Joint effects of sodium and potassium intake on subsequent cardiovascular disease: the Trials of Hypertension Prevention follow-up study

Dietary Patterns and Risk for Metabolic Syndrome in Korean Women: A Cross-Sectional Study

Dietary patterns are a risk factor for metabolic syndrome (MetS). The prevalence of MetS has increased in Korea, and this condition has become a public health issue. Therefore, the present cross-sectional study aimed to identify the associations between dietary patterns and the risk of MetS among Korean women.The data of 5189 participants were analyzed to determine dietary intake and lifestyle. A principal components analysis was employed to determine participant dietary patterns with regard to 106 food items. MetS was diagnosed using the National Cholesterol Education Program, Adult Treatment Panel III. Logistic regression analyses were applied to evaluate the associations between dietary pattern quintiles and MetS and to generate odds ratios (ORs) and 95% confidence intervals (CIs) after adjusting for potential confounders.Three dietary patterns were identified: "traditional," "western," and "prudent." The "prudent" dietary pattern consisted of a high intake of fruits and fruit products as well as nuts, dairy, and a low consumption of grains; this pattern was negatively associated with the risk of MetS. The highest quintile of the "prudent" dietary pattern was significantly less likely to develop MetS (OR: 0.5, 95% CI: 0.36-0.68, P for trend <0.001) compared with the lowest quintile. This pattern was also negatively associated with all of the MetS diagnostic criteria: abdominal obesity (OR: 0.52, 95% CI: 0.41-0.65), blood pressure (OR: 0.72, 95% CI: 0.59-0.87), triglycerides (OR: 0.67, 95% CI: 0.52-0.85), fasting glucose (OR: 0.64, 95% CI: 0.43-0.95), and high-density lipoprotein cholesterol (OR: 0.53, 95% CI: 0.42-0.68). However, the "traditional" and "western" dietary patterns were not associated with the risk of MetS.The "prudent" dietary pattern was negatively associated with the risk of developing MetS among Korean women.

Pathophysiology and treatment of resistant hypertension: the role of aldosterone and amiloride-sensitive sodium channels

Resistant hypertension is a clinically distinct subgroup of hypertension defined by the failure to achieve blood pressure control on optimal dosing of at least 3 antihypertensive medications of different classes, including a diuretic. The pathophysiology of hypertension can be attributed to aldosterone excess in more than 20% of patients with resistant hypertension. Existing dogma attributes the increase in blood pressure seen with increases in aldosterone to its antinatriuretic effects in the distal nephron. However, emerging research, which has identified and has begun to define the function of amiloride-sensitive sodium channels and mineralocorticoid receptors in the systemic vasculature, challenges impaired natriuresis as the sole cause of aldosterone-mediated resistant hypertension. This review integrates these findings to better define the role of the vasculature and aldosterone in the pathophysiology of resistant hypertension. In addition, a brief guide to the treatment of resistant hypertension is presented.

Frequent Canned Food Use is Positively Associated with Nutrient-Dense Food Group Consumption and Higher Nutrient Intakes in US Children and Adults

In addition to fresh foods, many canned foods also provide nutrient-dense dietary options, often at a lower price, with longer storage potential. The aim of this study was to compare nutrient-dense food group intake and nutrient intake between different levels of canned food consumption in the US. Consumption data were collected for this cross-sectional study from 9761 American canned food consumers (aged two years and older) from The NPD Group’s National Eating Trends^® (NET^®) database during 2011–2013; and the data were assessed using The NPD Group’s Nutrient Intake Database. Canned food consumers were placed into three groups: Frequent Can Users (≥6 canned items/week); n = 2584, Average Can Users (3–5 canned items/week); n = 4445, and Infrequent Can Users (≤2 canned items/week); n = 2732. The results provide evidence that Frequent Can Users consume more nutrient-dense food groups such as fruits, vegetables, dairy products, and protein-rich foods, and also have higher intakes of 17 essential nutrients including the shortfall nutrients—potassium, calcium and fiber—when compared to Infrequent Can Users. Therefore, in addition to fresh foods, diets higher in nutrient-dense canned food consumption can also offer dietary options which improve nutrient intakes and the overall diet quality of Americans.

Sodium intake and cardiovascular health

Sodium is an essential nutrient. Increasing sodium intake is associated with increasing blood pressure, whereas low sodium intake results in increased renin and aldosterone levels. Randomized controlled trials have reported reductions in blood pressure with reductions in sodium intake, to levels of sodium intake <1.5 g/d, and form the evidentiary basis for current population-wide guidelines recommending low sodium intake. Although low sodium intake (<2.0 g/d) has been achieved in short-term feeding clinical trials, sustained low sodium intake has not been achieved by any of the longer term clinical trials (>6-month duration). It is assumed that the blood pressure-lowering effects of reducing sodium intake to low levels will result in large reductions in cardiovascular disease globally. However, current evidence from prospective cohort studies suggests a J-shaped association between sodium intake and cardiovascular events, based on studies from >300 000 people, and suggests that the lowest risk of cardiovascular events and death occurs in populations consuming an average sodium intake range (3-5 g/d). The increased risk of cardiovascular events associated with higher sodium intake (>5 g/d) is most prominent in those with hypertension. A major deficit in the field is the absence of large randomized controlled trials to provide definitive evidence on optimal sodium intake for preventing cardiovascular events. Pending such trials, current evidence would suggest a recommendation for moderate sodium intake in the general population (3-5 g/d), with targeting the lower end of the moderate range among those with hypertension.

Serum Uric Acid and Prehypertension Among Adults Free of Cardiovascular Diseases and Diabetes

The association between serum uric acid (SUA) and prehypertension was evaluated in a racially admixed sample of civil servants aged 35 to 74 years, enrolled (2008-2010) in the Brazilian Longitudinal Study of Health (ELSA-Brasil). Of the 15 105 patients who enrolled in the study, we analyzed 3412 after excluding those who reported previous cardiovascular diseases, diabetes, or hypertension; were heavy drinkers; or had a body mass index (BMI) ≥35 kg/m2. Among the men, logistic regression, adjusted for age, race, income, birth weight, salt intake, insulin resistance, BMI, and renal function revealed odds ratios (ORs) and 95% confidence intervals (CIs) of prehypertension from the bottom quartile (referent) to the top quartile of SUA levels as follows: 0.84 (95% CI, 0.61-1.38), 0.97 (0.71-1.34) and 1.44 (1.04-2.0; P for trend .01). Analyzing for 1-standard deviation of change in SUA, the ORs were 1.19 (1.06-1.32). This association persisted in the subgroup analysis consisting of patients who were white, overweight, with a high salt intake but with normal renal function, and without metabolic syndrome. No association was found among women. In conclusion, SUA levels were associated with prehypertension among men.

