The association between blood pressure, age, and dietary sodium and potassium: a population study

Role of dietary potassium and salt substitution in the prevention and management of hypertension

Cardiovascular diseases (CVD) continue to be the leading cause of deaths and disability worldwide and the major contributor is hypertension. Despite all the improvements in detecting hypertension together with technological advances and affordable, efficacious and relatively free of adverse effects anti-hypertensive agents, we continue to struggle to prevent the onset of hypertension and to control blood pressure (BP) to acceptable targets. The poor control of hypertension is commonly due to non-adherence to medications. Another reason is the failure to adopt diet and lifestyle changes. Reduction of dietary salt intake is important for lowering BP but the role of potassium intake is also important. Globally the intake of sodium is double that of the recommended 2 gm per day (equivalent to 5 gm of sodium chloride/salt) and half that of the daily recommended intake of potassium of 3500 mg/day, giving a sodium-to-potassium ratio of >1, when ideally it should be <1. Many studies have shown that a higher potassium intake is associated with lower BPs, particularly when coupled concurrently with a lower sodium intake giving a lower sodium to potassium ratio. Most hypertension guidelines, while recommending reduction of salt intake to a set target, do not specifically recommend a target for potassium intake nor potassium supplementation. Here we review the role of potassium and salt substitution with potassium in the management of hypertension. Hence, the focus of dietary changes to lower BP and improve BP control should not be on reduction of salt intake alone but more importantly should include an increase in potassium intake.

The renin angiotensin aldosterone system

In this review, we will cover (i) the proteolytic cascade of the RAAS, (ii) its regulation by multiple feedback-controlled parameters, and (iii) the major effects of the RAAS. For the effects of the RAAS, we focus on the role of the RAAS in the regulation of volume homeostasis and vascular tone, as major determinants of arterial blood pressure.

Apolipoprotein L1 Genotypes and the Association of Urinary Potassium Excretion with CKD Progression

BACKGROUND AND OBJECTIVES

Progressive CKD in Black individuals is strongly associated with polymorphisms in the APOL1 gene, but it is unknown whether dietary risk factors for CKD progression vary in high- versus low-risk APOL1 genotypes. We investigated if APOL1 genotypes modify associations of dietary potassium and sodium with CKD progression and death.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We analyzed 1399 self-identified Black participants enrolled in the Chronic Renal Insufficiency Cohort from April 2003 to September 2008. Exposures were calibrated 24-hour urine potassium and sodium excretion. The primary outcome was CKD progression defined as the time to 50% decline in eGFR or kidney failure. The secondary outcome was CKD progression or death. We tested for an interaction between urinary potassium and sodium excretion and APOL1 genotypes.

RESULTS

Median 24-hour urinary sodium and potassium excretions in Black participants were 150 mmol (interquartile range, 118-188) and 43 mmol (interquartile range, 35-54), respectively. Individuals with high- and low-risk APOL1 genotypes numbered 276 (20%) and 1104 (79%), respectively. After a median follow-up of 5.23 years, CKD progression events equaled 605, and after 7.29 years, CKD progression and death events equaled 868. There was significant interaction between APOL1 genotypes and urinary potassium excretion with CKD progression and CKD progression or death (P=0.003 and P=0.03, respectively). In those with high-risk APOL1 genotypes, higher urinary potassium excretion was associated with a lower risk of CKD progression (quartiles 2-4 versus 1: hazard ratio, 0.83; 95% confidence interval, 0.50 to 1.39; hazard ratio, 0.54; 95% confidence interval, 0.31 to 0.93; and hazard ratio, 0.50; 95% confidence interval, 0.27 to 0.93, respectively). In the low-risk APOL1 genotypes, higher urinary potassium excretion was associated with a higher risk of CKD progression (quartiles 2-4 versus 1: hazard ratio, 1.01; 95% confidence interval, 0.75 to 1.36; hazard ratio, 1.23; 95% confidence interval, 0.91 to 1.66; and hazard ratio, 1.53; 95% confidence interval, 1.12 to 2.09, respectively). We found no interaction between APOL1 genotypes and urinary sodium excretion with CKD outcomes.

CONCLUSIONS

Higher urinary potassium excretion was associated with lower versus higher risk of CKD progression in APOL1 high-risk and low-risk genotypes, respectively.

Breastfeeding Duration and High Blood Pressure in Children and Adolescents: Results from a Cross-Sectional Study of Seven Provinces in China

This study was aimed to investigate the associations between breastfeeding duration and blood pressure (BP) levels, BP Z scores and high BP (HBP) in children and adolescents. A total of 57,201 participants including 29,491 boys and 27,710 girls aged 7−18 years were recruited from seven provinces in China in 2012. HBP was defined as BP levels of ≥95th percentiles of the referent age-, sex-, and height-specific population. Breastfeeding duration was divided into non-breastfeeding, 0−5 months, 6−12 months, and >12 months. Information on demographic, parental or family factors and dietary behaviors was collected through a self-administered questionnaire. Multivariable linear regression and logistic regression models were applied to assess the relationships of breastfeeding duration with BP levels and BP Z scores and with HBP, respectively. Stratified analyses were performed to further investigate the potential subgroup-specific associations. The reported prolonged breastfeeding (>12 months) rate was 22.53% in the total population. After full adjustment, compared to the non-breastfeeding group, breastfeeding for 6−12 months was correlated with 0.43 (95% CI: −0.75, −0.11) and 0.36 (95% CI: −0.61, −0.12) mmHg lower levels of SBP and DBP, respectively. Similar decrease trends were found for BP Z scores. Prolonged breastfeeding (>12 months) was associated with 1.33 (95% CI: 1.12, 1.58) and 1.12 (95% CI: 0.94, 1.33) higher odds of HBP in boys and girls, respectively. Based on nationally representative data, there was no evidence that a longer duration of breastfeeding is protective against childhood HBP. Breastfeeding for 6−12 months may be beneficial to BP, while prolonged breastfeeding durations might increase the odds of HBP in children and adolescents.

Trends in dietary salt sources in Japanese adults: data from the 2007-2019 National Health and Nutrition Survey

Identifying trends in dietary salt sources is essential for effectively reducing salt/Na intake. This study aimed to examine the trends in dietary salt sources among Japanese adults using the 2007-2019 National Health and Nutrition Survey data collected from 95 581 adults aged ≥ 20 years. Dietary intake was estimated using the 1-d household-based dietary record. Foods reported as potential sources of salt intake in Japan and other countries were categorised into twenty-one groups. Salt intake for each food group was adjusted using the density method based on the energy intake. Trends in dietary salt intake based on food sources by sex and age groups (20-39 years, 40-59 years and ≥ 60 years) were analysed using the Joinpoint Regression Program. Salt intake for each age group in both men and women decreased from 2007 (5·3 g/1000 kcal-6·4 g/1000 kcal) to 2019 (4·9 g/1000 kcal-5·6 g/1000 kcal). The major dietary source of salt continued to be seasonings such as soya sauce and soyabean paste (approximately 70 %). Salt intake from seasonings decreased over time in adults aged ≥ 40 years but did not change in those aged 20-39 years. Additionally, a decreasing salt intake from unprocessed fish and shellfish and an increasing salt intake from unprocessed meat were observed across all age categories for both sexes. This study demonstrated that a strategy targeting different age groups may be needed to reduce salt consumption from seasonings among the Japanese population. Further studies on salt content in seasonings and continued monitoring of trends in dietary salt sources are required.

