Effects of magnesium supplementation in hypertensive patients: assessment by office, home, and
ambulatory blood pressures.
Kawano Y, Matsuoka H, Takishita S, Omae T
Hypertension 1998 Aug 32:2 260-5

Abstract
An increase in magnesium intake has been suggested to lower blood pressure (BP). However, the results of clinical studies are
inconsistent. We studied the effects of magnesium supplementation on office, home, and ambulatory BPs in patients with essential
hypertension. Sixty untreated or treated patients (34 men and 26 women, aged 33 to 74 years) with office BP >140/90 mm Hg were
assigned to an 8-week magnesium supplementation period or an 8-week control period in a randomized crossover design. The
subjects were given 20 mmol/d magnesium in the form of magnesium oxide during the intervention period. In the control period,
office, home, and average 24-hour BPs (mean+/-SE) were 148.6+/-1.6/90.0+/-0.9, 136.4+/-1.3/86.8+/-0.9, and
133.7+/-1.3/81.0+/-0.8 mmHg, respectively. All of these BPs were significantly lower in the magnesium supplementation period than
in the control period, although the differences were small (office, 3.7+/-1.3/1.7+/-0.7 mmHg; home, 2.0+/-0.8/1.4+/-0.6 mmHg;
24-hour, 2.5+/-1.0/1.4+/-0.6 mm Hg). Serum concentration and urinary excretion of magnesium increased significantly with
magnesium supplementation. Changes in 24-hour systolic and diastolic BPs were correlated negatively with baseline BP or changes in
serum magnesium concentration. These results indicate that magnesium supplementation lowers BP in hypertensive subjects and this
effect is greater in subjects with higher BP. Our study supports the usefulness of increasing magnesium intake as a lifestyle
modification in the management of hypertension, although its antihypertensive effect may be small.