In the DASH (Dietary Approaches to Stop Hypertension) trials, a diet rich in fruits, vegetables, nuts and dairy products, and limited in fat content, was shown to be useful in controlling hypertension, particularly in African Americans (AA). Key components of such a diet are potassium, magnesium, and alkali, each of which has been implicated in lowering blood pressure. In the original IND 116,208, the investigators explored whether potassium-magnesium citrate (KMgCit) as a powder pharmaceutical formulation (dissolved in water before ingestion) could serve as a surrogate for the DASH diet and would lower blood pressure among patients with pre- or Stage I hypertension. Unfortunately, previous studies did not include adequate number of African American patients.

This is a double blind, randomized crossover trial comprising two phases: Placebo Phase (microcrystalline cellulose in water) and KMgCit Phase (KMgCit powder in water) to investigate the use of KMgCit in lowering blood pressure and reducing arterial stiffness. One half of the subjects will undergo the Placebo phase first followed by the KMgCit phase. The other half will undergo the KMgCit phase first followed by the Placebo phase. Each phase is 4 weeks in duration with at least 1 week washout between phases.

Forty-five African American patients of either sex with pre- or Stage I hypertension, with systolic blood pressure of 120-139 mm or diastolic of < 90 mmHg according the 2017 ACC/AHA high BP guideline, will be recruited into the trial, with the expectation that 36 patients would complete both phases of the trial (assuming 20% dropout). They may be AA adult men or women (> 21 years of age). They may be on ACE inhibitor or ARB, but not on spironolactone or diuretic. Excluded will be patients with diabetes mellitus, renal impairment, heart disease, chronic NSAID use, gastrointestinal reflux disease requiring treatment with acid reducing agent of antacid more than once a week, esophageal-gastric ulcer, chronic diarrhea, hyperkalemia, abnormal liver function test, subjects who require potassium supplementation on a regular basis for any reason, pregnancy, history of major depression, bipolar disorder or schizophrenia, and history of substance abuse

Inclusion Criteria:

-African American patients with pre- or Stage I hypertension, with systolic blood pressure of 120-139 mm or diastolic BP of < 90 mmHg.

Exclusion Criteria:

• Diabetes mellitus,
• Renal impairment (serum creatinine > 1.4 mg/dL),
• Any heart diseases such as congestive heart failure or sustained arrhythmia,
• Chronic NSAID use,
• Treatment with diuretics, including spironolactone
• Gastroesophageal reflux disease (GERD) requiring treatment with acid reducing agent or antacid more than once a week,
• Esophageal-gastric ulcer,
• Chronic diarrhea,
• Hyperkalemia (serum K > 5.0 mmol/L),
• Abnormal liver function test (AST or ALT above upper limit of normal range),
• Subjects who require any potassium supplement on a regular basis for any reason,
• Pregnancy,
• History of major depression, bipolar disorder, or schizophrenia, and
• History of substance abuse.

The study supplement will be dispensed in a blinded manner.