Systematic review of long term effects of advice to reduce dietary salt in adults

Dietary interventions and blood pressure in Latin America - systematic review and meta-analysis

BACKGROUND

High blood pressure is the major risk factor for cardiovascular disease. Low blood pressure control rates in Latin American populations emphasize the need for gathering evidence on effective therapies.

OBJECTIVE

To evaluate the effects of dietary interventions on blood pressure in Latin American populations.

METHODS

Systematic review. Electronic databases (MEDLINE/PubMed, Embase, Cochrane Library, CINAHL, Web of Science, Scopus, SciELO, LILACS and VHL) were searched and manual search for studies published up to April 2013 was performed. Parallel studies about dietary interventions in Latin American adult populations assessing arterial blood pressure (mm Hg) before and after intervention were included.

RESULTS

Of the 405 studies identified, 10 randomized controlled trials were included and divided into 3 subgroups according to the proposed dietary intervention. There was a non-significant reduction in systolic blood pressure in the subgroups of mineral replacement (-4.82; 95% CI: -11.36 to 1.73) and complex pattern diets (-3.17; 95% CI: -7.62 to 1.28). Regarding diastolic blood pressure, except for the hyperproteic diet subgroup, all subgroups showed a significant reduction in blood pressure: -4.66 mmHg (95% CI: -9.21 to -0.12) and -4.55 mmHg (95% CI: -7.04 to -2.06) for mineral replacement and complex pattern diets, respectively.

CONCLUSION

Available evidence on the effects of dietary changes on blood pressure in Latin American populations indicates a homogeneous effect of those interventions, although not significant for systolic blood pressure. Samples were small and the quality of the studies was generally low. Larger studies are required to build robust evidence.

Launching a salt substitute to reduce blood pressure at the population level: a cluster randomized stepped wedge trial in Peru

BACKGROUND

Controlling hypertension rates and maintaining normal blood pressure, particularly in resource-constrained settings, represent ongoing challenges of effective and affordable implementation in health care. One of the strategies being largely advocated to improve high blood pressure calls for salt reduction strategies. This study aims to estimate the impact of a population-level intervention based on sodium reduction and potassium increase - in practice, introducing a low-sodium, high-potassium salt substitute - on adult blood pressure levels.

METHODS/DESIGN

The proposed implementation research study includes two components: Phase 1, an exploratory component, and Phase 2, an intervention component. The exploratory component involves a triangle taste test and a formative research study designed to gain an understanding of the best implementation methods. Phase 2 involves a pragmatic stepped wedge trial design where the intervention will be progressively implemented in several clusters starting the intervention randomly at different times. In addition, we will evaluate the implementation strategy using a cost-effectiveness analysis.

DISCUSSION

This is the first project in a Latin-American setting to implement a salt substitution intervention at the population level to tackle high blood pressure. Data generated and lessons learnt from this study will provide a strong platform to address potential interventions applicable to other similar low- and middle-income settings.

TRIAL REGISTRATION

This study is registered in ClinicalTrials.gov NCT01960972.

Beyond the clinic: importance of community involvement in sodium-reduction efforts

Excessive sodium intake is a serious public health problem that is amenable to intervention. Despite campaigns that often target individuals to encourage lower sodium intake, consumption is far in excess of recommendations. There is increasing recognition of the importance of the food environment in shaping dietary behavior and the need for strategies that focus on changing community-level environmental factors that support a shift in behavior toward more healthful eating. Practice-based evidence should be coupled with evidence from well-conducted clinical studies of sodium and health to build the foundation for public health interventions that achieve and sustain sodium reduction in the general population. This article discusses the importance of moving beyond the clinic and engaging communities in this important public health effort.

Efficacy of a nurse-led email reminder program for cardiovascular prevention risk reduction in hypertensive patients: a randomized controlled trial

BACKGROUND

Many strategies have been evaluated to improve the prevention and control of cardiovascular (CVD) risk factors. Nursing telephonic and tele-counseling individualized lifestyle educational programs have been found to improve blood pressure control and adherence to lifestyle recommendation. This study tested the efficacy of a nurse-led reminder program through email (NRP-e) to improve CVD risk factors among hypertensive adults.

METHODS

All participants received usual CVD prevention and a guideline-based educational program. Subjects in the NRP-e group also received weekly email alerts and phone calls from a nurse care manager for 6 months. Emails contained a reminder program on the need for adherence with a healthy lifestyle based upon current guidelines. Follow-up visits were scheduled at 1, 3 and 6 months after enrollment; randomization was made centrally and blood samples were evaluated into a single laboratory.

RESULTS

The final sample consisted of 98 (control) and 100 (NRP-e) subjects (mean age 59.0 ± 14.5 years; 51.0% males). After 6 months, the following CVD risk factors significantly improved in both groups: body mass index, alcohol and fruit consumption, cigarette smoking, adherence to therapy hours, systolic and diastolic blood pressure, fasting blood glucose, low-density lipoproteins (LDL) and total cholesterol, triglycerides, and physical activity. In the NRP-e group, however, the prevalence of several behaviors or conditions at risk decreased significantly more than in the control group: obesity (-16%), low fruit consumption (-24%), uncontrolled hypertension (-61%), LDL (-56%), and total cholesterol (-40%).