The feasibility and acceptability of reducing salt in partially baked bread: a Spanish case study

OBJECTIVE

Bread is a staple of the Mediterranean diet but contributes substantially to its salt content (19 % in Spain). The objective of the present study was to assess the feasibility and acceptability of salt reduction in partially baked breads, partly replacing salt (NaCl) with a potassium salt, with subsequent follow-up.

DESIGN

During 2013, nine breads already on the market (1·8 % NaCl flour basis) had 0·5 % of NaCl replaced with potassium citrate (27·7 % reduction in sodium) and were commercialized in Spain. Later, breads were baked in bake-off stores and sold ready-to-eat to consumers. This market test was evaluated by comparing the sales between standard- v. reduced-salt breads and the complaints related to flavour attributes. The wholesalers involved in the market test were then surveyed.

SETTING

Spain.

RESULTS

The market test confirmed good acceptance of the reduced-salt breads, as 2013 sales were 3678 tonnes v. 2012 sales of 3577 tonnes for the same standard breads. No complaints were received. The wholesaler survey showed, in general, little awareness of salt reduction.

CONCLUSIONS

It is feasible that potassium citrate can reduce the salt content of bread without negatively affecting sales or complaints. This shows potential for introducing this type of bread on a larger scale.

Effect of sodium and potassium supplementation on vascular and endothelial function: a randomized controlled trial

BACKGROUND

It is known that increased potassium and reduced sodium intakes can improve postprandial endothelial function. However, the effect of increasing potassium in the presence of high sodium in the postprandial state is not known.

OBJECTIVE

We aimed to determine the effect of high potassium and high sodium on postprandial endothelial function as assessed by using flow-mediated dilatation (FMD) and arterial compliance as assessed by using pulse wave velocity (PWV) and central augmentation index (AIx).

DESIGN

Thirty-nine healthy, normotensive volunteers [21 women and 18 men; mean ± SD age: 37 ± 15 y; BMI (in kg/m(2)): 23.0 ± 2.8] received a meal with 3 mmol K and 65 mmol Na (low-potassium, high-sodium meal (LKHN)], a meal with 38 mmol K and 65 mmol Na [high-potassium, high-sodium meal (HKHN)], and a control meal with 3 mmol K and 6 mmol Na (low-potassium, low-sodium meal) on 3 separate occasions in a randomized crossover trial. Brachial artery FMD, carotid-femoral PWV, central AIx, and blood pressure (BP) were measured while participants were fasting and at 30, 60, 90, and 120 min after meals.

RESULTS

Compared with the LKHN, the addition of potassium (HKHN) significantly attenuated the postmeal decrease in FMD (P-meal by time interaction < 0.05). FMD was significantly lower after the LKHN than after the HKHN at 30 min (P < 0.01). AIx decreased after all meals (P < 0.05). There were no significant differences in AIx, PWV, or BP between treatments over time.

CONCLUSION

The addition of potassium to a high-sodium meal attenuates the sodium-induced postmeal reduction in endothelial function as assessed by FMD. This trial was registered at http://www.anzctr.org.au/ as ACTRN12613000772741.

Pooled results from 5 validation studies of dietary self-report instruments using recovery biomarkers for potassium and sodium intake

We pooled data from 5 large validation studies (1999-2009) of dietary self-report instruments that used recovery biomarkers as referents, to assess food frequency questionnaires (FFQs) and 24-hour recalls (24HRs). Here we report on total potassium and sodium intakes, their densities, and their ratio. Results were similar by sex but were heterogeneous across studies. For potassium, potassium density, sodium, sodium density, and sodium:potassium ratio, average correlation coefficients for the correlation of reported intake with true intake on the FFQs were 0.37, 0.47, 0.16, 0.32, and 0.49, respectively. For the same nutrients measured with a single 24HR, they were 0.47, 0.46, 0.32, 0.31, and 0.46, respectively, rising to 0.56, 0.53, 0.41, 0.38, and 0.60 for the average of three 24HRs. Average underreporting was 5%-6% with an FFQ and 0%-4% with a single 24HR for potassium but was 28%-39% and 4%-13%, respectively, for sodium. Higher body mass index was related to underreporting of sodium. Calibration equations for true intake that included personal characteristics provided improved prediction, except for sodium density. In summary, self-reports capture potassium intake quite well but sodium intake less well. Using densities improves the measurement of potassium and sodium on an FFQ. Sodium:potassium ratio is measured much better than sodium itself on both FFQs and 24HRs.

The feasibility of meeting the WHO guidelines for sodium and potassium: a cross-national comparison study

OBJECTIVE

To determine joint compliance with the WHO sodium-potassium goals in four different countries, using data from nationally representative dietary surveys.

SETTING

Compared to national and international recommendations and guidelines, the world's population consumes too much sodium and inadequate amounts of potassium. The WHO recommends consuming less than 2000 mg sodium (86 mmol) and at least 3510 mg potassium (90 mmol) per person per day.

PARTICIPANTS

Dietary surveillance data were obtained from the National Health and Nutrition Examination Survey (NHANES 2007-2010) for the USA; the Encuesta Nacional de Salud y Nutrición 2012 for Mexico; the Individual and National Study on Food Consumption (INCA2) for France; and the National Diet and Nutrition Survey (NDNS) for the UK.

PRIMARY OUTCOME MEASURES

We estimated the proportion of adults meeting the joint WHO sodium-potassium goals in the USA, the UK, France and Mexico.

RESULTS

The upper bounds of joint compliance with the WHO sodium-potassium goals were estimated at 0.3% in the USA, 0.15% in Mexico, 0.5% in France and 0.1% in the UK.

CONCLUSIONS

Given prevailing food consumption patterns and the current food supply, implementing WHO guidelines will be an enormous challenge for global public health.

