Daily supplements of the mineral for six months improved two out of three measures of insulin sensitivity, compared with placebo, while blood sugar levels, measured as fasting levels of glucose in the blood, improved by about 7 percent, report researchers in Diabetes, Obesity and Metabolism.
“The results of the current study provide significant evidence that magnesium supplementation ameliorates insulin resistance in obese, insulin resistant subjects,” report researchers, led by Prof. Frank Christoph Mooren, from the Institute of Sport Sciences at the Justus-Liebig-University in Giessen.
Insulin resistance occurs when insufficient insulin is released to produce a normal glucose response from fat, muscle and liver cells.
“The efficacy of magnesium supplementation – even in subjects with normal serum magnesium concentrations – addresses the question of a prophylactic administration for people at risk for metabolic syndrome and highlights the need of sufficient magnesium intake by food,” they added.
Magnesium in the diet
Dietary sources of magnesium include green, leafy vegetables, meats, starches, grains and nuts, and milk. Earlier dietary surveys show that a large portion of adults does not meet the RDA for magnesium (320 mg per day for women and 420 mg per day for men).
Interest in magnesium and its potential health benefits have increased recently. Indeed, a report from The Freedonia Group reported that global demand for nutrients and minerals will reach $12.6bn by 2013; a 6.4 per cent increase on last year’s level.
The report, World Nutraceutical Ingredients, highlighted magnesium as one of the minerals with fastest growth, along with calcium. Other fact growing ingredients included soy proteins and isoflavones, psyllium and resistant maltodextrin fibres, omega-3 fatty acids, probiotics, and carotenoids.
The German researchers randomized 52 volunteers to receive magnesium supplements in the form of magnesium-aspartate-hydrochloride at a dose of 365mg per day (Magnesiocard, Verla-Pharm Arzneimittel) or placebo for six months.
Verla-Pharm Arzneimittel sponsored the study, and one of the study researchers was an employee of the German company.
Results showed that two out of there measures of insulin sensitivity improved significantly following magnesium supplementation, while there was also a trend for an improvement in blood pressure in the mineral supplemented group, but such improvements were not statistically significant, added the researchers.
“Several mechanisms may be responsible for the beneficial effect of magnesium on insulin resistance,” wrote the researchers. “These include direct effects of magnesium on the insulin receptor and its downstream signalling processes, enhanced enzyme activities involved in glucose utilization, prevention of an intracellular calcium overload supposed to negatively affect insulin sensitivity, and finally, anti-inflammatory effects known to improve insulin resistance,” they added.
The results appear to echo conclusions from a meta-analysis of observational studies published in 2007 in the Journal of Internal Medicine (doi: 10.1111/j.1365-2796.2007.01840.x). Researchers at Stockholm's Karolinska Institutet reported that for every 100 milligram increase in magnesium intake, the risk of developing type-2 diabetes decreased by 15 percent.
Diabetes affects an estimated 24 million Americans, equal to 8 percent of the population. The total costs are thought to be as much as $174 billion, with $116 billion being direct costs from medication, according to 2005-2007 American Diabetes Association figures.
Source: Diabetes, Obesity and Metabolism
"Accepted Article" published online ahead of print, doi: 10.1111/j.1463-1326.2010.01332.x
“Oral magnesium supplementation reduces insulin resistance in non-diabetic subjects – a double-blind, placebo-controlled, randomized trial”
Authors: F. C. Mooren, K. Krüger, K. Völker, S. W. Golf, M. Wadepuhl, A. Kraus