CONCLUSIONS

The NRP-e improved a range of CVD risk factors. The program had low costs, required only an average of <20 min per day in addition to normal practice, and may deserve further evaluation for the inclusion among existing care management approaches.

Social adversity experience and blood pressure control following antihypertensive medication use in a community sample of older adults

BACKGROUND

Psychosocial stress is a risk factor for hypertension and has been shown to affect response to treatment for psychiatric illnesses.

PURPOSE

We investigate the relationship between a history of social adversity experience and blood pressure control following antihypertensive medication use.

METHODS

A total of 1,186 participants selected from the European Prospective Investigation into Cancer-Norfolk study (531 men and 655 women, aged 42 to 80 years) had attended two health checks at which blood pressure measurements were taken; were taking antihypertensive medication at the second, but not the first health check; and had completed a questionnaire assessment of their social and psychological circumstances which included details of traumatic experiences in childhood and of adverse life events, long-term difficulties, and perceived stress in adulthood.

RESULTS

Experience of recent loss events in adulthood was associated with a smaller reduction in systolic blood pressure after starting hypertension treatment (β = 1.78, 95 % confidence interval 0.15-3.40, per life event), independently of age, sex, preexisting health conditions, cigarette smoking history, alcohol consumption, physical activity, and obesity.

CONCLUSION

Results from this study suggest that stress caused by recent losses may be associated with reduced effectiveness of treatment for hypertension. Subject to replication, these findings may help determine the specific physiological mechanisms by which medication treatment effectiveness is affected by stress.

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.

Salt content of school meals and comparison of perception related to sodium intake in elementary, middle, and high schools

Excessive sodium intake leading to hypertension, stroke, and stomach cancer is mainly caused by excess use of salt in cooking. This study was performed to estimate the salt content in school meals and to compare differences in perceptions related to sodium intake between students and staffs working for school meal service. We collected 382 dishes for food from 24 schools (9 elementary, 7 middle, 8 high schools) in Gyeonggi-do and salt content was calculated from salinity and weight of individual food. The average salt content from elementary, middle, and high school meals were 2.44 g, 3.96 g, and 5.87 g, respectively. The amount of salt provided from the school lunch alone was over 80% of the recommended daily salt intake by WHO. Noodles, stews, sauces, and soups were major sources of salt intake at dish group level, while the most salty dishes were sauces, kimchies, and stir-fried foods. Dietary knowledge and attitude related to sodium intake and consumption frequency of the salty dishes were surveyed with questionnaire in 798 students and 256 staffs working for school meal service. Compared with the staffs, the students perceived school meals salty and the proportions of students who thought school meals were salty increased with going up from elementary to high schools (P < 0.001). Among the students, middle and high school students showed significant propensity for the preference to one-dish meal, processed foods, eating much broth and dipping sauce or seasoning compared with the elementary students, although they had higher nutrition knowledge scores. These results proposed that monitoring salt content of school meals and consideration on the contents and education methods in school are needed to lower sodium intake.

The effect of lowering salt intake on ambulatory blood pressure to reduce cardiovascular risk in chronic kidney disease (LowSALT CKD study): protocol of a randomized trial

BACKGROUND

Despite evidence implicating dietary sodium in the pathogenesis of cardiovascular disease (CVD) in chronic kidney disease (CKD), quality intervention trials in CKD patients are lacking. This study aims to investigate the effect of reducing sodium intake on blood pressure, risk factors for progression of CKD and other cardiovascular risk factors in CKD.

METHODS/DESIGN

The LowSALT CKD study is a six week randomized-crossover trial assessing the effect of a moderate (180 mmol/day) compared with a low (60 mmol/day) sodium intake on cardiovascular risk factors and risk factors for kidney function decline in mild-moderate CKD (stage III-IV). The primary outcome of interest is 24-hour ambulatory blood pressure, with secondary outcomes including arterial stiffness (pulse wave velocity), proteinuria and fluid status. The randomized crossover trial (Phase 1) is supported by an ancillary trial (Phase 2) of longitudinal-observational design to assess the longer term effectiveness of sodium restriction. Phase 2 will continue measurement of outcomes as per Phase 1, with the addition of patient-centered outcomes, such as dietary adherence to sodium restriction (degree of adherence and barriers/enablers), quality of life and taste assessment.

DISCUSSION

The LowSALT CKD study is an investigator-initiated study specifically designed to assess the proof-of-concept and efficacy of sodium restriction in patients with established CKD. Phase 2 will assess the longer term effectiveness of sodium restriction in the same participants, enhancing the translation of Phase 1 results into practice. This trial will provide much-needed insight into sodium restriction as a treatment option to reduce risk of CVD and CKD progression in CKD patients.

TRIAL REGISTRATION

Universal Trial Number: U1111-1125-2149. Australian New Zealand Clinical Trials Registry Number: ACTRN12611001097932.

Salt reduction in a population for the prevention of hypertension

Hypertension is one of the major risk factors for cardiovascular disease, the prevention of which is acknowledged to be critically important. Human beings are the only animal species which consume large quantities of salt, and their consumption has increased with the advancement of civilization. Many observational and interventional epidemiologic studies have demonstrated that a high intake of salt results in elevation of blood pressure, and that a salt-reduced diet induces blood pressure reduction in patients with hypertension as well as in individuals with normal blood pressure. Reduced salt intake, blood pressure reduction, and a remarkable decrease in mortality due to stroke in Japan are important examples of this effect. A decrease in the mean blood pressure in an entire population can contribute significantly to decreased incidence of cardiovascular diseases. A population-based strategy for preventing hypertension, including a salt-reduced diet, is therefore desirable. Proposed measures include public health education by the mass media, reduced salt content in processed foods, salt reduction in foods served by schools or organizations and at restaurants, and labeling of salt content. Further studies are needed of population-wide salt reduction methods, and the effectiveness of such methods.