Effect of Salt Intake and Potassium Supplementation on Urinary Renalase and Serum Dopamine Levels in Chinese Adults

Objective: The aim of our study was to assess the effects of altered salt and potassium intake on urinary renalase and serum dopamine levels in humans. Methods: Forty-two subjects (28-65 years of age) were selected from a rural community of northern China. All subjects were sequentially maintained on a low-salt diet for 7 days (3.0 g/day of NaCl), a high-salt diet for an additional 7 days (18.0 g/day of NaCl), and a high-salt diet with potassium supplementation for a final 7 days (18.0 g/day of NaCl + 4.5 g/day of KCl). Results: Urinary renalase excretions were significantly higher during the high-salt diet intervention than during the low-salt diet. During high-potassium intake, urinary renalase excretions were not significantly different from the high-salt diet, whereas they were significantly higher than the low-salt levels. Serum dopamine levels exhibited similar trends across the interventions. Additionally, a significant positive relationship was observed between the urine renalase and serum dopamine among the different dietary interventions. Also, 24-hour urinary sodium excretion positively correlated with urine renalase and serum dopamine in the whole population. Conclusions: The present study indicates that dietary salt intake and potassium supplementation increase urinary renalase and serum dopamine levels in Chinese subjects.

Association between 24 h urinary sodium and potassium excretion and the metabolic syndrome in Chinese adults: the Shandong and Ministry of Health Action on Salt and Hypertension (SMASH) study

The association of 24 h urinary Na and potassium excretion with the risk of the metabolic syndrome (MetS) has not been studied in China. The aim of the present study was to examine this association by analysing the data from 1906 study participants living in north China. To this end, 24 h urine samples were collected. Of the 1906 participants, 471 (24·7 %) had the MetS. The mean urinary Na and K excretion was 228·7 and 40·8 mmol/d, respectively. After multivariate adjustment, the odds of the MetS significantly increased across the increasing tertiles of urinary Na excretion (1·00, 1·40 and 1·54, respectively). For the components of the MetS, the odds of central obesity, elevated blood pressure and elevated TAG, but not the odds of low HDL-cholesterol and elevated fasting glucose, significantly increased with the successive tertiles of urinary Na excretion. Furthermore, for every 100 mmol/d increase in urinary Na excretion, the odds of the MetS, central obesity, elevated blood pressure and elevated TAG was significantly increased by 29, 63, 22 and 21 %, respectively. However, urinary K excretion was not significantly associated with the risk of the MetS. These findings suggest that high Na intake might be an important risk factor for the MetS in Chinese adults.

Reducing salt intake for prevention of cardiovascular disease--times are changing

The evidence relating blood pressure to salt intake in humans originates from population studies and randomized clinical trials of interventions on dietary salt intake. Estimates from meta-analyses of trials in normotensive subjects generally are similar to estimates derived from prospective population studies (+1.7 mm Hg increase in systolic blood pressure per 100-mmol increment in 24-hour urinary sodium). This estimate, however, does not translate into an increased risk of incident hypertension in subjects consuming a high salt diet. Prospective studies relating health outcomes to 24-hour urinary sodium excretion produced inconsistent results. Taken together, available evidence does not support the current recommendations of a generalized and indiscriminate reduction of salt intake at the population level, although the blood pressure-lowering effect of dietary sodium restriction might be of value in hypertensive patients.

Cross-Sectional Study of 24-Hour Urinary Electrolyte Excretion and Associated Health Outcomes in a Convenience Sample of Australian Primary Schoolchildren: The Salt and Other Nutrients in Children (SONIC) Study Protocol

BACKGROUND

Dietary sodium and potassium are involved in the pathogenesis of cardiovascular disease. Data exploring the cardiovascular outcomes associated with these electrolytes within Australian children is sparse. Furthermore, an objective measure of sodium and potassium intake within this group is lacking.

OBJECTIVE

The primary aim of the Salt and Other Nutrient Intakes in Children ("SONIC") study was to measure sodium and potassium intakes in a sample of primary schoolchildren located in Victoria, Australia, using 24-hour urine collections. Secondary aims were to identify the dietary sources of sodium and potassium, examine the association between these electrolytes and cardiovascular risk factors, and assess children's taste preferences and saltiness perception of manufactured foods.

METHODS

A cross-sectional study was conducted in a convenience sample of schoolchildren attending primary schools in Victoria, Australia. Participants completed one 24-hour urine collection, which was analyzed for sodium, potassium, and creatinine. Completeness of collections was assessed using collection time, total volume, and urinary creatinine. One 24-hour dietary recall was completed to assess dietary intake. Other data collected included blood pressure, body weight, height, waist and hip circumference. Children were also presented with high and low sodium variants of food products and asked to discriminate salt level and choose their preferred variant. Parents provided demographic information and information on use of discretionary salt. Descriptive statistics will be used to describe sodium and potassium intakes. Linear and logistic regression models with clustered robust standard errors will be used to assess the association between electrolyte intake and health outcomes (blood pressure and body mass index/BMI z-score and waist circumference) and to assess differences in taste preference and discrimination between high and low sodium foods, and correlations between preference, sodium intake, and covariates.

RESULTS

A total of 780 children across 43 schools participated. The results from this study are expected at the end of 2015.

CONCLUSIONS

This study will provide the first objective measure of sodium and potassium intake in Australian schoolchildren and improve our understanding of the relationship of these electrolytes to cardiovascular risk factors. Furthermore, this study will provide insight into child taste preferences and explore related factors. Given the cardiovascular implications of consuming too much sodium and too little potassium, monitoring of these nutrients during childhood is an important public health initiative.

The relation of potassium and sodium intakes to diet cost among U.S. adults

The 2010 Dietary Guidelines recommended that Americans increase potassium and decrease sodium intakes to reduce the burden of hypertension. One reason why so few Americans meet the recommended potassium or sodium goals may be perceived or actual food costs. This study explored the monetary costs associated with potassium and sodium intakes using national food prices and a representative sample of US adults. Dietary intake data from the 2001-2002 National Health and Nutrition Examination Survey were merged with a national food prices database. In a population of 4744 adults, the association between the energy-adjusted sodium and potassium intakes, and the sodium-to-potassium ratio (Na:K) and energy-adjusted diet cost was evaluated. Diets that were more potassium-rich or had lower Na:K ratios were associated with higher diet costs, while sodium intakes were not related to cost. The difference in diet cost between extreme quintiles of potassium intakes was $1.49 (95% confidence interval: 1.29, 1.69). A food-level analysis showed that beans, potatoes, coffee, milk, bananas, citrus juices and carrots are frequently consumed and low-cost sources of potassium. Based on existing dietary data and current American eating habits, a potassium-dense diet was associated with higher diet costs, while sodium was not. Price interventions may be an effective approach to improve potassium intakes and reduce the Na:K ratio of the diet. The present methods helped identify some alternative low-cost foods that were effective in increasing potassium intakes. The identification and promotion of lower-cost foods to help individuals meet targeted dietary recommendations could accompany future dietary guidelines.

