The efficacy of oral
magnesium supplementation in correcting
magnesium deficiency was examined in a group of 40 elderly patients with suspected
magnesium deficiency. The patients were randomized in a double-blind, placebo-controlled fashion to oral
magnesium-
lactate-
citrate for 6 weeks.
Magnesium status was assessed by an intravenous
magnesium-loading test at baseline and
after treatment. For comparison, another group of 23 patients received 30 mmol
magnesium sulfate intravenously daily for 7 days. A group of 30 patients without known predisposition to
magnesium deficiency and a group of 27 young healthy subjects served as controls. The initial
magnesium-loading test in the placebo group reduced
magnesium retention from a mean 41% (95% confidence intervals 34-49) to 22% (15-29) (p less than 0.01). In the group receiving oral
magnesium supplementation for 6 weeks,
magnesium retention decreased from 39% (31-47) to 10% (2-18) (p less than 0.01), which was significantly better than with placebo treatment (p less than 0.01). The
magnesium retention after oral
magnesium supplementation was comparable to that observed after parenteral administration of
magnesium for 7 days, 6% (-4 to 16), and to that in the reference groups of patients 4% (-2 to 10) and healthy control subjects 3% (-2 to 8). The study suggests that the bioavailability of orally given
magnesium-
lactate-
citrate is satisfactory, and that
oral administration of
magnesium for 6 weeks may restore
magnesium depots in patients with
magnesium deficiency.