Electrolyte intake and nonpharmacologic blood pressure control

To characterize relationships between sodium and potassium intakes and blood pressure control.

We analyzed repeated 24-hour diet recalls and 24-hour urine assays from 873 elderly participants with established hypertension in a 3-year clinical trial of lifestyle interventions. Pooled estimates of electrolyte intakes were developed using hierarchical measurement error models and related to nonpharmacologic blood pressure control.

Relative decreases in sodium and increases in potassium intakes each had graded relationships with better blood pressure control. After adjustment for measurement error, a 100 mmol/24-hour decrease in sodium intake was associated with an odds ratio of 2.93 [95% confidence interval: 1.83, 4.64] for maintaining nonpharmacologic blood pressure control throughout follow-up. A 50 mmol/24-hour increase in potassium intake was associated with an odds ratio of 2.00 [1.12, 3.55]. These relationships were independent of each other and of baseline levels of intakes. Blood pressure control was most strongly associated with sodium intake for participants with lower systolic blood pressures and longer duration of hypertension, and with potassium for those with elevated diastolic blood pressures.

Sodium and potassium intakes exert independent graded influences on nonpharmacologic blood pressure control. Correlated measurement error may spuriously introduce a dependency among these relationships.