A comprehensive review on salt and health and current experience of worldwide salt reduction programmes

National approaches to monitoring population salt intake: a trade-off between accuracy and practicality?

Aims

There is strong evidence that diets high in salt are bad for health and that salt reduction strategies are cost effective. However, whilst it is clear that most people are eating too much salt, obtaining an accurate assessment of population salt intake is not straightforward, particularly in resource poor settings. The objective of this study is to identify what approaches governments are taking to monitoring salt intake, with the ultimate goal of identifying what actions are needed to address challenges to monitoring salt intake, especially in low and middle-income countries.

Methods and Results

A written survey was issued to governments to establish the details of their monitoring methods. Of the 30 countries that reported conducting formal government salt monitoring activities, 73% were high income countries. Less than half of the 30 countries, used the most accurate assessment of salt through 24 hour urine, and only two of these were developing countries. The remainder mainly relied on estimates through dietary surveys.

Conclusions

The study identified a strong need to establish more practical ways of assessing salt intake as well as technical support and advice to ensure that low and middle income countries can implement salt monitoring activities effectively.

Can noncommunicable diseases be prevented? Lessons from studies of populations and individuals

Noncommunicable diseases (NCDs)--mainly cancers, cardiovascular diseases, diabetes, and chronic respiratory diseases--are responsible for about two-thirds of deaths worldwide, mostly in low- and middle-income countries. There is an urgent need for policies and strategies that prevent NCDs by reducing their major risk factors. Effective approaches for large-scale NCD prevention include comprehensive tobacco and alcohol control through taxes and regulation of sales and advertising; reducing dietary salt, unhealthy fats, and sugars through regulation and well-designed public education; increasing the consumption of fresh fruits and vegetables, healthy fats, and whole grains by lowering prices and improving availability; and implementing a universal, effective, and equitable primary-care system that reduces NCD risk factors, including cardiometabolic risk factors and infections that are precursors to NCDs, through clinical interventions.

ASH position paper: Dietary approaches to lower blood pressure

A substantial body of evidence has implicated several aspects of diet in the pathogenesis of elevated blood pressure (BP). Well-established risk factors for elevated BP include excess salt intake, low potassium intake, excess weight, high alcohol consumption, and suboptimal dietary pattern. African Americans are especially sensitive to the BP-raising effects of excess salt intake, insufficient potassium intake, and suboptimal diet. In this setting, dietary changes have the potential to substantially reduce racial disparities in BP and its consequences. In view of the age-related rise in BP in both children and adults, the direct, progressive relationship of BP with cardiovascular-renal diseases throughout the usual range of BP, and the worldwide epidemic of BP-related disease, efforts to reduce BP in nonhypertensive as well as hypertensive individuals are warranted. In nonhypertensives, dietary changes can lower BP and delay, if not prevent, hypertension. In uncomplicated stage I hypertension, dietary changes serve as initial treatment before drug therapy. In hypertensive individuals already on drug therapy, lifestyle modifications can further lower BP. The current challenge is designing and implementing effective clinical and public health interventions that lead to sustained dietary changes among individuals and more broadly in the general population.

Does salt intake in the first two years of life affect the development of cardiovascular disorders in adulthood?

Excess salt intake impacts on blood pressure (BP) and the pathogenetic mechanisms of atherosclerosis predisposing to stroke and other cardiovascular disorders. The influence of salt starts early in life. Two randomized controlled trials in newborn infants suggest a direct association between dietary sodium intake and BP since the first few months of life. Newborn infants display aversion to the salt taste to develop a "preference" for salt only at age 2-3 years, in part in relation to post-natal events: this preference might be associated with later development of hypertension. The amount of sodium to be retained by an infant for proper physiological growth is largely covered by breast feeding (or low sodium formula milk) in the first six months, and later on by the gradual implementation of complementary feeding, without the need for any added salt upon food preparation. Given the lack of dose-dependence data, reference nutrient intakes (RNI) or adequate intakes (AI) for sodium have been established by national health institutions in various countries. The U.K. RNI was set at 242 mg a day for infants 0-6 months with gradual increase to 0.5 g up until age 3. The U.S. AI is somewhat lower for age 0-6 months but larger for age 1-3 years. According to a recent report, the average sodium intake in U.S. children is close to the AI up to age 2 years, to become progressively greater exceeding the Institute of Medicine recommendation later on.

Urinary and dietary sodium and potassium associated with blood pressure control in treated hypertensive kidney transplant recipients: an observational study

Background

In kidney transplant (Kt) recipients , hypertension is a major risk for cardiovascular complications but also for graft failure. Blood pressure (BP) control is therefore mandatory. Office BP (OBP) remains frequently used for clinical decisions, however home BP (HBP) have brought a significant improvement in the BP control. Sodium is a modifiable risk factor, many studies accounted for a decrease of BP with a sodium restricted diet. Increased potassium intake has been also recommended in hypertension management. Using an agreement between office and home BP, the present study investigated the relations between the BP control in Kt recipients and their urinary excretion and dietary consumption of sodium and potassium.

Methods

The BP control defined by OBP <140/90 mmHg and HBP <135/85 mmHg was tested in 70 Kt recipients (mean age 56 ± 11.5 years; mean graft survival 7 ± 6.6 years) treated with antihypertensive medications. OBP and HBP were measured with a validated oscillometric device (Omron M6®). The 24-hour urinary sodium (Na+) and potassium (K+) excretions as well as dietary intakes were compared between controlled and uncontrolled (in office and at home) recipients. Non parametric Wilcoxon Mann–Whitney Test was used for between groups comparisons and Fisher's exact test for frequencies comparisons. Pearson correlation coefficients and paired t-test were used when sample size was >30.

Results

Using an agreement between OBP and HBP, we identified controlled (21%) and uncontrolled recipients (49%). Major confounding effects susceptible to interfere with the BP regulation did not differ between groups, the amounts of sodium excretion were similar (154 ± 93 vs 162 ± 88 mmol/24 h) but uncontrolled patients excreted less potassium (68 ± 14 vs 54 ± 20 mmol/24 h; P = 0.029) and had significantly lower potassium intakes (3279 ± 753 vs 2208 ± 720 mg/24 h; P = 0.009), associated with a higher urinary Na+/K + ratio. Systolic HBP was inversely and significantly correlated to urinary potassium (r = −0.48; P = 0.002), a positive but non significant relation was observed with urinary sodium (r = 0,30;P = 0.074).

