Double-blind randomised crossover trial of moderate sodium restriction in essential hypertension.

Nineteen unselected patients with mild to moderate essential hypertension, whose average supine blood pressure after two months' observation on no treatment was 156/98 mm Hg, were advised not to add salt to food and to avoid sodium-laden foods. After 2 weeks of sodium restriction patients were entered into an 8-week double-blind randomised crossover study of 'Slow Sodium' (Ciba) versus slow sodium placebo. The mean supine blood pressure was 7.1 mm Hg (6.1%) lower in the fourth week of placebo than that in the fourth week of slow sodium (p less than 0.001). Urinary sodium excretion in the fourth week of slow sodium was 162 +/- 9 mmol/24 h and that in the fourth week of placebo was 86 mmol +/- 9 mmol/24 h (p less than 0.001). There was no difference in potassium excretion. These results suggest that moderate sodium restriction achieved by not adding salt and avoiding sodium-laden foods should, if not already, become part of the management of essential hypertension.