Sodium and Potassium Content of the Most Commonly Available Street Foods in Maputo, Mozambique

Street foods can contribute largely for dietary sodium intake of populations in developing countries. We aimed to assess the variability in sodium and potassium composition of the most commonly available homemade street foods in Maputo city, capital of Mozambique. In a cross-sectional evaluation, researchers canvassed areas with 500-m diameter centered around 20 randomly selected public transport stops, identified all street food vending sites and, in randomly selected sites, purchased 56 samples of the most frequently available homemade foods. Samples were analyzed for sodium and potassium concentrations, using flame photometry. The 56 samples represented main dishes (45 samples of 12 types of food item), sandwiches (8 samples of 5 types of food item) and fried snacks (3 samples of 2 types of food item). Median contents (range), in mg/serving, were 921 (198 to 2525) of sodium and 385 (24 to 1140) of potassium. Median (range) of sodium to potassium molar ratio was 4.1 (1.3 to 41.5). One serving of main dishes was estimated to contribute from 32.1% to 99.9% of the recommended maximum daily sodium intake. The present study shows a large variability and potential for improvement in sodium and potassium contents of homemade foods frequently available in the streets of Maputo city.

Association of dietary calcium, magnesium, sodium, and potassium intake and hypertension: a study on an 8-year dietary intake data from the National Health and Nutrition Examination Survey

BACKGROUND/OBJECTIVES

There has been an increased interest in determining calcium magnesium, sodium, and potassium's distinct effects on hypertension over the past decade, yet they simultaneously regulate blood pressure. We aimed at examining the association of dietary calcium, magnesium, sodium, and potassium independently and jointly with hypertension using National Health and Nutrition Examination Survey data from 2007 to 2014.

MATERIALS/METHODS

The associations were examined on a large cross-sectional study involving 16684 US adults aged>20 years, using multivariate analyses with logistical models.

RESULTS

Sodium and calcium quartiles assessed alone were not associated with hypertension. Potassium was negatively associated with hypertension in the highest quartile, 0.64 (95% confidence interval [CI], 0.48–0.87). When jointly assessed using the high and low cut-off points, low sodium and corresponding high calcium, magnesium, and potassium intake somewhat reduced the odds of hypertension 0.39 (95% CI, 0.20–0.76). The sodium-to-potassium ratio was positively associated with hypertension in the highest quartile1.50 (95% CI, 1.11–2.02). When potassium was adjusted for sodium intake and sodium-to-potassium ratio assessed among women, increased odds of hypertension were reported in the highest quartile as 2.02 (95% CI, 1.18–3.34) and 1.69 (95% CI, 1.12–2.57), respectively. The association of combined minerals on hypertension using dietary goals established that men meeting the reference intakes for calcium and exceeding for magnesium had reduced odds of hypertension 0.51 (95% CI, 0.30–0.89). Women exceeding the recommendations for both calcium and magnesium had the lower reduced odds of 0.30 (95% CI, 0.10–0.69).

CONCLUSIONS

Our results suggest that the studied minerals' association on hypertension is stronger when jointly assessed, mostly after gender stratification. As compared to men, women increased their risk of hypertension even with a low sodium intake. Women would also reasonably reduce their risk of developing hypertension by increasing calcium and magnesium intake. In comparison, men would somewhat be protected from developing hypertension with calcium intake meeting the dietary goals and magnesium exceeding the nutritional goals.

Validation of Self-Monitoring Devices Supporting Sodium Intake Reduction: An Experimental Feeding Study Using Standardized Low-Salt and High-Salt Meals among Healthy Japanese Volunteers

INTRODUCTION

Although several approaches for approximating daily Na intake and the Na/K ratio using casual urine are available, the most useful method remains unclear during daily practice and at home.

METHODS

Twenty-seven participants measured their casual urinary Na/K ratio repeatedly using a Na/K ratio monitor and also measured overnight urine once daily using a monitoring device which delivers on-site feedback to estimate their salt intake under unrestricted, low-salt (LS) (6 g/day), and high-salt (HS) (12 g/day) diets.

RESULTS

The monitoring method utilizing overnight urine to estimate daily Na remained insensitive, resulting in significant overestimation during the LS diet and underestimation during the HS diet periods; estimated salt intake during the LS and HS diet periods plateaued at 7-8 g/day and 9-10 g/day within 3 day; mean estimated salt intake was 11.3 g/day, 7.9 g/day, and 9.8 g/day on the last day of the unrestricted, LS, and HS diets; the coefficient of variation (CV) of the estimated Na intake was 0.23 and 0.17 in the latter half of the low- and high-salt diet periods, respectively. The mean urinary Na/K molar ratio was 5.6, 2.5, and 5.3 on the last day of the unrestricted, LS, and HS diets; the CV of the daily mean Na/K ratio was 0.41 and 0.36 in the latter half of the LS and HS diet periods, respectively. The urinary Na/K ratio during the LS and HS diet periods plateaued within 2 days. The monitoring method based on the daily mean of the casual urinary Na/K ratio reflected the actual change in Na intake, and the estimated value tracked the actual changes in salt intake with smaller difference than the overnight urine estimates when using the estimation coefficient set at 2; estimated salt intake during the LS and HS diet periods plateaued at 5-6 g/day and 10-12 g/day within 2-3 day; mean estimated salt intake was 11.0 g/day, 5.7 g/day, and 10.7 g/day on the last day of the unrestricted, LS, and HS diets, respectively.

DISCUSSION/CONCLUSION

Estimates of daily Na intake derived from overnight urine may remain insensitive during dietary interventions. The urinary Na/K ratio reflects the actual change in Na intake during dietary modification and may serve as a practical marker, particularly during short-term interventions. Conversion from the urinary Na/K ratio to estimated salt intake may be useful, if the coefficient was set appropriate by further investigations.

Short-Term RCT of Increased Dietary Potassium from Potato or Potassium Gluconate: Effect on Blood Pressure, Microcirculation, and Potassium and Sodium Retention in Pre-Hypertensive-to-Hypertensive Adults

Increased potassium intake has been linked to improvements in cardiovascular and other health outcomes. We assessed increasing potassium intake through food or supplements as part of a controlled diet on blood pressure (BP), microcirculation (endothelial function), and potassium and sodium retention in thirty pre-hypertensive-to-hypertensive men and women. Participants were randomly assigned to a sequence of four 17 day dietary potassium treatments: a basal diet (control) of 60 mmol/d and three phases of 85 mmol/d added as potatoes, French fries, or a potassium gluconate supplement. Blood pressure was measured by manual auscultation, cutaneous microvascular and endothelial function by thermal hyperemia, utilizing laser Doppler flowmetry, and mineral retention by metabolic balance. There were no significant differences among treatments for end-of-treatment BP, change in BP over time, or endothelial function using a mixed-model ANOVA. However, there was a greater change in systolic blood pressure (SBP) over time by feeding baked/boiled potatoes compared with control (-6.0 mmHg vs. -2.6 mmHg; p = 0.011) using contrast analysis. Potassium retention was highest with supplements. Individuals with a higher cardiometabolic risk may benefit by increasing potassium intake. This trial was registered at ClinicalTrials.gov as NCT02697708.

