Effects of oral magnesium supplementation on insulin sensitivity and blood pressure in normo-magnesemic nondiabetic overweight Korean adults
Received 16 July 2008; received in revised form 16 December 2008; accepted 9 January 2009. published online 09 April 2009.
Abstract
Background and aim
Little is known about the effect of magnesium on insulin sensitivity and BP in healthy individuals. Therefore, we investigated whether magnesium could improve insulin sensitivity and blood pressure (BP) in normo-magnesemic nondiabetic overweight adults.
Methods and results
In a double-blinded, placebo-controlled, randomized trial, a total of 155 participants (BMI≥23kg/m2) received either 12.3mmol (300mg) of elemental magnesium in the form of magnesium oxide (n=75) or placebo (n=80) each day for 12 weeks, constituting the intent-to-treat population. A repeated-measures ANOVA was used to evaluate the between-group changes in variables during the study. The baseline characteristics between the intervention and control groups were similar. There were no significant differences between the groups in the pattern of change of the homeostasis model assessment insulin resistance index, BP over time during the 12-week study. In subgroup analysis, magnesium supplementation (n=8, 27, and 24, respectively) lowered BP much more than placebo (n=16, 29, and 25, respectively) in those subjects whose systolic BP≥140mmHg, diastolic BP 80–90mmHg, and diastolic BP≥90mmHg at the start of the study (P=0.016, 0.043, and 0.023, respectively); in comparison, those subjects whose initial BP reading was low at baseline did not show a change in BP. No significant adverse events related to magnesium supplementation were recorded.
Conclusions
These results suggested that magnesium supplementation does not reduce BP and enhance insulin sensitivity in normo-magnesemic nondiabetic overweight people. However, it appears that magnesium supplementation may lower BP in healthy adults with higher BP.
aCenter for Obesity, Nutrition and Metabolism, Department of Family Medicine, Pusan National University Hospital, 1-10 Ami-dong, Seo-gu, Busan 602 739, South Korea
bMedical Education Unit, Pusan National University School of Medicine, Yangsan, 626 770, South Korea
cMedical Research Institute, Pusan National University, Yangsan, 626 770, South Korea
eDepartment of Internal Medicine, Bongseng Memorial Hospital, Busan, 601 723, South Korea
fDepartment of Internal Medicine, Busan St. Mary's Medical Center, Busan, 608 838, South Korea
gDepartment of Internal Medicine, Pusan National University School of Medicine, Busan, 602 739, South Korea
hDepartment of Physical Education, Pusan National University College of Education, Busan, 609 735, South Korea
Corresponding author. Department of Family Medicine, Pusan National University Hospital, 1-10 Ami-dong, Seo-gu, Busan 602 739, South Korea. Tel.: +82 51 240 7834; fax: +82 51 242 8671.
ABSTRACT