Interactive Effects of Sodium and Potassium on Vascular Health in Older Adults

Cardiovascular health declines with age, especially in postmenopausal females. High sodium diets are a major contributor to cardiovascular disease. Unfortunately, reducing sodium intake can be challenging. It is known that increasing potassium intake can improve cardiovascular disease risk factors in young adults, even if sodium intake remains high. The investigators are hoping to show that potassium can improve cardiovascular health in the context of a high sodium diets in older adults. In this study, participants will consume three 10-day controlled diets in a randomized order. The study diets will include: 1) a low sodium (2,000 mg/day)/low potassium (2,000 mg/day) diet; 2) a high sodium (4,700 mg/day)/usual potassium diet; and 3) a high sodium/high potassium (4,700 mg/day). All food will be provided to participants during these periods, and participants will be instructed not to consume any outside food or beverages. Dietary interventions will be separated by a minimum two-week washout period. Measurements of cardiovascular health will be collected at the end of each diet.

Inclusion criteria

• Adults ages 55-75 years
• At least one-year post-menopause (females)
• Willing and able to attend laboratory visits

Exclusion criteria

• BMI ≥35 kg/m2
• Seated blood pressure >135/85 mmHg
• Current diagnosis or history of cardiovascular disease, diabetes, renal disease, cancer, or major cardiovascular event (e.g. heart attack or stroke)
• Taking exogenous hormones or hormone replacement therapy
• Following a vegan or gluten free diet
• Significant weight loss (>10% of body weight) in the last 6 months, or actively trying to lose weight
• Current or recent use of a diuretic (within the past 6 months) (e.g. spironolactone, eplerenone)
• Current or recent use of a potassium binding medication (within the past 6 months)
• Current use of blood pressure lowering medications (e.g. ACE inhibitors, calcium channel blockers, diuretics, vasodilators, beta blockers, AngII receptor blockers)
• Current or recent use of the medication trimethoprim
• Elevated blood lipids (LDL cholesterol ≥190 mg/dL)
• Elevated serum potassium level (>5.1 mmol/L)
• Elevated BUN (>22 mg/dL)
• Elevated creatinine (>1.2 mg/dL)
• Low eGFR (<90 mL/min/1.73 m²)
• Current or recent use of tobacco, nicotine, or illicit drugs
• Radical hysterectomy or oophorectomy (females)