[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.

Impact of a community-based lifestyle intervention program on blood pressure and salt intake of normotensive adult population in a developing country

BACKGROUND

Data on the effect of lifestyle intervention programs on salt intake and blood pressure in developing countries are scarce. This study aimed to assess the impact of a healthy lifestyle community-based trial on salt intake and blood pressure among a representative sample of normotensive Iranian adults.

MATERIALS AND METHODS

We compared the data for salt intake, urinary sodium levels and blood pressure from three cross-sectional surveys in time points of 1999, 2001-2002 (beginning of the community interventions), and 2007 (after the community trial) for normotensive adult population of Isfahan, Iran in the framework of Isfahan Healthy Heart Program. Using multi-stage cluster sampling method, one of the family members at each household was randomly selected with Iranian adult population as a target. Dietary salt intake was estimated based on 24 hour urinary sodium levels. Systolic and diastolic blood pressures were measured according to standard methods.

RESULTS

Dietary sodium intake and urinary sodium levels as well as systolic and diastolic blood pressure were significantly decreased during the 9-year study period. Unlike systolic and diastolic blood pressures that had a consistent decrement between 1999 and 2007, dietary sodium intake and urinary sodium levels were slightly raised from 1999 to 2000-2001 and then reduced between 2001-2 and 2007 evaluations. The same findings were reached when data were analyzed separately by gender or weight status.

CONCLUSIONS

A lifestyle community trial was effective in controlling the escalating trend of blood pressure and salt intake in Iranian population. It can be considered as a model to be adopted in other developing countries.

Sodium Consumption: An Individual's Choice?

Excess intake of dietary salt is estimated to be one of the leading risks to health worldwide. Major national and international health organizations, along with many governments around the world, have called for reductions in the consumption of dietary salt. This paper discusses behavioural and population interventions as mechanisms to reduce dietary salt. In developed countries, salt added during food processing is the dominant source of salt and largely outside of the direct control of individuals. Population-based interventions have the potential to improve health and to be cost saving for these countries. In developing economies, where salt added in cooking and at the table is the dominant source, interventions based on education and behaviour change have been estimated to be highly cost effective. Regardless, countries with either developed or developing economies can benefit from the integration of both population and behavioural change interventions.

Effects of low-sodium diet vs. high-sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride (Cochrane Review)

BACKGROUND

The question of whether reduced sodium intake is effective as a health prophylaxis initiative is unsolved. The purpose was to estimate the effects of low-sodium vs. high-sodium intake on blood pressure (BP), renin, aldosterone, catecholamines, and lipids.

METHODS

Studies randomizing persons to low-sodium and high-sodium diets evaluating at least one of the above outcome parameters were included. Data were analyzed with Review Manager 5.1.

RESULTS

A total of 167 studies were included. The effect of sodium reduction in: (i) Normotensives: Caucasians: systolic BP (SBP) -1.27 mm Hg (95% confidence interval (CI): -1.88, -0.66; P = 0.0001), diastolic BP (DBP) -0.05 mm Hg (95% CI: -0.51, 0.42; P = 0.85). Blacks: SBP -4.02 mm Hg (95% CI: -7.37, -0.68; P = 0.002), DBP -2.01 mm Hg (95% CI: -4.37, 0.35; P = 0.09). Asians: SBP -1.27 mm Hg (95% CI: -3.07, 0.54; P = 0.17), DBP -1.68 mm Hg (95% CI: -3.29, -0.06; P = 0.04). (ii) Hypertensives: Caucasians: SBP -5.48 mm Hg (95% CI: -6.53, -4.43; P < 0.00001), DBP -2.75 mm Hg (95% CI: -3.34, -2.17; P < 0.00001). Blacks: SBP -6.44 mm Hg (95% CI: -8.85, -4.03; P = 0.00001), DBP -2.40 mm Hg (95% CI: -4.68, -0.12; P = 0.04). Asians: SBP -10.21 mm Hg (95% CI: -16.98, -3.44; P = 0.003), DBP -2.60 mm Hg (95% CI: -4.03, -1.16; P = 0.0004). Sodium reduction resulted in significant increases in renin (P < 0.00001), aldosterone (P < 0.00001), noradrenaline (P < 0.00001), adrenaline (P < 0.0002), cholesterol (P < 0.001), and triglyceride (P < 0.0008).

CONCLUSIONS

Sodium reduction resulted in a significant decrease in BP of 1% (normotensives), 3.5% (hypertensives), and a significant increase in plasma renin, plasma aldosterone, plasma adrenaline, and plasma noradrenaline, a 2.5% increase in cholesterol, and a 7% increase in triglyceride.

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

Background:

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

Objectives:

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

Materials and Methods:

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

Results:

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

Conclusion:

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

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

BACKGROUND

In spite of more than 100 years of investigations the question of reduced sodium intake as a health prophylaxis initiative is still unsolved.

