This humble mineral ranks as perhaps the most undervalued and underconsumed of all the essential human nutrients.
Perhaps most importantly, lack of magnesium promotes various adverse arterial changes linked to cardiovascular disease and hypertension.
Supplements providing cheap heart-health insurance… and 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.
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.
Unfortunately, relatively few Americans get the recommended daily allowance… which is 320 mg for women and 420 mg for men.
When most people think about nutrients for heart health, omega-3s usually come to mind first, for good reasons.
The clinically demonstrated ability of omega-3 fatty acids to reduce the risk of heart-related death may stem in part from their proposed normalizing effects on heart rhythms.
Omega-3s also exert anti-inflammatory and other beneficial effects that probably play major roles in their exceptional ability to support heart health.
But judging by the findings of two recent epidemiological studies, magnesium may be just as important to reducing the risk of sudden cardiac death.
Sudden cardiac death… a very common bolt from the blue
According to the American Heart Association, "Sudden death from cardiac arrest is a major health problem that's received much less publicity than heart attack” (AHA 2010).
In fact, sudden cardiac death (SCD) accounts for about half of all heart-related fatalities, and it's the kind that omega-3s are virtually proven to help deter.
The most common underlying reason for SCD is coronary heart disease—fatty buildup in the arteries that supply blood to the heart muscle.
But the common immediate cause of the cardiac arrest that leads to SCD is an abnormal heart rhythm (arrhythmia).
As the American Heart Association says, "The victim may or may not have diagnosed heart disease. The time and mode of death are unexpected. It occurs within minutes after symptoms appear” (AHA 2010).
In other words, SCD truly is a bolt from the blue… and its unpredictable nature makes it even more critical to ensure that you take every credible step to reduce the risk.
Harvard's hearty findings on magnesium follow Minnesota team's
Last fall, a University of Minnesota team concluded—based on their analysis of blood, diet and health data from 14,232 men and women—that low blood levels of magnesium "… may be an important predictor of SCD [sudden cardiac death].”
They Minnesota team made a very reasonable recommendation: "Further research into the effectiveness of Mg [magnesium] supplementation for those considered to be at high risk for SCD is warranted” (Peacock JM et al. 2010).
Coincidentally, scientists from Harvard just published the results of their analysis of blood, diet and health data from a subset of the 88,375 women who participated in the famed Nurses' Health Study (Chiuve SE et al. 2010).
Like all the Nurses' Health Study participants, the women chosen for comparison—99 who died from sudden cardiac death and 291 healthy "controls”—had completed diet questionnaires and given blood samples in 1980 and again every few years.
After adjusting the results for other influences on heart risk, the Harvard team concluded that the women with high reported magnesium intakes were 37 percent less likely to have died from SCD, compared with women reporting low magnesium intakes.
Better yet, the women with high magnesium blood levels were 77 percent less likely to have died from SCD, compared with the women showing low blood levels.
Affirming magnesium as the source of the risk reduction, the analysis showed that the risk of SCD dropped 41 percent for every incremental rise of 0.25 milligrams of magnesium per deciliter of blood.
The Harvard team's finding echo those reported by the Minnesota group: "…higher plasma [blood] concentrations and dietary magnesium intakes were associated with lower risks of SCD.”
And they expressed a similar view of logical future steps:
"If the observed association is causal [i.e., magnesium is causing the risk reduction], interventions directed at increasing dietary or plasma [blood] magnesium [levels] might lower the risk of SCD” (Chiuve SE et al. 2010).
Chiuve SE, Korngold EC, Januzzi JL Jr, Gantzer ML, Albert CM. Plasma and dietary magnesium and risk of sudden cardiac death in women. Am J Clin Nutr. 2010 Nov 24. [Epub ahead of print]
Hamilton B, Jaques R, Budgett R. Observations on the "Lausanne Recommendations" on sudden cardiovascular death in sport. Br J Sports Med. 2007 Feb;41(2):e1.
Peacock JM, Ohira T, Post W, Sotoodehnia N, Rosamond W, Folsom AR. Serum magnesium and risk of sudden cardiac death in the Atherosclerosis Risk in Communities (ARIC) Study. Am Heart J. 2010 Sep;160(3):464-70.
NutritionData.com (NDC). Foods highest in Magnesium.2010. Accessed at http://nutritiondata.self.com/foods-000120000000000000000-w.html