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.

Inclusion criteria

• Resident at Jack Satter House in Revere
• Age >= 60 years
• Resting systolic blood pressure 100-149 mm Hg and diastolic blood pressure <100 mm Hg
• Stable BP medications (no recent or intended changes)

Exclusion criteria

• Cognitive Impairment (Montreal Cognitive Assessment test <18)
• Unstable blood pressure medications in the past 2 months
• Terminal or mental illness
• Severe allergies to common foods
• Unwillingness to comply with the diet
• Physical inability to do a timed up and go test
• Active kidney dialysis or history of kidney transplant