By how much does dietary salt reduction lower blood pressure? I--Analysis of observational data among populations

Sodium - a systematic review for Nordic Nutrition Recommendations 2023

Blood pressure (BP) rises along with increasing sodium intake from early childhood to late adulthood, and leads to hypertension among most men and women living in Nordic and Baltic countries. Elevated BP is the leading global risk factor for premature deaths and disability-adjusted life-years. A reduction in sodium intake is essential in the prevention of hypertension in individuals, in the lowering of BP levels, in the treatment of hypertensive individuals, and in decreasing risks associated with elevated BP. There is a progressive linear dose-response relationship between sodium intake and BP beginning from a sodium intake of less than 0.8 g/day. Sodium reduction decreases BP linearly by a dose-response manner down to a sodium intake level of less than 2 g/day. Randomised intervention studies with a duration of at least 4 weeks confirm the efficiency and safety of reducing blood sodium intake to a level of less than 2 g/day. Results from prospective cohort studies show that higher sodium intake is positively associated with an increased risk of stroke and cardiovascular events and mortality among the general adult population, and the associations are linear in studies using proper sodium assessment methods. Analyses assessing sodium intake using at least two 24-h urine samples have shown a linear positive relationship between sodium intake and the risk of a cardiovascular event or death. Based on an overall evaluation of the available data, a limitation of the sodium intake to 2.0 g/day is suggested for adults. The optimal sodium intake level would be probably about 1.5 g/day. Sodium intake recommended for children can be extrapolated from the recommended sodium intake for adults. According to national dietary surveys, the average sodium intakes in Nordic countries range in adult men from 3.6 to 4.4 g/day and in adult women from 2.6. to 3.2 g/day, and in Baltic countries in men from 2.6 to 5.1 g/day and in women from 1.8 to 3.6 g/day.

Salt intake, blood pressure and cardiovascular disease mortality in England, 2003-2018

OBJECTIVES

The aim of this study was to assess the changes in salt intake and concomitant changes in blood pressure (BP) and cardiovascular disease (CVD) mortality in England from 2003 to 2018.

METHODS

National surveys and death registration data were used for the analysis of salt intake as measured by 24-h urinary sodium excretion (449-1069 participants per year), BP (2651-6738 participants per year) and CVD mortality.

RESULTS

A decline in salt intake from 9.38 (SD 4.64) to 7.58 (3.41) g/d was observed between 2003 and 2014 ( P  < 0.01), followed by an increase to 8.39 (4.13) g/d in 2018 ( P  < 0.01). Similar trends in BP and CVD mortality were also observed between 2003 and 2018. SBP/DBP decreased from 125.3 (15.92)/74.48 (11.33) mmHg to 122.57 (14.92)/73.33 (10.75) mmHg between 2003 and 2014 ( P  < 0.01), followed by a plateau up to 2018 [122.04 (14.64)/73.84 (10.54) mmHg, P  > 0.05]. Likewise, a fall in stroke and ischaemic heart disease mortality rates was observed between 2003 and 2014, from 12.24 and 43.44 cases per 100 000, to 8.19 and 27.23 cases per 100 000 ( P  < 0.01), respectively, followed by a plateau afterwards ( P  > 0.05).

CONCLUSION

The UK salt reduction programme was initially successful in reducing population salt intake by 19% (from 9.38 g/d in 2003 to 7.58 g/d in 2014). However, in recent years, the programme stalled and thus led to an interruption in the decline of salt intake. BP and CVD mortality reduction was also interrupted when salt reduction stalled. The changes in salt intake may have played an important role in the concomitant changes in BP and CVD mortality. Urgent action is needed to reinvigorate the UK's once world-leading salt reduction programme.

Reduction of Cardiovascular Events and Related Healthcare Expenditures through Achieving Population-Level Targets of Dietary Salt Intake in Japan: A Simulation Model Based on the National Health and Nutrition Survey

Reducing population dietary salt intake is expected to help prevent cardiovascular disease and thus constrain increasing national healthcare expenditures in Japan’s super-aged society. We aimed to estimate the impact of achieving global and national salt-reduction targets (8, <6, and <5 grams/day) on cardiovascular events and national healthcare spending in Japan. Using published data including mean salt intake and systolic blood pressure from the 2019 National Health and Nutrition Survey, we developed a Markov model of a closed cohort of adults aged 40−79 years in 2019 (n = 66,955,000) transitioning among six health states based on the disease course of ischemic heart disease (IHD) and stroke. If mean salt intake were to remain at 2019 levels over 10 years, cumulative incident cases in the cohort would be approximately 2.0 million for IHD and 2.6 million for stroke, costing USD 61.6 billion for IHD and USD 104.6 billion for stroke. Compared with the status quo, reducing mean salt intake towards the targets over 10 years would avert 1−3% of IHD and stroke events and save up to 2% of related national healthcare costs. Attaining dietary salt-reduction goals among adults would yield moderate health economic benefits in Japan.

Feasibility of Low-Sodium, High-Potassium Processed Foods and Their Effect on Blood Pressure in Free-Living Japanese Men: A Randomized, Double-Blind Controlled Trial

We aimed to verify the effect of new low-sodium high-potassium seasonings and processed foods containing poly-γ-glutamic acid on blood pressure in free-living settings. To this end, we conducted a randomized, double-blind controlled trial on 187 Japanese men, aged 35–67 years, who did not use antihypertensives. Participants were randomly allocated to an intervention (n = 93) or a control group (n = 94). They were given a boxed lunch and miso soup (average Na and K content for the intervention group: 1175 and 1476 mg; for the control group: 2243 and 703 mg, respectively). Blood pressure was measured three times every morning for 1 week immediately before and during the final week of the trial. On the day before and the final day of the intervention period, 24 h urine samples were collected. After intervention, the intervention group showed a significantly stronger decrease in the urinary sodium-to-potassium ratio than the control group (p < 0.001). The mean difference in systolic blood pressure change after adjustment for baseline values between the two groups was −2.1 (95% CI: −3.6, −0.6) mmHg. Compliance between the groups was similar, suggesting successful blinding. In conclusion, the use of new seasonings and processed foods aimed at lowering blood pressure in free-living settings may be feasible and effective.

Biomarker-estimated flavan-3-ol intake is associated with lower blood pressure in cross-sectional analysis in EPIC Norfolk

Flavan-3-ols are a group of bioactive compounds that have been shown to improve vascular function in intervention studies. They are therefore of great interest for the development of dietary recommendation for the prevention of cardio-vascular diseases. However, there are currently no reliable data from observational studies, as the high variability in the flavan-3-ol content of food makes it difficult to estimate actual intake without nutritional biomarkers. In this study, we investigated cross-sectional associations between biomarker-estimated flavan-3-ol intake and blood pressure and other CVD risk markers, as well as longitudinal associations with CVD risk in 25,618 participants of the European Prospective Investigation into Cancer (EPIC) Norfolk cohort. High flavan-3-ol intake, achievable as part of an habitual diet, was associated with a significantly lower systolic blood pressure (- 1.9 (- 2.7; - 1.1) mmHg in men and - 2.5 (- 3.3; - 1.8) mmHg in women; lowest vs highest decile of biomarker), comparable to adherence to a Mediterranean Diet or moderate salt reduction. Subgroup analyses showed that hypertensive participants had stronger inverse association between flavan-3-ol biomarker and systolic blood pressure when compared to normotensive participants. Flavanol intake could therefore have a role in the maintenance of cardiovascular health on a population scale.

