Nutrigenomics shows benefit of magnesium’s metabolic actions
Four weeks of magnesium supplementation were associated with a decrease in levels of C-peptide, a marker of improved insulin sensitivity. The mineral was also linked to down-regulation of certain “genes related to metabolic and inflammatory pathways”, according to findings published in the American Journal of Clinical Nutrition.
“These findings lend support to the hypothesis that dietary magnesium plays a beneficial role in the regulation of insulin and glucose homeostasis,” wrote researchers led by Simin Liu, MD, ScD, Professor of Epidemiology and Medicine at the University of California, Los Angeles (UCLA).
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 2009’s level.
The report, World Nutraceutical Ingredients, highlighted magnesium as one of the minerals with fastest growth, along with calcium.
The new study adds to a growing body of science supporting the potential health benefits of magnesium and employed a raft of techniques, including biochemical assays of blood samples, RNA extraction, and urine proteomic profiling.
Professor Liu and his co-workers recruited 14 overweight but otherwise healthy people, and randomly assigned them to receive 500 mg per day doses of elemental magnesium in the citrate form, or placebo for four weeks. After the intervention, participants underwent a one month ‘washout’ period before crossing over to the other intervention.
Results showed that magnesium supplementation was linked to significantly decreased levels of C-peptide, “which suggested a reduction in pancreatic insulin secretion that may have resulted from an improvement in insulin sensitivity and a subsequent lowered demand on the pancreas”, said the researchers.
In addition, a reduction in the concentrations of fasting insulin was measured by Prof Liu and his team.
No changes in inflammatory biomarkers were recorded, added the researchers.
In terms of gene expression, 24 genes were up-regulated, and 36 genes were down-regulated in response to magnesium supplementation, they said. Amongst the down-regulated genes were ones linked to metabolic and inflammatory pathways, explained the researchers.
“Although a number of the other genes identified as differentially expressed in this trial are unknown,” said the researchers, “our exploratory findings indicated a systemic effect of magnesium supplementation at the level of gene expression.
“This is consistent with our findings that showed a distinct protein profile in urine collected after treatment with magnesium compared with after treatment with the placebo.
“Our findings were suggestive of measurable physiologic changes in the urinary proteome after treatment with magnesium for four weeks, which warrants further investigation into these changes and identification of the proteins involved,” they added.
The rise of ‘omics’
Many food companies – both ingredient suppliers and food manufacturers are taking the potential of nutrigenomics very seriously. Companies such as Nestle, DSM, and Chr Hansen are all investing heavily in the area. Indeed, the new study was partly funded by General Mills. However, actual products are as yet, scarce.
Nutrigenomics is seen by many as the future of nutrition. Nutrigenomics is defined as how food and ingested nutrients influence the genome (personalized nutrition). Nutrigenetics is defined as how a person's genetic make-up affects a response to diet (individual nutrition). The difference between the two is important.
In addition to General Mills, funding was also provided by the Burroughs Wellcome Fund Institutional Program Unifying Population and Laboratory Based Sciences, the University of California, Los Angeles, and the National Institute of Diabetes and Digestive and Kidney Diseases, the National Institutes of Health.
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.110.002949.
“Magnesium supplementation, metabolic and inflammatory markers, and global genomic and proteomic profiling: a randomized, double-blind, controlled, crossover trial in overweight individuals”
Authors: S.A. Chacko, J. Sul, Y. Song, X. Li, J. LeBlanc, Y. You, A. Butch, S. Liu