Effects of a reduced-sodium added-potassium salt substitute on blood pressure in rural Indian hypertensive patients: a randomized, double-blind, controlled trial

Abstract

ABSTRACT Background High salt intake is a major modifiable risk factor of hypertension which is prevalent in India. It is not yet clear if salt substitutes reduce blood pressure (BP) among Indian hypertensive patients. Objectives Examine the acceptability, usage, and BP effects of a reduced-sodium and added-potassium salt substitute among hypertensive patients. Methods We enrolled 502 participants with hypertension (aged 61.6 ± 12.0 y, 58.8% women) from 7 villages in rural India. Participants were randomly assigned to receive either regular salt (100% sodium chloride) or the salt substitute (70% sodium chloride/30% potassium chloride blend), and advised to replace all home salt use. The primary outcome was the change in systolic BP (SBP) from baseline to 3 mo comparing the salt substitute and regular salt groups. Secondary outcomes included the change in diastolic BP (DBP), 24-h urinary biomarkers, and self-reported use and satisfaction with the study salt provided. Results A total of 494 (98%) participants completed 1 mo and 476 (95%) participants completed the 3-mo follow-up. At 3 mo, the salt substitute intervention significantly decreased the average SBP by 4.6 mmHg (95% CI: 3.0, 6.2, P < 0.001) and DBP by 1.1 mmHg (95% CI: 0.2, 2.1 mmHg, P = 0.02). There was a significant increase in 24-h urinary potassium excretion in the salt substitute group by 0.24 g/d (95% CI: 0.12, 0.35 g/d, P < 0.001) and a decrease in the urinary sodium to potassium ratio by 0.71 (95% CI: 0.55, 0.87, P < 0.0001) compared with the control group. Participants reported that they used the study salt nearly every day of the week (mean ± SD, 6.3 ± 1.8 d) and rated the taste of the study salts similarly. Conclusion The reduced-sodium added-potassium salt led to a substantial reduction in SBP in hypertensive patients, supporting salt substitution as an effective, low-cost intervention for BP lowering in rural India. This trial was registered at clinicaltrials.gov as NCT03909659.