Assessment of groundwater quality for drinking purpose with special emphasis on salinity and nitrate contamination in the shallow aquifer of Guenniche (Northern Tunisia)

Monitoring the groundwater quality situation and identifying the various pollution loads' sources are a prerequisites to finding solutions. In many areas, nitrate and salinity are one of the prime pollutants in the groundwater. This investigation is carried to present the results of a monitoring study focusing on 20 wells samples collected from the shallow groundwater of Guenniche plain (North Tunisia) during the wet season of May 2016, to present its suitability for drinking purposes with emphasis on the assessment of the presence of nitrate and salinity elements. Nitrate levels' results show that 55% of the samples exceeded the National Tunisian standard limit (NT) and the World Health Organization standard limit (WHO). The salinity results, measured as total dissolved solids (TDS), show that 95% of the samples exceed the international standard, and 25% exceed the national standard. A total of 20% of the wells exceeded the nitrite standards. The total hardness levels indicate that 90% of the samples present very hard water. The Guenniche shallow groundwater average concentrations are categorized as follows: Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ for the cations and Cl^- > SO₄^2- > HCO₃^- > NO₃^- for the anions. Nitrate and salinity variations during the period 2006-2015 follow the rainfall fluctuation patterns. The assessment of water quality using Water Quality Index revealed that 95% of the wells' water classes ranged between "poor", "very poor," and "unsuitable for drinking purposes". Therefore, these wells are affected by anthropogenic and/or natural factors and they are inadvisable for drinking purposes, unless the water from these wells undergoes appropriate treatment before use.

Reduction in saturated fat intake for cardiovascular disease

BACKGROUND

Reducing saturated fat reduces serum cholesterol, but effects on other intermediate outcomes may be less clear. Additionally, it is unclear whether the energy from saturated fats eliminated from the diet are more helpfully replaced by polyunsaturated fats, monounsaturated fats, carbohydrate or protein.

OBJECTIVES

To assess the effect of reducing saturated fat intake and replacing it with carbohydrate (CHO), polyunsaturated (PUFA), monounsaturated fat (MUFA) and/or protein on mortality and cardiovascular morbidity, using all available randomised clinical trials.

SEARCH METHODS

We updated our searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and Embase (Ovid) on 15 October 2019, and searched Clinicaltrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) on 17 October 2019.

SELECTION CRITERIA

Included trials fulfilled the following criteria: 1) randomised; 2) intention to reduce saturated fat intake OR intention to alter dietary fats and achieving a reduction in saturated fat; 3) compared with higher saturated fat intake or usual diet; 4) not multifactorial; 5) in adult humans with or without cardiovascular disease (but not acutely ill, pregnant or breastfeeding); 6) intervention duration at least 24 months; 7) mortality or cardiovascular morbidity data available.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed inclusion, extracted study data and assessed risk of bias. We performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity analyses, funnel plots and GRADE assessment.

MAIN RESULTS

We included 15 randomised controlled trials (RCTs) (16 comparisons, 56,675 participants), that used a variety of interventions from providing all food to advice on reducing saturated fat. The included long-term trials suggested that reducing dietary saturated fat reduced the risk of combined cardiovascular events by 17% (risk ratio (RR) 0.83; 95% confidence interval (CI) 0.70 to 0.98, 12 trials, 53,758 participants of whom 8% had a cardiovascular event, I² = 67%, GRADE moderate-quality evidence). Meta-regression suggested that greater reductions in saturated fat (reflected in greater reductions in serum cholesterol) resulted in greater reductions in risk of CVD events, explaining most heterogeneity between trials. The number needed to treat for an additional beneficial outcome (NNTB) was 56 in primary prevention trials, so 56 people need to reduce their saturated fat intake for ~four years for one person to avoid experiencing a CVD event. In secondary prevention trials, the NNTB was 53. Subgrouping did not suggest significant differences between replacement of saturated fat calories with polyunsaturated fat or carbohydrate, and data on replacement with monounsaturated fat and protein was very limited. We found little or no effect of reducing saturated fat on all-cause mortality (RR 0.96; 95% CI 0.90 to 1.03; 11 trials, 55,858 participants) or cardiovascular mortality (RR 0.95; 95% CI 0.80 to 1.12, 10 trials, 53,421 participants), both with GRADE moderate-quality evidence. There was little or no effect of reducing saturated fats on non-fatal myocardial infarction (RR 0.97, 95% CI 0.87 to 1.07) or CHD mortality (RR 0.97, 95% CI 0.82 to 1.16, both low-quality evidence), but effects on total (fatal or non-fatal) myocardial infarction, stroke and CHD events (fatal or non-fatal) were all unclear as the evidence was of very low quality. There was little or no effect on cancer mortality, cancer diagnoses, diabetes diagnosis, HDL cholesterol, serum triglycerides or blood pressure, and small reductions in weight, serum total cholesterol, LDL cholesterol and BMI. There was no evidence of harmful effects of reducing saturated fat intakes.

AUTHORS' CONCLUSIONS

The findings of this updated review suggest that reducing saturated fat intake for at least two years causes a potentially important reduction in combined cardiovascular events. Replacing the energy from saturated fat with polyunsaturated fat or carbohydrate appear to be useful strategies, while effects of replacement with monounsaturated fat are unclear. The reduction in combined cardiovascular events resulting from reducing saturated fat did not alter by study duration, sex or baseline level of cardiovascular risk, but greater reduction in saturated fat caused greater reductions in cardiovascular events.

Reduction in saturated fat intake for cardiovascular disease

BACKGROUND

Reducing saturated fat reduces serum cholesterol, but effects on other intermediate outcomes may be less clear. Additionally, it is unclear whether the energy from saturated fats eliminated from the diet are more helpfully replaced by polyunsaturated fats, monounsaturated fats, carbohydrate or protein.

OBJECTIVES

To assess the effect of reducing saturated fat intake and replacing it with carbohydrate (CHO), polyunsaturated (PUFA), monounsaturated fat (MUFA) and/or protein on mortality and cardiovascular morbidity, using all available randomised clinical trials.

SEARCH METHODS

We updated our searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and Embase (Ovid) on 15 October 2019, and searched Clinicaltrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) on 17 October 2019.

SELECTION CRITERIA

Included trials fulfilled the following criteria: 1) randomised; 2) intention to reduce saturated fat intake OR intention to alter dietary fats and achieving a reduction in saturated fat; 3) compared with higher saturated fat intake or usual diet; 4) not multifactorial; 5) in adult humans with or without cardiovascular disease (but not acutely ill, pregnant or breastfeeding); 6) intervention duration at least 24 months; 7) mortality or cardiovascular morbidity data available.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed inclusion, extracted study data and assessed risk of bias. We performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity analyses, funnel plots and GRADE assessment.

MAIN RESULTS

We included 15 randomised controlled trials (RCTs) (16 comparisons, ~59,000 participants), that used a variety of interventions from providing all food to advice on reducing saturated fat. The included long-term trials suggested that reducing dietary saturated fat reduced the risk of combined cardiovascular events by 21% (risk ratio (RR) 0.79; 95% confidence interval (CI) 0.66 to 0.93, 11 trials, 53,300 participants of whom 8% had a cardiovascular event, I² = 65%, GRADE moderate-quality evidence). Meta-regression suggested that greater reductions in saturated fat (reflected in greater reductions in serum cholesterol) resulted in greater reductions in risk of CVD events, explaining most heterogeneity between trials. The number needed to treat for an additional beneficial outcome (NNTB) was 56 in primary prevention trials, so 56 people need to reduce their saturated fat intake for ~four years for one person to avoid experiencing a CVD event. In secondary prevention trials, the NNTB was 32. Subgrouping did not suggest significant differences between replacement of saturated fat calories with polyunsaturated fat or carbohydrate, and data on replacement with monounsaturated fat and protein was very limited. We found little or no effect of reducing saturated fat on all-cause mortality (RR 0.96; 95% CI 0.90 to 1.03; 11 trials, 55,858 participants) or cardiovascular mortality (RR 0.95; 95% CI 0.80 to 1.12, 10 trials, 53,421 participants), both with GRADE moderate-quality evidence. There was little or no effect of reducing saturated fats on non-fatal myocardial infarction (RR 0.97, 95% CI 0.87 to 1.07) or CHD mortality (RR 0.97, 95% CI 0.82 to 1.16, both low-quality evidence), but effects on total (fatal or non-fatal) myocardial infarction, stroke and CHD events (fatal or non-fatal) were all unclear as the evidence was of very low quality. There was little or no effect on cancer mortality, cancer diagnoses, diabetes diagnosis, HDL cholesterol, serum triglycerides or blood pressure, and small reductions in weight, serum total cholesterol, LDL cholesterol and BMI. There was no evidence of harmful effects of reducing saturated fat intakes.