OBJECTIVES

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

SEARCH METHODS

PUBMED, EMBASE and Cochrane Central and reference lists of relevant articles were searched from 1950 to July 2011.

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

Two authors independently collected data, which were analysed with Review Manager 5.1.

MAIN RESULTS

A total of 167 studies were included in this 2011 update.The effect of sodium reduction in normotensive Caucasians was SBP -1.27 mmHg (95% CI: -1.88, -0.66; p=0.0001), DBP -0.05 mmHg (95% CI: -0.51, 0.42; p=0.85). The effect of sodium reduction in normotensive Blacks was SBP -4.02 mmHg (95% CI:-7.37, -0.68; p=0.002), DBP -2.01 mmHg (95% CI:-4.37, 0.35; p=0.09). The effect of sodium reduction in normotensive Asians was SBP -1.27 mmHg (95% CI: -3.07, 0.54; p=0.17), DBP -1.68 mmHg (95% CI:-3.29, -0.06; p=0.04). The effect of sodium reduction in hypertensive Caucasians was SBP -5.48 mmHg (95% CI: -6.53, -4.43; p<0.00001), DBP -2.75 mmHg (95% CI: -3.34, -2.17; p<0.00001). The effect of sodium reduction in hypertensive Blacks was SBP -6.44 mmHg (95% CI:-8.85, -4.03; p=0.00001), DBP -2.40 mmHg (95% CI:-4.68, -0.12; p=0.04). The effect of sodium reduction in hypertensive Asians was SBP -10.21 mmHg (95% CI:-16.98, -3.44; p=0.003), DBP -2.60 mmHg (95% CI: -4.03, -1.16; p=0.0004).In plasma or serum there was a significant increase in renin (p<0.00001), aldosterone (p<0.00001), noradrenaline (p<0.00001), adrenaline (p<0.0002), cholesterol (p<0.001) and triglyceride (p<0.0008) with low sodium intake as compared with high sodium intake. In general the results were similar in studies with a duration of at least 2 weeks.

AUTHORS' CONCLUSIONS

Sodium reduction resulted in a 1% decrease in blood pressure in normotensives, a 3.5% decrease in hypertensives, a significant increase in plasma renin, plasma aldosterone, plasma adrenaline and plasma noradrenaline, a 2.5% increase in cholesterol, and a 7% increase in triglyceride. In general, these effects were stable in studies lasting for 2 weeks or more.

Feasibility and antihypertensive effect of replacing regular salt with mineral salt -rich in magnesium and potassium- in subjects with mildly elevated blood pressure

Background

High salt intake is linked to hypertension whereas a restriction of dietary salt lowers blood pressure (BP). Substituting potassium and/or magnesium salts for sodium chloride (NaCl) may enhance the feasibility of salt restriction and lower blood pressure beyond the sodium reduction alone. The aim of this study was to determine the feasibility and effect on blood pressure of replacing NaCl (Regular salt) with a novel mineral salt [50% sodium chloride and rich in potassium chloride (25%), magnesium ammonium potassium chloride, hydrate (25%)] (Smart Salt).

Methods

A randomized, double-blind, placebo-controlled study was conducted with an intervention period of 8-weeks in subjects (n = 45) with systolic (S)BP 130-159 mmHg and/or diastolic (D)BP 85-99 mmHg. During the intervention period, subjects consumed processed foods salted with either NaCl or Smart Salt. The primary endpoint was the change in SBP. Secondary endpoints were changes in DBP, daily urine excretion of sodium (24-h dU-Na), potassium (dU-K) and magnesium (dU-Mg).

Results

24-h dU-Na decreased significantly in the Smart Salt group (-29.8 mmol; p = 0.012) and remained unchanged in the control group: resulting in a 3.3 g difference in NaCl intake between the groups. Replacement of NaCl with Smart Salt resulted in a significant reduction in SBP over 8 weeks (-7.5 mmHg; p = 0.016). SBP increased (+3.8 mmHg, p = 0.072) slightly in the Regular salt group. The difference in the change of SBP between study groups was significant (p < 0.002).

Conclusions

The substitution of Smart Salt for Regular salt in subjects with high normal or mildly elevated BP resulted in a significant reduction in their daily sodium intake as well as a reduction in SBP.

Trial Registration

ISRCTN: ISRCTN01739816

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

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

Reducing sodium in foods: the effect on flavor

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

Sex-specific associations of nutrition with hypertension and systolic blood pressure in Alaska Natives findings from the GOCADAN study

OBJECTIVES

To examine sex-specific associations of nutritional factors with prevalent hypertension (HTN) and systolic blood pressure (SBP) in Alaska Natives. Diet is known to affect SBP, a major risk factor for cardiovascular disease.

STUDY DESIGN

Cross-sectional analysis of participants without diabetes in the Genetics of Coronary Artery Disease in Alaska Natives study.

METHODS

Macronutrients such as fat, carbohydrate and protein and micronutrients such as sodium were investigated. HTN was defined as SBP≥140 mmHg, diastolic blood pressure≥90 mmHg and/or taking anti-HTN medication. Analyses were stratified by sex and covariates included age, body mass index (BMI), energy intake, smoking and physical activity.