Urinary sodium and potassium excretions in young adulthood and blood pressure by middle age: the Coronary Artery Risk Development in Young Adults (CARDIA) Study

OBJECTIVE

Data are sparse regarding the impact of sodium and potassium intakes on serial blood pressure (BP) levels during long-term follow-up.

METHODS

Among 1007 Coronary Artery Risk Development in Young Adults participants (mean age, 30.2 years; 53% blacks; 57% women) who had at least two 24-h urine samples collected at year 5 (Y5) examination, we assessed associations of urinary sodium and potassium excretions with BP trends and incident hypertension in the subsequent 25 years. Participants were classified by sex-specific medians for averaged 24-h urinary excretions: lower sodium and higher potassium (Na-Lo-K-Hi); higher sodium and lower potassium (Na-Hi-K-Lo); and others.

RESULTS

In the adjusted generalized estimating equation model, SBP and DBP greatly increased in the Na-Hi-K-Lo group (n = 185) compared with the Na-Lo-K-Hi group (n = 185), with statistically significant BP differences at Y20, Y25, and Y30 (mean SBP, 3.93, 4.94, and 4.88 mmHg, respectively; and mean DBP, 4.70, 4.95, and 4.59 mmHg, respectively). During 25-year follow-up, among 926 participants without prevalent hypertension by Y5, 381 (41.1%) developed hypertension. In the adjusted Cox proportional hazards model, the Na-Hi-K-Lo group had hazard ratio (95% confidence interval), 1.45 (1.00-2.10) for incident hypertension compared with the Na-Lo-K-Hi group. The association with incident hypertension was predominant in blacks and white women (race--sex interaction, P = 0.03). Sodium-to-potassium ratio and sodium excretion were positively, whereas potassium excretion was inversely, associated with incident hypertension (all P trend <0.05).

CONCLUSION

Our findings highlight the importance of dietary sodium reduction and higher potassium intake for hypertension prevention among young adults.

Should we eat more potassium to better control blood pressure in hypertension?

Changes in lifestyle and nutrition are recommended as the first-step approach to the management of hypertension by all national and international guidelines. Today, when considering nutritional factors in hypertension, almost all the attention is focused on the reduction of salt intake to improve blood pressure (BP) control. Changes in potassium intake are only briefly evoked in guidelines. Few physicians actually think about proposing to eat more foods that are high in potassium (fruits, vegetables, nuts) to better control BP. Yet, during the last 40 years, increasing evidence has accumulated demonstrating that increasing potassium intake, either with food products or with supplements, is associated with significant reductions of both systolic and diastolic BP. The hypotensive effect of potassium is particularly marked in patients with hypertension and in subjects with a very high sodium intake, suggesting that potassium counterbalances the effects of sodium. In addition, several meta-analyses have now confirmed that high potassium intake reduces the risk of stroke by ∼ 25%. Finally, increasing potassium in the diet may perhaps be beneficial for some renal patients, as post hoc analyses have suggested that a high potassium intake may retard the decline of renal function in patients with early chronic kidney disease (CKD) stages. However, high potassium intake may be risky and sometimes even dangerous in hypertensive patients with CKD stages 3-5, specifically diabetics. In this context, however, as the level of evidence remains low, more prospective clinical studies are needed. The goal of this review is to discuss the actual evidence that supports the recommendation to eat more potassium in order to better control BP in essential hypertension and to review the restrictions in CKD patients with hypertension.

Kidney Is Essential for Blood Pressure Modulation by Dietary Potassium

Eating more potassium may reduce blood pressure and the occurrence of other cardiovascular diseases by actions on various systems, including the vasculature, the sympathetic nervous system, systemic metabolism, and body fluid volume. Among these, the kidney plays a major role in the potassium-rich diet-mediated blood pressure reduction. PURPOSE OF REVIEW: To provide an overview of recent discoveries about the mechanisms by which a potassium-rich diet leads to natriuresis. RECENT FINDINGS: Although the distal convoluted tubule (DCT) is a short part of the nephron that reabsorbs salt, via the sodium-chloride cotransporter (NCC), it is highly sensitive to changes in plasma potassium concentration. Activation or inhibition of NCC raises or lowers blood pressure. Recent work suggests that extracellular potassium concentration is sensed by the DCT via intracellular chloride concentration which regulates WNK kinases in the DCT. High-potassium diet targets NCC in the DCT, resulting in natriuresis and fluid volume reduction, which are protective from hypertension and other cardiovascular problems.

Urinary sodium-to-potassium ratio and intake of sodium and potassium among men and women from multiethnic general populations: the INTERSALT Study

The Na/K ratio may be more strongly related to blood pressure and cardiovascular disease than sodium or potassium. The casual urine Na/K ratio can provide prompt on-site feedback, and with repeated measurements, may provide useful individual estimates of the 24-h ratio. The World Health Organization has published guidelines for sodium and potassium intake, but no generally accepted guideline prevails for the Na/K ratio. We used standardized data on 24 h and casual urinary electrolyte excretion obtained from the INTERSALT Study for 10,065 individuals aged 20-59 years from 32 countries (52 populations). Associations between the casual urinary Na/K ratio and the 24-h sodium and potassium excretion of individuals were assessed by correlation and stratification analyses. The mean 24-h sodium and potassium excretions were 156.0 mmol/24 h and 55.2 mmol/24 h, respectively; the mean 24-h urinary Na/K molar ratio was 3.24. Pearson's correlation coefficients (r) for the casual urinary Na/K ratio with 24-h sodium and potassium excretions were 0.42 and -0.34, respectively, and these were 0.57 and -0.48 for the 24-h ratio. The urinary Na/K ratio predicted a 24-h urine Na excretion of <85 mmol/day (the WHO recommended guidelines) with a sensitivity of 99.7% and 94.0%, specificity of 39.5% and 48.0%, and positive predictive value of 96.3% and 61.1% at the cutoff point of 1 in 24 h and casual urine Na/K ratios, respectively. A urinary Na/K molar ratio <1 may be a useful indicator for adherence to the WHO recommended levels of sodium and, to a lesser extent, the potassium intake across different populations; however, cutoff points for Na/K ratio may be tuned for localization.

Molecular mechanisms for the regulation of blood pressure by potassium

It has been well documented that the amount of potassium in the diet is associated with blood pressure levels in the population: the higher the potassium consumption, the lower the blood pressure and the cardiovascular mortality. In the last few years certain mechanisms for potassium regulation of salt reabsorption in the kidney have been elucidated at the molecular level. In this work we discuss the evidence demonstrating the relationship between potassium intake and blood pressure levels in human populations and in animal models, as well as the experimental data that reveal the effects of potassium on transepithelial Na⁺ reabsorption in different nephron segments. We also discuss the physiological relevance of K⁺-induced natriuresis, and finally, we focus on the molecular mechanisms by which extracellular potassium modulates the activity of the renal NaCl cotransporter, which is the mechanism that has been best dissected so far.