Conclusions

Half of the treated hypertensive Kt recipients remained uncontrolled in office and at home. Restoring a well-balanced sodium/potassium ratio intakes could be a non pharmacological opportunity to improve blood pressure control.

NaCl potentiates human fibrocyte differentiation

Excessive NaCl intake is associated with a variety of fibrosing diseases such as renal and cardiac fibrosis. This association has been attributed to increased blood pressure as the result of high NaCl intake. However, studies in patients with high NaCl intake and fibrosis reveal a connection between NaCl intake and fibrosis that is independent of blood pressure. We find that increasing the extracellular concentration of NaCl to levels that may occur in human blood after high-salt intake can potentiate, in serum-free culture conditions, the differentiation of freshly-isolated human monocytes into fibroblast-like cells called fibrocytes. NaCl affects the monocytes directly during their adhesion. Potassium chloride and sodium nitrate also potentiate fibrocyte differentiation. The plasma protein Serum Amyloid P (SAP) inhibits fibrocyte differentiation. High levels of extracellular NaCl change the SAP Hill coefficient from 1.7 to 0.8, and cause a four-fold increase in the concentration of SAP needed to inhibit fibrocyte differentiation by 95%. Together, our data suggest that NaCl potentiates fibrocyte differentiation. NaCl-increased fibrocyte differentiation may thus contribute to NaCl-increased renal and cardiac fibrosis.

Dietary salt reduction and cardiovascular disease rates in India: a mathematical model

BACKGROUND

Reducing salt intake has been proposed to prevent cardiovascular disease in India. We sought to determine whether salt reductions would be beneficial or feasible, given the worry that unrealistically large reductions would be required, worsening iodine deficiency and benefiting only urban subpopulations.

METHODS AND RESULTS

Future myocardial infarctions (MI) and strokes in India were predicted with a Markov model simulating men and women aged 40 to 69 in both urban and rural locations, incorporating the risk reduction from lower salt intake. If salt intake does not change, we expect ~8.3 million MIs (95% CI: 6.9-9.6 million), 830,000 strokes (690,000-960,000) and 2.0 million associated deaths (1.5-2.4 million) per year among Indian adults aged 40 to 69 over the next three decades. Reducing intake by 3 g/day over 30 years (-0.1 g/year, 25% reduction) would reduce annual MIs by 350,000 (a 4.6% reduction; 95% CI: 320,000-380,000), strokes by 48,000 (-6.5%; 13,000-83,000) and deaths by 81,000 (-4.9%; 59,000-100,000) among this group. The largest decline in MIs would be among younger urban men, but the greatest number of averted strokes would be among rural men, and nearly one-third of averted strokes and one-fifth of averted MIs would be among rural women. Only under a highly pessimistic scenario would iodine deficiency increase (by <0.0001%, ~1600 persons), since inadequate iodized salt access--not low intake of iodized salt--is the major cause of deficiency and would be unaffected by dietary salt reduction.

CONCLUSIONS

Modest reductions in salt intake could substantially reduce cardiovascular disease throughout India.

Population approaches to improve diet, physical activity, and smoking habits: a scientific statement from the American Heart Association

BACKGROUND

Poor lifestyle behaviors, including suboptimal diet, physical inactivity, and tobacco use, are leading causes of preventable diseases globally. Although even modest population shifts in risk substantially alter health outcomes, the optimal population-level approaches to improve lifestyle are not well established.

METHODS AND RESULTS

For this American Heart Association scientific statement, the writing group systematically reviewed and graded the current scientific evidence for effective population approaches to improve dietary habits, increase physical activity, and reduce tobacco use. Strategies were considered in 6 broad domains: (1) Media and educational campaigns; (2) labeling and consumer information; (3) taxation, subsidies, and other economic incentives; (4) school and workplace approaches; (5) local environmental changes; and (6) direct restrictions and mandates. The writing group also reviewed the potential contributions of healthcare systems and surveillance systems to behavior change efforts. Several specific population interventions that achieved a Class I or IIa recommendation with grade A or B evidence were identified, providing a set of specific evidence-based strategies that deserve close attention and prioritization for wider implementation. Effective interventions included specific approaches in all 6 domains evaluated for improving diet, increasing activity, and reducing tobacco use. The writing group also identified several specific interventions in each of these domains for which current evidence was less robust, as well as other inconsistencies and evidence gaps, informing the need for further rigorous and interdisciplinary approaches to evaluate population programs and policies.

CONCLUSIONS

This systematic review identified and graded the evidence for a range of population-based strategies to promote lifestyle change. The findings provide a framework for policy makers, advocacy groups, researchers, clinicians, communities, and other stakeholders to understand and implement the most effective approaches. New strategic initiatives and partnerships are needed to translate this evidence into action.

Dietary salt intake assessed by 24 h urinary sodium excretion in Australian schoolchildren aged 5–13 years

Objective

To measure total daily salt intake using 24 h urinary Na excretion within a sample of Victorian schoolchildren aged 5–13 years and to assess discretionary salt use habits of children and parents.

Design

Cross-sectional study.

Setting

Completed within a convenience sample of independent primary schools (n9) located in Victoria, Australia.

Subjects

Two hundred and sixty children completed a 24 h urine collection over a school (34 %) or non-school day (66 %). Samples deemed incomplete (n18), an over-collection (n1) or that were incorrectly processed at the laboratory (n3) were excluded.

Results

The sample comprised 120 boys and 118 girls with a mean age of 9·8 (sd1·7) years. The average 24 h urinary Na excretion (n238) was 103 (sd43) mmol/24 h (salt equivalent 6·0 (sd2·5) g/d). Daily Na excretion did not differ by sex; boys 105 (sd46) mmol/24 h (salt equivalent 6·1 (sd2·7) g/d) and girls 100 (sd41) mmol/24 h (salt equivalent 5·9 (sd2·4) g/d;P= 0·38). Sixty-nine per cent of children (n164) exceeded the recommended daily Upper Limit for Na. Reported discretionary salt use was common: two-thirds of parents reported adding salt during cooking and almost half of children reported adding salt at the table.