AUTHORS' CONCLUSIONS

The findings of this updated review suggest that reducing saturated fat intake for at least two years causes a potentially important reduction in combined cardiovascular events. Replacing the energy from saturated fat with polyunsaturated fat or carbohydrate appear to be useful strategies, while effects of replacement with monounsaturated fat are unclear. The reduction in combined cardiovascular events resulting from reducing saturated fat did not alter by study duration, sex or baseline level of cardiovascular risk, but greater reduction in saturated fat caused greater reductions in cardiovascular events.

Dietary reference values for sodium

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

Sodium excretion and associated factors in urine samples of African descendants in Alcântara, Brazil: a population based study

In most countries, salt intake has been excessive and constitutes one of the main risk factors for disease development, especially hypertension. Factors such as age, gender, sedentary lifestyle, smoking, African descent, obesity, dietary habits and family history of hypertension may be associated with high blood pressure. Studies show a positive association between the excretion of sodium and increased blood pressure. We evaluated the urinary excretion of sodium and associated factors in isolated urine samples of African descendants from remaining Quilombos. We performed a cross-sectional, population-based study with 1162 African descendants living in remaining quilombos in Alcântara, Maranhão, Brazil. Demographic, nutritional, clinical and laboratory data were analyzed. Urinary sodium excretion was estimated using the Kawasaki equation. A multivariate linear regression model was used to identify the variables related to sodium excretion. The average age was 37.6 ± 11.8 years and 51.2% were women. The prevalence of hypertension was 21.3%. The average urinary excretion of sodium was high, especially among the hypertensive (217.9 ± 90.1 vs. 199.2 ± 83.0 mmol/d; p = .002). After an adjusted analysis, only the waist circumference (odds ratios (OR) = 1.16; confidence intervals(CI)95%: 1.03-1.30), triglyceride (OR = 1.13; CI95%: 1.05-1.22), systolic blood pressure (OR = 1.19; CI95%: 1.08-1.32) and Chronic Kidney Disease Epidemiology (CKD-EPI;OR = 1.24; CI95%: 1.15-1.35) remained related to urinary sodium excretion. African descendants had a high rate of sodium excretion, especially among those who had hypertension. Abdominal adiposity, triglyceride and systolic blood pressure levels and renal function by CKD-EPI equation were associated to urinary sodium excretion.

Validation of single measurement of 12-hour urine excretion for estimation of sodium and potassium intake. A longitudinal study

BACKGROUND

Evaluation of sodium and potassium intake can be carried out using different methods. Biological markers are able to capture intra and inter-individual variability and are used as separate measurements of consumption. The aim of this study was to test the validity of a single measurement of urinary sodium and potassium excretion as representative of habitual intake.

DESIGN AND SETTING

Longitudinal study, federal university.

METHODS

Food consumption data from a sample of adult university students and public servants (25 to 74 years old) were collected through 24-hour records and 12-hour urinary sodium and potassium excretion at five different times over a one-year period. The dietary data were entered into a nutritional research data software system and the sodium and potassium intakes were estimated. The variables were tested for normal distribution using the Kolmogorov-Smirnov test. One-way analysis of variance or the Kruskal-Wallis test was used to evaluate means. Correlations between measurements using Pearson or Spearman coefficients were calculated. The degree of agreement between the five measurements was given by the intraclass correlation coefficient.

RESULTS

Satisfactory agreement was found between the five measurements of urinary sodium and potassium excretion over a year, with little variability in consumption.

CONCLUSION

A single measurement of urinary sodium and potassium accurately estimated the usual average consumption of these electrolytes. This can be used in population-based studies.

Understanding the Two Faces of Low-Salt Intake

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

Identification of differences in health impact modelling of salt reduction

We examined whether specific input data and assumptions explain outcome differences in otherwise comparable health impact assessment models. Seven population health models estimating the impact of salt reduction on morbidity and mortality in western populations were compared on four sets of key features, their underlying assumptions and input data. Next, assumptions and input data were varied one by one in a default approach (the DYNAMO-HIA model) to examine how it influences the estimated health impact. Major differences in outcome were related to the size and shape of the dose-response relation between salt and blood pressure and blood pressure and disease. Modifying the effect sizes in the salt to health association resulted in the largest change in health impact estimates (33% lower), whereas other changes had less influence. Differences in health impact assessment model structure and input data may affect the health impact estimate. Therefore, clearly defined assumptions and transparent reporting for different models is crucial. However, the estimated impact of salt reduction was substantial in all of the models used, emphasizing the need for public health actions.

Taxes and Subsidies for Improving Diet and Population Health in Australia: A Cost-Effectiveness Modelling Study

BACKGROUND

An increasing number of countries are implementing taxes on unhealthy foods and drinks to address the growing burden of dietary-related disease, but the cost-effectiveness of combining taxes on unhealthy foods and subsidies on healthy foods is not well understood.

METHODS AND FINDINGS

Using a population model of dietary-related diseases and health care costs and food price elasticities, we simulated the effect of taxes on saturated fat, salt, sugar, and sugar-sweetened beverages and a subsidy on fruits and vegetables, over the lifetime of the Australian population. The sizes of the taxes and subsidy were set such that, when combined as a package, there would be a negligible effect on average weekly expenditure on food (<1% change). We evaluated the cost-effectiveness of the interventions individually, then determined the optimal combination based on maximising net monetary benefit at a threshold of AU$50,000 per disability-adjusted life year (DALY). The simulations suggested that the combination of taxes and subsidy might avert as many as 470,000 DALYs (95% uncertainty interval [UI]: 420,000 to 510,000) in the Australian population of 22 million, with a net cost-saving of AU$3.4 billion (95% UI: AU$2.4 billion to AU$4.6 billion; US$2.3 billion) to the health sector. Of the taxes evaluated, the sugar tax produced the biggest estimates of health gain (270,000 [95% UI: 250,000 to 290,000] DALYs averted), followed by the salt tax (130,000 [95% UI: 120,000 to 140,000] DALYs), the saturated fat tax (97,000 [95% UI: 77,000 to 120,000] DALYs), and the sugar-sweetened beverage tax (12,000 [95% UI: 2,100 to 21,000] DALYs). The fruit and vegetable subsidy (-13,000 [95% UI: -44,000 to 18,000] DALYs) was a cost-effective addition to the package of taxes. However, it did not necessarily lead to a net health benefit for the population when modelled as an intervention on its own, because of the possible adverse cross-price elasticity effects on consumption of other foods (e.g., foods high in saturated fat and salt). The study suggests that taxes and subsidies on foods and beverages can potentially be combined to achieve substantial improvements in population health and cost-savings to the health sector. However, the magnitude of health benefits is sensitive to measures of price elasticity, and further work is needed to incorporate potential benefits or harms associated with changes in other foods and nutrients that are not currently modelled, such as red and processed meats and fibre.

CONCLUSIONS

With potentially large health benefits for the Australian population and large benefits in reducing health sector spending on the treatment of non-communicable diseases, the formulation of a tax and subsidy package should be given a more prominent role in Australia's public health nutrition strategy.

The health gains and cost savings of dietary salt reduction interventions, with equity and age distributional aspects

BACKGROUND

A "diet high in sodium" is the second most important dietary risk factor for health loss identified in the Global Burden of Disease Study 2013. We therefore aimed to model health gains and costs (savings) of salt reduction interventions related to salt substitution and maximum levels in bread, including by ethnicity and age. We also ranked these four interventions compared to eight other modelled interventions.