Sodium intake in a cross-sectional, representative sample of New York City adults

OBJECTIVES

We estimated sodium intake, which is associated with elevated blood pressure, a major risk factor for cardiovascular disease, and assessed its association with related variables among New York City adults.

METHODS

In 2010 we conducted a cross-sectional, population-based survey of 1656 adults, the Heart Follow-Up Study, that collected self-reported health information, measured blood pressure, and obtained sodium, potassium, and creatinine values from 24-hour urine collections.

RESULTS

Mean daily sodium intake was 3239 milligrams per day; 81% of participants exceeded their recommended limit. Sodium intake was higher in non-Hispanic Blacks (3477 mg/d) and Hispanics (3395 mg/d) than in non-Hispanic Whites (3066 mg/d; both P < .05). Higher sodium intake was associated with higher blood pressure in adjusted models, and this association varied by race/ethnicity.

CONCLUSIONS

Higher sodium intake among non-Hispanic Blacks and Hispanics than among Whites was not previously documented in population surveys relying on self-report. These results demonstrate the feasibility of 24-hour urine collection for the purposes of research, surveillance, and program evaluation.

Highlighting the ratio of sodium to potassium in population-level dietary assessments: cross-sectional data from New York City, USA

OBJECTIVE

To contrast mean values of Na:K with Na and K mean intakes by demographic factors, and to calculate the prevalence of New York City (NYC) adults meeting the WHO guideline for optimal Na:K (<1 mmol/mmol, i.e. <0·59 mg/mg) using 24 h urinary values.

DESIGN

Data were from the 2010 Community Health Survey Heart Follow-Up Study, a population-based, representative study including data from 24 h urine collections.

SETTING

Participants were interviewed using a dual-frame sample design consisting of random-digit dial telephone exchanges that cover NYC. Data were weighted to be representative of NYC adults as a whole.

SUBJECTS

The final sample of 1656 adults provided 24 h urine collections and self-reported health data.

RESULTS

Mean Na:K in NYC adults was 1·7 mg/mg. Elevated Na:K was observed in young, minority, low-education and high-poverty adults. Only 5·2 % of NYC adults had Na:K in the optimal range.

CONCLUSIONS

Na intake is high and K intake is low in NYC adults, leading to high Na:K. Na:K is a useful marker and its inclusion for nutrition surveillance in populations, in addition to Na and K intakes, is indicated.

Potassium intake and risk of stroke in women with hypertension and nonhypertension in the Women's Health Initiative

BACKGROUND AND PURPOSE

Dietary potassium has been associated with lower risk of stroke, but there are little data on dietary potassium effects on different stroke subtypes or in older women with hypertension and nonhypertension.

METHODS

The study population consisted of 90 137 postmenopausal women aged 50 to 79 at enrollment, free of stroke history at baseline, followed up prospectively for an average of 11 years. Outcome variables were total, ischemic, and hemorrhagic stroke, and all-cause mortality. Incidence was compared across quartiles of dietary potassium intake, and hazard ratios were obtained from Cox proportional hazards models after adjusting for potential confounding variables, and in women with hypertension and nonhypertension separately.

RESULTS

Mean dietary potassium intake was 2611 mg/d. Highest quartile of potassium intake was associated with lower incidence of ischemic and hemorrhagic stroke and total mortality. Multivariate analyses comparing highest to lowest quartile of potassium intake indicated a hazard ratio of 0.90 (95% confidence interval, 0.85-0.95) for all-cause mortality, 0.88 (95% confidence interval, 0.79-0.98) for all stroke, and 0.84 (95% confidence interval, 0.74-0.96) for ischemic stroke. The effect on ischemic stroke was more apparent in women with nonhypertension among whom there was a 27% lower risk with hazard ratio of 0.73 (95% confidence interval, 0.60-0.88), interaction P<0.10. There was no association with hemorrhagic stroke.

CONCLUSIONS

High potassium intake is associated with a lower risk of all stroke and ischemic stroke, as well as all-cause mortality in older women, particularly those who are not hypertensive.

Compared with usual sodium intake, low- and excessive-sodium diets are associated with increased mortality: a meta-analysis

BACKGROUND

The effect of sodium intake on population health remains controversial. The objective was to investigate the incidence of all-cause mortality (ACM) and cardiovascular disease events (CVDEs) in populations exposed to dietary intakes of low sodium (<115 mmol), usual sodium (low usual sodium: 115-165 mmol; high usual sodium: 166-215 mmol), and high sodium (>215 mmol).

METHODS

The relationship between individual measures of dietary sodium intake vs. outcome in cohort studies and randomized controlled trials (RCTs) measured as hazard ratios (HRs) were integrated in meta-analyses.

RESULTS

No RCTs in healthy population samples were identified. Data from 23 cohort studies and 2 follow-up studies of RCTs (n = 274,683) showed that the risks of ACM and CVDEs were decreased in usual sodium vs. low sodium intake (ACM: HR = 0.91, 95% confidence interval (CI) = 0.82-0.99; CVDEs: HR = 0.90, 95% CI = 0.82-0.99) and increased in high sodium vs. usual sodium intake (ACM: HR = 1.16, 95% CI = 1.03-1.30; CVDEs: HR = 1.12, 95% CI = 1.02-1.24). In population representative samples adjusted for multiple confounders, the HR for ACM was consistently decreased in usual sodium vs. low sodium intake (HR = 0.86; 95% CI = 0.81-0.92), but not increased in high sodium vs. usual sodium intake (HR = 1.04; 95% CI = 0.91-1.18). Within the usual sodium intake range, the number of events was stable (high usual sodium vs. low usual sodium: HR = 0.98; 95% CI = 0.92-1.03).

CONCLUSIONS

Both low sodium intakes and high sodium intakes are associated with increased mortality, consistent with a U-shaped association between sodium intake and health outcomes.

Attitudes and beliefs of health risks associated with sodium intake in diabetes

BACKGROUND

  Despite good evidence that reducing sodium intake can reduce blood pressure (BP), salt intake in people with type 1 diabetes (T1DM) or type 2 diabetes (T2DM) remains high. The purpose of this study was to describe the knowledge and beliefs of health risks associated with a high salt diet in adults with diabetes.

METHODS

Men and women with T1DM (n = 27; age 38 ± 16 years) or T2DM (n = 124; age 60 ± 11 years) were recruited.