RESULTS

Mean age was 42 years for men (n=456) and women (n=602). Men with HTN (n=106) compared to men without HTN consumed a higher proportion of calories from total (p=0.01), saturated (p<0.01) and trans fatty acid (p=0.03) fats. Women with HTN (n=99) compared to women without HTN consumed more total (p=0.03) and monounsaturated (p=0.04) fat, higher protein (p=0.02) and lower total (p<0.01) and simple (p<0.01) carbohydrates. After covariate adjustment, men not on anti-HTN medications (n=407) had significantly higher average SBP with increasing quartiles of trans fatty acid intake (p for linear trend=0.01) and sodium intake (p for linear trend=0.02). For women not on anti-HTN medications (n=528), after covariate adjustment, average SBP decreased with increasing quartiles of omega 3 fatty acid intake (p for linear trend <0.01).

CONCLUSIONS

Prospective evaluation of the sex-specific associations of nutritional factors with HTN and SBP on outcomes is needed along with novel interventions to lower the risk of cardiovascular disease.

Dietary patterns among British adults: compatibility with dietary guidelines for salt/sodium, fat, saturated fat and sugars

OBJECTIVE

To examine dietary patterns among British adults, associations with Na and macronutrient intakes, and implications for dietary advice.

DESIGN

Principal component analysis of 7 d weighed dietary records.

SUBJECTS

Adults aged 19-64 years (n 1724).

SETTING

National Diet and Nutrition Survey (2000/2001).

RESULTS

High Na intake was associated with more energy-dense diets, higher in fat and SFA (percentage of energy) but lower in non-milk extrinsic sugars (NMES). Eight patterns (PC1 to PC8) explained 40 % of the total variance in food intakes. Three patterns - PC3 (high loadings on bread, fats and cheese), PC2 (meat products, eggs and chips) and PC7 (red meat, sauces and alcohol) - were associated with high Na intake. Of these, PC3 correlated with high Na density and Na:K ratio, while PC2 correlated with fat. By contrast, three patterns - 'health-conscious' (PC1; vegetables, fruit, fruit juice, fish), 'breakfast cereals and milk' (PC6) and 'chicken and rice' (PC8) - were associated with modest Na intake, lower Na density and lower fat and SFA. PC2 was positively correlated, and PC1 was negatively correlated, with adding salt to food. Other patterns were 'tea/coffee and cakes' (PC4; associated with high SFA and NMES) and 'soft drinks and snacks' (PC5; associated with high NMES but not fat or SFA). The dietary patterns of males and females differed slightly.

CONCLUSIONS

Dietary patterns PC1, PC6, PC8 (vegetables, fruit, fish, milk, breakfast cereals, poultry) were broadly compatible with guidelines for salt, fat, SFA and NMES. However, other patterns tended to be high in either salt or NMES.

Hypertension in aging patients

Hypertension, especially isolated systolic hypertension, is commonly found in older (60-79 years of age) and elderly (≥80 years of age) people. Antihypertensive drug therapy should be considered in all aging hypertensive patients, as treatment greatly reduces cardiovascular events. Most classes of antihypertensive medications may be used as first-line treatment with the possible exception of α- and β-blockers. An initial blood pressure treatment goal is less than 140/90 mmHg in all older patients and less than 150/80 mmHg in the nonfrail elderly. The current paradigm of delaying therapeutic interventions until people are at moderate or high cardiovascular risk, a universal feature of hypertensive patients over 60 years of age, leads to vascular injury or disease that is only partially reversible with treatment. Future management will likely focus on intervening earlier to prevent accelerated vascular aging and irreversible arterial damage.

Prevention of hypertension in patients with pre-hypertension: protocol for the PREVER-prevention trial

Background

Blood pressure (BP) within pre-hypertensive levels confers higher cardiovascular risk and is an intermediate stage for full hypertension, which develops in an annual rate of 7 out of 100 individuals with 40 to 50 years of age. Non-drug interventions to prevent hypertension have had low effectiveness. In individuals with previous cardiovascular disease or diabetes, the use of BP-lowering agents reduces the incidence of major cardiovascular events. In the absence of higher baseline risk, the use of BP agents reduces the incidence of hypertension. The PREVER-prevention trial aims to investigate the efficacy, safety and feasibility of a population-based intervention to prevent the incidence of hypertension and the development of target-organ damage.

Methods

This is a randomized, double-blind, placebo-controlled clinical trial, with participants aged 30 to 70 years, with pre-hypertension. The trial arms will be chlorthalidone 12.5 mg plus amiloride 2.5 mg or identical placebo. The primary outcomes will be the incidence of hypertension, adverse events and development or worsening of microalbuminuria and of left ventricular hypertrophy in the EKG. The secondary outcomes will be fatal or non-fatal cardiovascular events: myocardial infarction, stroke, heart failure, evidence of new sub-clinical atherosclerosis, and sudden death. The study will last 18 months. The sample size was calculated on the basis of an incidence of hypertension of 14% in the control group, a size effect of 40%, power of 85% and P alpha of 5%, resulting in 625 participants per group. The project was approved by the Ethics committee of each participating institution.

Discussion

The early use of blood pressure-lowering drugs, particularly diuretics, which act on the main mechanism of blood pressure rising with age, may prevent cardiovascular events and the incidence of hypertension in individuals with hypertension. If this intervention shows to be effective and safe in a population-based perspective, it could be the basis for an innovative public health program to prevent hypertension in Brazil.

Trial Registration

Clinical Trials NCT00970931.

