg Na) were assessed from 24-h dietary recall in 4487 children participating in the Australian 2007 Children's Nutrition and Physical Activity Survey. Greatest contributors to Na intake across all ages were cereals and cereal-based products/dishes (43%), including bread (13%) and breakfast cereals (4%). Other moderate sources were meat, poultry products (16%), including processed meats (8%) and sausages (3%); milk products/dishes (11%) and savoury sauces and condiments (7%). Between 37 and 42% reported that the person who prepares their meal adds salt when cooking and between 11 and 39% added salt at the table. Those over the age of 9 years were more likely to report adding salt at the table (χ2 199·5, df 6, P < 0·001). Attainment of the UK FSA Na reduction targets, within the present food supply, would result in a 20% reduction in daily Na intake in children aged 2-16 years. Incremental reductions of this magnitude over a period of years could significantly reduce the Na intake of this group and further reductions could be achieved by reducing discretionary salt use.

Urbanization, ethnicity and cardiovascular risk in a population in transition in Nakuru, Kenya: a population-based survey

Background

Cardiovascular disease (CVD) is the leading cause of death among older people in Africa. This study aimed to investigate the relationship of urbanization and ethnicity with CVD risk markers in Kenya.

Methods

A cross-sectional population-based survey was carried out in Nakuru Kenya in 2007-2008. 100 clusters of 50 people aged ≥50 years were selected by probability proportionate to size sampling. Households within clusters were selected through compact segment sampling. Participants were interviewed by nurses to collect socio-demographic and lifestyle information. Nurses measured blood pressure, height, weight and waist and hip circumference. A random finger-prick blood sample was taken to measure glucose and cholesterol levels.

Hypertension was defined as systolic blood pressure (SBP) ≥140 mm Hg, or diastolic blood pressure (DBP) ≥90 mm Hg or current use of antihypertensive medication; Diabetes as reported current medication or diet control for diabetes or random blood glucose level ≥11.1 mmol/L; High cholesterol as random blood cholesterol level ≥5.2 mmol/L; and Obesity as Body Mass Index (BMI)≥30 kg/m².

Results

5010 eligible subjects were selected, of whom 4396 (88%) were examined. There was a high prevalence of hypertension (50.1%, 47.5-52.6%), obesity (13.0%, 11.7-14.5%), diabetes (6.6%, 5.6-7.7%) and high cholesterol (21.1%, 18.6-23.9). Hypertension, diabetes and obesity were more common in urban compared to rural groups and the elevated prevalence generally persisted after adjustment for socio-demographic, lifestyle, obesity and cardiovascular risk markers. There was also a higher prevalence of hypertension, obesity, diabetes and high cholesterol among Kikuyus compared to Kalenjins, even after multivariate adjustment. CVD risk markers were clustered both across the district and within individuals. Few people received treatment for hypertension (15%), while the majority of cases with diabetes received treatment (68%).

Conclusions

CVD risk markers are common in Kenya, particularly in urban areas. Exploring differences in CVD risk markers between ethnic groups may help to elucidate the epidemiology of these conditions.

WASH-world action on salt and health

There is overwhelming evidence that our current high-salt intake is the major factor increasing blood pressure (BP) and, thereby, a major cause of cardiovascular disease and kidney disease worldwide. A reduction in salt intake to the recommended level of <5-6 g/day is very beneficial, and could prevent millions of deaths each year and make major savings for healthcare services. Several countries, e.g., Finland and the UK, have already reduced the amount of salt being consumed by a combined policy of getting the food industry to decrease the amount of salt added to foods, clear labelling on food products, and increasing public awareness of the harmful effects of salt on health. Many other developed countries, e.g., Australia, Canada, and the US, are also stepping up their activities. The major challenge now is to spread this out worldwide, particularly to developing countries where ≈80% of global BP-related disease burden occurs. In many developing countries, most of the salt consumed comes from salt added during cooking or from sauces; therefore, public health campaigns are needed to encourage consumers to use less salt. A modest reduction in salt intake across the whole population will result in major improvements in public health and have huge economic benefits in all countries around the world. World Action on Salt and Health (WASH) is a coalition of health professionals from different countries who know very well the harm of high BP and has a major role in implementing changes in their own countries. We welcome nephrologists to join (http://www.worldactiononsalt.com).