RESULTS

Nine (6.0%) respondents knew the correct maximum daily recommended upper limit for salt intake. Thirty-six (23.9%) participants were not concerned with the amount of salt in their diet. Most participants knew that a diet high in salt was related to high BP (88.1%) and stroke (78.1%) and that foods such as pizza (80.8%) and bacon (84.8%) were high in salt. Fewer than 30% of people knew that foods such as white bread, cheese and breakfast cereals are high in salt (white bread 28.5%, cheese 29.1%, breakfast cereals 19.9%) and 51.0% correctly ranked three different nutrition information panels based on the sodium content. Label reading and purchase of low salt products was used by 60-80% of the group. Estimated average 24 hour urinary sodium excretion was 169 ± 32 mmol/24 h in men and 115 ± 27 mmol/24 h in women.

CONCLUSION

Label reading and purchase of low salt products was used by the majority of the group but their salt excretion was still high. Men who used label reading had a lower salt intake. Other strategies to promote a lower sodium intake such as reducing sodium in staple foods such as bread need investigation.

Urinary sodium and potassium excretion, mortality, and cardiovascular events

BACKGROUND

The optimal range of sodium intake for cardiovascular health is controversial.

METHODS

We obtained morning fasting urine samples from 101,945 persons in 17 countries and estimated 24-hour sodium and potassium excretion (used as a surrogate for intake). We examined the association between estimated urinary sodium and potassium excretion and the composite outcome of death and major cardiovascular events.

RESULTS

The mean estimated sodium and potassium excretion was 4.93 g per day and 2.12 g per day, respectively. With a mean follow-up of 3.7 years, the composite outcome occurred in 3317 participants (3.3%). As compared with an estimated sodium excretion of 4.00 to 5.99 g per day (reference range), a higher estimated sodium excretion (≥ 7.00 g per day) was associated with an increased risk of the composite outcome (odds ratio, 1.15; 95% confidence interval [CI], 1.02 to 1.30), as well as increased risks of death and major cardiovascular events considered separately. The association between a high estimated sodium excretion and the composite outcome was strongest among participants with hypertension (P=0.02 for interaction), with an increased risk at an estimated sodium excretion of 6.00 g or more per day. As compared with the reference range, an estimated sodium excretion that was below 3.00 g per day was also associated with an increased risk of the composite outcome (odds ratio, 1.27; 95% CI, 1.12 to 1.44). As compared with an estimated potassium excretion that was less than 1.50 g per day, higher potassium excretion was associated with a reduced risk of the composite outcome.

CONCLUSIONS

In this study in which sodium intake was estimated on the basis of measured urinary excretion, an estimated sodium intake between 3 g per day and 6 g per day was associated with a lower risk of death and cardiovascular events than was either a higher or lower estimated level of intake. As compared with an estimated potassium excretion that was less than 1.50 g per day, higher potassium excretion was associated with a lower risk of death and cardiovascular events. (Funded by the Population Health Research Institute and others.).

Clinical update on nursing home medicine: 2013

This is the seventh article in the series of Clinical Updates on Nursing Home Care. The topics covered are antiresorptive drugs, hip fracture, hypertension, orthostatic hypotension, depression, undernutrition, anorexia, cachexia, sarcopenia, exercise, pain, and behavioral and psychological symptoms of dementia.

Plasma adipocytokines and antioxidants-status in Korean overweight and obese females with dyslipidemia

BACKGROUD/OBEJECTIVES

It is hypothesized that obese people with dyslipidemia is more likely to have increased oxidative stress and decreased antioxidant status, in comparison with the controls who were obese without dyslipidemia. Thus, the aims of the present study were to determine the dietary intakes, plasma adipokines, and antioxidative systems between obese with dyslipidemia and obese without dyslipidemia were investigated.

SUBJECTS/METHODS

Female subjects who were between 20 and 55 years old, and whose BMI was 23 or greater were recruited. Subjects who met the criteria of BMI ≥ 23, total cholesterol ≥ 200 mg/dL, LDL cholesterol ≥ 130 mg/dL, and TG ≥ 110 mg/dL were categorized Obese with dyslipidemia. Anthropometric measurements and blood biochemical tests were conducted. The diet survey was conducted by a trained dietitian using two days of 24 hour dietary recall. The lipid peroxidation, the plasma total antioxidant capacity (TAC), the activities of antioxidantive enzymes, and various antioxidantive vitamins levels were determined.

RESULTS

Plasma adiponectin and leptin levels were also determined. There were no significant differences for age, Body Mass index (BMI), and body fat (%), waist-size between two groups. Obese with dyslipidemia had significantly high levels of total cholesterol, triglyceride, LDL-cholesterol, the ratio of total cholesterol/HDL-C, and the ratio of HDL-C/LDL-C, respectively. Blood alkaline phosphatase level was statistically different between the two groups (P < 0.05). No statistical significance in dietary intake between two groups was shown. In case of obese with dyslipidemia group, the levels of GSH-Px (P < 0.05) and catalase (P < 0.05) as well as adjusted blood retinol (P < 0.05) and tocopherol level (P < 0.05) were significantly low. However, the plasma concentration of leptin was significantly high (P < 0.05).

CONCLUSIONS

Obesity with dyslipidemia was shown to have high arthtrogenic index, depleted antioxidant status, and higher blood leptin levels which suggest higher risks of oxidative stress and cardiovascular diseases.

Monitoring salt and iodine intakes in Dutch adults between 2006 and 2010 using 24 h urinary sodium and iodine excretions

OBJECTIVE

To monitor the effectiveness of salt-reduction initiatives in processed foods and changes in Dutch iodine policy on Na and iodine intakes in Dutch adults between 2006 and 2010.

DESIGN

Two cross-sectional studies among adults, conducted in 2006 and 2010, using identical protocols. Participants collected single 24 h urine samples and completed two short questionnaires on food consumption and urine collection procedures. Daily intakes of salt, iodine, K and Na:K were estimated, based on the analysis of Na, K and iodine excreted in urine.

SETTING

Doetinchem, the Netherlands.

SUBJECTS

Men and women aged 19 to 70 years were recruited through random sampling of the Doetinchem population and among participants of the Doetinchem Cohort Study (2006: n 317, mean age 48·9 years, 43 % men; 2010: n 342, mean age 46·2 years, 45 % men).