Prehypertension: the rationale for early drug therapy

Blood pressure within prehypertensive levels confers higher cardiovascular risk by two means. At first, these levels are associated with higher risk for cardiovascular events, starting at BP values as low as 115/75 mmHg, and doubling at each 20 mmHg for systolic or 10 mmHg for diastolic BP. Prehypertension is also an intermediate stage for full hypertension, which develops in an annual rate of 7 out 100 individuals with 40-50 years of age. The precocious drug intervention in patients with prehypertension is therefore appealing. In individuals with previous cardiovascular disease or diabetes the use of BP-lowering agents is compulsory, since the 18-42% reduction of major cardiovascular events demonstrated in randomized clinical trials translates in palpable clinical benefit. In the absence of higher baseline risk, the absolute benefit of treatment is presumably small and was not demonstrated to date. These individuals could be candidate to treatment with the aim to prevent the development of full hypertension. The long-lasting effectiveness of non-drug therapies is low outside the controlled conditions of randomized clinical trials, and there are evidences that the use of BP-lowering drugs reduces the incidence of hypertension in individuals with prehypertension by more than 60%. Clinical trials testing the efficacy and safety of BP agents to prevent hypertension in a population-based perspective are required. In the meantime, it is worthy to present the option to start low doses of BP agents for individuals with prehypertension without co-morbidities who do not respond to the prescription of lifestyle modification.

Higher aldosterone and lower N-terminal proatrial natriuretic peptide as biomarkers of salt sensitivity in the community

BACKGROUND

Salt sensitivity, a trait characterized by a pressor blood pressure response to increased dietary salt intake, has been associated with higher rates of cardiovascular target organ damage and cardiovascular disease events. Recent experimental studies have highlighted the potential role of the natriuretic peptides and aldosterone in mediating salt sensitivity.

DESIGN

Prospective cohort study.

METHODS

We evaluated 1575 non-hypertensive Framingham Offspring cohort participants (mean age 55 ± 9 years, 58% women) who underwent routine measurements of circulating aldosterone and N-terminal proatrial natriuretic peptide (NT-ANP) and assessment of dietary sodium intake. Participants were categorized as potentially 'salt sensitive' if their serum aldosterone was >sex-specific median but plasma NT-ANP was ≤sex-specific median value. Dietary sodium intake was categorized as lower versus higher (dichotomized at the sex-specific median). We used multivariable linear regression to relate presence of salt sensitivity (as defined above) to longitudinal changes (Δ) in systolic and diastolic blood pressure on follow-up (median four years).

RESULTS

Participants who were 'salt sensitive' (N = 437) experienced significantly greater increases in blood pressure (Δ systolic, +4.4 and +2.3 mmHg; Δ diastolic, +1.9 and -0.3 mmHg; on a higher versus lower sodium diet, respectively) as compared to the other participants (Δ systolic, +2.8 and +1.0 mmHg; Δ diastolic, +0.5 and -0.2 mmHg; on higher versus lower sodium diet, respectively; P = 0.033 and P = 0.0127 for differences between groups in Δ systolic and Δ diastolic blood pressure, respectively).

CONCLUSIONS

Our observational data suggest that higher circulating aldosterone and lower NT-ANP concentrations may be markers of salt sensitivity in the community. Additional studies are warranted to confirm these observations.

Altered dietary salt intake for preventing and treating diabetic kidney disease

BACKGROUND

There is strong evidence that our current consumption of salt is a major factor for increased blood pressure (BP) and a modest reduction in salt intake lowers BP whether BP levels are normal or raised. Tight control of BP in diabetics lowers the risk of strokes, heart attacks and heart failure and slows the progression of diabetic kidney disease (DKD). Currently there is no consensus in restricting salt intake in diabetic patients.

OBJECTIVES

To evaluate the effect of altered salt intake on BP and markers of cardiovascular disease and DKD.

SEARCH STRATEGY

In January 2010, we searched the Cochrane Renal Group's Specialised Register, CENTRAL (in The Cochrane Library), MEDLINE (from 1966) and EMBASE (from 1980) to identify appropriate articles.

SELECTION CRITERIA

We included all randomised controlled trials of salt reduction in individuals with type 1 and type 2 diabetes.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies and resolved differences by discussion with a third independent author. We calculated mean effect sizes using both the fixed-effect and random-effects models.

MAIN RESULTS

Thirteen studies (254 individuals) met our inclusion criteria. These included 75 individuals with type 1 diabetes and 158 individuals with type 2 diabetes. The median reduction in urinary sodium was 203 mmol/24 h (11.9 g/day) in type 1 diabetes and 125 mmol/24 h (7.3 g/day) in type 2 diabetes. The median duration of salt restriction was one week in both type 1 and type 2 diabetes. BP was reduced in both type 1 and type 2 diabetes. In type 1 diabetes (56 individuals), salt restriction reduced BP by -7.11/-3.13 mm Hg (systolic/diastolic); 95% CI: systolic BP (SBP) -9.13 to -5.10; diastolic BP (DBP) -4.28 to -1.98). In type 2 diabetes (56 individuals), salt restriction reduced BP by -6.90/-2.87 mm Hg (95% CI: SBP -9.84 to -3.95; DBP -4.39 to -1.35). There was a greater reduction in BP in normotensive patients, possibly due to a larger decrease in salt intake in this group.