Elemental Metabolomics and Pregnancy Outcomes

Trace elements are important for human health and development. The body requires specific micronutrients to function, with aberrant changes associated with a variety of negative health outcomes. Despite this evidence, the status and function of micronutrients during pregnancy are relatively unknown and more information is required to ensure that women receive optimal intakes for foetal development. Changes in trace element status have been associated with pregnancy complications such as gestational diabetes mellitus (GDM), pre-eclampsia (PE), intrauterine growth restriction (IUGR), and preterm birth. Measuring micronutrients with methodologies such as elemental metabolomics, which involves the simultaneous quantification and characterisation of multiple elements, could provide insight into gestational disorders. Identifying unique and subtle micronutrient changes may highlight associated proteins that are affected underpinning the pathophysiology of these complications, leading to new means of disease diagnosis. This review will provide a comprehensive summary of micronutrient status during pregnancy, and their associations with gestational disorders. Furthermore, it will also comment on the potential use of elemental metabolomics as a technique for disease characterisation and prediction.

Assessment of Sodium and Potassium Intakes in Children Aged 6 to 18 Years by 24 h Urinary Excretion in City of Rabat, Morocco

Background

The incidence of noncommunicable diseases (NCDs) has greatly increased, mainly due to high level of dietary sodium. Thus, reduction of sodium intake in population has been recognized as one of the most cost-effective strategies to reduce NCDs. The aim of this study was to estimate sodium and potassium consumption in a sample of Moroccan children as a baseline study to implement national strategy for salt intake reduction.

Methods

The study was conducted on 131 children aged 6-18 years recruited from Rabat and its region. Sodium excretion and potassium excretion were measured on 24 h urinary collection, and the creatinine excretion was used to validate completeness of urine collections.

Results

The average of urinary sodium was 2235.3 ± 823.2 mg/day, and 50% of children consume more than 2 g/d of sodium (equivalent to 5 g/day of salt), recommended by the WHO. However, daily urinary excretion of potassium was 1431 ± 636.5 mg/day, and 75% of children consume less than adequate intake. Sodium consumption increased significantly with age. Of particular interest, 46.7% of children aged 6-8 years and 49.3% of children aged 9-13 years consume more than the corresponding upper limits.

Conclusions

Children have high sodium and low potassium status. There is evidence of the urgent need to implement a strategy for reduction of dietary sodium intake in Morocco.

Nutrition education in the care of patients with chronic kidney disease and end-stage renal disease

Diet counseling and nutrition education are recommended in the prevention and management of chronic kidney disease (CKD) and end-stage renal disease (ESRD). The importance of effectively addressing nutrition with patients has grown given the increasing prevalence of obesity, hypertension, and diabetes; conditions which influence CKD/ESRD. Dietary advice for individuals with CKD/ESRD can be seen as complex; and successful dietary management requires careful planning, periodic assessment of nutritional status, as well as monitoring of dietary compliance. In spite of recommendations and pressing need, formal training in nutrition and adequate preparation for providers is limited; and for physicians the lack of nutrition education has been acknowledged, repeatedly, as an area for improvement in medical training curricula. It has also been suggested that dietitians have an essential role in management of CKD in the primary care setting; however, dietitians who do not practice renal education daily may need training on the specific challenges in CKD/ESRD. The objectives of this chapter were to: characterize select nutrition education resources for providers who care for patients with CKD/ESRD; summarize key dietary components emphasized in the care of patients with CKD/ESRD; and address practical considerations in educational efforts focused on nutrition and CKD/ESRD.

Effectiveness of a Self-monitoring Device for Urinary Sodium-to-Potassium Ratio on Dietary Improvement in Free-Living Adults: a Randomized Controlled Trial

BACKGROUND

Reducing the urinary sodium-to-potassium ratio is important for reducing both blood pressure and risk of cardiovascular disease. Among free-living Japanese individuals, we carried out a randomized trial to clarify the effect of lifestyle modification for lowering urinary sodium-to-potassium ratio using a self-monitoring device.

METHODS

This was an open, prospective, parallel randomized, controlled trial. Ninety-two individuals were recruited from Japanese volunteers. Participants were randomly allocated into intervention and control groups. A month-long dietary intervention on self-monitoring urinary sodium-to-potassium ratio was carried out using monitors (HEU-001F, OMRON Healthcare Co., Ltd., Kyoto, Japan). All participants had brief dietary education and received a leaflet as usual care. Monitors were handed out to the intervention group, but not to the control group. The intervention group was asked to measure at least one spot urine sodium-to-potassium ratio daily, and advised to lower their sodium-to-potassium ratio toward the target of less than 1. Outcomes included changes in 24-hour urinary sodium-to-potassium ratio, sodium excretion, potassium excretion, blood pressure, and body weight in both groups.

RESULTS

Mean measurement frequency of monitoring was 2.8 times/day during the intervention. Changes in urinary sodium-to-potassium ratio were -0.55 in the intervention group and -0.06 in the control group (P = 0.088); respective sodium excretion changes were -18.5 mmol/24 hours and -8.7 mmol/24 hours (P = 0.528); and corresponding potassium excretion was 2.6 mmol/24 hours and -1.5 mmol/24 hours (P = 0.300). No significant reductions were observed in either blood pressure or body weight after the intervention.

CONCLUSIONS

Providing the device to self-monitor a sodium-to-potassium ratio did not achieve the targeted reduction of the ratio in "pure self-management" settings, indicating further needs to study an effective method to enhance the synergetic effect of dietary programs and self-monitoring practice to achieve the reduction. However, we cannot deny the possibility of reducing sodium-to-potassium ratio using a self-monitoring device.

Estimating 24-h urinary sodium/potassium ratio from casual ('spot') urinary sodium/potassium ratio: the INTERSALT Study

Background

Association between casual and 24-h urinary sodium-to-potassium (Na/K) ratio is well recognized, although it has not been validated in diverse demographic groups. Our aim was to assess utility across and within populations of casual urine to estimate 24-h urinary Na/K ratio using data from the INTERSALT Study.

Methods

The INTERSALT Study collected cross-sectional standardized data on casual urinary sodium and potassium and also on timed 24-h urinary sodium and potassium for 10 065 individuals from 52 population samples in 32 countries (1985-87). Pearson correlation coefficients and agreement were computed for Na/K ratio of casual urine against 24-h urinary Na/K ratio both at population and individual levels.

Results

Pearson correlation coefficients relating means of 24-h urine and casual urine Na/K ratio were r = 0.96 and r = 0.69 in analyses across populations and individuals, respectively. Correlations of casual urine Na/creatinine and K/creatinine ratios with 24-h urinary Na and K excretion, respectively, were lower than correlation of casual and 24-h urinary Na/K ratio in analyses across populations and individuals. The bias estimate with the Bland-Altman method, defined as the difference between Na/K ratio of 24-h urine and casual urine, was approximately 0.4 across both populations and individuals. Spread around, the mean bias was higher for individuals than populations.

Conclusion

With appropriate bias correction, casual urine Na/K ratio may be a useful, low-burden alternative method to 24-h urine for estimation of population urinary Na/K ratio. It may also be applicable for assessment of the urinary Na/K ratio of individuals, with use of repeated measurements to reduce measurement error and increase precision.