METHODS

A Markov macro-simulation model was used to estimate QALYs gained and net health system costs for four dietary sodium reduction interventions, discounted at 3 % per annum. The setting was New Zealand (NZ) (2.3 million adults, aged 35+ years) which has detailed individual-level administrative cost data.

RESULTS

The health gain was greatest for an intervention where most (59 %) of the sodium in processed foods was replaced by potassium and magnesium salts. This intervention gained 294,000 QALYs over the remaining lifetime of the cohort (95 % UI: 238,000 to 359,000; 0.13 QALY per 35+ year old). Such salt substitution also produced the highest net cost-savings of NZ$ 1.5 billion (US$ 1.0 billion) (95 % UI: NZ$ 1.1 to 2.0 billion). All interventions generated relatively larger per capita QALYs for men vs women and for the indigenous Māori population vs non-Māori (e.g., 0.16 vs 0.12 QALYs per adult for the 59 % salt substitution intervention). Of relevance to workforce productivity, in the first 10 years post-intervention, 22 % of the QALY gain was among those aged <65 years (and 37 % for those aged <70).

CONCLUSIONS

The benefits are consistent with the international literature, with large health gains and cost savings possible from some, but not all, sodium reduction interventions. Health gain appears likely to occur among working-age adults and all interventions contributed to reducing health inequalities.

Modeling health gains and cost savings for ten dietary salt reduction targets

BACKGROUND

Dietary salt reduction is included in the top five priority actions for non-communicable disease control internationally. We therefore aimed to identify health gain and cost impacts of achieving a national target for sodium reduction, along with component targets in different food groups.

METHODS

We used an established dietary sodium intervention model to study 10 interventions to achieve sodium reduction targets. The 2011 New Zealand (NZ) adult population (2.3 million aged 35+ years) was simulated over the remainder of their lifetime in a Markov model with a 3 % discount rate.

RESULTS

Achieving an overall 35 % reduction in dietary salt intake via implementation of mandatory maximum levels of sodium in packaged foods along with reduced sodium from fast foods/restaurant food and discretionary intake (the "full target"), was estimated to gain 235,000 QALYs over the lifetime of the cohort (95 % uncertainty interval [UI]: 176,000 to 298,000). For specific target components the range was from 122,000 QALYs gained (for the packaged foods target) down to the snack foods target (6100 QALYs; and representing a 34-48 % sodium reduction in such products). All ten target interventions studied were cost-saving, with the greatest costs saved for the mandatory "full target" at NZ$1260 million (US$820 million). There were relatively greater health gains per adult for men and for Māori (indigenous population).

CONCLUSIONS

This work provides modeling-level evidence that achieving dietary sodium reduction targets (including specific food category targets) could generate large health gains and cost savings for a national health sector. Demographic groups with the highest cardiovascular disease rates stand to gain most, assisting in reducing health inequalities between sex and ethnic groups.

Changes in Body Weight From Young Adulthood to Middle Age and Its Association With Blood Pressure and Hypertension: A Cross-Sectional Study in Hong Kong Chinese Women

BACKGROUND

Few studies have examined the associations of weight changes from young adulthood to middle age with blood pressure (BP) and hypertension among Hong Kong Chinese women.

METHODS AND RESULTS

Weight at age 18 (W18), current weight (Wcurrent), height, BP, demographics, and lifestyle factors were obtained from 1253 female nurses (35-65 years) by a self-administered questionnaire through mail survey in Hong Kong. The conditional relative weight (CRW; a residual of Wcurrent regressed on W18) was used to express the relative weight change from age 18 to current age. The study results show that from young adulthood to middle age, 76.9%, 15.1%, and 8.0% of women had weight gain, weight loss, and stable weight, respectively. Women in the weight loss group had heavier W18 than those in the weight gain group (P<0.05). Higher weight gain was associated with higher BP (P for trend <0.01). Women who belonged to the heaviest 10% both at age 18 and at present had highest BP than women in other weight categories. By giving W18, a 1-kg increase in weight change predicted 0.63 and 0.42 mm Hg increases in systolic and diastolic BP, respectively (both P<0.001) and 12% greater odds of being hypertension (95% confidence interval, 1.08, 1.17). The CRW was positively associated with BP and hypertension; no interaction was found between CRW and Wcurrent on BP/hypertension.

CONCLUSIONS

A majority of Chinese women tended to become heavier throughout adult life. More weight gain led to the higher BP. Weight change is an independent predictor for later-life BP and hypertension.

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

AIMS

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

METHODS AND RESULTS

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

CONCLUSION

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

Effects of a behavioral intervention that emphasizes spices and herbs on adherence to recommended sodium intake: results of the SPICE randomized clinical trial

BACKGROUND

For decades, dietary sodium intake in the United States has remained high, and few studies have examined strategies for maintaining recommended intakes.

OBJECTIVE

We examined the effects of a behavioral intervention, which emphasized spices and herbs, on the maintenance of sodium intake at the recommended intake of 1500 mg/d in individuals to whom the US Dietary Guidelines for Americans apply.

DESIGN

We conducted a 2-phase study that included adults ≥18 y of age for whom Dietary Guidelines for Americans recommends 1500 mg Na/d. The study was conducted in Baltimore, Maryland, from 2012 to 2014. In phase 1, 55 individuals consumed a low-sodium diet for 4 wk. Participants were provided all foods, snacks, and calorie-containing drinks. In phase 2, 40 participants from phase 1 were randomly assigned to either a behavioral intervention to reduce sodium intake (n = 20) or a self-directed control group (n = 20) for 20 wk. The primary study outcome was the change in mean 24-h urinary sodium excretion during phase 2. Linear regression analyses were used to determine intervention effects on urinary sodium excretion.

RESULTS

Participant characteristics were as follows: women: 65%; African American: 88%; hypertension: 63%; diabetes: 18%; mean age: 61 y; and mean body mass index (in kg/m(2)): 30. At the end of phase 2, mean 24-h sodium excretion was lower in the behavioral intervention than in the self-directed group (mean difference: -956.8 mg/d; 95% CI: -1538.7, -374.9 mg/d) after sodium intake at screening was controlled for (P = 0.002). These findings persisted in sensitivity analyses that excluded potentially incomplete urine collections [Mage's equation mean difference: -1090 mg/d (P = 0.001); Joosens' equation mean difference: -796 mg/d (P = 0.04)].

CONCLUSIONS

A multifactorial behavioral intervention emphasizing spices and herbs significantly reduced sodium intake. Because of the ubiquity of sodium in the US food supply, multilevel strategies addressing individual behaviors and the food supply are needed to improve adherence to recommendations. This trial was registered at clinicaltrials.gov as NCT01615159.

Reduction in saturated fat intake for cardiovascular disease

BACKGROUND

Reducing saturated fat reduces serum cholesterol, but effects on other intermediate outcomes may be less clear. Additionally it is unclear whether the energy from saturated fats that are lost in the diet are more helpfully replaced by polyunsaturated fats, monounsaturated fats, carbohydrate or protein. This review is part of a series split from and updating an overarching review.

OBJECTIVES

To assess the effect of reducing saturated fat intake and replacing it with carbohydrate (CHO), polyunsaturated (PUFA) or monounsaturated fat (MUFA) and/or protein on mortality and cardiovascular morbidity, using all available randomised clinical trials.

SEARCH METHODS

We updated our searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and EMBASE (Ovid) on 5 March 2014. We also checked references of included studies and reviews.

SELECTION CRITERIA

Trials fulfilled the following criteria: 1) randomised with appropriate control group; 2) intention to reduce saturated fat intake OR intention to alter dietary fats and achieving a reduction in saturated fat; 3) not multifactorial; 4) adult humans with or without cardiovascular disease (but not acutely ill, pregnant or breastfeeding); 5) intervention at least 24 months; 6) mortality or cardiovascular morbidity data available.

DATA COLLECTION AND ANALYSIS

Two review authors working independently extracted participant numbers experiencing health outcomes in each arm, and we performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity analyses and funnel plots.