Conclusions

The majority of children had salt intakes exceeding the recommended daily Upper Limit. Strategies to lower salt intake in children are urgently required, and should include product reformulation of lower-sodium food products combined with interventions targeting discretionary salt use within the home.

Device-guided breathing exercises in the control of human blood pressure: systematic review and meta-analysis

OBJECTIVE

To evaluate whether device-guided breathing (DGB) lowers blood pressure (BP) in adults.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

We searched Medline (1950-2010), Embase (1980-2010), the Cochrane Library including the Cochrane Central register of Controlled Trials (CENTRAL), AMED (1985-2010), CINAHL (1980-2010) and the Current Controlled Trials registry (as of October 2010).

OUTCOME MEASURES

Primary outcomes included the mean change in SBP and DBP. Secondary outcomes included change in heart rate, quality of life, compliance with the device and any side effects of the device.

RESULTS

We included eight trials of the Resperate device (InterCure Ltd, Lod, Israel), consisting of 494 adult patients. Use of this device resulted in significantly reduced SBP by 3.67 mmHg [95% confidence interval (CI) = -5.99 to -1.39; P = 0.002] and decreased DBP by 2.51 mmHg (95% CI = -4.15 to -0.87; P = 0.003). However, sensitivity analysis was carried out excluding the five trials sponsored by or involving the manufacturers of the device, which revealed no overall effect on BP using the device. The maximum trial duration was 9 weeks and no overall effect was seen on heart rate or quality of life using the device.

CONCLUSION

There is evidence that short-term use of DGB may reduce both DBP and DBP. However, five of the eight trials were sponsored by or involved the manufactures of the device. When these trials were excluded we found no overall effect. We conclude that longer term, independent trials are required to validate this intervention.

Hypertension in developing countries

Data from different national and regional surveys show that hypertension is common in developing countries, particularly in urban areas, and that rates of awareness, treatment, and control are low. Several hypertension risk factors seem to be more common in developing countries than in developed regions. Findings from serial surveys show an increasing prevalence of hypertension in developing countries, possibly caused by urbanisation, ageing of population, changes to dietary habits, and social stress. High illiteracy rates, poor access to health facilities, bad dietary habits, poverty, and high costs of drugs contribute to poor blood pressure control. The health system in many developing countries is inadequate because of low funds, poor infrastructure, and inexperience. Priority is given to acute disorders, child and maternal health care, and control of communicable diseases. Governments, together with medical societies and non-governmental organisations, should support and promote preventive programmes aiming to increase public awareness, educate physicians, and reduce salt intake. Regulations for the food industry and the production and availability of generic drugs should be reinforced.

The impact of adding front-of-package sodium content labels to grocery products: an experimental study

Objective

Canadians consume approximately twice the daily Adequate Intake of sodium. The present study examined the efficacy of four types of front-of-package (FOP) sodium labels at influencing consumers’ selection of products low v. high in sodium.

Design

Participants were randomly assigned to one of five experimental conditions: (i) control condition with no FOP label; (ii) basic numeric FOP label; (iii) numeric FOP label with ‘high’ and ‘low’ sodium content descriptors; (iv) detailed Traffic Light (TL) label with colour coding, content descriptors and numeric information; and (v) simple TL label with no numeric information. Participants were shown pairs of grocery products that varied in sodium content and told they could choose a free sample. Selection of the low-sodium v. the high-sodium product was the primary behavioural outcome, in addition to ratings of effectiveness, understanding, liking and believability.

Setting

Waterloo, Ontario, Canada.

Subjects

Adults (n 430) aged ≥18 years, recruited from community settings.

Results

Participants in the three FOP conditions with ‘high/low’ sodium content descriptors were significantly more likely to choose the lower-sodium product compared with the control group. The detailed TL label was ranked most effective at helping participants select low-sodium products, and was rated significantly higher than other formats in liking, understanding and believability. Product selection did not differ significantly across sociodemographic groups.

Conclusions

FOP labels that include content descriptors may be more effective in helping consumers to select lower-sodium products. TL labels, which incorporate content descriptors and colour coding, should be considered for future FOP labelling initiatives.

Predictors of resistant hypertension in an unselected sample of an adult male population in Italy

Prevalence, incidence and predictors of resistant hypertension (RH), (defined as blood pressure persistently above goal in spite of the concurrent use of three antihypertensive agents of different classes) in the general population remain largely unknown. A complete database including anthropometric and biochemical data was collected in 1994-1995 (baseline examination) in 1,019 participants (mean age 51.8, range: 25-79 years) and again in 2002-2004 in 794 male participants of the Olivetti Heart Study (OHS) in southern Italy. The incidence of RH over the average follow-up time of 7.9 years was 4.8% (38/794) in the whole study population and 10.1% (31/307) among hypertensive participants. Basal blood pressure (systolic, diastolic or pulse pressure), cholesterol and urinary albumin/creatinine ratio (ACR) significantly predicted the risk of developing RH using a logistic regression model that also included age as covariates. If in the same model we added basal pharmacological treatment, the fractional excretion of sodium (FENa) also became a statistically significant predictor, and this last model explained nearly 25% of the risk of developing RH. In this unselected sample of an adult male population, ACR (an early marker of organ damage), an elevated FENa (a proxy for dietary sodium intake), cholesterol and a higher basal blood pressure level were independent predictors of RH.

