One of the hottest fields in biomedical research is “nutrigenomics” – the science of how nutrients and other food factors influence our genes in their roles as active, second-to-second directors of key bodily processes.
For example, while the polyphenols in fruits, vegetables, cocoa, tea, coffee, whole grains, nuts, and other plant foods act as antioxidants in the test tube, they exert only very minor direct antioxidant effects in the body.
Instead, polyphenols seem to bring us health benefits by influencing the “expression” (activation) of genes in our cells.
Gene expression is a process in which a gene is “switched on” at a certain time and commands a cell to take certain actions, such as assembly of proteins or RNA that initiates or influences bodily processes.
Top magnesium sources
According to USDA data, the top food sources of magnesium include these, in descending order of magnesium content:
Cocoa powder – 456mg per 3 oz (27mg per Tbsp)
King salmon – 122mg per 3 oz, cooked
Halibut – 90-107mg per 3 oz, cooked
Sablefish – 71mg per 3 oz, cooked
Almonds or cashews – 225-240mg per 3 oz (75-80mg per oz)
Other major food sources include bran, seaweed, leafy green vegetables, meats, grains, and milk.
What about supplements? Conventional wisdom calls for taking about one part magnesium to two parts calcium.
But other researchers argue, persuasively, that a one-to-one ratio is healthier, given the overload of calcium in most Americans' diets, and the lack of magnesium.
Also, prehistoric diets seem to have provided the minerals in a one-to-one ratio, suggesting that this ratio is what humans evolved in response to.
Finally, magnesium aids calcium absorption into bones, but the opposite is not true, with excess calcium impeding magnesium uptake.
Thus, gene expression is the most fundamental level at which a person's genetic profile or “genotype” gives rise to their unique set of physical and mental characteristics, or “phenotype”.
(In contrast, “nutrigenetics” is the study of how a person's genetic makeup influences their body's responses to specific nutrients and food factors.)
Now a new study from the University of California at Los Angeles suggests that magnesium brings many of its benefits through its nutrigenomic effects.
In the new study, people assigned to take magnesium supplements enjoyed a decrease in levels of C-peptide – which indicates improved insulin sensitivity – and down-regulation (suppression) of genes that promote chronic inflammation and other metabolic effects linked to diabetes.
As the UCLA team wrote, “These findings lend support to the hypothesis that dietary magnesium plays a beneficial role in the regulation of insulin and [blood] glucose homeostasis [stability].”
Unfortunately, dietary surveys show that many adults do not consume the recommended daily allowance (RDA) for magnesium … 320mg for women and 420mg for men. For some of the top food sources, see our “Top magnesium sources” sidebar.
Let's take a closer look at the new study and see what it means for human health.
UCLA study finds benefits from magnesium
Researchers led by Simin Liu, MD, ScD, recruited 14 overweight but otherwise healthy people, and randomly assigned them to take either 500mg of magnesium citrate – a common supplemental form – or placebo pills daily for four weeks (Chacko SA et al. 2011).
After four weeks, participants underwent a one-month “washout” period before crossing over to the other intervention.
(In other words, after a month of taking no pills, the group taking magnesium pills started taking the placebo pills, and vice versa.)
The results showed that magnesium supplementation was linked to significantly lower levels of C-peptide. This effect suggested that the magnesium group enjoyed a reduction in insulin secretion that may have resulted from an improvement in insulin sensitivity.
In addition, the UCLA team detected a reduction in fasting insulin levels, which is a sign of reduced diabetes risk.
However, no changes in inflammatory biomarkers were recorded.
In terms of gene expression, 24 genes were “up-regulated” (made active), and 36 genes were “down-regulated” (made inactive) when participants were taking magnesium supplements.
Amongst the down-regulated genes were ones linked to metabolic and inflammatory pathways, explained the researchers.
As the UCLA researchers wrote, “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.” (Chacko SA et al. 2011)
- Chacko SA, Sul J, Song Y, Li X, LeBlanc J, You Y, Butch A, Liu S. Magnesium supplementation, metabolic and inflammatory markers, and global genomic and proteomic profiling: a randomized, double-blind, controlled, crossover trial in overweight individuals. Am J Clin Nutr. 2011 Feb;93(2):463-73. Epub 2010 Dec 15.