RESULTS

While median iodine intake was lower in 2010 (179 μg/d) compared with 2006 (257 μg/d; P < 0·0001), no difference in median salt intake was observed (8·7 g/d in 2006 v. 8·5 g/d in 2010, P = 0·70). In 2006, median K intake was 2·6 g/d v. 2·8 g/d in 2010 (P < 0·01). In this 4-year period, median Na:K improved from 2·4 in 2006 to 2·2 in 2010 (P < 0·001).

CONCLUSIONS

Despite initiatives to lower salt in processed foods, dietary salt intake in this population remains well above the recommended intake of 6 g/d. Iodine intake is still adequate, although a decline was observed between 2006 and 2010. This reduction is probably due to changes in iodine policy.

Effect of salt intake and potassium supplementation on serum renalase levels in Chinese adults: a randomized trial

Renalase, a recently discovered enzyme released by the kidneys, breaks down blood-borne catecholamines and may thus regulate blood pressure (BP). Animal studies have suggested that high levels of dietary salt might reduce blood and kidney renalase levels. We conducted a randomized trial to assess the effects of altered salt and potassium intake on serum renalase levels and the relationship between serum renalase levels and BP in humans.Forty-two subjects (28-65 years of age) were selected from a rural community of northern China. All subjects were sequentially maintained on a low-salt diet for 7 days (3.0 g/day of NaCl), a high-salt diet for additional 7 days (18.0 g/day of NaCl), and a high-salt diet with potassium supplementation for final 7 days (18.0 g/day of NaCl + 4.5 g/day of KCl).Serum renalase levels were significantly higher than baseline levels during the low-salt diet intervention period. Renalase levels decreased with the change from the low-salt to high-salt diet, whereas dietary potassium prevented the decrease in serum renalase induced by the high-salt diet. There was a significant inverse correlation between the serum renalase level and 24-h urinary sodium excretion. No significant correlation was found between the renalase level and BP among the different dietary interventions.The present study indicates that variations in dietary salt intake and potassium supplementation affect the serum renalase concentration in Chinese subjects.

Development and validation of a salt knowledge questionnaire

OBJECTIVE

Initiatives promoting the reduction of high-salt food consumption by consumers need to be partly based on current levels of salt knowledge in the population. However, to date there is no validated salt knowledge questionnaire that could be used to assess population knowledge about dietary salt (i.e. salt knowledge). Therefore, the aim of the present study was to develop and validate a salt knowledge questionnaire.

DESIGN

A cross-sectional study was conducted on an online web survey platform using convenience, snowball sampling. The survey questionnaire was evaluated for content and face validity before being administered to the respondents.

SETTING

Online survey.

SUBJECTS

A total of forty-one nutrition experts, thirty-two nutrition students and thirty-six lay people participated in the study.

RESULTS

Item analyses were performed to evaluate the psychometric properties of the test items. Twenty-five items were retained to form the final set of questions. The total scores of the experts were higher than those of the students and lay people (P < 0·05). The total salt knowledge score showed significant correlations with use of salt at the table (ρ = -0·197, P < 0·05) and inspection of the salt content in food products when shopping (ρ = 0·400; P < 0·01).

CONCLUSIONS

The questionnaire demonstrated sufficient evidence of construct validity and internal consistencies between the items. It is likely to be a useful tool for the evaluation and measurement of levels of salt knowledge in the general population.

Association of urinary sodium-to-potassium ratio with obesity in a multiethnic cohort

BACKGROUND

Previous studies that reported an association of dietary Na(+) intake with metabolic syndrome were limited by the use of imprecise measures of obesity, Na(+) intake, or exclusion of multiethnic populations. The effect of dietary K(+) intake on obesity is less well described.

OBJECTIVE

We hypothesized that high dietary Na(+) and low K(+), based on the ratio of urinary Na(+) to K(+) (U[Na(+)]/[K(+)]) in a first-void morning urinary sample, is independently associated with total body fat.

DESIGN

In a prospective population-based cohort, 2782 participants in the community-dwelling, probability-sampled, multiethnic Dallas Heart Study were analyzed. The primary outcome established a priori was total-body percentage fat (TBPF) measured by dual-energy X-ray absorptiometry. The main predictor was U[Na(+)]/[K(+)]. Robust linear regression was used to explore an independent association between U[Na(+)]/[K(+)] and TBPF. The analyses were stratified by sex and race after their effect modifications were analyzed.

RESULTS

Of the cohort, 55.4% were female, 49.8% African American, 30.8% white, 17.2% Hispanic, and 2.2% other races. The mean (±SD) age was 44 ± 10 y, BMI (in kg/m(2)) was 30 ± 7, TBPF was 32 ± 10%, and U[Na(+)]/[K(+)] was 4.2 ± 2.6; 12% had diabetes. In the unadjusted and adjusted models, TBPF increased by 0.75 (95% CI: 0.25, 1.25) and 0.43 (0.15, 0.72), respectively (P = 0.003 for both), for every 3-unit increase in U[Na(+)]/[K(+)]. A statistically significant interaction was found between race and U[Na(+)] /[K(+)], so that the non-African American races had a higher TBPF than did the African Americans per unit increase in U[Na(+)]/[K(+)] (P-interaction < 0.0001 for both). No interaction was found between sex and U[Na(+)]/[K(+)].

CONCLUSIONS

The ratio of dietary Na(+) to K(+) intake may be independently associated with TBPF, and this association may be more pronounced in non-African Americans. Future studies should explore whether easily measured spot U[Na(+)]/[K(+)] can be used to monitor dietary patterns and guide strategies for obesity management.

Lower potassium intake is associated with increased wave reflection in young healthy adults

Background

Increased potassium intake has been shown to lower blood pressure (BP) even in the presence of high sodium consumption however the role of dietary potassium on vascular function has received less attention. The aim of this study was to evaluate the relationship between habitual intake of sodium (Na) and potassium (K) and measures of arterial stiffness and wave reflection.

Methods

Thirty-six young healthy adults (21 M, 15 F; 24 ± 0.6 yrs; systolic BP 117 ± 2; diastolic BP 63 ± 1 mmHg) recorded their dietary intake for 3 days and collected their urine for 24 hours on the 3rd day. Carotid-femoral pulse wave velocity (PWV) and the synthesis of a central aortic pressure waveform (by radial artery applanation tonometry and generalized transfer function) were performed. Aortic augmentation index (AI), an index of wave reflection, was calculated from the aortic pressure waveform.

