Magnesium Supplementation and Blood Pressure Reduction

This double-blind, placebo-controlled randomized clinical trial will test whether a magnesium glycinate supplement (480 mg/day) taken for 12 weeks lowers blood pressure in 60 adults aged 30-74 who have elevated blood pressure or stage 1 hypertension and are not taking anti-hypertensive medication. Animal studies, epidemiologic studies, and small randomized trials suggest that supplemental Mg may reduce blood pressure, but the evidence is not definitive. Eligibility to participate in the trial will be determined by a 2-stage screening process -- completion of a pre-screening form online followed by an in-person screening clinic visit. Eligible participants will assigned by chance (like a coin toss) to daily magnesium or to placebo and will receive a supply of study capsules via U.S. mail. Participants will take 4 study capsules per day (2 capsules in the morning and 2 capsules in the evening). Assessments at the screening visit include seated blood pressure; 24-hour ambulatory blood pressure (monitor will be worn by the participant for 24 hours and then returned via mail); pulse; weight, height, waist and hip circumference measurements; fasting blood and urine collection; and health and diet questionnaires. Participants will return for clinic visits at 6 weeks and at 12 weeks to assess these measures, including 24-hour ambulatory blood pressure.