Strategies to reduce dietary sodium intake

OPINION STATEMENT

Excess sodium intake has an important, if not predominant, role in the pathogenesis of elevated blood pressure, one of the most important modifiable determinants of cardiovascular disease (CVD). In the United States, almost 80 % of sodium in the diet comes from packaged and restaurant foods. Given the current food environment, educational efforts such as clinician counseling are useful, but a comprehensive public health approach is necessary to achieve meaningful reductions in sodium intake. A successful approach includes several key strategies, which together will both promote positive decisions by individuals and change the context in which they make those decisions. The strategies include 1) public education, 2) individual dietary counseling, 3) food labeling, 4) coordinated and voluntary industry sodium reduction, 5) government and private sector food procurement policies, and 6) FDA regulations, as recommended by the Institute of Medicine, to modify sodium's generally regarded as safe (GRAS) status. Population-wide reduction in sodium intake has the potential to substantially reduce the public burden of preventable CVD and reduce health care costs.

Population-wide sodium reduction: the bumpy road from evidence to policy

Elevated blood pressure is a highly prevalent condition that is etiologically related to coronary heart disease and stroke, two of the leading causes of morbidity and mortality throughout the world. Excess salt (sodium chloride) intake is a major determinant of elevated blood pressure. In this article, we discuss the scientific rationale for population-wide salt reduction, the types and strength of available evidence, policy-making on dietary salt intake in the United States and other countries, and the role and impact of key stakeholders. We highlight a number of lessons learned, many of which are germane to policy development in other domains.

Enhancing saltiness in emulsion based foods

Background

The concept of enhancing saltiness perception in emulsions and a liquid food formulated with the emulsions (ambient vegetable soup) through increasing salt concentration in the continuous phase while retaining the fat content of the (aqueous continuous) product was evaluated. This was accomplished by increasing the droplet phase volume using duplex emulsion technology. Viscosity and droplet size distribution was measured. Saltiness evaluation was based on simple paired comparison testing (2-Alternate Forced Choice tests, BS ISO 5495:2007).

Results

Single and duplex emulsions and emulsion-based products had comparable mean oil droplet diameters (25 to 30 μm); however, viscosity of the duplex emulsion systems was considerably higher. Sensory assessment of saltiness of emulsion pairs (2AFC) indicated duplex technology enhanced saltiness perception compared to a single emulsion product at the same salt content (6.3 g/100 g) in both simple emulsions and the formulated food product (P = 0.0596 and 0.0004 respectively) although assessors noted the increased viscosity of the duplex systems. The formulated food product also contained pea starch particles which may have aided product mixing with saliva and thus accelerated tastant transport to the taste buds. Lowering salt content in the duplex systems (to levels of aqueous phase salt concentration similar to the level in the single systems) resulted in duplex systems being perceived as less salty than the single system. It appears that the higher viscosity of the duplex systems could not be “overruled” by enhanced mixing through increased droplet phase volume at lowered salt content.

Conclusions

The results showed that salt reduction may be possible despite the added technology of duplex systems increasing the overall measured viscosity of the product. The changes in viscosity behavior impact mouthfeel, which may be exploitable in addition to the contribution towards salt reduction. With a view to applying this technology to real processed foods, it needs to be tested for the product in question but it should be considered as part of a salt reduction tool box.

Nutrition standards for away-from-home foods in the USA

Away-from-home foods are regulated with respect to the prevention of food-borne diseases and potential contaminants, but not for their contribution to dietary-related chronic diseases. Away-from-home foods have more calories, salt, sugar and fat, and include fewer fruits and vegetables than recommended by national nutrition guidelines. Thus, frequent consumption of away-from-home foods contributes to obesity, hypertension, diabetes, heart disease, and cancer. In light of this, many localities are already adopting regulations or sponsoring programs to improve the quality of away-from-home foods. We review the rationale for developing nutritional performance standards for away-from-home foods in light of limited human capacity to regulate intake or physiologically compensate for a poor diet. We offer a set of model performance standards to be considered as a new area of environmental regulation. Models for voluntary implementation of consumer standards exist in the environmental domain and may be useful templates for implementation. Implementing such standards, whether voluntarily or via regulations, will require addressing a number of practical and ideological challenges. Politically, regulatory standards contradict the belief that adults should be able to navigate dietary risks in away-from-home settings unaided.

Effect of alginate supplementation on weight loss in obese subjects completing a 12-wk energy-restricted diet: a randomized controlled trial

BACKGROUND

Acute studies with alginate-based preloads suggested that these strong gelling fibers may induce increased feelings of satiety and reduce energy intakes. However, the long-term efficacy and safety of alginate supplementation on body weight regulation are lacking.

OBJECTIVE

The primary aim of the study was to investigate the effects in subjects of alginate supplementation in conjunction with energy restriction (-300 kcal/d) on loss of body weight and fat and, second, on metabolic risk markers in comparison with in a placebo group.

DESIGN

In a parallel, double-blind, placebo-controlled study, we randomly assigned 96 obese subjects to either an energy-restricted diet plus a placebo preload supplement or an energy-restricted diet plus an alginate-based preload supplement (15 g fiber). The preload was administered as a beverage 3 times/d before main meals for a period of 12 wk.

RESULTS

No differences in loss of body weight and fat between groups were shown in the intension-to-treat (ITT) analysis (P > 0.1). However, in the completer analysis (n = 80), we showed a greater weight loss with alginate (6.78 ± 3.67 kg) than with the placebo (5.04 ± 3.40 kg) (P = 0.03), which was mainly attributed to a reduction in the percentage of body fat (P = 0.03). In the ITT analysis, a larger decrease in systolic and diastolic blood pressure was shown in the placebo group than in the alginate group (P < 0.05). Plasma concentrations of glucose, insulin, C-reactive protein, and ghrelin, HOMA-IR, and lipid metabolism did not differ between treatment groups in the ITT analysis (P > 0.1).

CONCLUSION

These results suggest that alginate supplementation as an adjunct to energy restriction may improve weight loss in obese subjects who complete a 12-wk dietary intervention.

Epidemiology and prevention of stroke: a worldwide perspective

This paper reviews how epidemiological studies during the last 5 years have advanced our knowledge in addressing the global stroke epidemic. The specific objectives were to review the current evidence supporting management of ten major modifiable risk factors for prevention of stroke: hypertension, current smoking, diabetes, obesity, poor diet, physical inactivity, atrial fibrillation, excessive alcohol consumption, abnormal lipid profile and psychosocial stress/depression.