Results

Subjects consumed an average of 2244 kcals, 3763 mg Na, and 2876 mg of K. Average urinary K excretion was 67 ± 5.3 mmol/24 hr, Na excretion was 157 ± 11 mmol/24 hr and the average Na/K excretion ratio was 2.7 ± 0.2. An inverse relationship between AI and K excretion was found (r = -0.323; p < 0.05). A positive relationship between AI and the Na/K excretion ratio was seen (r = 0.318; p < 0.05) while no relationship was noted with Na excretion alone (r = 0.071; p > 0.05). Reflection magnitude, the ratio of reflected and forward waves, was significantly associated with the Na/K excretion ratio (r = 0.365; p <0.05) but not Na or K alone. PWV did not correlate with Na or the Na/K excretion ratio (p > 0.05) but showed an inverse relationship with K excretion (r = -0.308; p < 0.05).

Conclusions

These data suggest that lower potassium intakes are associated with greater wave reflection and stiffer arteries in young healthy adults.

The impact of sodium and potassium on hypertension risk

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

Six random specimens of daytime casual urine on different days are sufficient to estimate daily sodium/potassium ratio in comparison to 7-day 24-h urine collections

The objective of this study was to determine the optimal number and type of casual (spot) urine specimens required to estimate an individual's urinary sodium/potassium (Na/K) ratio. A total of 48 participants, 25 men and 23 women, aged between 25 and 59 years, was recruited from healthy volunteers. The Na/K ratio in each casual urine and 7-day 24-h urine sample was measured. Correlation analysis and the quality of agreement by the Bland and Altman method between casual urine and 24-h urine were analyzed. The mean Na/K ratio of 7-day 24-h urine was 4.3. The mean Na/K ratio of six random specimens of daytime (collected between 09 and 17 hours) casual urine correlated most strongly with the Na/K ratio of 7-day 24-h urine (r=0.87). The bias for the mean Na/K ratio between 7-day 24-h urine and daytime casual urine was almost negligible (0.03), and the quality of agreement for the mean of the six random, daytime casual urine specimens on different days was similar to that of the 2-day 24-h urine samples for estimating 7-day 24-h values. Our findings show that the mean Na/K ratio of six random daytime casual urine specimens on different days was a good substitute for the 2-day 24-h urine Na/K ratio.

Methodological Issues in Cohort Studies That Relate Sodium Intake to Cardiovascular Disease Outcomes

Background—

The results of cohort studies relating sodium (Na) intake to blood pressure–related cardiovascular disease (CVD) are inconsistent. To understand whether methodological issues account for the inconsistency, we reviewed the quality of these studies.

Methods and Results—

We reviewed cohort studies that examined the association between Na and CVD. We then identified methodological issues with greatest potential to alter the direction of association (reverse causality, systematic error in Na assessment), some potential to alter the direction of association (residual confounding, inadequate follow-up), and the potential to yield false null results (random error in Na assessment, insufficient power). We included 26 studies with 31 independent analyses. Of these, 13 found direct associations between Na and CVD, 8 found inverse associations, 2 found J-shaped associations, and 8 found null associations only. On average there were 3 to 4 methodological issues per study. Issues with greater potential to alter the direction of association were present in all but 1 of the 26 studies (systematic error, 22; reverse causality, 16). Issues with lesser potential to alter the direction of association were present in 18 studies, whereas those with potential to yield false null results were present in 23.

Conclusions—

Methodological issues may account for the inconsistent findings in currently available observational studies relating Na to CVD. Until well-designed cohort studies in the general population are available, it remains appropriate to base Na guidelines on the robust body of evidence linking Na with elevated blood pressure and the few existing general population trials of the effects of Na reduction on CVD.

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.

Measurement error corrected sodium and potassium intake estimation using 24-hour urinary excretion

Epidemiological studies of the association of sodium and potassium intake with cardiovascular disease risk have almost exclusively relied on self-reported dietary data. Here, 24-hour urinary excretion assessments are used to correct the dietary self-report data for measurement error under the assumption that 24-hour urine recovery provides a biomarker that differs from usual intake according to a classical measurement model. Under this assumption, dietary self-reports underestimate sodium by 0% to 15%, overestimate potassium by 8% to 15%, and underestimate sodium/potassium ratio by ≈20% using food frequency questionnaires, 4-day food records, or three 24-hour dietary recalls in Women's Health Initiative studies. Calibration equations are developed by linear regression of log-transformed 24-hour urine assessments on corresponding log-transformed self-report assessments and several study subject characteristics. For each self-report method, the calibration equations turned out to depend on race and age and strongly on body mass index. After adjustment for temporal variation, calibration equations using food records or recalls explained 45% to 50% of the variation in (log-transformed) 24-hour urine assessments for sodium, 60% to 70% of the variation for potassium, and 55% to 60% of the variation for sodium/potassium ratio. These equations may be suitable for use in epidemiological disease association studies among postmenopausal women. The corresponding signals from food frequency questionnaire data were weak, but calibration equations for the ratios of sodium and potassium/total energy explained ≈35%, 50%, and 45% of log-biomarker variation for sodium, potassium, and their ratio, respectively, after the adjustment for temporal biomarker variation and may be suitable for cautious use in epidemiological studies. Clinical Trial Registration- URL: www.clinicaltrials.gov. Unique identifier: NCT00000611.

Potassium and fruit and vegetable intakes in relation to social determinants and access to produce in New York City

BACKGROUND

Potassium-rich diets are inversely associated with blood pressure. Potassium intake before this study had not been objectively measured by using potassium excretion in a population-based sample in the United States.

OBJECTIVES

The objectives of the analysis were to 1) report mean potassium excretion in a diverse urban population by using 24-h urine collections, 2) corroborate potassium excretion by using self-reported fruit and vegetable consumption, and 3) characterize associations between potassium excretion and socioeconomic indicators and access to produce.

DESIGN

Participants were from the 2010 Community Health Survey Heart Follow-Up Study-a population-based study including data from 24-h urine collections. The final sample of 1656 adults was weighted to be representative of New York City (NYC) adults as a whole.

RESULTS

Mean urinary potassium excretion was 2180 mg/d, and mean self-reported fruit and vegetable intake was 2.5 servings/d. Adjusted urinary potassium excretion was 21% lower in blacks than in whites (P < 0.001), 13% lower in non-college graduates than in college graduates (P < 0.001), and 9% lower in the lowest-income than in the highest-income group (P = 0.03). Potassium excretion was correlated with fruit and vegetable intake. Most NYC residents reported a <10-min walk to fresh fruit and vegetables; this indicator of access was not associated with potassium excretion or fruit and vegetable intake.