MAIN RESULTS

We include 15 randomised controlled trials (RCTs) (17 comparisons, ˜59,000 participants), which used a variety of interventions from providing all food to advice on how to reduce saturated fat. The included long-term trials suggested that reducing dietary saturated fat reduced the risk of cardiovascular events by 17% (risk ratio (RR) 0.83; 95% confidence interval (CI) 0.72 to 0.96, 13 comparisons, 53,300 participants of whom 8% had a cardiovascular event, I² 65%, GRADE moderate quality of evidence), but effects on all-cause mortality (RR 0.97; 95% CI 0.90 to 1.05; 12 trials, 55,858 participants) and cardiovascular mortality (RR 0.95; 95% CI 0.80 to 1.12, 12 trials, 53,421 participants) were less clear (both GRADE moderate quality of evidence). There was some evidence that reducing saturated fats reduced the risk of myocardial infarction (fatal and non-fatal, RR 0.90; 95% CI 0.80 to 1.01; 11 trials, 53,167 participants), but evidence for non-fatal myocardial infarction (RR 0.95; 95% CI 0.80 to 1.13; 9 trials, 52,834 participants) was unclear and there were no clear effects on stroke (any stroke, RR 1.00; 95% CI 0.89 to 1.12; 8 trials, 50,952 participants). These relationships did not alter with sensitivity analysis. Subgrouping suggested that the reduction in cardiovascular events was seen in studies that primarily replaced saturated fat calories with polyunsaturated fat, and no effects were seen in studies replacing saturated fat with carbohydrate or protein, but effects in studies replacing with monounsaturated fats were unclear (as we located only one small trial). Subgrouping and meta-regression suggested that the degree of reduction in cardiovascular events was related to the degree of reduction of serum total cholesterol, and there were suggestions of greater protection with greater saturated fat reduction or greater increase in polyunsaturated and monounsaturated fats. There was no evidence of harmful effects of reducing saturated fat intakes on cancer mortality, cancer diagnoses or blood pressure, while there was some evidence of improvements in weight and BMI.

AUTHORS' CONCLUSIONS

The findings of this updated review are suggestive of a small but potentially important reduction in cardiovascular risk on reduction of saturated fat intake. Replacing the energy from saturated fat with polyunsaturated fat appears to be a useful strategy, and replacement with carbohydrate appears less useful, but effects of replacement with monounsaturated fat were unclear due to inclusion of only one small trial. This effect did not appear to alter by study duration, sex or baseline level of cardiovascular risk. Lifestyle advice to all those at risk of cardiovascular disease and to lower risk population groups should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturated fats. The ideal type of unsaturated fat is unclear.

Potassium urinary excretion and dietary intake: a cross-sectional analysis in 8-10 year-old children

BACKGROUND

Data from studies assessing the intake of potassium, and the concomitant sodium-to-potassium ratio are limited. The aim of this study was to evaluate potassium and sodium-to-potassium ratio intake in 8-10 year-old children.

METHODS

A cross-sectional survey was carried out from January to June 2014 and data from 163 children (81 boys) were included. Potassium intake was estimated by 24-h urine collection and coefficient of creatinine was used to validate completeness of urine collections. Urinary sodium and sodium-to-potassium ratio were also analysed. A 24-h dietary recall was used to provide information on dietary sources of potassium. Height and weight were measured according to international standards.

RESULTS

The mean urinary potassium excretion was 1701 ± 594 mg/day in boys, and 1682 ± 541 mg/day in girls (p = 0.835); 8.0% of children met the WHO recommendations for potassium intake. The mean sodium excretion was 2935 ± 1075 mg/day in boys and 2381 ± 1045 mg/day in girls (p <0.001) and urinary sodium-to-potassium ratio was 3.2 ± 1.4 in boys, and 2.5 ± 1.1 in girls (p = 0.002). The mean fruit and vegetable intake was 353.1 ± 232.5 g/day in boys, and 290.8 ± 213.1 g/day in girls (p = 0.101).

CONCLUSIONS

This study reported a low compliance of potassium intake recommendations in 8-10 year-old children. Health promotion interventions are needed in order to broaden public awareness of potassium inadequacy and to increase potassium intake.

Health and economic impacts of eight different dietary salt reduction interventions

BACKGROUND

Given the high importance of dietary sodium (salt) as a global disease risk factor, our objective was to compare the impact of eight sodium reduction interventions, including feasible and more theoretical ones, to assist prioritisation.

METHODS

Epidemiological modelling and cost-utility analysis were performed using a Markov macro-simulation model. The setting was New Zealand (NZ) (2.3 million citizens, aged 35+ years) which has detailed individual-level administrative cost data.

RESULTS

Of the most feasible interventions, the largest health gains were from (in descending order): (i) mandatory 25% reduction in sodium levels in all processed foods; (ii) the package of interventions performed in the United Kingdom (UK); (iii) mandatory 25% reduction in sodium levels in bread, processed meats and sauces; (iv) media campaign (as per a previous UK one); (v) voluntary food labelling as currently used in NZ; (vi) dietary counselling as currently used in NZ. Even larger health gains came from the more theoretical options of a "sinking lid" on the amount of food salt released to the national market to achieve an average adult intake of 2300 mg sodium/day (211,000 QALYs gained, 95% uncertainty interval: 170,000-255,000), and from a salt tax. All the interventions produced net cost savings (except counseling--albeit still cost-effective). Cost savings were especially large with the sinking lid (NZ$ 1.1 billion, US$ 0.7 billion). Also the salt tax would raise revenue (up to NZ$ 452 million/year). Health gain per person was greater for Māori (indigenous population) men and women compared to non-Māori.

CONCLUSIONS

This study substantially expands on the range of previously modelled salt reduction interventions and suggests that some of these might achieve major health gains and major cost savings (particularly the regulatory interventions). They could also reduce ethnic inequalities in health.

Reduced dietary salt for the prevention of cardiovascular disease

BACKGROUND

This is an update of a Cochrane review that was first published in 2011 of the effects of reducing dietary salt intake, through advice to reduce salt intake or low-sodium salt substitution, on mortality and cardiovascular events.

OBJECTIVES

1. To assess the long-term effects of advice and salt substitution, aimed at reducing dietary salt, on mortality and cardiovascular morbidity.2. To investigate whether a reduction in blood pressure is an explanatory factor in the effect of such dietary interventions on mortality and cardiovascular outcomes.

SEARCH METHODS

We updated the searches of CENTRAL (2013, Issue 4), MEDLINE (OVID, 1946 to April week 3 2013), EMBASE (OVID, 1947 to 30 April 2013) and CINAHL (EBSCO, inception to 1 April 2013) and last ran these on 1 May 2013. We also checked the references of included studies and reviews. We applied no language restrictions.

SELECTION CRITERIA

Trials fulfilled the following criteria: (1) randomised, with follow-up of at least six months, (2) the intervention was reduced dietary salt (through advice to reduce salt intake or low-sodium salt substitution), (3) participants were adults and (4) mortality or cardiovascular morbidity data were available. Two review authors independently assessed whether studies met these criteria.

DATA COLLECTION AND ANALYSIS

A single author extracted data and assessed study validity, and a second author checked this. We contacted trial authors where possible to obtain missing information. We extracted events and calculated risk ratios (RRs) and 95% confidence intervals (CIs).