Association between sodium intake and change in uric acid, urine albumin excretion, and the risk of developing hypertension

BACKGROUND

A high-sodium diet has little short-term effect on blood pressure in nonhypertensive individuals but, for unclear reasons, is associated with hypertension if consumed long term. We hypothesized that a chronically high sodium intake would be associated with increases in biomarkers of endothelial dysfunction, specifically serum uric acid (SUA) and urine albumin excretion (UAE), and that high sodium intake would be associated with incident hypertension among those with higher SUA and UAE.

METHODS AND RESULTS

We prospectively analyzed the associations between sodium intake and the change in SUA (n=4062) and UAE (n=4146) among participants of the Prevention of Renal and Vascular End Stage Disease (PREVEND) study who were not taking antihypertensive medications. We also examined the association of sodium intake with the incidence of hypertension (n=5556) among nonhypertensive participants. After adjustment for confounders, each 1-g-higher sodium intake was associated with a 1.2-μmol/L increase in SUA (P=0.01) and a 4.6-mg/d increase in UAE (P<0.001). The relation between sodium intake and incident hypertension varied according to SUA and UAE. For each 1-g-higher sodium intake, the adjusted hazard ratio for developing hypertension was 0.98 (95% confidence interval, 0.89-1.08) among those in the lowest tertile of SUA and 1.09 (1.02-1.16) among those in the highest tertile. Corresponding hazard ratios were 0.99 (confidence interval, 0.93-1.06) among participants whose UAE was <10 mg/d and 1.18 (confidence interval, 1.07-1.29) among those whose UAE was >15 mg/d.

CONCLUSIONS

Over time, higher sodium intake is associated with increases in SUA and UAE. Among individuals with higher SUA and urine UAE, a higher sodium intake is an independent risk factor for developing hypertension.

Dementia and Alzheimer's disease: a new direction.The 2010 Jay L. Foster Memorial Lecture

BACKGROUND

The modern era of Alzheimer's disease (AD) research began in the early 1980s with the establishment of AD research centers and expanded research programs at the National Institute on Aging.

METHODS

Over the past 30 years, there has been success in defining criteria for AD and dementia, association of important genetic disorders related to premature dementia in families, the association of apolipoprotein-E(4), and measurement of incidence and prevalence and selected risk factors. However, prevention and treatment have been elusive.

RESULTS

The development of new technologies, especially magnetic resonance imaging, positron emission tomography to measure amyloid in vivo in the brain and glucose metabolism, cerebrospinal fluid examination, better genetic markers, large-scale longitudinal epidemiology studies, and preventive clinical trials has rapidly begun a new era of research that offers opportunities to better understand etiology, that is, determinants of amyloid biology in the brain, neurofibrillary tangles, synaptic loss, and dementia.

CONCLUSIONS

There are three major hypotheses related to dementia: amyloid deposition and secondary synaptic loss as a unique disease, vascular injury, and "aging." New research must be hypothesis-driven and lead to testable approaches for treatment and prevention.

Sodium reduction and the correction of iodine intake in Belgium: Policy options

Many studies suggest that high salt intakes are related to high blood pressure and consequently cardiovascular diseases. In addition salt intake was found to be related with obesity, renal stones, osteoporosis and stomach cancer. Belgium, such as other European countries, is suffering from both salt intakes that are twice as high as the recommended intakes and mild iodine deficiency. No comprehensive strategy encompassing both public health problems has been developed. While specific salt reduction targets for processed foods are still under discussion using a consensus approach with industry, an agreement was signed between the bakery sector and the Ministry of Health in April 2009, to encourage and increase the use of iodised salt in the production of bread. Based on results of recent surveys on population iodine status it is advised not to currently revise iodine concentrations in salt in bread but to advocate for a higher percentage of bakers using iodised salt and to install a good monitoring system to control the percentage of bakers effectively using adequately iodised salt. With regard to salt reduction, it is of utmost importance that all companies contribute and harmonise the salt content of their products according to the lowest possible thresholds in a first step. In order to achieve this goal, it will be necessary, in addition to the consensus approach, to come up with at least some legislative tools such as a salt tax or mandatory labelling of foods exceeding a specific sodium concentration. Once salt reduction targets have been clearly defined in Belgium over the longer term, a legal framework should be set in place where iodine concentration in salt for the production of bread and household salt is strictly regulated by law, to avoid a large variability in the iodine content of salt brands consumed. In conclusion, it is possible to tackle salt reduction and iodine deficiency at the same time on the condition that the approach is coordinated and well monitored. All the interventions and measures taken should clearly include education and communication directed towards consumers, food producers, public health professionals, pharmacists, healthcare workers, and media representatives.

How can diet influence the risk of stroke?

Cerebrovascular diseases are the second cause of mortality in the world, and hypertension is considered a main risk factor for occurrence of stroke. The mechanisms responsible for the increased stroke risk remain unclear. However, dietary interventions have been applied in the management and treatment of their risk factors, which include increased blood pressure levels, obesity, diabetes, and dyslipidemia. Further studies should be conducted to assess the effects of carotenoids, flavonoids, n-3 polyunsaturated fats, and lower salt and high glycemic index intake in risk of stroke.

Blood pressure and particulate air pollution in schoolchildren of Lahore, Pakistan

BACKGROUND

Air pollution is a growing health problem for urban populations in emerging economies. The present study examines the (cross-sectional) relation between blood pressure and particulate air pollution in schoolchildren of Lahore (Pakistan).

METHODS

We recruited a sample of 8-12 year-old children (mean age 9.9 years; 45% girls) from two schools in Lahore situated in areas with low (n = 79) and high (n = 100) air pollution, respectively. During the study period (January-April 2009) particulate pollution [PM(10) and PM(2.5) i.e. particles with aerodynamic diameters below 10 μm or 2.5 μm, respectively] was measured at the school sites with a laser operated device (Metone Aerocet 531). Blood pressure was measured, after 5 minutes of sitting rest, using an automated device (average of 5 consecutive measurements). Spot urine samples were also collected and concentrations of Na and K were measured.

