Change in Blood Pressure in Relation to Change in Nutrients Effected by Manipulation of Dietary Sodium and Potassium

Abstract

1. As part of a study investigating the effect of dietary alterations of sodium and potassium intake on blood pressure, the changes in nutrients that occurred with dietary intervention were determined. 2. Mild hypertensive subjects were randomized to one of four dietary intervention groups: control; high potassium; low sodium; low sodium, high potassium. The changes in nutrients in each diet group were assessed by dietary history and five repeat 24 h dietary recalls. Assessment was validated by measurement of urinary nitrogen excretion and urinary electrolytes. 3. The three dietary intervention groups experienced a fall in blood pressure (systolic: 4.4 +/- 1.0 mmHg, P less than 0.005; diastolic: 3.3 +/- 0.7 mmHg, P less than 0.001), greater than that observed in the control group. 4. The only significant dietary change across all diet groups was a reduction in the dietary sodium/potassium ratio, which was significantly less than that of the control group. The only other nutrient to differ from the control in all groups was fat intake, which was reduced. 5. In the control group there was a small but significant decrease in energy, fibre, protein, carbohydrate, potassium and magnesium intake. In the high potassium group there was a significant increase in fibre, carbohydrate, potassium, magnesium, and a decrease in calcium intake. In the low sodium group there was a decrease in energy intake with a subsequent reduction in all nutrients except alcohol. In the low sodium, high potassium group there was a significant reduction in dietary sodium and protein and an increase in fibre, carbohydrate, potassium and magnesium. 6. The reduction of the dietary sodium/potassium ratio correlated with a reduction in the urinary sodium/potassium ratio. This was the best predictor for change in diastolic pressure in all groups, suggesting that reduction in the sodium/potassium ratio contributed to the fall in blood pressure. 7. Reduction of sodium intake and increase in potassium intake by dietary means caused a reduction in blood pressure which does not appear to be due to alteration of other measured dietary constituents.

Sodium-to-Potassium Ratio and Blood Pressure, Hypertension, and Related Factors

“…Twenty-two cross-sectional studies , 1 observational cohort study (37), and 18 RCTs [conducted in 13 hypertensive populations (38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50), 1 prehypertensive/hypertensive population (8), and 4 normotensive populations (50)(51)(52)(53)] were included in this review. Of note, classification of prehypertension status in the DASH diet RCT was based on blood pressure >120/80 mm Hg.…”

“…One crossover RCT included both hypertensive and normotensive adults but reported the results by hypertension status (50). There were 7 parallel-arm RCTs (38,39,41,42,44,45,47) and 6 crossover RCTs (40,43,46,(48)(49)(50) conducted in hypertensive populations only (Table 1). These RCTs enrolled subjects from Australia (41), Austria (49), India (38), Italy (40,42,44,45), Japan (47), New Zealand (48), The Netherlands (43), the United Kingdom (46,50), and the United States (39).…”

Blood pressure response to changes in sodium and potassium intake: a metaregression analysis of randomised trials

“…In addition, one potassium trial was excluded because of markedly outlying blood pressure reductions (À41/À17 mmHg). 20 A total of 40 trials of sodium and blood pressure (47 relevant strata) and 27 trials of potassium and blood pressure (30 relevant strata) 23,33,35,37,40, remained for the present analysis (flow diagrams given in Figures 1 and 2, respectively).…”

“…RCT withdrawn, by outcome: n=0 RCT excluded, with reasons: -duration <2 weeks: n=54 -co-intervention(s): n=25 -duplicate publication: n=11 -conducted in patients or pregnant women: n=7 -non-placebo control group: n=5 -lack of (appropriate) BP data: n=3 Data on body weight (initial level and change) of the trial population could not be retrieved for 11 sodium trials (28%) 21,22,24,28,30,35,40,41,46,57,58 and 7 potassium trials (26%) 35,40,61,66,67,73,76 Data on body mass index were missing for 80% of the trials and could therefore not be taken into account in the analysis.…”

Adherence to the salt restriction diet among people with mildly elevated blood pressure

“…Generally, the energy intake has remained the same in studies where the goal has been to maintain weight Wassertheil-Smoller et al, 1985;Witschi et al, 1985). In studies where subjects were asked to reduce sodium intake and not asked to maintain their calorie intake, the energy and nutrient intakes have often decreased (Gillum et al, 1983;McCarron et al, 1997;Nowson & Morgan, 1985;Wylie-Rosett et al, 1993).…”