The Effect of Sodium Reduction on Blood Pressure and Physical Function in Older Adults

Hypertension in older adults is a known contributor to both cardiovascular disease and falls. The Centers of Disease Control advocates for low sodium, senior meal plans as a strategy to lower blood pressure (BP). However, sodium is recommended to treat orthostatic hypotension (OH), a risk factor of falls. The long-term effects of low sodium intake on physical function are largely unknown in older adults. The objective of this proposed pilot study is to determine the feasibility of an individual-level, randomized feeding study that examines the impact of sodium reduction on BP regulation among 40 semi-independent, older adults aged 60 and above. Primary Aim 1: To determine the effects of a low sodium (\<0.9 mg per kcal of energy intake), 2-week meal plan compared with a usual meal plan (average sodium \~2 mg per kcal of energy intake) on seated BP among independently living older adults. Hypothesis Aim 1: Compared with the usual meal plan, a reduced sodium meal plan will lower seated BP in older adults after 2 weeks. Feasibility Aim 1: To evaluate the recruitment experience, meal cost, meal delivery logistics, and compliance with and tolerability of the meal plan (urine sodium and palatability questionnaires). Feasibility Aim 2: To determine effect size (variance) of secondary outcomes: standing BP, OH (standing minus seated BP), orthostatic symptoms, and a timed up and go test (TUG). Eligible participants will be randomized to low versus usual sodium meal plans for two weeks. Assessments will be made at the in-person baseline visit, one week telephonic interview and 2 week in person follow-up visit. The primary outcome is seated BP and secondary outcomes include orthostatic hypertension and Timed Up and Go (TUG) tests. Both primary and secondary outcomes will be measured twice: (1) before the study begins (baseline), and (2) after 2 week period. Patient-reported outcomes, dietary compliance, and urine electrolytes will be assessed as well. Intent-to-treat analysis will be conducted for all endpoints.