Effects of potassium supplementation on office, home, and 24-h blood pressure in patients with essential hypertension☆

An increase in potassium (K) intake may lower blood pressure (BP), but inconsistent results have been obtained in clinical trials. We studied the effects of K supplementation in hypertensive patients with monitoring of home and ambulatory BP. Fifty-five patients with essential hypertension (26 men, 29 women, 36-77 years old) participated in this study. A 4-week K supplementation period and 4-week control period were assigned in a randomized crossover manner. During the K period, the subjects were given 64 mmol/day of K as slow-release KCl tablets. Office, home, and 24-h BP, as well as serum and urinary electrolytes, were measured at the end of each period. In the control period, office, home, and 24-h BP were 151 +/- 2/88 +/- 1 (mean +/- SE), 138 +/- 1/83 +/- 1, and 137 +/- 1/81 +/- 1 mm Hg, respectively. Serum K increased from 4.15 +/- 0.04 to 4.42 +/- 0.05 mmol/L, and urinary K increased from 54 +/- 2 to 96 +/- 3 mmol/day with the K supplementation. Office, home, and 24-h BP were significantly lower in the K period than in the control period, although the differences were small (2.7 +/- 1.1/1.4 +/- 0.6, 3.6 +/- 0.9/1.7 +/- 0.5, 3.4 +/- 1.0/1.2 +/- 0.5 mm Hg, respectively). Changes in home and 24-h systolic BP with K supplementation were highly significant (P < .001), compared with office BP (P < .05). The change in 24-h systolic BP was correlated negatively with baseline BP and urinary Na/K ratio, and positively with baseline urinary K excretion. The changes in daytime and nighttime BP were comparable. These results indicate that increasing K intake lowers BP in hypertensive subjects, especially in those with higher BP and lower K intake. Our study supports the usefulness of K supplementation in the treatment of hypertension, although its antihypertensive effect may be small.