AUTHORS' CONCLUSIONS

Although the studies are not extensive, this meta-analysis shows a large fall in BP with salt restriction, similar to that of single drug therapy. All diabetics should consider reducing salt intake at least to less than 5-6 g/day in keeping with current recommendations for the general population and may consider lowering salt intake to lower levels, although further studies are needed.

Renal cortical and medullary blood flow responses to altered NO availability in humans

The objective of this study was to quantify regional renal blood flow in humans. In nine young volunteers on a controlled diet, the lower abdomen was CT-scanned, and regional renal blood flow was determined by positron emission tomography (PET) scanning using H(2)(15)O as tracer. Measurements were performed at baseline, during constant intravenous infusion of nitric oxide (NO) donor glyceryl nitrate and after intravenous injection of NO synthase inhibitor N(ω)-monomethyl-L-arginine (L-NMMA). Using the CT image, the kidney pole areas were delineated as volumes of interest (VOI). In the data analysis, tissue layers with a thickness of one voxel were eliminated stepwise from the external surface of the VOI (voxel peeling), and the blood flow subsequently was determined in each new, reduced VOI. Blood flow in the shrinking VOIs decreased as the number of cycles of voxel peeling increased. After 4-5 cycles, blood flow was not reduced further by additional voxel peeling. This volume-insensitive flow was measured to be 2.30 ± 0.17 ml·g tissue(-1)·min(-1) during the control period; it increased during infusion of glyceryl nitrate to 2.97 ± 0.18 ml·g tissue(-1)·min(-1) (P < 0.05) and decreased after L-NMMA injection to 1.57 ± 0.17 ml·g tissue(-1)·min(-1) (P < 0.05). Cortical blood flow was 4.67 ± 0.31 ml·g tissue(-1)·min(-1) during control, unchanged by glyceryl nitrate, and decreased after L-NMMA [3.48 ± 0.23 ml·(g·min)(-1), P < 0.05]. PET/CT scanning allows identification of a renal medullary region in which the measured blood flow is 1) low, 2) independent of reduction in the VOI, and 3) reactive to changes in systemic NO supply. The technique seems to provide indices of renal medullary blood flow in humans.

Urinary sodium excretion, dietary sources of sodium intake and knowledge and practices around salt use in a group of healthy Australian women

OBJECTIVE

Strategies that aim to facilitate reduction of the salt content of foods in Australia are hampered by sparse and outdated data on habitual salt intakes. This study assessed habitual sodium intake through urinary excretion analyses, and identified food sources of dietary sodium, as well as knowledge and practices related to salt use in healthy women.

METHODS

Cross-sectional, convenient sample of 76 women aged 20 to 55 years, Wollongong, NSW. Data included a 24 hour urine sample, three-day food diary and a self-administered questionnaire.

RESULTS

Mean Na excretion equated to a NaCl (salt) intake of 6.41 (SD=2.61) g/day; 43% had values <6 g/day. Food groups contributing to dietary sodium were: bread and cereals (27%); dressings/sauces (20%); meat/egg-based dishes (18%); snacks/desserts/extras (11%); and milk and dairy products (11%). Approximately half the sample reported using salt in cooking or at the table. Dietary practices reflected a high awareness of salt-related health issues and a good knowledge of food sources of sodium.

CONCLUSION

These findings from a sample of healthy women in the Illawarra indicate that dietary sodium intakes are lower in this group than previously reported in Australia. However, personal food choices and high levels of awareness of the salt reduction messages are not enough to achieve more stringent dietary targets of <4 g salt per day.

IMPLICATIONS

Urinary Na excretion data are required from a larger nationally representative sample to confirm habitual salt intakes. The bread and cereals food group are an obvious target for sodium reduction strategies in manufactured foods.

Coronary mortality declines in the U.S. between 1980 and 2000 quantifying the contributions from primary and secondary prevention

BACKGROUND

Coronary heart disease (CHD) mortality rates in the U.S. have halved since 1980. However, CHD remains a leading cause of death. The relative importance of secondary and primary prevention in explaining falls in coronary heart disease mortality is debated.

PURPOSE

The aim of this study was to quantify the primary and secondary preventive contributions to the U.S. CHD mortality fall between 1980 and 2000.

METHODS

The IMPACT model was used to estimate contributions to the U.S. CHD mortality fall from risk factor declines in asymptomatic individuals (primary prevention) and in CHD patients (secondary prevention). Analyses were carried out in 2008.

RESULTS

Approximately 316,100 fewer deaths were attributable to risk factor declines: 64,930 in CHD patients (21%) and 251,170 in asymptomatic individuals (79%). Smoking declines accounted for approximately 8390 fewer deaths in CHD patients and for 46,315 fewer deaths in asymptomatic people. Cholesterol falls gave approximately 22,210 fewer deaths in CHD patients and 107,300 fewer deaths in asymptomatic people. Statins accounted for approximately 16,580 fewer deaths, that is, one sixth of this mortality fall. Systolic blood pressure declines accounted for approximately 34,330 fewer deaths among CHD patients and 97,555 fewer deaths in asymptomatic individuals. Antihypertensive medications accounted for approximately 23,845 fewer deaths.

CONCLUSIONS

Half of the U.S. mortality fall in coronary heart disease between 1980 and 2000 was attributable to risk factor declines, with primary prevention producing substantially larger mortality reductions than secondary.