Urinary Sodium and Potassium Excretion and Dietary Sources of Sodium in Maputo, Mozambique

This study aimed to evaluate the urinary excretion of sodium and potassium, and to estimate the main food sources of sodium in Maputo dwellers. A cross-sectional evaluation of a sample of 100 hospital workers was conducted between October 2012 and May 2013. Sodium and potassium urinary excretion was assessed in a 24-h urine sample; creatinine excretion was used to exclude unlikely urine values. Food intake in the same period of urine collection was assessed using a 24-h dietary recall. The Food Processor Plus^® was used to estimate sodium intake corresponding to naturally occurring sodium and sodium added to processed foods (non-discretionary sodium). Salt added during culinary preparations (discretionary sodium) was computed as the difference between urinary sodium excretion and non-discretionary sodium. The mean (standard deviation) urinary sodium excretion was 4220 (1830) mg/day, and 92% of the participants were above the World Health Organization (WHO) recommendations. Discretionary sodium contributed 60.1% of total dietary sodium intake, followed by sodium from processed foods (29.0%) and naturally occurring sodium (10.9%). The mean (standard deviation) urinary potassium excretion was 1909 (778) mg/day, and 96% of the participants were below the WHO potassium intake recommendation. The mean (standard deviation) sodium to potassium molar ratio was 4.2 (2.4). Interventions to decrease sodium and increase potassium intake are needed in Mozambique.

Diurnal variation of urinary sodium-to-potassium ratio in free-living Japanese individuals

High sodium-to-potassium ratios are associated with elevated blood pressure levels and an increased risk of cardiovascular diseases. We aimed to determine whether urinary sodium-to-potassium ratios fluctuate diurnally during the day to understand measured values of casual urinary sodium-to-potassium ratios. A total of 13,277 casual urine specimens were collected under free-living conditions from 122 Japanese normotensive and hypertensive individuals. Participants collected all casual urine samples in aliquot tubes, reported urine volumes and the time at each voiding for 10-22 days. Then, specimens were classified into hourly data. Diurnal patterns of urinary sodium-to-potassium ratios and urinary concentrations of sodium and potassium were evaluated. Overall mean values of hourly urinary sodium-to-potassium ratios were highest (4.1-5.0) in the early morning, lower (3.3-3.8) in the daytime and higher (4.0-4.4) toward evening hours. The mean urinary sodium and potassium concentrations were the lowest (90-110 and 24-32 mmol l-1, respectively) during the early morning and higher (110-140 and 35-43 mmol l-1, respectively) after mid-morning. Diurnal variability of potassium concentrations was larger than for sodium concentrations. Diurnal variations in urinary sodium-to-potassium ratios were comparable between normotensive and hypertensive individuals, between hypertensive individuals with and without antihypertensive medications, and among age and gender-specific subgroups. Overall mean hourly urinary sodium-to-potassium ratios fluctuated diurnally under free-living conditions and were higher during the morning and evening and lower during the daytime compared with 24-h urinary sodium-to-potassium ratios. Diurnal variation in urinary sodium-to-potassium ratios should be considered to understand actual daily dietary levels and avoid over- and under-estimation in clinical practice.

Oral potassium supplementation for management of essential hypertension: A meta-analysis of randomized controlled trials

IMPORTANCE

Increased dietary potassium intake is thought to be associated with low blood pressure (BP). Whether potassium supplementation may be used as an antihypertensive agent is a question that should be answered.

OBJECTIVE

To assess the effect of oral potassium supplementation on blood pressure in patients with primary hypertension.

SEARCH METHODS

We searched Medline, Web of Science, Scopus, Cochrane Central Register of Controlled Trials until October 2016. We also screened reference lists of articles and previous reviews. We applied no language restrictions.

SELECTION CRITERIA

We included randomized placebo-controlled clinical trials addressing the effect of potassium supplementation on primary hypertension for a minimum of 4 weeks.

DATA COLLECTION AND ANALYSIS

We extracted data on systolic and diastolic BP (SBP and DBP) at the final follow-up. We explored the heterogeneity across studies using Cochran's test and I2 statistic and assessed the probability of publication bias using Begg's and Egger's tests. We reported the mean difference (MD) of SBP and DBP in a random-effects model.

RESULTS

We found a total of 9059 articles and included 23 trials with 1213 participants. Compared to placebo, potassium supplementation resulted in modest but significant reductions in both SBP (MD -4.25 mmHg; 95% CI: -5.96 to -2.53; I2 = 41%) and DBP (MD -2.53 mmHg; 95% CI: -4.05 to -1.02; I2 = 65%). According to the change-score analysis, based on 8 out of 23 trials, compared to baseline, the mean changes in SBP (MD -8.89 mmHg; 95% CI: -13.67 to -4.11) and DBP (MD -6.42 mmHg; 95% CI: -10.99 to -1.84) was significantly higher in the intervention group than the control group.

CONCLUSIONS

Our findings indicated that potassium supplementation is a safe medication with no important adverse effects that has a modest but significant impact BP and may be recommended as an adjuvant antihypertensive agent for patients with essential hypertension.

Osmotic expression of aldose reductase in retinal pigment epithelial cells: involvement of NFAT5

BACKGROUND

Diabetic retinopathy is associated with osmotic stress resulting from hyperglycemia and intracellular sorbitol accumulation. Systemic hypertension is a risk factor of diabetic retinopathy. High intake of dietary salt increases extracellular osmolarity resulting in systemic hypertension. We determined the effects of extracellular hyperosmolarity, chemical hypoxia, and oxidative stress on the gene expression of enzymes involved in sorbitol production and conversion in cultured human retinal pigment epithelial (RPE) cells.

METHODS

Alterations in the expression of aldose reductase (AR) and sorbitol dehydrogenase (SDH) genes were examined with real-time RT-PCR. Protein levels were determined with Western blot analysis. Nuclear factor of activated T cell 5 (NFAT5) was knocked down with siRNA.

RESULTS

AR gene expression in RPE cells was increased by high (25 mM) extracellular glucose, CoCl₂ (150 μM)-induced chemical hypoxia, H₂O₂ (20 μM)-induced oxidative stress, and extracellular hyperosmolarity induced by addition of NaCl or sucrose. Extracellular hyperosmolarity (but not hypoxia) also increased AR protein level. SDH gene expression was increased by hypoxia and oxidative stress, but not extracellular hyperosmolarity. Hyperosmolarity and hypoxia did not alter the SDH protein level. The hyperosmotic AR gene expression was dependent on activation of metalloproteinases, autocrine/paracrine TGF-β signaling, activation of p38 MAPK, ERK1/2, and PI3K signal transduction pathways, and the transcriptional activity of NFAT5. Knockdown of NAFT5 or inhibition of AR decreased the cell viability under hyperosmotic (but not hypoxic) conditions and aggravated the hyperosmotic inhibition of cell proliferation.

CONCLUSIONS

The data suggest that sorbitol accumulation in RPE cells occurs under hyperosmotic, but not hypoxic and oxidative stress conditions. NFAT5- and AR-mediated sorbitol accumulation may protect RPE cells under conditions of osmotic stress.