Effect of modest salt reduction on skin capillary rarefaction in white, black, and Asian individuals with mild hypertension

Microvascular rarefaction occurs in hypertension. We carried out a 12-week randomized double-blind crossover trial to determine the effect of a modest reduction in salt intake on capillary rarefaction in 71 whites, 69 blacks, and 29 Asians with untreated mildly raised blood pressure. Both basal and maximal (during venous congestion) skin capillary density were measured by capillaroscopy at the dorsum and the side of the fingers. In addition, we used orthogonal polarization spectral imaging to measure skin capillary density at the dorsum of the fingers and the hand web. With a reduction in salt intake from 9.7 to 6.5 g/day, there was an increase in capillary density (capillaries per millimeter squared) from 101+/-21 to 106+/-23 (basal) and 108+/-22 to 115+/-22 (maximal) at the dorsum, and 101+/-25 to 107+/-26 (basal) and 110+/-26 to 116+/-26 (maximal) at the side of the fingers (P<0.001 for all). Orthogonal polarization spectral imaging also showed a significant increase in capillary density both at the dorsum of the fingers and the web. Subgroup analysis showed that most of the changes were significant in all of the ethnic groups. Furthermore, there was a significant relationship between the change in 24-hour urinary sodium and the change in capillary density at the side of the fingers. These results demonstrate that a modest reduction in salt intake, as currently recommended, improves both functional and structural capillary rarefactions that occur in hypertension, and a larger reduction in salt intake would have a greater effect. The increase in capillary density may possibly carry additional beneficial effects on target organs.

Dietary sources of sodium in China, Japan, the United Kingdom, and the United States, women and men aged 40 to 59 years: the INTERMAP study

Public health campaigns in several countries encourage population-wide reduced sodium (salt) intake, but excessive intake remains a major problem. Excessive sodium intake is independently related to adverse blood pressure and is a key factor in the epidemic of prehypertension/hypertension. Identification of food sources of sodium in modern diets is critical to effective reduction of sodium intake worldwide. We used data from the INTERMAP Study to define major food sources of sodium in diverse East Asian and Western population samples. INTERMAP is an international, cross-sectional, epidemiologic study of 4, 680 individuals ages 40 to 59 years from Japan (four samples), People's Republic of China (three rural samples), the United Kingdom (two samples), and the United States (eight samples); four in-depth, multipass 24-hour dietary recalls/person were used to identify foods accounting for most dietary sodium intake. In the People's Republic of China sample, most (76%) dietary sodium was from salt added in home cooking, about 50% less in southern than northern samples. In Japan, most (63%) dietary sodium came from soy sauce (20%), commercially processed fish/seafood (15%), salted soups (15%), and preserved vegetables (13%). Processed foods, including breads/cereals/grains, contributed heavily to sodium intake in the United Kingdom (95%) and the United States (for methodological reasons, underestimated at 71%). To prevent and control prehypertension/hypertension and improve health, efforts to remove excess sodium from diets in rural China should focus on reducing salt in home cooking. To avoid excess sodium intake in Japan, the United Kingdom, and the United States, salt must be reduced in commercially processed foods.

Reducing population salt intake worldwide: from evidence to implementation

Raised blood pressure is a major cause of cardiovascular disease, responsible for 62% of stroke and 49% of coronary heart disease. There is overwhelming evidence that dietary salt is the major cause of raised blood pressure and that a reduction in salt intake lowers blood pressure, thereby, reducing blood pressure-related diseases. Several lines of evidence including ecological, population, and prospective cohort studies, as well as outcome trials, demonstrate that a reduction in salt intake is related to a lower risk of cardiovascular disease. Increasing evidence also suggests that a high salt intake may directly increase the risk of stroke, left ventricular hypertrophy, and renal disease; is associated with obesity through soft drink consumption; is related to renal stones and osteoporosis; is linked to the severity of asthma; and is probably a major cause of stomach cancer. In most developed countries, a reduction in salt intake can be achieved by a gradual and sustained reduction in the amount of salt added to foods by the food industry. In other countries where most of the salt consumed comes from salt added during cooking or from sauces, a public health campaign is needed to encourage consumers to use less salt. Several countries have already reduced salt intake. The challenge now is to spread this out to all other countries. A modest reduction in population salt intake worldwide will result in a major improvement in public health.

Salt intake of the Slovene population assessed by 24 h urinary sodium excretion

OBJECTIVE

To investigate average sodium excretion in 24 h urine as a marker for salt intake in the Slovene population.

DESIGN

Salt intake was determined by measuring sodium excretion in 24 h urine collected from a representative sample of geographically diverse Slovene adults.

SETTING

Slovenia.

SUBJECTS

A random sample of 600 adults aged 25-65 years was generated from census data. The effective sample yield was 143 people, 42·7 % men and 57·3 % women.

