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Abstract
The purpose of this study was to investigate the influence of dietary potassium on the sodium effect on blood pressure (BP) in the general population and the adherence of current recommendations for sodium and potassium intake. An overnight (12-hour) urine sample was collected in a population-based study to investigate cardiovascular risk. A sub-sample of 1285 subjects (age range, 25–64 years) free from any medication interfering with BP or potassium excretion was studied. Of the participants, 86.0% consumed over 6 g of salt/day and 87.7% less than the recommended intake of potassium (4.7 g). Potassium excretion and the sodium to potassium ratio were significantly related to systolic and diastolic BP only in subjects consuming more than 6 g/day of salt. Subjects in the highest sodium to potassium ratio quartile (surrogate of unhealthy diet) presented 8 mm Hg and 7 mm Hg higher values of systolic and diastolic BP, respectively, when compared with the first quartile, while individuals in the fourth quartile of urinary potassium excretion (healthier diet) showed 6 mm Hg and 4 mm Hg lower systolic and diastolic BP, respectively, compared with the first quartile. Our data indicate that when people have an increased intake of potassium, high intake of sodium is not associated with higher BP.
Introduction
Reduction of the intake of sodium has been established as a lifestyle change recommended to reduce cardiovascular diseases (CVD) mainly by decreasing blood pressure (BP) levels.1 Recently, the relationship between mortality and usual intake of sodium and potassium in American adults was reported. Higher intake of sodium was associated with increased overall mortality. Moreover, diets with higher sodium to potassium ratio (Na/K) were associated with increased risk of CVD and all-cause mortality.2
Diets with elevated content of sodium or increased Na/K ratio are related to increased BP and higher prevalence of hypertension.3, 4 Hypertension is a major risk factor for several CVD including stroke, cardiac arrhythmias, heart failure, sudden cardiac death and chronic kidney disease.5 Therefore, it is not surprising that hypertension is present in around 69% of patients with the first myocardial infarction and around in 77% of patients with the first stroke.6
The association between the intake of sodium and hypertension is well established.2, 3, 7, 8 However, the potential role of the intake of potassium to cardiovascular health has received less attention. It was reported that the intake of potassium estimated by food records was not independently associated with blood pressure.9 Conversely, two population-based studies showed that potassium intake—assessed by semi quantitative food frequency questionnaire10 or 24-hour recall dietary history11—was inversely related to both diastolic BP (DBP) and systolic BP (SBP). Reports on interventional studies have also shown an inverse relation between potassium intake and BP. However, these studies were based on the use of potassium supplementation and/or controlled diets.12, 13, 14, 15, 16, 17 It is worth mentioning that diet in interventional studies provides larger amounts of potassium, calcium, and magnesium than the typical diet, which can be a factor of confusion.18
Despite the elevated prevalence of hypertension associated with high salt consumption (around 12.8 g/day) in the Brazilian population,7 to date, there is scarce information regarding the influence of potassium intake on BP in the general population. Accordingly, a recent report on potassium intake and the estimated potential impact of increased potassium intake on population BP levels included 21 countries spread across North America, Europe, Asia, and Oceania, but South America in general and Brazil in particular.19
Therefore, the aim of this investigation was to estimate the influence of dietary potassium intake on the sodium effect on BP levels in the general population free from the influence of any medication interfering with blood pressure or potassium excretion and also to determine the adherence of the participants to the current recommendations for sodium and potassium intake.20
Section snippets
Study Design and Sample Selection
Data were collected to determine the prevalence and severity of cardiovascular risk factors in the urban population of Vitoria, Brazil. The design and sampling of this survey was described elsewhere.7, 21 Briefly, a sample of 1661 individuals was selected by a procedure of household randomization. These individuals attended University Hospital to undergo clinical and laboratory exams to determine presence of cardiovascular risk factors. The project was approved by the Institutional Ethics
Results
Baseline characteristics of the sample are depicted in Table 1. SBP, DBP, and WC were higher in men, as were triglycerides, glucose, and creatinine. As expected, high density lipoprotein (HDL)-cholesterol lipoprotein was higher in women. Age, serum cholesterol levels, and BMI, as well as prevalence of obesity and diabetes, were similar in both genders, whereas the prevalence of hypertension and smoking was higher in men. As urine was collected during the night and in the absence of exercise (to
Discussion
Our data confirm observations in other countries2, 24 that the intake of sodium is above while potassium is below the values recommended for daily consumption of these minerals, 6.0 g and 4.7 g, respectively.25 In our study 86% (88.4% of men and 83.8% of women) of the participants consumed over than 6 g of salt daily and 87.7% (84.2% of men and 90.9% of women) ingested less than 4.7 g of potassium daily. Importantly, we confirmed in our population-based study—which estimated the urinary
References (40)
- et al.
Pathogenesis of hypertension: interactions among sodium, potassium, and aldosterone
Am J Kidney Dis
(2010)
- A.K. Kant
Dietary patterns and health outcomes
J Am Diet Assoc
(2004)
- C. Donfrancesco et al.
Excess dietary sodium and inadequate potassium intake in Italy: results of the MINISAL study
Nutr Met Cardiovasc Dis
(2013)
- S. Lewington et al.
Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies
Lancet
(2002)
- Q. Yang et al.
Sodium and potassium intake and mortality among US adults: prospective data from the Third National Health and Nutrition Examination Survey
Arch Intern Med
(2011)
INTERSALT: an international study of electrolyte excretion and blood pressure: results for 24 hour urinary sodium and potassium excretion
BMJ
(1988)
- N.R. Cook et al.
Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the Trials Of Hypertension Prevention (TOHP)
BMJ
(2007)
- P.
Strazzullo et al.
Salt intake, stroke, and cardiovascular disease: meta-analysis of prospective studies
BMJ
(2009)
- D. Lloyd-Jones et al.
Heart disease and stroke statistics-2009 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee
Circulation
(2009)
- M.C.B.
Molina et al.
Hypertension and salt intake in an urban population
Rev Saude Publica
(2003)
Salt excretion in normotensive individuals with metabolic syndrome: a population-based study
Hypertens Res
(2009)
Relationship of dietary sodium, potassium, calcium, and magnesium with blood pressure. Belgian Interuniversity Research on Nutrition and Health
Hypertension
(1988)
Dietary potassium and blood pressure in a population
Am J Clin Nutr
(1984)
Dietary electrolyte intake and blood pressure in older subjects: the Rotterdam Study
J Hypertens
(1996)
Does potassium supplementation lower blood pressure? A meta-analysis of published trials
J Hypertens
(1991)
Effects of oral potassium on blood pressure: meta-analysis of randomized controlled clinical trials
JAMA
(1997)
Blood pressure response to changes in sodium and potassium intake: a metaregression analysis of randomised trials
J Hum Hypertens
(2003)
Decreasing dietary sodium while following a self-selected potassium-rich diet reduces blood pressure
J Nutr
(2003)
Effects on blood pressure of reduced dietary sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. DASH Sodium Collaborative Research Group
N Engl J Med
(2001)
Normotensive salt sensitivity: effects of race and dietary potassium
Hypertension
(1999)
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Moreover, high potassium intake may have the greatest effect when salt intake is high, and it was associated with a lower risk of death and cardiovascular events [24]. Recently, it has been reported that high intake of sodium is not associated with higher BP in people who have an increased intake of potassium [25]. Our results showed that Na/K ratio was 2 times higher in this sample than what is recommended by WHO [26] which could mean a higher cardiovascular risk for this population.
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From the Editor
Journal of the American Society of Hypertension, Volume 8, Issue 4, 2014, p. 215
Copyright © 2014 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.