Osmotic induction of placental growth factor in retinal pigment epithelial cells in vitro: contribution of NFAT5 activity

One risk factor of neovascular age-related macular degeneration is systemic hypertension; hypertension is mainly caused by extracellular hyperosmolarity after consumption of dietary salt. In retinal pigment epithelial (RPE) cells, high extracellular osmolarity induces vascular endothelial growth factor (VEGF)-A (Hollborn et al. in Mol Vis 21:360-377, 2015). The aim of the present study was to determine whether extracellular hyperosmolarity and chemical hypoxia trigger the expression of further VEGF family members including placental growth factor (PlGF) in human RPE cells. Hyperosmotic media were made up by addition of 100 mM NaCl or sucrose. Chemical hypoxia was induced by CoCl2. Gene expression was quantified by real-time RT-PCR, and secretion of PlGF-2 was investigated with ELISA. Nuclear factor of activated T cell 5 (NFAT5) was depleted using siRNA. Extracellular hyperosmolarity triggered expression of VEGF-A, VEGF-D, and PlGF genes, and secretion of PlGF-2. Hypoosmolarity decreased PlGF gene expression. Hypoxia induced expression of VEGF-A, VEGF-B, VEGF-D, and PlGF genes. Extracellular hyperosmolarity and hypoxia produced additive PlGF gene expression. Both hyperosmolarity and hypoxia induced expression of KDR and FLT-4 receptor genes, while hyperosmolarity caused neuropilin-2 and hypoxia neuropilin-1 gene expression. The hyperosmotic, but not the hypoxic, PlGF gene expression was in part mediated by NFAT5. The expression of PlGF in RPE cells depends on the extracellular osmolarity. The data suggest that high consumption of dietary salt may exacerbate the angiogenic response of RPE cells in the hypoxic retina via transcriptional activation of various VEGF family member genes.

Osmotic Induction of Angiogenic Growth Factor Expression in Human Retinal Pigment Epithelial Cells

BACKGROUND

Although systemic hypertension is a risk factor of age-related macular degeneration, antihypertensive medications do not affect the risk of the disease. One condition that induces hypertension is high intake of dietary salt resulting in increased blood osmolarity. In order to prove the assumption that, in addition to hypertension, high osmolarity may aggravate neovascular retinal diseases, we determined the effect of extracellular hyperosmolarity on the expression of angiogenic cytokines in cultured human retinal pigment epithelial (RPE) cells.

METHODOLOGY/PRINCIPAL FINDINGS

Hyperosmolarity was induced by the addition of 100 mM NaCl or sucrose to the culture medium. Hypoxia and oxidative stress were induced by the addition of the hypoxia mimetic CoCl2 and H2O2, respectively. Alterations in gene expression were determined with real-time RT-PCR. Secretion of bFGF was evaluated by ELISA. Cell viability was determined by trypan blue exclusion. Nuclear factor of activated T cell 5 (NFAT5) expression was knocked down with siRNA. Hyperosmolarity induced transcriptional activation of bFGF, HB-EGF, and VEGF genes, while the expression of other cytokines such as EGF, PDGF-A, TGF-β1, HGF, and PEDF was not or moderately altered. Hypoxia induced increased expression of the HB-EGF, EGF, PDGF-A, TGF-β1, and VEGF genes, but not of the bFGF gene. Oxidative stress induced gene expression of HB-EGF, but not of bFGF. The hyperosmotic expression of the bFGF gene was dependent on the activation of p38α/β MAPK, JNK, PI3K, and the transcriptional activity of NFAT5. The hyperosmotic expression of the HB-EGF gene was dependent on the activation of p38α/β MAPK, ERK1/2, and JNK. The hyperosmotic expression of bFGF, HB-EGF, and VEGF genes was reduced by inhibitors of TGF-β1 superfamily activin receptor-like kinase receptors and the FGF receptor kinase, respectively. Hyperosmolarity induced secretion of bFGF that was reduced by inhibition of autocrine/paracrine TGF-β1 signaling and by NFAT5 siRNA, respectively. Hyperosmolarity decreased the viability of the cells; this effect was not altered by exogenous bFGF and HB-EGF. Various vegetable polyphenols (luteolin, quercetin, apigenin) inhibited the hyperosmotic expression of bFGF, HB-EGF, and NFAT5 genes.

CONCLUSION

Hyperosmolarity induces transcription of bFGF and HB-EGF genes, and secretion of bFGF from RPE cells. This is in part mediated by autocrine/paracrine TGF-β1 and FGF signaling. It is suggested that high intake of dietary salt resulting in osmotic stress may aggravate neovascular retinal diseases via stimulation of the production of angiogenic factors in RPE cells, independent of hypertension.

Relationship between nutrition and blood pressure: a cross-sectional analysis from the NutriNet-Santé Study, a French web-based cohort study

BACKGROUND

Hypertension is the most prevalent chronic disease worldwide. Lifestyle behaviors for its prevention and control are recommended within worldwide guidelines. Nevertheless, their combined relationship with blood pressure (BP) level, particularly in the general population, would need more investigations. Our aim in this study was to evaluate the relative impact of lifestyle and nutritional factors on BP level.

METHODS

Cross-sectional analyses were performed using data from 8,670 volunteers from the NutriNet-Santé Study, an ongoing French web-based cohort study. Dietary intakes were assessed using three 24-hour records. Information on lifestyle factors was collected using questionnaires and 3 BP measurements following a standardized protocol. Age-adjusted associations and then multivariate associations between systolic BP (SBP) and lifestyle behaviors were estimated using multiple linear regressions.

RESULTS

SBP was higher in participants with elevated body mass indices (BMIs). Salt intake was positively associated with SBP in men but not in women. The negative relationship between consumption of fruits and vegetables and SBP was significant in both sexes. Alcohol intake was positively associated with SBP in both sexes; physical activity was not. The 5 parameters representing the well-accepted modifiable factors for hypertension reduction plus age and education level, accounted for 19.7% of the SBP variance in women and 12.8% in men. Considering their squared partial correlation coefficient, age and BMI were the most important parameters relating to SBP level. Salt intake was not associated with SBP in either sex after multiple adjustments.

CONCLUSIONS

BMI was the main contributory modifiable factor of BP level after multiple adjustments.

Comprehensive assessment of the association of WNK4 polymorphisms with hypertension: evidence from a meta-analysis

The relationship between with-no-lysine [K] kinase 4 (WNK4) gene polymorphisms and hypertension has been widely investigated, However, the studies yielded contradictory results. To evaluate these inconclusive findings comprehensively, we therefore performed a meta-analysis. Ten articles encompassing 16 independent case-control studies with 6089 hypertensive cases and 4881 normotensive controls were selected for this meta-analysis. Four WNK4 gene polymorphisms were identified (G1155942T, G1156666A, T1155547C, and C6749T). The results showed statistically significant associations of G1155942T polymorphism (allelic genetic model: odds ration or OR = 1.62, 95% confidence interval or CI: 1.11–2.38, P = 0.01; dominant model: OR = 1.85, 95% CI: 1.07–3.19, P = 0.03) and C6749T polymorphism (allele contrast: OR = 2.04, 95% CI: 1.60–2.59, P<0.01; dominant model: OR = 2.04, 95%CI: 1.59–2.62, P<0.01; and homozygous model: OR = 5.01, 95% CI: 1.29–19.54, P = 0.02) with hypertension risk. However, neither C1155547T nor G1156666A was associated significantly with hypertension susceptibility. In conclusion, this meta-analysis suggested that WNK4 G1155942T and C6749T gene polymorphisms may contribute to the susceptibility and development of hypertension. Further well-designed studies with larger sample size are required to elucidate the association of WNK4 gene multiple polymorphisms with hypertension risk.