MAIN RESULTS

Eight studies met the inclusion criteria: three in normotensives (n = 3518) and five in hypertensives or mixed populations of normo- and hypertensives (n = 3766). End of trial follow-up ranged from six to 36 months and the longest observational follow-up (after trial end) was 12.7 years.The risk ratios (RR) for all-cause mortality in normotensives were imprecise and showed no evidence of reduction (end of trial RR 0.67, 95% confidence interval (CI) 0.40 to 1.12, 60 deaths; longest follow-up RR 0.90, 95% CI 0.58 to 1.40, 79 deaths n=3518) or in hypertensives (end of trial RR 1.00, 95% CI 0.86 to 1.15, 565 deaths; longest follow-up RR 0.99, 95% CI 0.87 to 1.14, 674 deaths n=3085). There was weak evidence of benefit for cardiovascular mortality (hypertensives: end of trial RR 0.67, 95% CI 0.45 to 1.01, 106 events n=2656) and for cardiovascular events (hypertensives: end of trial RR 0.76, 95% CI 0.57 to 1.01, 194 events, four studies, n = 3397; normotensives: at longest follow-up RR 0.71, 95% CI 0.42 to 1.20, 200 events; hypertensives: RR 0.77, 95% CI 0.57 to 1.02, 192 events; pooled analysis of six trials RR 0.77, 95% CI 0.63 to 0.95, n = 5912). These findings were driven by one trial among retirement home residents that reduced salt intake in the kitchens of the homes, thereby not requiring individual behaviour change.Advice to reduce salt showed small reductions in systolic blood pressure (mean difference (MD) -1.15 mmHg, 95% CI -2.32 to 0.02 n=2079) and diastolic blood pressure (MD -0.80 mmHg, 95% CI -1.37 to -0.23 n=2079) in normotensives and greater reductions in systolic blood pressure in hypertensives (MD -4.14 mmHg, 95% CI -5.84 to -2.43 n=675), but no difference in diastolic blood pressure (MD -3.74 mmHg, 95% CI -8.41 to 0.93 n=675).Overall many of the trials failed to report sufficient detail to assess their potential risk of bias. Health-related quality of life was assessed in one trial in normotensives, which reported significant improvements in well-being but no data were presented.

AUTHORS' CONCLUSIONS

Despite collating more event data than previous systematic reviews of randomised controlled trials, there is insufficient power to confirm clinically important effects of dietary advice and salt substitution on cardiovascular mortality in normotensive or hypertensive populations. Our estimates of the clinical benefits from advice to reduce dietary salt are imprecise, but are larger than would be predicted from the small blood pressure reductions achieved. Further well-powered studies would be needed to obtain more precise estimates. Our findings do not support individual dietary advice as a means of restricting salt intake. It is possible that alternative strategies that do not require individual behaviour change may be effective and merit further trials.

Quantifying the health benefits of chronic disease prevention: a fresh approach using cardiovascular disease as an example

Current methods of determining the proportion of people who benefit from a preventive intervention and the years of life gained can underestimate the former and overestimate the latter. We describe how to overcome these errors, using two examples relating to the prevention of myocardial infarction (MI) and stroke, one using a specified polypill daily from age 50 and another reducing salt intake in the population. Standard life table analysis was used to calculate the person-years of life gained without an MI or stroke, based on estimates of the incidence of these disorders in England and Wales. The proportion of individuals who benefit was taken as everyone who would, without treatment, have an MI or stroke (holistic model), rather than limiting the benefit to the proportion calculated from the relative risk reduction (reductionist model), as is current practice. Under the holistic model, 33% of people who take the polypill from age 50 benefit, gaining, on average, 8 years of life without an MI or stroke (19% and 14 years under the reductionist model). Estimates for reducing salt intake by 6 g/day are 33% and 2.8 years respectively under the holistic model (6% and 16 years under the reductionist model). In the prevention of disorders such as stroke by reducing exposure to causal factors such as blood pressure, the use of a holistic model corrects the underestimation of the proportion of people who benefit and the overestimation of their years of life gained associated with current methods.

The impact of sodium and potassium on hypertension risk

The pathogenic role of sodium surfeit in primary hypertension is widely recognized but that of potassium deficiency usually has been ignored or at best assigned subsidiary status. Weighing the available evidence, we recently proposed that the chief environmental factor in the pathogenesis of primary hypertension and the associated cardiovascular risk is the interaction of the sodium surfeit and potassium deficiency in the body. Here, we present the major evidence highlighting the relationship between high-sodium intake and hypertension. We then examine the blood pressure-lowering effects of potassium in conjunction with the pernicious impact of potassium deficiency on hypertension and cardiovascular risk. We conclude with summarizing recent human trials that have probed the joint effects of sodium and potassium intake on hypertension and its cardiovascular sequelae. The latter studies lend considerable fresh support to the thesis that the interaction of the sodium surfeit and potassium deficiency in the body, rather than either disturbance by itself, is the critical environmental factor in the pathogenesis of hypertension.

Drop the Salt! Assessing the impact of a public health advocacy strategy on Australian government policy on salt

OBJECTIVE

In 2007 the Australian Division of World Action on Salt and Health (AWASH) launched a campaign to encourage the Australian government to take action to reduce population salt intake. The objective of the present research was to assess the impact of the Drop the Salt! campaign on government policy.

DESIGN

A review of government activities related to salt reduction was conducted and an advocacy strategy implemented to increase government action on salt. Advocacy actions were documented and the resulting outcomes identified. An analysis of stakeholder views on the effectiveness of the advocacy strategy was also undertaken. Settings Advocacy activities were coordinated through AWASH at the George Institute for Global Health in Sydney.

SUBJECTS

All relevant State and Federal government statements and actions were reviewed and thirteen stakeholders with known interests or responsibilities regarding dietary salt, including food industry, government and health organisations, were interviewed.

RESULTS

Stakeholder analysis affirmed that AWASH influenced the government's agenda on salt reduction and four key outputs were attributed to the campaign: (i) the Food Regulation Standing Committee discussions on salt, (ii) the Food and Health Dialogue salt targets, (iii) National Health and Medical Research Council partnership funding and (iv) the New South Wales Premier's Forum on Fast Foods.

CONCLUSIONS

While it is not possible to definitively attribute changes in government policy to one organisation, stakeholder research indicated that the AWASH campaign increased the priority of salt reduction on the government's agenda. However, a coordinated government strategy on salt reduction is still required to ensure that the potential health benefits are fully realised.

DASH diet score and distribution of blood pressure in middle-aged men and women

BACKGROUND

The Dietary Approaches to Stop Hypertension (DASH) Trial provides critical data on the impact of a specific diet pattern (low in salt, fat, and processed foods and high in fruit and vegetables) on blood pressure (BP). The effect of compliance with a DASH-type diet on BP in a general population sample is less well defined. We studied associations between a DASH style diet and BP.

METHODS

We used cross-sectional data from a study of men and women aged 47-73 years (n = 2,047). Participants completed a physical examination that included 3 standardized clinical BP recordings. A subsample (n = 1,187) had ambulatory BP measurements (ABPM) taken. Diet was assessed using a DASH dietary score constructed from a standard Food Frequency Questionnaire. Lower scores indicated less healthy diets. Hypertension was defined as clinic BP ≥ 140/90 mm Hg on medication or as 24-hour ABPM ≥ 130/80 mmHg.

RESULTS

Inverse associations were evident between DASH and systolic BP (SBP). There was a difference in clinic SBP of 7.5 mm Hg and 5.1 mm Hg and a difference in ABPM SBP of 6.3mm Hg and 5.4mm Hg in men and women, respectively, between the highest and lowest DASH quintiles. In fully adjusted multivariable regression analysis, DASH score was inversely associated with SBP. Clear population differences in SBP were evident across DASH quintiles.

CONCLUSIONS

The observed associations indicate that the findings are consistent with the hypothesis that adherence to DASH-equivalent diet can reduce BP at the population level. Public policy promoting a DASH-style healthy diet could have a significant impact on population health by reducing average BP in the population.

High dietary sodium intake impairs endothelium-dependent dilation in healthy salt-resistant humans

BACKGROUND

Excess dietary sodium has been linked to the development of hypertension and other cardiovascular diseases. In humans, the effects of sodium consumption on endothelial function have not been separated from the effects on blood pressure. The present study was designed to determine if dietary sodium intake affected endothelium-dependent dilation (EDD) independently of changes in blood pressure.

