by Craig Weatherby
Magnesium plays an essential part in the regulation of many cell and metabolic processes.
This probably explains the accumulating evidence that magnesium improves blood sugar control.
Top magnesium sources
According to USDA data, the top food sources of magnesium include these, in descending order of magnesium content:
  • Cocoa powder – 456 mg per 3 oz (27 mg per Tbsp)
  • King salmon – 122 mg per 3 oz, cooked
  • Halibut – 90-107 mg per 3 oz, cooked
  • Sablefish – 71 mg per 3 oz, cooked
  • Almonds or cashews – 225-240 mg per 3 oz (75-80 mg 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.
And judging by the results of a new study, having low magnesium blood levels worsens diabetes complications.
The results show that magnesium intake was inadequate in 82 percent of the diabetics studied, with the lowest levels found in those with kidney complications.
Further, about two-thirds (63 percent) of the subjects had low blood levels of magnesium.
Last year, a USDA researcher published an evidence review, in which he made several key points (Nielsen FH 2010):
  • About 60 percent of American adults do not consume sufficient magnesium.
  • Low magnesium levels are associated with many disease conditions characterized by chronic inflammation, including obesity.
  • Magnesium deficiency may contribute significantly to development chronic diseases such as atherosclerosis, hypertension, osteoporosis, diabetes mellitus, and cancer.
Before we take a look at a recent Brazilian study that strengthens the link between diabetes and magnesium, let's review the existing evidence.
Low blood magnesium levels linked to diabetes risk and complications
Epidemiological studies suggest that adequate magnesium intake reduces the risk of developing diabetes significantly.
But the links between low magnesium blood levels and greater risk of the disease and worse symptoms is even greater… possibly indicating that some diabetics have difficulty using magnesium they consume.
The body's capacity to produce insulin relies in part on magnesium, which is needed for the activation of insulin receptors and for stimulation of body chemicals involved in insulin “signaling”.
And the chronically high blood sugar levels (hyperglycemia) that characterize diabetes lead to excessive loss of magnesium in the urine while increasing the risk of kidney damage and other complications associated with diabetes.
New study puts more importance on magnesium
The new research, conducted in Brazil, examined magnesium intake and blood levels in 51 patients with type 2 diabetes.
And the results tied the diabetics' blood sugar (glucose) levels to their blood magnesium levels.
Specifically, those with higher blood magnesium levels had lower fasting and after-meal blood glucose levels.
In addition, higher urine levels of magnesium were linked to higher fasting glucose levels.
The authors noted that because magnesium is essential to all reactions that use and supply energy, it is not very surprising that low blood levels of the mineral are implicated in metabolic dysfunctions like diabetes.
They concluded that the impaired kidney function associated with diabetes may lead to high levels of magnesium in the urine, which, together with low magnesium intake, can cause a rise in blood sugar.
  • Sales CH, Pedrosa LF, Lima JG, Lemos TM, Colli C. Influence of magnesium status and magnesium intake on the blood glucose control in patients with type 2 diabetes. Clin Nutr. 2011 Jan 31. [Epub ahead of print]
  • de Lordes Lima M, Cruz T, Pousada JC, Rodrigues LE, Barbosa K, Canguçu V. The effect of magnesium supplementation in increasing doses on the control of type 2 diabetes. Diabetes Care. 1998 May;21(5):682-6.
  • Kao WH, Folsom AR, Nieto FJ, Mo JP, Watson RL, Brancati FL. Serum and dietary magnesium and the risk for type 2 diabetes mellitus: the Atherosclerosis Risk in Communities Study. Arch Intern Med. 1999 Oct 11;159(18):2151-9.
  • Wang JL, Shaw NS, Yeh HY, Kao MD. Magnesium status and association with diabetes in the Taiwanese elderly. Asia Pac J Clin Nutr. 2005;14(3):263-9.
  • Nielsen FH. Magnesium, inflammation, and obesity in chronic disease. Nutr Rev. 2010 Jun;68(6):333-40. Review.
  • Barbagallo M, Dominguez LJ. Magnesium and aging. Curr Pharm Des. 2010;16(7):832-9. Review.