Lower levels of sodium intake and reduced cardiovascular risk

BACKGROUND

Recent studies have raised the possibility of adverse effects of low sodium, particularly <2300 mg/d, on cardiovascular disease; however, these paradoxical findings might have resulted from suboptimal measurement of sodium and potential biases related to indication or reverse causation.

METHODS AND RESULTS

Phases 1 and 2 of the Trials of Hypertension Prevention (TOHP) collected multiple 24-hour urine specimens among prehypertensive individuals. During extended post-trial surveillance, 193 cardiovascular events or cardiovascular disease deaths occurred among 2275 participants not in a sodium reduction intervention with 10 (TOHP II) or 15 (TOHP I) years of post-trial follow-up. Median sodium excretion was 3630 mg/d, with 1.4% of the participants having intake <1500 mg/d and 10% <2300 mg/d, consistent with national levels. Compared with those with sodium excretion of 3600 to <4800 mg/d, risk for those with sodium <2300 mg/d was 32% lower after multivariable adjustment (hazard ratio, 0.68; 95% confidence interval, 0.34-1.37; P for trend=0.13). There was a linear 17% increase in risk per 1000 mg/d increase in sodium (P=0.05). Spline curves supported a linear association of sodium with cardiovascular events, which continued to decrease from 3600 to 2300 and 1500 mg/d, although the data were sparse at the lowest levels. Controlling for creatinine levels had little effect on these results.

CONCLUSIONS

Results from the TOHP studies, which overcome the major methodological challenges of prior studies, are consistent with overall health benefits of reducing sodium intake to the 1500 to 2300 mg/d range in the majority of the population, in agreement with current dietary guidelines.

Dietary sodium intakes and food sources of sodium in Canadian-born and Asian-born individuals of Chinese ethnicity at a Canadian university campus

OBJECTIVE

To document the sodium intake and food sources of sodium of Canadian-born Chinese (CBC) and Asian-born Chinese (ABC) individuals at a Canadian university campus.

PARTICIPANTS

Healthy adults aged 18-58 years originating from Canada, China, Hong Kong, or Taiwan were recruited from the University of Alberta (n=40 CBC, n=41 ABC) between May and December 2010.

METHODS

Two in-person multipass 24-hour dietary recall interviews were administered for 1 weekday and 1 weekend day.

RESULTS

The mean sodium intake was 3,623±1,406 mg/day. The major food sources of sodium were commercially prepared and processed foods for both CBC and ABC (59.9% and 54.7% of sodium, respectively). Condiments contributed substantially to dietary sodium intake of CBC and ABC (27.8% and 35.1% of sodium, respectively).

CONCLUSIONS

Efforts to reduce dietary sodium among students and other adults of Chinese ethnicity should focus on limiting consumption of commercially processed foods and moderation in discretionary use of salt and soy sauce.

Association between usual sodium and potassium intake and blood pressure and hypertension among U.S. adults: NHANES 2005-2010

OBJECTIVES

Studies indicate high sodium and low potassium intake can increase blood pressure suggesting the ratio of sodium-to-potassium may be informative. Yet, limited studies examine the association of the sodium-to-potassium ratio with blood pressure and hypertension.

METHODS

We analyzed data on 10,563 participants aged ≥20 years in the 2005-2010 National Health and Nutrition Examination Survey who were neither taking anti-hypertensive medication nor on a low sodium diet. We used measurement error models to estimate usual intakes, multivariable linear regression to assess their associations with blood pressure, and logistic regression to assess their associations with hypertension.

RESULTS

The average usual intakes of sodium, potassium and sodium-to-potassium ratio were 3,569 mg/d, 2,745 mg/d, and 1.41, respectively. All three measures were significantly associated with systolic blood pressure, with an increase of 1.04 mmHg (95% CI, 0.27-1.82) and a decrease of 1.24 mmHg (95% CI, 0.31-2.70) per 1,000 mg/d increase in sodium or potassium intake, respectively, and an increase of 1.05 mmHg (95% CI, 0.12-1.98) per 0.5 unit increase in sodium-to-potassium ratio. The adjusted odds ratios for hypertension were 1.40 (95% CI, 1.07-1.83), 0.72 (95% CI, 0.53-0.97) and 1.30 (95% CI, 1.05-1.61), respectively, comparing the highest and lowest quartiles of usual intake of sodium, potassium or sodium-to-potassium ratio.

CONCLUSIONS

Our results provide population-based evidence that concurrent higher sodium and lower potassium consumption are associated with hypertension.

Food pattern modeling shows that the 2010 Dietary Guidelines for sodium and potassium cannot be met simultaneously

The 2010 US Dietary Guidelines recommended limiting intake of sodium to 1500 mg/d for people older than 50 years, African Americans, and those suffering from chronic disease. The guidelines recommended that all other people consume less than 2300 mg sodium and 4700 mg of potassium per day. The theoretical feasibility of meeting the sodium and potassium guidelines while simultaneously maintaining nutritional adequacy of the diet was tested using food pattern modeling based on linear programming. Dietary data from the National Health and Nutrition Examination Survey 2001-2002 were used to create optimized food patterns for 6 age-sex groups. Linear programming models determined the boundary conditions for the potassium and sodium content of the modeled food patterns that would also be compatible with other nutrient goals. Linear programming models also sought to determine the amounts of sodium and potassium that both would be consistent with the ratio of Na to K of 0.49 and would cause the least deviation from the existing food habits. The 6 sets of food patterns were created before and after an across-the-board 10% reduction in sodium content of all foods in the Food and Nutrition Database for Dietary Studies. Modeling analyses showed that the 2010 Dietary Guidelines for sodium were incompatible with potassium guidelines and with nutritionally adequate diets, even after reducing the sodium content of all US foods by 10%. Feasibility studies should precede or accompany the issuing of dietary guidelines to the public.

Serum potassium predicts time to blood pressure response among African Americans with hypertensive nephrosclerosis

It is not known whether serum potassium levels affect blood pressure response to anti-hypertensive medication. The African American trial of Kidney disease and Hypertension (AASK) Genomics Study (N=828) is a subset of the AASK trial that randomized 1,094 African American men and women with hypertensive nephrosclerosis to ramipril, amlodipine or metoprolol. Participants were also randomized to a usual (102–107 mmHg) or low (≤92 mmHg) mean arterial pressure (MAP) treatment goal. Time-to-event analyses were used to determine the relationship between serum potassium prior to randomization and time (days) to reach an MAP of 107 mmHg. Mean baseline serum potassium was 4.22 (standard deviation +/− 0.56 and range 2.8–6.0) mmol/L and the median days to reach target MAP was 32 (interquartile range 8–95) days. The adjusted hazard ratio (HR) for each 1mmol/L increase in serum potassium was 1.31 (95%CI: 1.08–1.59) in the usual MAP group, and 1.21 (95%CI: 1.02–1.44) in the low MAP group. Secondary findings suggested that women in the usual MAP group on amlodipine were more likely to reach target MAP compared to women randomized to ramipril (HR: 2.05, 95%CI: 1.30–3.21). Older subjects in the low MAP group (≥55 years) were also more likely to reach target MAP on amlodipine compared to ramipril (HR: 1.57, 95%CI: 1.03–2.38). Serum potassium appears to be a significant predictor of time to blood pressure response, independent of drug class. Results also suggest a benefit of using amlodipine when more rapid blood pressure control is clinically indicated among women and more aggressively managed older subjects.