RESULTS

Mean daily values of PM2.5 were 28.5 μg/m(3) (SD: 10.3) and 183 μg/m(3) (SD: 30.2), in the low and high pollution areas, respectively. Systolic and diastolic blood pressure were significantly higher in children living in the high pollution area (115.9/70.9 mm Hg) than in the low pollution area (108.3/66.4 mm Hg), independently of age, gender, height, weight, socio-economic status, passive smoking and the urinary concentrations of Na, K, and creatinine.

CONCLUSIONS

In 8-12 year-old children, exposure to (traffic-related) air pollution was associated with higher systolic and diastolic blood pressure. These findings, if they persist, might have clinical relevance at older age.

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.

Patterns of sodium and potassium excretion and blood pressure in the African Diaspora

Habitual levels of dietary sodium and potassium are correlated with age-related increases in blood pressure (BP) and likely have a role in this phenomenon. Although extensive published evidence exists from randomized trials, relatively few large-scale community surveys with multiple 24-h urine collections have been reported. We obtained three 24-h samples from 2704 individuals from Nigeria, Jamaica and the United States to evaluate patterns of intake and within-person relationships with BP. The average (±s.d.) age and weight of the participants across all the three sites were 39.9±8.6 years and 76.1±21.2 kg, respectively, and 55% of the total participants were females. Sodium excretion increased across the East-West gradient (for example, 123.9±54.6, 134.1±48.8, 176.6±71.0 (±s.d.) mmol, Nigeria, Jamaica and US, respectively), whereas potassium was essentially unchanged (for example, 46.3±22.9, 40.7±16.1, 44.7±16.4 (±s.d.) mmol, respectively). In multivariate analyses both sodium (positively) and potassium (negatively) were strongly correlated with BP (P<0.001); quantitatively the association was stronger, and more consistent in each site individually, for potassium. The within-population day-to-day variation was also greater for sodium than for potassium. Among each population group, a significant correlation was observed between sodium and urine volume, supporting the prior finding of sodium as a determinant of fluid intake in free-living individuals. These data confirm the consistency with the possible role of dietary electrolytes as hypertension risk factors, reinforcing the relevance of potassium in these populations.

Monitoring of blood pressure among children and adolescents in a coastal province in China: results of a 2010 survey

BACKGROUND

Several studies have provided ample evidence that hypertension in adults has its onset in childhood; children and adolescents with elevated blood pressure (BP) are more likely to become hypertensive adults. The present study examined the prevalence of relatively high BP among children and adolescents in Shandong, China.

SUBJECTS AND METHODS

Data for this study were obtained from a large cross-sectional survey of schoolchildren carried out in 2010. A total of 38 860 students (19 481 boys and 19 379 girls) aged 7 to 17 years participated in this study. Relatively high BP status was defined as systolic blood pressure and/or diastolic blood pressure ≥95th percentile for age and gender.

RESULTS

Shandong children had a high BP level, with the 50th percentiles of systolic and diastolic blood pressure of children and adolescents aged 7 to 17 years in Shandong being above the reference values for Chinese children and adolescents by 3 to 12 mm Hg and 3 to 7 mm Hg for boys, and by 3 to 6 mm Hg and 3 to 5 mmHg for girls, respectively. The overall prevalence of relatively high BP was 26.22% for boys and 20.27% for girls.

CONCLUSION

There is a high prevalence of relatively high BP among children and adolescents in Shandong, China. It has become a threatening hazard to children and adolescents and should arouse special attention.

Potential cardiovascular mortality reductions with stricter food policies in the United Kingdom of Great Britain and Northern Ireland

OBJECTIVE

To estimate how much more cardiovascular disease (CVD) mortality could be reduced in the United Kingdom through more progressive nutritional targets.

METHODS

Potential reductions in CVD mortality in the United Kingdom between 2006 (baseline) and 2015 were estimated by synthesizing data on population, diet and mortality among adults aged 25 to 84 years. The effect of specific dietary changes on CVD mortality was obtained from recent meta-analyses. The potential reduction in CVD deaths was then estimated for two dietary policy scenarios: (i) modest improvements (simply assuming recent trends will continue until 2015) and (ii) more substantial but feasible reductions (already seen in several countries) in saturated fats, industrial trans fats and salt consumption, plus increased fruit and vegetable intake. A probabilistic sensitivity analysis was conducted. Results were stratified by age and sex.

FINDINGS

The first scenario would result in approximately 12 500 fewer CVD deaths per year (range: 5500-30 300). Approximately 4800 fewer deaths from coronary heart disease and 1800 fewer deaths from stroke would occur among men, and 3500 and 2400 fewer, respectively, would occur among women. More substantial dietary improvements (no industrial trans fats, reduction in saturated fats and salt and substantial increases in fruit and vegetable intake) could result in approximately 30 000 fewer (range: 13 300-74 900) CVD deaths.

CONCLUSION

Excess dietary trans fats, saturated fats and salt, along with insufficient fruits and vegetables, generate a substantial burden of CVD in the United Kingdom. Further improvements resembling those attained by other countries are achievable through stricter dietary policies.

Brazilian solar saltworks - ancient uses and future possibilities

Coastal solar saltworks of Brazil are exploited for sea salt, which becomes progressively concentrated by evaporation. This study aimed to review the current and new potential uses of these systems, in order to provide more dynamic for this activity. The first evaporation ponds are also used for artisanal fisheries, ensuring the livelihood of many families. All the brine rich in secondary salts (bittern) can be widely used by the chemical industry, while the Brazil shows an incipient production of "flower of salt", a salt with distinct characteristics with higher market value than sodium chloride. On the other hand, the saltponds have a high potential for management and obtaining of large populations of Artemia spp., purifying the brine through the action as biological filter. This microcrustacean occurs naturally in intermediate salinity ponds, being commonly used in aquaculture. Species of microalgae and halobacteria found in the saltworks are employed for extraction of beta-carotene and glycerol, used in an extensive list of products with high commercial value. These ecosystems represent refuge zones for many species of migratory birds, becoming imperative to promote the conservation of these hypersaline wetlands.