Nutritional profiles in a public health perspective: a critical review

Nutritional profiling is defined as 'the science of categorizing foods according to their nutritional composition' and it is useful for food labelling and regulation of health claims. The evidence for the link between nutrients and health outcomes was reviewed. A reduced salt intake reduces blood pressure, but only a few randomized controlled trials have verified the effect of salt on overall and cardiovascular mortality. Evidence linking a reduced fat intake with cardiovascular mortality and obesity is generally non-significant. Studies that have examined the relationship between obesity and diet have produced contrasting results. A simulation exercise that demonstrated that the impact of a reduced salt and fat intake on overall mortality would be negligible in the European population was carried out. Consideration of the literature and the results of this simulation exercise suggest that the introduction of nutritional profiles in Europe would be expected to have a very limited impact on health outcomes.

Prehypertension: detection, evaluation, and management

Prehypertension was defined as a discrete category in 1993. There is evidence to support active management of this entity given the increased risk of hypertension, cardiovascular disease, heart failure, and stroke. There have been few comprehensive summaries on the management of this population. Therefore, this article summarizes the latest guidelines and studies on the detection, evaluation, and management of prehypertension.

Achieving the salt intake target of 6 g/day in the current food supply in free-living adults using two dietary education strategies

There are national targets for salt intake of 6 g salt/day in Australia and the United States. Despite this, there is limited knowledge about the effectiveness of dietary education in reducing salt intake to this level. The objective of this study was to investigate whether dietary education enabled a reduction in salt consumption. In an 8-week parallel study, 49 healthy free-living adults were recruited from the Adelaide community by newspaper advertisement. In a randomized parallel design, participants received dietary education to choose foods identified by either Australia's National Heart Foundation Tick symbol or by the Food Standards Australia and New Zealand's low-salt guideline of 120 mg sodium/100 g food. Sodium excretion was assessed by 24-hour urinary sodium collections at baseline and weeks 4 and 8. Participants' experiences of following the education strategies were recorded by self-administered questionnaire. These data were collected between August and October 2008. Forty-three participants completed the study. After 8 weeks, urinary sodium excretion decreased from 121+/-50 to 106+/-47 mmol/24 hours (7.3+/-3.0 to 6.4+/-2.8 g salt/24 hours) in the Tick group and from 132+/-44 to 98+/-50 mmol/24 hours (7.9+/-2.6 to 6.0+/-3.0 g salt/24 hours) in the Food Standards Australia New Zealand group (P<0.05, with no between-group difference). Barriers to salt reduction were limited variety and food choice, difficulty when eating out, and increased time associated with identifying foods. In conclusion, dietary sodium reduction is possible among free-living individuals who received dietary advice.

Metabolic syndrome and cardiovascular risk

The constellation of dyslipidemia (hypertriglyceridemia and low levels of high-density lipoprotein cholesterol), elevated blood pressure, impaired glucose tolerance, and central obesity is now classified as metabolic syndrome, also called syndrome X. In the past few years, several expert groups have attempted to set forth simple diagnostic criteria for use in clinical practice to identify patients who manifest the multiple components of the metabolic syndrome. These criteria have varied somewhat in specific elements, but in general, they include a combination of multiple and metabolic risk factors. The most widely recognized of the metabolic risk factors are atherogenic dyslipidemia, elevated blood pressure, and elevated plasma glucose. Individuals with these characteristics, commonly manifest a prothrombotic state as well as and a proinflammatory state. Atherogenic dyslipidemia consists of an aggregation of lipoprotein abnormalities including elevated serum triglyceride and apolipoprotein B (apoB), increased small LDL particles, and a reduced level of HDL cholesterol (HDL-C). The metabolic syndrome is often referred to as if it were a discrete entity with a single cause. Available data suggest that it truly is a syndrome, ie, a grouping of atherosclerotic cardiovascular disease (ASCVD) risk factors, that probably has more than one cause. Regardless of cause, the syndrome identifies individuals at an elevated risk for ASCVD. The magnitude of the increased risk can vary according to the components of the syndrome present as well as the other, non-metabolic syndrome risk factors in a particular person.

Reducing population salt intake worldwide: from evidence to implementation

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

Meta-analysis of blood pressure tracking from childhood to adulthood and implications for the design of intervention trials

AIM

Blood pressure (BP) is related with cardiovascular disease. BP tracking in childhood and its implication for intervention trials are unknown.

METHODS

A systematic review and meta-analysis were conducted to estimate BP tracking.

RESULTS

In 29 independent studies on 27,820 subjects, follow-up length and baseline age were associated with systolic BP tracking (both p < 0.05), while gender, BP measurement method and study place were not (p = 0.215, p = 0.185 and p = 0.391). The overall adjusted systolic BP correlation coefficient was 0.44 between 10 and 11 years and decreased to 0.37 between 10 and 20 years. Comparison of BP changes before and after intervention need a 26% increased sample size for a 10-year follow-up of 10 year olds, while trials comparing BP values at study end only require smaller sample sizes.

CONCLUSION

Blood pressure tracking from childhood to adulthood affects trials assessing long-term effects on BP and was low-to-moderate. Therefore, regular BP controls are also needed in children with normal BP measurements possibly identifying hypertensive children earlier. A slight short-term intervention effect on BP may not have any long-term effects because of low BP tracking and its decrease by age.