Potassium Intake-response Trial to Control Hypertension

The Potassium Intake-response Trial to Control Hypertension (PITCH) will test the intake-response relationship between potassium supplementation and blood pressure, which may inform clinical guidelines on the optimal level of potassium supplementation for blood pressure lowering among adults with elevated blood pressure or hypertension and dietary guidelines for population intake.

Hypertension is the leading preventable risk factor for cardiovascular disease (CVD) and all-cause mortality, and prevention and treatment of high blood pressure (BP) is crucial for reducing the global burden of CVD.

Nonpharmacological interventions, including dietary interventions, are recommended as the primary approach for prevention and treatment of elevated BP and hypertension in US adults. Observational epidemiological studies have reported an inverse association between dietary potassium intake and BP, and clinical trials have documented that potassium supplementation reduces BP. However, previous clinical trials of potassium supplementation and BP have been limited to comparing one single dose of potassium supplementation (mostly 60 mmol/day or 1173 mg/day) to placebo control. Therefore, the optimal level of dietary intake of potassium in the population is currently unknown. In 2019, the National Academies of Science, Engineering, and Medicine updated the Dietary Reference Intake (DRI) recommendations for potassium intake based on the most current evidence associating potassium intake with CVD outcomes, including BP. Limited evidence precluded the DRI Committee from establishing a Chronic Disease Risk Reduction Intake level. The specific goal of the proposed randomized controlled trial is to study the intake-response effect for 4 levels of potassium supplementation on BP among adults with elevated BP or hypertension (defined as average untreated office systolic BP 120-159 mm Hg and diastolic BP \<100 mm Hg). The investigators will test the primary hypothesis that compared with placebo (0 mmol/day potassium supplementation), there is a progressive relationship between increasing doses of oral potassium supplementation (30, 60, and 90 mmol/day or 1173, 2346, 3519 mg/day) and decreasing levels of 24-hour systolic BP from baseline to 12-weeks of follow-up. The investigators will also evaluate effects on daytime (awake) and nighttime (asleep) BP, office systolic and diastolic BP, sodium excretion, and effect mediation and moderation by age, sex, race, central adiposity, baseline urine excretion of sodium and potassium, and change in urine sodium. The results from the proposed trial will fill a critical knowledge gap and may identify the optimal level of potassium supplementation for BP lowering among adults with elevated BP and hypertension. This information can be used to develop dietary guidelines for the prevention and treatment of elevated BP, hypertension, and CVD.

Eligibility Criteria:
Inclusion Criteria:

* Men or women aged \>18 years of any race/ethnicity
* Elevated BP or hypertension at screening (untreated office systolic BP 120-159 and diastolic BP \<100 mm Hg)
* Willing and able to provide informed consent

Exclusion Criteria:

* Medical condition in which potassium supplementation is contraindicated: history of heart failure, myocardial infarction, stroke, cardiac arrythmia, chronic kidney disease or estimated glomerular filtration rate \<60 ml/min/1.73 m\^2, diabetes or non-fasting glucose \>200 mg/dL, major depressive disorder (PHQ-9 score ≥15), psychosis, ulcer diseases including esophageal-gastric ulcer, malignancy in the past 5 years, liver disease, organ transplant, Addison's disease (adrenal insufficiency)
* Use of medications which may alter serum potassium levels or in which potassium supplementation is contraindicated: antihypertensive agents, antihistamines, antiparkinson agents, antimuscarinic agents, antipsychotics, muscle relaxants, systemic corticosteroids, or chronic use of non-steroidal anti-inflammatory drugs
* Serum potassium ≥5.0 mEq/L
* Metabolic acidosis
* Consumption of \>85th percentile of usual potassium intake among US adults (\>3,750 mg/day)
* For women, current pregnancy, breastfeeding, or plans to become pregnant during the study
* Consumption of ≥21 alcoholic beverages per week or consumption of ≥6 beverages per occasion
* Current or planned residence making it difficult to meet trial requirements or travel to the study site
* Current participation in another intervention or pharmaceutical trial
* Unable or unwilling to complete 24-hour BP or urinary sample collection
* Other concerns regarding ability to meet trial requirements, at the discretion of the investigators or staff