Does increasing potassium intake lower blood pressure in essential hypertension?

Twenty-three unselected patients with mild to moderate essential hypertension whose average supine blood pressure after 2 months of observation on no treatment was 154/99 mm Hg were entered into an 8-week double-blind randomised crossover study of 1 month's treatment with slow release potassium tablets (64 mmol/day) versus placebo without alteration of dietary sodium or potassium intake. By the fourth week mean supine blood pressure had fallen by 4% with potassium supplementation compared with placebo. In a separate metabolic study the effect of 12 slow release potassium tablets (98 mmol/day) was studied in 12 patients with mild essential hypertension who had a fixed sodium and potassium intake. The increase in potassium intake caused immediate natriuresis with an average cumulative sodium loss of 110 mmol per patient. In spite of this loss of sodium there was no rise in plasma renin activity, but there was a significant increase in plasma noradrenaline level. On an average western diet containing approximately 150 mmol of sodium/day, potassium chloride supplementation causes a small but worthwhile fall in blood pressure in many patients with essential hypertension. It is likely that part of the mechanism of this fall in blood pressure is related to the increase in potassium intake causing a loss of sodium with no compensatory rise in renin release.