Diuretic use is associated with better learning and memory in older adults in the Ginkgo Evaluation of Memory Study

BACKGROUND

To investigate the association between diuretics, angiotensin-converting enzyme inhibitors (ACE-I), angiotensin II receptor blockers (AT2RB), and cognitive function.

METHODS

This post hoc analysis of the randomized controlled Ginkgo Evaluation of Memory Study trial focuses on 3069 nondemented community-dwelling participants aged >75 years. At baseline visit, detailed information about medication use was collected and five cognitive domains were assessed. Multivariate linear regression analyses were used to assess cross-sectional associations between medication use and cognitive function.

RESULTS

In all, 36% of participants reported history of hypertension and 53% reported antihypertensive medication use, with 17% reporting diuretic, 11% ACE-I, and 2% AT2RB use. Potassium-sparing diuretic use (N = 192) was associated with better verbal learning and memory measured by California Verbal Learning Test as compared with no antihypertensive medication users (β = 0.068, P = .01; β = 0.094, P < .001) and other antihypertensive medication users (β = 0.080, P = .03; β = 0.153, P < .001). Use of ACE-I or AT2RB was not associated with better cognitive function.

CONCLUSION

Results warrant further investigation into possible protective effects of potassium-sparing diuretics and the role of potassium in mitigating cognitive decline.

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

Association of sodium and potassium intake with left ventricular mass: coronary artery risk development in young adults

High salt intake may affect left ventricular mass (LVM). We hypothesized that urinary sodium (UNa) and sodium/potassium ratio (UNa/K) are associated with LVM in a predominantly normotensive cohort of young adults. The Coronary Artery Risk Development in Young Adults (CARDIA) Study is a multicenter cohort of black and white men and women aged 30±3.6 years at the time of baseline echocardiographic examination (1990-1991). 2D guided M-mode LVM indexed to body size (grams per meter(2.7)) was calculated, and UNa and potassium excretion assessed (average of three 24-hour urinary samples, n=1042). Linear and logistic regression analysis was used. Participants were 57% women and 55% black. Only 4% were hypertensive. UNa, urinary potassium, and UNa/K ratios were (mean±SD) 175.6±131.0, 56.4±46.3, and 3.4±1.4 mmol/24 h, respectively. Participants in the highest versus the lowest UNa excretion quartile had the greatest LVM (37.5 versus 34.0 g/m(2.7); P<0.001). Adjusted for age, sex, education, and race, LVM averaged 0.945 g/m(2.7) higher per SD of UNa/K (P=0.001). The relationship between UNa/K and LVM persisted among 399 participants with repeat echocardiographic measures 5 years later. In logistic regression analysis adjusted for age, sex, education, and race, each SD higher baseline UNa/K was associated with 23% and 38% greater chances of being in the highest quartile of LVM at baseline (odds ratio: 1.23; P=0.005) and 5 years later (odds ratio: 1.38; P=0.02). A higher sodium/potassium excretion ratio is significantly related to cardiac structure, even among healthy young adults.

Development and use of FFQ among adults in diverse settings across the globe

In nutritional epidemiology, development of valid dietary assessment instruments specific to populations in diverse settings is of paramount importance. Such instruments are essential when trying to characterise dietary patterns and intake, investigate diet-disease associations, inform and evaluate nutrition interventions, assess nutrient-gene interactions, conduct cross-country comparison studies and monitor nutrition transitions. The FFQ is a relatively inexpensive tool for measuring long-term dietary intake for large populations and for allowing researchers to track dietary changes over time. However, FFQ must be population specific to capture the local diet and available foods. Collecting 24-h dietary recalls and utilising community feedback to build the FFQ ensures that a culturally appropriate instrument is developed. This article presents several examples describing FFQ development and utilisation in different settings globally. In the Canadian Arctic, FFQ were developed and utilised to inform and evaluate a community-based intervention programme, characterise the diet and track dietary changes occurring among Inuit and Inuvialuit, populations experiencing rising rates of chronic disease and likely to be extremely vulnerable to the potential effects of climate change. Another example is an FFQ developed to assess sodium intake and evaluate a sodium reduction trial in a high-risk population in Barbados. An example is provided from Brazil, where an FFQ was developed to assess associations between diet, heterocyclic aromatic amines and colorectal adenoma among Japanese Brazilians and to conduct cross-country comparisons. These and other case studies highlight the diversity in dietary intake between populations and the need for FFQ to be developed to capture this diversity.

Lifestyle Intervention Strategies for the Prevention and Treatment of Hypertension: A Review

Hypertension (HTN) is an extraordinarily common progressive cardiovascular syndrome in the United States, afflicting approximately one third of the adult population. HTN is a powerful and unequivocal independent risk factor for cardiovascular and renal diseases, including coronary heart disease, stroke, and renal failure. Despite major advances in the understanding and treatment of HTN over the past several decades, the disease remains the most common primary diagnosis in the United States and is a major public health concern. Adoption of healthy lifestyle modifications has proven to be highly effective in both the prevention of new-onset HTN and in the treatment of those diagnosed with HTN. In view of the continuing epidemic of HTN and blood pressure (BP)—related diseases and the invaluable role of applying nonpharmacological therapy in the prevention and management of HTN, a review of current therapeutic lifestyle strategies appears warranted. This review will define 6 well-established nonpharmacological lifestyle modifications for preventing and managing HTN in addition to 3 novel lifestyle interventions that show promise as effective adjunct strategies for lowering BP. A healthy lifestyle prescription ideally comprising a number of these BP-lowering lifestyle intervention strategies should be dispensed by all primary care physicians for both the prevention and treatment of elevated BP, an action that would have major, positive public health ramifications.

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

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

The key to life nutrition program: results from a community-based dietary sodium reduction trial

OBJECTIVE

Evaluation of a dietary Na reduction trial in a community setting.

DESIGN

Community-based randomized trial. Ten-week nutrition intervention activities focused on lifestyle modification to decrease dietary Na intake, under the supervision of a registered dietitian. Twenty-four hour urine specimens were collected at baseline and follow-up visits to determine 24 h urinary Na excretion.

SETTING

The University of Pittsburgh Center for Healthy Aging, Key to Life Nutrition Program.

SUBJECTS

Hypertensive adults at least 65 years of age.

RESULTS

Mean age of participants was 75 years. Twenty-four hour mean urinary Na excretion at baseline was 3174 mg/d. This reduced to 2944 mg/d (P = 0.30) and 2875 mg/d (P <or= 0.03) at 6- and 12-month follow-ups, respectively. In a sub-sample (urine volume of >or=1000 ml, baseline to 12 months), mean urinary Na excretion decreased from 3220 mg/d to 2875 mg/d (P <or= 0.02).

CONCLUSIONS

Significant reductions in mean 24 h urinary Na were reported, but results fell short of the recommended guidelines of 1500 mg/d for at-risk individuals. Our results reiterate the difficulty in implementing these guidelines in community-based programmes. More aggressive public health efforts, food industry support and health policy changes are needed to decrease Na levels in older adults to the recommended guidelines.