Key Points
- The See Sodium to Treat (SSTT) Trial tested whether isolated oral KCl intake without sodium reduction could lower body Na⁺ content and blood pressure in patients with hypertension.
- Standardized KCl supplementation raised plasma K⁺ and 24-h urine K⁺ excretion, eliminated muscle Na⁺ excess, and reduced systolic BP by 8.33 mmHg (95% CI –55 to –2.12).
- No participant developed hyperkalemia ([K⁺] > 5.5 mmol/L), and treatment was well tolerated and cost-effective.
For decades, potassium-enriched salt substitutes have been known to reduce blood pressure and cardiovascular risk, but whether the benefit derives from reduced sodium, increased potassium, or both has remained uncertain; this trial isolated the effect of potassium alone.
At the 2025 American Heart Association Scientific Sessions, Dr. Jens Titze presented the SSTT Trial (NCT06569589), a prospective, open-label, longitudinal study evaluating the isolated effect of oral KCl on body Na⁺/K⁺ distribution and blood pressure in patients with arterial hypertension. Forty participants undergoing evaluation for hypertension or suspected hyperaldosteronism were enrolled. They received standardized oral KCl supplementation (Span-K 600 mg tablets) adjusted to achieve normokalaemia. Randomization to placebo was not feasible because of baseline hypokalemia (plasma K⁺ < 3.0 mmol/L in 10%). After medication review and adjustment of antihypertensive therapy, dosing ranged from 1.2 to 3.6 g/day (20–60 mmol K⁺), individualized by plasma K⁺ response.
Oral potassium chloride supplementation increased plasma potassium levels and 24-hoururinary potassium excretion, while urinary sodium remained stable. No participant developed hyperkalemia (plasma [K⁺] > 5.5 mmol/L). At baseline, patients with hyperaldosteronism had higher muscle sodium and lower potassium compared with those with essential hypertension. After supplementation, muscle sodium decreased by more than 10%, correcting the excess seen at baseline.
Overall, oral KCl safely restored sodium–potassium balance, normalized plasma potassium, and significantly lowered systolic blood pressure without the need for sodium restriction. The treatment was practical, well tolerated, and cost-effective, reducing blood pressure at a cost of about 100 SGD (≈75 USD) per patient per year.
Dr. Titze and colleagues conclude that “Oral KCl supplementation reversed the body Na⁺/K⁺ redistribution disorder in humans and efficiently lowered blood pressure.”