Effect of sodium and potassium supplementation on vascular and endothelial function: a randomized controlled trial.

Healthy normotensive adults in Australia were studied in a randomized crossover design. The active intervention arms each included 39 participants; the sample was 21 women and 18 men, aged 18 to 70 years, with mean age 37 ± 15 years and mean BMI 23.0 ± 2.8 kg/m2.

This randomized crossover trial compared a single oral high-potassium, high-sodium meal with a low-potassium, high-sodium meal. The HKHN meal provided 38 mmol potassium and 65 mmol sodium per meal, while the LKHN meal provided 3 mmol potassium and 65 mmol sodium per meal.

Adding potassium to the high-sodium meal attenuated the postprandial decline in endothelial function. The largest between-meal difference in flow-mediated dilatation occurred at 30 minutes, when FMD differed by -3.58 ± 0.85%, and the potassium-containing meal blunted the sodium-associated reduction in FMD. Potassium also altered low-flow-mediated constriction, while the meals did not differ significantly for central augmentation index, pulse wave velocity, or blood pressure over time. Serum potassium rose after the HKHN meal, with a maximum increase of 0.6 ± 0.3 mmol/L at 90 minutes, supporting a possible mechanistic link.

The trial tested only acute, single-meal effects, so long-term cardiovascular implications remain unknown. The sample was small and restricted to healthy, normotensive adults, limiting generalizability to people with hypertension or established cardiovascular disease. Several vascular outcomes were unchanged, so the benefit was specific to endothelial function rather than broad hemodynamic improvement.