Design and baseline characteristics of the 10 Small Steps Study: a randomised controlled trial of an intervention to promote healthy behaviour using a lifestyle score and personalised feedback

Background

Non-communicable diseases (NCDs) are the leading causes of death globally and are associated with a limited set of common, modifiable health behaviours: tobacco use, physical inactivity, harmful use of alcohol and unhealthy diet. General practice offers an ideal avenue for addressing such health behaviours on a population-wide basis. This paper describes the protocol of a multiple health behaviour change intervention designed for implementation in general practice and summarises the baseline characteristics of its participants.

Method/Design

The 10 Small Steps (10SS) study, a randomised controlled trial, involved 4,678 adult general practice patients in Queensland, Australia. Self-reported data were collected to establish the proportion of participants meeting recommended guidelines for ten health behaviours: physical activity, body mass index, alcohol, smoking and six dietary behaviours. Participants were randomised to four groups: contact at baseline only ('single intervention' and corresponding control group) and contact at baseline and 3 months ('dual intervention' and corresponding control group). At each contact the participants received a computer-tailored feedback and one page information sheet according to their allocation to intervention or control groups. Change in the intervention group compared to the control group was assessed at 3 and12 months after baseline data collection.

Responses were summed to calculate an individual lifestyle score (the Prudence Score), which ranged from 0 to 10. The baseline response was 56.5% (4678 of 8343 invited participants) and the study sample was primarily female (68.7%) with an average age of 47 years. The mean Prudence Score was 5.8 (95%CI 5.75-5.85).

Discussion

Baseline data from the 10SS study show that nearly all participants engage in some health behaviours but relatively few adhere simultaneously to a core set of dietary and lifestyle behaviours associated with risk of NCDs. Ample scope exists to improve health behaviour to reduce NCDs in the general practice setting and the 10SS study trial will provide data on the extent to which a minimal computer-tailored intervention can meet this objective. The protocol developed for the 10SS study has potential for translation into routine general practice as it has minimal impact on practice routine whilst contributing to primary prevention objectives.

Trial Registration

The Australian New Zealand Clinical Trials Registry ACTRN12611001213932

Population based strategy for dietary salt intake reduction: Italian initiatives in the European framework

Excess dietary sodium chloride (salt) intake is etiologically related to hypertension and cardiovascular disease (CVD). Moderate reduction of salt intake reduces blood pressure (BP) and is expected to contribute to reduce the risk of CVD. Previous community-based trials to reduce BP by means of salt reduction were very successful. The initial positive results of national strategies of dietary salt intake reduction in several European countries, driven by the initiative of the World Health Organisation (WHO) and non-governmental organisations such as the World Action of Salt and Health (WASH), have paved the way for action in other European Union (EU) member states. In Italy, several initiatives aiming at reduction of salt intake at the population level have been recently undertaken. These initiatives include i) the evaluation of current dietary habits promoted by the Working Group for Dietary Salt Reduction in Italy (GIRCSI); ii) the chemical analysis of the bread salt content, a major source of sodium intake in Italy, and the agreement between the bakers' associations and the Ministry of Health for a gradual reduction of the bread salt content; iii) the implementation of educational campaigns to increase population awareness, iv) the involvement of the food catering system. In the immediate future, food reformulation must be extended to other food categories in collaboration with industry, foods' salt targets ought to be defined, the food labelling system must be improved and population salt awareness must be further increased through educational campaigns. The GIRCSI Working Group is committed to pursue these objectives.

Habitual dietary sodium intake is inversely associated with coronary flow reserve in middle-aged male twins

BACKGROUND

Evidence links dietary sodium to hypertension and cardiovascular disease (CVD), but investigation of its influence on cardiovascular function is limited.

OBJECTIVE

We examined the relation between habitual dietary sodium and coronary flow reserve (CFR), which is a measure of overall coronary vasodilator capacity and microvascular function. We hypothesized that increased sodium consumption is associated with lower CFR.

DESIGN

Habitual daily sodium intake for the previous 12 mo was measured in 286 male middle-aged twins (133 monozygotic and dizygotic pairs and 20 unpaired twins) by using the Willett food-frequency questionnaire. CFR was measured by positron emission tomography [N(13)]-ammonia, with quantitation of myocardial blood flow at rest and after adenosine stress. Mixed-effects regression analysis was used to assess the association between dietary sodium and CFR.

RESULTS

An increase in dietary sodium of 1000 mg/d was associated with a 10.0% lower CFR (95% CI: -17.0%, -2.5%) after adjustment for demographic, lifestyle, nutritional, and CVD risk factors (P = 0.01). Across quintiles of sodium consumption, dietary sodium was inversely associated with CFR (P-trend = 0.03), with the top quintile (>1456 mg/d) having a 20% lower CFR than the bottom quintile (<732 mg /d). This association also persisted within pairs: a 1000-mg/d difference in dietary sodium between brothers was associated with a 10.3% difference in CFR after adjustment for potential confounders (P = 0.02).

CONCLUSIONS

Habitual dietary sodium is inversely associated with CFR independent of CVD risk factors and shared familial and genetic factors. Our study suggests a potential novel mechanism for the adverse effects of dietary sodium on the cardiovascular system. This trial was registered at clinicaltrials.gov as NCT00017836.

Second morning urine method is superior to the casual urine method for estimating daily salt intake in patients with hypertension

The accuracy of the casual urine (CU) method for estimating daily salt intake was compared with the second morning urine (SMU) method and with 24-h urine collection (24 UC) method as the gold standard. Data were obtained from three previously reported studies, in which we evaluated the daily salt intake by the SMU method. Using SMU samples from 1315 outpatients, the estimated salt intake was lower with the CU method than the SMU method. In inpatients with a daily salt intake of 7, 8 or 18 g, the CU method was applied to SMU specimens. It underestimated salt intake compared with the 24-h collection method whereas the SMU method and 24 UC method gave similar results. In the present study, 24 UC was done and then urine was collected at 0800, 1100, 1400, 1700 and 1900 hours, with a daily salt intake of 6 g in 8 inpatients, 10 g in 11 inpatients or 15 g in 5 inpatients. In comparison with the 24 UC method, the CU method underestimated a high salt intake (15 g) when morning specimens were used and overestimated a low salt intake (6 g) when afternoon specimens were used. The correlation between the CU method and 24 UC method was weaker (R = 0.57) than that between the SMU method and 24 UC method (R = 0.85). In conclusion, the CU method is heavily influenced by the timing of urine collection and by the actual daily salt intake, so the SMU method provides a better estimate of individual salt intake.