CONCLUSIONS

Potassium intake is low in NYC adults, especially in lower socioeconomic groups. Innovative programs that increase fruit and vegetable intake may help increase dietary potassium and reduce hypertension-related disease. This trial is registered at clinicaltrials.gov as NCT01889589.

Twenty-two-year population trends in sodium and potassium consumption: the Minnesota Heart Survey

Background

Limiting dietary sodium consumption is a core lifestyle recommendation for the prevention of hypertension. There is increasing evidence that low potassium consumption also increases hypertension risk. We estimated sex‐specific 22‐year trends in sodium and potassium consumption.

Methods and Results

We used data from the Minnesota Heart Survey, which performs surveillance of risk factors for cardiovascular disease in the Minneapolis–St. Paul metropolitan area. The Minnesota Heart Survey is a random population‐based sample of free‐living adults aged 25 to 74. Surveys were conducted in 1985–1987 (n=2273), 1990–1992 (n=2487), 1995–1997 (n=1842), 2000–2002 (n=2759), and 2007–2009 (n=1502). Dietary intake of sodium and potassium was estimated from one 24‐hour dietary recall. Over 22 years, age‐adjusted sodium and potassium intake among men remained relatively stable in 1985–1987 and 2007–2009 (P_trend=0.41 and 0.29, respectively); sodium ranged from 3820 mg/day (1995–1997) to 3968 mg/day (2007–2009) and potassium from 3111 mg/day (2000–2002) to 3249 mg/day (1995–1997). Sodium and potassium intake increased among women, from 2531 mg/day in 1985–1987 to 2854 mg/day in 2007–2009 (P_trend=0.001) for sodium and from 2285 to 2533 mg/day (P_trend<0.0001) for potassium. We observed stable or increasing sodium and potassium intake within some strata of age, education, and body mass index.

Conclusions

Despite long‐standing public health recommendations to limit sodium intake to <2300 mg/day, high sodium intake levels have persisted over the past 22 years. Furthermore, although potassium consumption increased in some subgroups over the study period, mean consumption remained significantly lower than the recommended 4700 mg/day in all groups.

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSION

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

The increasing burden of hypertension in Nigeria - can a dietary salt reduction strategy change the trend?

Developing countries face a dual challenge of both communicable and non-communicable disease - 80% of deaths from cardiovascular disease occur in low and middle-income countries. Hypertension ranks highest as an attributable cause of mortality in both developed and developing countries. The prevalence of hypertension is rising rapidly in Nigeria, from 11% two decades ago to about 30% in recent times. This review explores salt reduction in the diet at the population-wide level as a means of reducing the burden of hypertension in Nigeria. The evidence behind this strategy is explored, methods of how this goal was achieved in other countries are investigated and recommendations on how it could be accomplished in the Nigerian context are considered. There are suggestions that if salt reductions are effectively implemented on a population-wide basis, it will have an impact on morbidity and mortality as large as that which the provision of drains and safe water had in the 19(th) century.

Role of dietary salt and potassium intake in cardiovascular health and disease: a review of the evidence

The objective of this review was to provide a synthesis of the evidence on the effect of dietary salt and potassium intake on population blood pressure, cardiovascular disease, and mortality. Dietary guidelines and recommendations are outlined, current controversies regarding the evidence are discussed, and recommendations are made on the basis of the evidence. Designed search strategies were used to search various databases for available studies. Randomized trials of the effect of dietary salt intake reduction or increased potassium intake on blood pressure, target organ damage, cardiovascular disease, and mortality were included. Fifty-two publications from January 1, 1990, to January 31, 2013, were identified for inclusion. Consideration was given to variations in the search terms used and the spelling of terms so that studies were not overlooked, and search terms took the following general form: (dietary salt or dietary sodium or [synonyms]) and (dietary potassium or [synonyms]) and (blood pressure or hypertension or vascular disease or heart disease or chronic kidney disease or stroke or mortality or [synonyms]). Evidence from these studies demonstrates that high salt intake not only increases blood pressure but also plays a role in endothelial dysfunction, cardiovascular structure and function, albuminuria and kidney disease progression, and cardiovascular morbidity and mortality in the general population. Conversely, dietary potassium intake attenuates these effects, showing a linkage to reduction in stroke rates and cardiovascular disease risk. Various subpopulations, such as overweight and obese individuals and aging adults, exhibit greater sensitivity to the effects of reduced salt intake and may gain the most benefits. A diet that includes modest salt restriction while increasing potassium intake serves as a strategy to prevent or control hypertension and decrease cardiovascular morbidity and mortality. Thus, the body of evidence supports population-wide sodium intake reduction and recommended increases in dietary potassium intake as outlined by current guidelines as an essential public health effort to prevent kidney disease, stroke, and cardiovascular disease.

Association between dietary sodium and potassium intake with chronic kidney disease in US adults: a cross-sectional study

BACKGROUND/AIMS

Clinical guidelines recommend a diet low in sodium and high in potassium to reduce blood pressure and cardiovascular events. Little is known about the relationship between dietary sodium and potassium intake and chronic kidney disease (CKD).

METHODS

13,917 participants from the National Health and Nutrition Examination Survey (2001-2006) were examined. Sodium and potassium intake were calculated from 24-hour recall and evaluated in quartiles. CKD was defined as estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2) or eGFR ≥60 ml/min/1.73 m(2) with albuminuria (>30 mg/g creatinine).

RESULTS

The mean (SE) age and eGFR of participants were 45.0 ± 0.4 years and 88.0 ± 0.60 ml/min/1.73 m(2), respectively. 2,333 (14.2%) had CKD: 1,146 (7.3%) had an eGFR <60 ml/min/1.73 m(2) and 1,514 (8.4%) had an eGFR ≥60 ml/min/1.73 m(2) and albuminuria. After adjustment for age, sex, race, BMI, diabetes, hypertension, cardiovascular disease and congestive heart failure, subjects in the highest quartile of sodium intake had lower odds of CKD compared to subjects in the lowest quartile (adjusted OR: 0.79; 95% CI: 0.66-0.96; p < 0.016). Compared to the highest quartile, the odds of CKD increased 44% for participants in the lowest quartile of potassium intake (adjusted OR: 1.44; 95% CI: 1.16-1.79; p = 0.0011).

CONCLUSIONS

Higher intake of sodium and potassium is associated with lower odds of CKD among US adults. These results should be corroborated through longitudinal studies and clinical trials designed specifically to examine the effects of dietary sodium and potassium intake on kidney disease and its progression.