METHOD

Fourteen healthy salt-resistant adults were studied (9M, 5F; age 33 ± 2.4 years) in a controlled feeding study. After a baseline run-in diet, participants were randomized to a 7-day high-sodium (300-350 mmol/day) and 7-day low-sodium (20 mmol/day) diet. Salt resistance, defined as a 5 mmHg or less change in a 24-h mean arterial pressure, was individually assessed while on the low-sodium and high-sodium diets and confirmed in the participants undergoing study (low-sodium: 85 ± 1 mmHg; high-sodium: 85 ± 2 mmHg). EDD was determined in each participant via brachial artery flow-mediated dilation on the last day of each diet.

RESULTS

Sodium excretion increased during the high-sodium diet (P < 0.01). EDD was reduced on the high-sodium diet (low: 10.3 ± 0.9%, high: 7.3 ± 0.7%; P < 0.05). The high-sodium diet significantly suppressed plasma renin activity (PRA), plasma angiotensin II, and aldosterone (P < 0.05).

CONCLUSION

These data demonstrate that excess salt intake in humans impairs endothelium-dependent dilation independently of changes in blood pressure.

Atrial endothelial impairment through Toll-like receptor 4 signaling causes atrial thrombogenesis

Low-grade inflammation associated with heart failure (HF) is known to deteriorate cardioembolic stroke in patients with atrial fibrillation (AF). Little is known about the relationship between atrial endothelial impairment induced by innate immunity and thrombus formation. We examined whether atrial endothelial impairment through Toll-like receptor (TLR) 4 signaling causes atrial thrombogenesis. TLR4, heat shock protein 60, and vascular cell adhesion molecule (VCAM)-1 expression were higher in the atrium of AF patients who underwent valve replacement surgery with HF compared with those without it (p < 0.05). We created thoracic transverse aortic constriction (TAC) in TLR4 knock-out (KO) and wild-type (WT) mice. Atrial thrombosis was observed less frequently in TLR4 KO mice (4/15) than in WT mice (16/20) 4 weeks after TAC despite similar severity of heart failure. The decrease in endothelial nitric oxide synthase (eNOS) phosphorylation and increase in VCAM-1 and plasminogen activator inhibitor (PAI)-1 expression, observed in the atrium of WT mice following TAC, were significantly attenuated in TLR4 KO mice (p < 0.05). Nuclear factor-κB (NF-κB) activation after TAC was attenuated in TLR4 KO mice compared with WT mice. Activation of mitogen-activated protein kinase p38 (p38) after TAC was also attenuated in TLR4 KO mice (p < 0.05). Thus, increased VCAM-1 and PAI-1, and decreased eNOS phosphorylation through the TLR4/NFκB/p38 pathway, may be associated with atrial thrombogenesis in the heart failure mice model. Atrial endothelial impairment through the TLR4 signaling may play a role in atrial thrombogenesis in AF patients with HF.

Associations between dietary patterns and hypertension among Korean adults: the Korean National Health and Nutrition Examination Survey (2008-2010)

The objective of this study is to identify the dietary patterns associated with the risk of hypertensions among Korean adults using data from the Korean National Health and Nutrition Examination Survey (KNHANES, 2008-2010). This study analyzes data from 11,883 subjects who participated in the health and nutrition survey, aging from 20 to 64 years. We performed factor analysis based on the weekly mean intake frequencies of 36 food groups to identify major dietary patterns. We identified three major dietary patterns in both sexes, namely "traditional", "western" and "dairy and carbohydrate" patterns. Participants in the highest quartile of western pattern scores had significantly higher blood pressure, serum total cholesterol, and triglyceride levels than those in the lowest quartile. Although not statistically significant, a trend (P for trend = 0.0732) toward a positive association between the western dietary pattern and hypertension risk was observed after adjustments for age, sex, education, income, body mass index (BMI), smoking, physical activity, and energy intake. The dairy and carbohydrate pattern was inversely related with BMI and blood pressures and positively associated with serum high-density lipoprotein (HDL)-cholesterol. After adjusting the age, sex, education, income, BMI, smoking, physical activity and energy intake, the dairy and carbohydrate pattern showed inverse associations with hypertension prevalence (OR = 0.64, 95% CI = 0.55-0.75; P for trend < 0.0001). Intakes of fiber, sodium, and antioxidant vitamins were significantly higher in the top quartile for the traditional pattern than in the lowest quartile for the traditional pattern (P for trend < 0.0001). Intakes of fiber (P for trend < 0.0001), calcium (P for trend < 0.0001), retinol (P for trend = 0.0164), vitamin B₁ (P for trend = 0.001), vitamin B₂ (P for trend < 0.0001), niacin (P for trend = 0.0025), and vitamin C (P for trend < 0.0001) were significantly increased across quartiles for the dairy and carbohydrate pattern whereas sodium (P for trend < 0.0001) intake was decreased for this pattern. In conclusion, the dairy and carbohydrate pattern may be associated with a reduced risk of hypertension whereas the western pattern may be associated with an increased risk of hypertension among Korean adults.

Sodium in the food supply: challenges and opportunities

This article is based on proceedings from the Symposium on Sodium in the Food Supply: Challenges and Opportunities, sponsored by the North American Branch of the International Life Sciences Institute, at Experimental Biology 2010 in Anaheim, California. The symposium aimed to address the issue of dietary sodium and its consequences for public health. Presenters spoke on a variety of key topics, including salt taste reception mechanisms and preferences, methods and measures to assess sodium in the US food supply, and considerations regarding the reduction of sodium in processed foods. Information from these presentations, as well as literature references, are provided in this article.

The impact of salt and fat level variation on the physiochemical properties and sensory quality of pork breakfast sausages

The sensory and physiochemical properties of sausages with varying fat and salt levels were investigated. Twenty eight sausages were produced with varying concentrations of fat (22.5%, 27.5%, 32.5%, 37.5% w/w) and salt (0.8%, 1%, 1.2%, 1.4%, 1.6%, 2%, 2.4% w/w). Sausages were assessed instrumentally for colour, moisture, fat, cooking loss and texture profile analysis. Consumers (n = 25), evaluated each product in duplicate for colour, texture, tenderness, juiciness, salt taste, meat flavour, off-flavour and overall acceptability using a hedonic scale. Lowering fat produced products which consumers rated as less dark in colour, tougher, less juicy and taste less salty than higher fat products. However, no significant preferred sample was found amongst consumers. Salt reduction in products produced sausages which consumers rated as paler in colour, more tender and with greater meat flavour than higher salt containing products. The sausages containing 1.4% and 1.0% salt were significantly (P<0.01) found to be more acceptable to consumers than other salt levels.

Effects of a diet high in salt, fat, and sugar on telemetric blood pressure measurements in conscious, unrestrained adult Yucatan miniature swine (Sus scrofa)

Radiotelemetry was used to evaluate diet-related elevation of blood pressure in adult Yucatan miniature swine. Systolic arterial blood pressure (SAP), diastolic atrial blood pressure (DAP), heart rate, and locomotor activity were assessed in 9- or 11-mo-old Yucatan miniature pigs fed a standard diet or a North American-type diet high in salt, fat, and sugar (HSFS). Compared with pigs fed standard diet, pigs fed HSFS diet showed markedly elevated SAP (132 ± 3 compared with 156 ± 6 mm Hg), whereas DAP was unchanged (92 ± 2 compared with 99 ± 5 mm Hg). In addition, all pigs were modestly sensitive to short-term changes in dietary salt, as indicated by a 6% to 7% response in blood pressure parameters. According to these data, the increase in SAP for pigs on the HSFS diet was too large to be explained by the NaCl content of the diet alone. We found no evidence of endothelial dysfunction, and the relaxation responses of isolated coronary arteries actually were enhanced in the HSFS group. In conclusion, in a Yucatan miniature pigs model chronically fed a HSFS diet, DAP did not increase, but SAP and pulse pressure appeared to be affected by high dietary levels of fat or sugar (or both).

Which interventions offer best value for money in primary prevention of cardiovascular disease?

