Is high potassium intake a risk factor for hypertension

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

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

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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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