RESULTS

Urinary sodium excretion was significantly higher in men (220·9 (sd 86·0) mmol Na/d) than in women (169·8 (sd 73·8) mmol Na/d); t test = 14·5, P < 0·001. Average salt intake was 11·3 (sd 4·9) g/d, higher in men than in women (13·0 (sd 5·1) v. 9·9 (sd 4·3) g/d, respectively). Average intakes of salt among regions were not significantly different. Salt intake increases slightly with increasing age, but there was no significant correlation between age and salt intake. Salt intake was increased with BMI (r = 0·384, P < 0·001).

CONCLUSIONS

Salt intake in Slovene adults, especially in men, exceeds the WHO recommended population nutrient intake goal of 5 g by more than twofold. A national programme for reducing salt intake in Slovenia needs to be implemented through systematic efforts including public education and involving the health-care sector and the food industry.

Reducing dietary sodium intake: the Canadian context

Sodium is a required nutrient; Adequate Intakes for adults range from 1200 to 1500 mg·day–1, depending on age. The Tolerable Upper Intake Level (UL) for sodium is 2300 mg·day–1 for adults, based on the relationship between sodium intake and increased blood pressure. Elevated blood pressure, which is prevalent among Canadians, is, in turn, a major risk factor for stroke, cardiovascular disease, and renal disease. Sodium intake is not the only determinant of blood pressure; other modifiable risk factors include relative mass, physical activity, overall dietary quality, and alcohol consumption. However, because >90% of adult Canadian men and two thirds of Canadian women have sodium intakes above the UL, Health Canada’s Working Group on Dietary Sodium Reduction has been charged with developing, implementing, and overseeing a strategy to reduce Canadians’ sodium intakes. It is estimated that ∼75% of dietary sodium is added during food processing; in addition to taste and palatability, sodium also has functional roles in food manufacturing and preservation, although the amounts used often exceed those required. Because of the central role of processed foods in sodium intake, the strategy proposed by Health Canada’s Working Group includes voluntary reduction of sodium in processed foods and foods sold in food service establishments. It will also include an education and awareness campaign, and research and surveillance. Initiatives to reduce sodium in other parts of the world have demonstrated that it will be challenging to reduce sodium intake to the recommended range and will likely require many years to accomplish.

Low dietary sodium intake increases the death risk in peritoneal dialysis

BACKGROUND AND OBJECTIVES

To explore the correlation between dietary sodium intake and cardiovascular and overall mortality, and then determine whether this correlation can be explained by protein and energy intake paralleled with sodium intake in dialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This single-center retrospective cohort study enrolled 305 incident patients who started peritoneal dialysis in our unit from July 2002 to February 2007. All patients were followed until death or until being censored in February 2008. Demographic data were collected at baseline. Biochemical, dietary, and nutrition data were examined at baseline and thereafter at regular intervals to calculate the average values throughout the study.

RESULTS

Participants with the highest average sodium intake were more likely to be younger, male, and overweight. Patients in the high tertile of average sodium intake had higher albumin, prealbumin, and lean body mass levels, and more nutrient intakes paralleling with sodium intake. Low average sodium intake independently predicted the increased risk for overall and cardiovascular death after adjusting for recognized confounders. Further adjustment for dietary protein, energy, and other nutrient intakes individually had minimal impact on the association between average sodium intake and overall death, with hazard ratios varying between 0.35 and 0.44, and cardiovascular death, with hazard ratios varying between 0.06 and 0.11.

CONCLUSIONS

This study revealed that low dietary sodium intake independently predicts the high overall and cardiovascular mortality in dialysis patients. This correlation could not be entirely explained by deficient protein and energy intake.

Hypertension in the developing world: challenges and opportunities

Hypertension is a major public health problem and a leading cause of death and disability in developing countries. One-quarter of the world's adult population has hypertension, and this is likely to increase to 29% by 2025. Modeled projections indicate an increase to 1.15 billion hypertensive patients by 2025 in developing countries. There is variability in the global prevalence of hypertension: hypertension is present in approximately 35% of the Latin American population, 20%-30% of the Chinese and Indian population, and approximately 14% in Sub-Saharan African countries. This heterogeneity has been attributed to several factors, including urbanization with its associated changes in lifestyle, racial ethnic differences, nutritional status, and birth weight. Compounding this high burden of hypertension is a lack of awareness and insufficient treatment in those with hypertension. The public health response to this challenge should drive greater promotion of awareness efforts, studies of risk factors for hypertension, and understanding of the impact of lifestyle changes. Also important are efforts to develop multipronged strategies for hypertension management in developing nations.