BACKGROUND

Despite many decades of declining mortality rates in the Western world, cardiovascular disease remains the leading cause of death worldwide. In this research we evaluate the optimal mix of lifestyle, pharmaceutical and population-wide interventions for primary prevention of cardiovascular disease.

METHODS AND FINDINGS

In a discrete time Markov model we simulate the ischaemic heart disease and stroke outcomes and cost impacts of intervention over the lifetime of all Australian men and women, aged 35 to 84 years, who have never experienced a heart disease or stroke event. Best value for money is achieved by mandating moderate limits on salt in the manufacture of bread, margarine and cereal. A combination of diuretic, calcium channel blocker, ACE inhibitor and low-cost statin, for everyone with at least 5% five-year risk of cardiovascular disease, is also cost-effective, but lifestyle interventions aiming to change risky dietary and exercise behaviours are extremely poor value for money and have little population health benefit.

CONCLUSIONS

There is huge potential for improving efficiency in cardiovascular disease prevention in Australia. A tougher approach from Government to mandating limits on salt in processed foods and reducing excessive statin prices, and a shift away from lifestyle counselling to more efficient absolute risk-based prescription of preventive drugs, could cut health care costs while improving population health.

Salt intake, plasma sodium, and worldwide salt reduction

There is overwhelming evidence that a reduction in salt intake from the current level of approximately 9-12 g/d in most countries of the world to the recommended level of 5-6 g/d lowers blood pressure (BP) in both hypertensive and normotensive individuals. A further reduction to 3-4 g/d has a greater effect. Prospective studies and outcome trials have demonstrated that a lower salt intake is related to a reduced risk of cardiovascular disease. Cost-effectiveness analyses have documented that salt reduction is more or at the very least just as cost-effective as tobacco control in reducing cardiovascular disease, the leading cause of death and disability worldwide. The mechanisms whereby salt raises blood pressure and increases cardiovascular risk are not fully understood. The existing concepts focus on the tendency for an increase in extracellular fluid volume. Increasing evidence suggests that small increases in plasma sodium may have a direct effect on BP and the cardiovascular system, independent of extracellular volume. All countries should adopt a coherent and workable strategy to reduce salt intake in the whole population. Even a modest reduction in population salt intake will have major beneficial effects on health, along with major cost savings.

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

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

Reduced or modified dietary fat for preventing cardiovascular disease

BACKGROUND

Reduction and modification of dietary fats have differing effects on cardiovascular risk factors (such as serum cholesterol), but their effects on important health outcomes are less clear.

OBJECTIVES

To assess the effect of reduction and/or modification of dietary fats on mortality, cardiovascular mortality, cardiovascular morbidity and individual outcomes including myocardial infarction, stroke and cancer diagnoses in randomised clinical trials of at least 6 months duration.

SEARCH METHODS

For this review update, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE, were searched through to June 2010. References of Included studies and reviews were also checked.

SELECTION CRITERIA

Trials fulfilled the following criteria: 1) randomised with appropriate control group, 2) intention to reduce or modify fat or cholesterol intake (excluding exclusively omega-3 fat interventions), 3) not multi factorial, 4) adult humans with or without cardiovascular disease, 5) intervention at least six months, 6) mortality or cardiovascular morbidity data available.

DATA COLLECTION AND ANALYSIS

Participant numbers experiencing health outcomes in each arm were extracted independently in duplicate and random effects meta-analyses, meta-regression, sub-grouping, sensitivity analyses and funnel plots were performed.

MAIN RESULTS

This updated review suggested that reducing saturated fat by reducing and/or modifying dietary fat reduced the risk of cardiovascular events by 14% (RR 0.86, 95% CI 0.77 to 0.96, 24 comparisons, 65,508 participants of whom 7% had a cardiovascular event, I(2) 50%). Subgrouping suggested that this reduction in cardiovascular events was seen in studies of fat modification (not reduction - which related directly to the degree of effect on serum total and LDL cholesterol and triglycerides), of at least two years duration and in studies of men (not of women). There were no clear effects of dietary fat changes on total mortality (RR 0.98, 95% CI 0.93 to 1.04, 71,790 participants) or cardiovascular mortality (RR 0.94, 95% CI 0.85 to 1.04, 65,978 participants). This did not alter with sub-grouping or sensitivity analysis.Few studies compared reduced with modified fat diets, so direct comparison was not possible.

AUTHORS' CONCLUSIONS

The findings are suggestive of a small but potentially important reduction in cardiovascular risk on modification of dietary fat, but not reduction of total fat, in longer trials. Lifestyle advice to all those at risk of cardiovascular disease and to lower risk population groups, should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturates. The ideal type of unsaturated fat is unclear.

The age associations of blood pressure, cholesterol, and glucose: analysis of health examination surveys from international populations

BACKGROUND

The age association of cardiovascular disease may be in part because its metabolic risk factors tend to rise with age. Few studies have analyzed age associations of multiple metabolic risks in the same population, especially in nationally representative samples. We examined worldwide variations in the age associations of systolic blood pressure (SBP), total cholesterol (TC), and fasting plasma glucose (FPG).

METHODS AND RESULTS

We used individual records from 83 nationally or subnationally representative health examination surveys in 52 countries to fit a linear model to risk factor data between ages 30 and 64 years for SBP and FPG, and between 30 and 54 years for TC. We report the cross-country variation of the slope and intercept of this relationship. We also assessed nonlinear associations in older ages. Between 30 and 64 years of age, SBP increased by 1.7 to 11.6 mm Hg per 10 years of age, and FPG increased by 0.8 to 20.4 mg/dL per 10 years of age in different countries and in the 2 sexes. Between 30 and 54 years of age, TC increased by 0.2 to 22.4 mg/dL per 10 years of age in different surveys and in the 2 sexes. For all risk factors and in most countries, risk factor levels rose more steeply among women than among men, especially for TC. On average, there was a flattening of age-SBP relationship in older ages; TC and FPG age associations reversed in older ages, leading to lower levels in older ages than in middle ages.

CONCLUSIONS

The rise with age of major metabolic cardiovascular disease risk factors varied substantially across populations, especially for FPG and TC. TC rose more steeply in high-income countries and FPG in the Oceania countries, the Middle East, and the United States. The SBP age association had no specific income or geographical pattern.

Effect of varying salt and fat levels on the sensory quality of beef patties

The interactive effects of varying levels of salt and fat on the sensory and physiochemical properties of beef patties were investigated. Twenty beef patties with varying levels of fat (30% 40% 50% 60% w/w) and salt (0.5%, 0.75% 1.0% 1.25% 1.5% w/w) were manufactured. All samples were assessed instrumentally for colour, moisture, fat, cooking loss and texture profile analysis. Sensory consumer evaluation was conducted using 25 consumers. The consumers rated each coded product, in duplicate, in terms of colour, texture, tenderness, juiciness, salt, taste, meat flavour, off flavour and overall acceptability. The data indicate that the most consumer acceptable beef patty was that containing 40% fat with a salt level of 1%. This is a 20% decrease in fat and a 50% decrease in salt levels when compared to commercial patties available in Ireland and the UK.

Low-sodium meat products: retaining salty taste for sweet health

There is a positive correlation between excessive intake of sodium and incidence of hypertension. As diet is the main source of sodium, awareness among people regarding its possible role upon health has driven demand for various low sodium foods including meat products. Meat products contribute a significant amount of dietary sodium, thus maligning their own image. However, this is not an easy task as common salt affects taste and flavor, functional attributes, stability, and food safety of meat products. The various properties such as taste and flavor, binding, as well as microbiological characteristics should be given due care while developing low salt meat products and accordingly different approaches have been proposed for processing of such products. Potassium chloride has been mostly used to replace sodium; however, a number of other salts, flavor enhancers, bitter blockers and water, as well as fat binders have also been attempted either alone or in different combinations. A number of low sodium meat products have been developed but their economy and consumer acceptability are the major concerns needing proper attention. In future it is anticipated that these challenges would be overcome to provide well acceptable and cost-effective healthier meat products to the consumers.

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.