The sodium-potassium ratio: adherence to guidelines in the Multi-Ethnic Study of Atherosclerosis

Thesis (Master's)--University of Washington, 2015-12Introduction: Few Americans meet the guidelines for sodium and potassium consumption. Yet, sodium reduction remains a major public health aim due to its relationship with hypertension and cardiovascular disease (CVD), increasing potassium is not equally emphasized. The sodium- potassium ratio may better reflect dietary quality with respect to hypertension. Few studies have investigated guideline adherence to a sodium-potassium ratio in an ethnically diverse sample. This is a notable gap due to ethnic differences in CVD risk and cultural differences in food intake among varying groups. Methods: Secondary analysis of data collected in a large, prospective cohort study, the Multi- Ethnic Study of Atherosclerosis, was performed using sodium and potassium estimates from food frequency questionnaires and spot urine measures. Dietary and urinary sodium-potassium ratios were compared to assess compliance to the guidelines. The association between the urinary sodium-potassium ratio and systolic blood pressure was assessed using linear regression and adjusting for covariates. Results: With a mean dietary sodium-potassium ratio equal to 1.0, very few participants (0.3%) met the guidelines. The average urinary sodium-potassium ratio (1.3) was greater than dietary estimates. A 1.0 unit change in the urinary sodium-potassium ratio was associated with a 3.4 mmHG increase in systolic blood pressure (P<0.0001) even after adjusting for antihypertensive medication use. When modeled separately, the change in systolic blood pressure for 1 gm/dl of potassium (-2.5 mmHG, p<0.0001) was much greater than that for sodium (1.0 mmHG, P<0.001). Conclusion: Current sodium and potassium guidelines are generally not achievable and require reassessment. Dietary potassium greatly impacts systolic blood pressure and should be considered with sodium in nutrition interventions for hypertension. Use of a sodium-potassium ratio will strengthen public health planning and clinical interventions