Effect of potassium supplementation on blood pressure in African Americans on a low-potassium diet. A randomized, double-blind, placebo-controlled trial.
OBJECTIVE
To determine the effect of potassium supplementation on blood pressure in African Americans consuming a low-potassium diet.


METHODS
Randomized, double-blind, placebo-controlled trial with two parallel arms.


METHODS
Community-based research site.


METHODS
Eighty-seven healthy African Americans aged 27 to 65 years with a systolic blood pressure between 100 and 159 mm Hg and a diastolic blood pressure between 70 and 94 mm Hg.


METHODS
During the 21-day intervention period, all participants were provided with a low-potassium diet (32 to 35 mmol/d). In addition to this diet, they were randomly assigned to receive either potassium supplements (80 mmol/d) or placebo.


METHODS
Change in blood pressure in the potassium vs the placebo group, based on a total of nine blood pressure readings at three visits. Blood pressures were taken before and during the intervention by means of random-zero sphygmomanometry.


RESULTS
At baseline, the placebo and potassium groups were similar for mean blood pressure (127/78 vs 125/77 mm Hg), 24-hour urinary potassium excretion (50 vs 44 mmol), and all other variables measured (all P > .05). During the intervention, the net difference in 24-hour urinary potassium excretion between groups was 70 mmol. Compared with the placebo group, the potassium supplementation group experienced a net decline in systolic blood pressure of 6.9 mm Hg (95% confidence interval, -9.3 to -4.4 mm Hg; P < .001) and a decline in diastolic blood pressure of 2.5 mm Hg (95% confidence interval, -4.3 to -0.8 mm Hg; P = .004). Simultaneous adjustment for differences in baseline characteristics only strengthened these estimates.


CONCLUSIONS
Potassium supplementation reduces blood pressure substantially in African Americans consuming a diet low in potassium. Increased potassium intake may play an important role in reducing blood pressure in this population at high risk for hypertension.
Brancati
F L
FL
Welch Center for Prevention, Epidemiology, & Clinical Research, Johns Hopkins Medical Institutions, Baltimore, Md., USA.
Appel
L J
LJ
Seidler
A J
AJ
Whelton
P K
PK
D000328:Adult; D044383:Black People; D001794:Blood Pressure / Q000187:drug effects*; D004311:Double-Blind Method; D005260:Female; D005527:Food, Fortified; D006801:Humans; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000008:administration & dosage / Q000494:pharmacology*; D012016:Reference Values; D001741:Black or African American
D011188:Potassium