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.

Effects of alternative label formats on choice of high- and low-sodium products in a New Zealand population sample

OBJECTIVE

Dietary sodium reduction is a cost-effective public health intervention to reduce chronic disease. In response to calls for further research into front-of-pack labelling systems, we examined how alternative sodium nutrition label formats and nutrition claims influenced consumers' choice behaviour and whether consumers with or without a diagnosis of hypertension differed in their choice patterns.

DESIGN

An anonymous online experiment in which participants viewed ten choice sets featuring three fictitious brands of baked beans with varied label formats and nutritional profiles (high and low sodium) and indicated which brand in each set they would purchase if shopping for this product.

SETTING

Participants were recruited from New Zealand's largest online nationwide research panel.

SUBJECTS

Five hundred people with self-reported hypertension and 191 people without hypertension aged 18 to 79 years.

RESULTS

The addition of a front-of-pack label increased both groups' ability to discriminate between products with high and low sodium, while the Traffic Light label enabled better identification of the high-sodium product. Both front-of-pack formats enhanced discrimination in the presence of a reduced salt claim, but the Traffic Light label also performed better than the Percentage Daily Intake label in moderating the effect of the claim for the high-sodium product.

CONCLUSIONS

Front-of-pack labels, particularly those with simple visual cues, enhance consumers' ability to discriminate between high- and low-sodium products, even when those products feature nutrition claims.

The influence of dietary sodium on bone development in growing rats

The present study investigated the effects of dietary sodium on bone growth in young rats. Five-week-old rats were fed one of three different diets for 60 days: low sodium (NaCl, 0.32 g/kg diet), normal sodium (NaCl, 2.6 g/kg) and high sodium (NaCl, 20 g/kg). The proximal tibial metaphysis (PTM), the fifth lumbar vertebra (LV5) and the middle part of the tibia shaft (TX) were analysed by bone histomorphometry. The expression of three osteogenesis genes, Runx2, osteopontin and osteocalcin, was determined by RT-PCR in bone samples from the skull. In both the PTM and LV5, trabecular area and thickness were increased by the low-sodium diet, while the high-sodium diet decreased trabecular area in LV5. Dynamic data revealed that sodium restriction increased bone formation parameters in the PTM and LV5, but decreased bone resorption in LV5. In TX, endosteal bone formation was enhanced by the low-sodium diet and depressed by the high-sodium diet compared to the normal sodium group. But there were no statistically changes in the cortical bone area of TX. Low-sodium intake significantly enhanced the expression of all three osteogenesis genes compared to the normal sodium group, while high-sodium intake suppressed osteogenic gene expression. Our results suggest that sodium restriction in growing rats promotes bone development by influencing both bone formation and resorption.

Intensity of Salt Taste and Prevalence of Hypertension Are Not Related in the Beaver Dam Offspring Study

BACKGROUND: Standard clinical advice for the prevention and treatment of hypertension includes limitation of salt intake. Previous studies of the association between perception of salt taste and hypertension prevalence have not reported consistent results and have usually been conducted in small study populations. PURPOSE: To determine the cross-sectional relationship between intensity of salt taste, discretionary salt use, and hypertension. METHODS: Subjects (n=2371, mean age=48.8 years) were participants in the Beaver Dam Offspring Study (BOSS), an investigation of sensory loss and aging conducted in 2005-2008. Salt taste intensity was measured using a filter paper disk impregnated with 1.0 M sodium chloride and a general Labeled Magnitude Scale (gLMS). Hypertension was defined as systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg, or use of high blood pressure medication. RESULTS: Nearly 32% of the participants rated the salt disk as weak or having no taste while approximately 10% considered it to be very strong or stronger. The intensity was reported to be less strong by males (P < 0.001) and college graduates (P = 0.02) and was inversely associated with frequency of adding salt to foods (P = 0.02). There was no significant association between hypertension and the intensity of salt taste, before and after adjustment for covariates. Exclusion of subjects with a history of physician diagnosed hypertension did not appreciably alter these findings. CONCLUSIONS: The perception of salt taste was related to the frequency of discretionary salt use but not to hypertension status or mean blood pressure.

Impacts of a national strategy to reduce population salt intake in England: serial cross sectional study

BACKGROUND

The UK introduced an ambitious national strategy to reduce population levels of salt intake in 2003. The aim of this study was to evaluate the impact of this strategy on salt intake in England, including potential effects on health inequalities.

METHODS

Secondary analysis of data from the Health Survey for England. Our main outcome measure was trends in estimated daily salt intake from 2003-2007, as measured by spot urine. Secondary outcome measures were knowledge of government guidance and voluntary use of salt in food preparation over this time period.

RESULTS

There were significant reductions in salt intake between 2003 and 2007 (-0.175 grams per day per year, p<0.001). Intake decreased uniformly across all other groups but remained significantly higher in younger persons, men, ethnic minorities and lower social class groups and those without hypertension in 2007. Awareness of government guidance on salt use was lowest in those groups with the highest intake (semi-skilled manual v professional; 64.9% v 71.0% AOR 0.76 95% CI 0.58-0.99). Self reported use of salt added at the table reduced significantly during the study period (56.5% to 40.2% p<0.001). Respondents from ethnic minority groups remained significantly more likely to add salt during cooking (white 42.8%, black 74.1%, south Asian 88.3%) and those from lower social class groups (unskilled manual 46.6%, professional 35.2%) were more likely to add salt at the table.

CONCLUSIONS

The introduction a national salt reduction strategy was associated with uniform but modest reductions in salt intake in England, although it is not clear precisely which aspects of the strategy contributed to this. Knowledge of government guidance was lower and voluntary salt use and total salt intake was higher among occupational and ethnic groups at greatest risk of cardiovascular disease.