When it comes to deterring cardiovascular disease, there are no magic bullets.
That holds true for its major adverse outcomes: stroke, heart failure, heart attack, and sudden cardiac death.
We can’t control our genes, which leaves diet and exercise as the major adjustable risk factors.
Statin drugs can help, but there’s good evidence that – with exceptions for unusual circumstances – their benefits can be matched more safely by optimal nutrition and exercise.
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 wild salmon species provide 25-30mg per cooked 3 oz serving.
Beside these, the major food sources of magnesium include wheat bran, beans, seaweed, leafy green vegetables, whole grains, and milk.
The adult Recommended Dietary Allowances (RDAs) for magnesium are 420mg (men) and 320mg (women). For all RDAs by age, gender, and health status, see the U.S. Office of Dietary Supplements' Magnesium Fact Sheet.
What about supplements?
Conventional wisdom calls for taking about one part magnesium to two parts calcium.
But many researchers argue that a one-to-one ratio is healthier, given the near-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 adapted to over millenia of evolution.
Finally, magnesium aids calcium absorption into bones, while excess calcium impedes magnesium uptake.
Optimal nutrition can include supplemental omega-3s, vitamin D, and coenzyme Q10 … but no nutrient can do it all alone.
And it’s common for people and physicians alike to overlook nutrients that aren’t thought of as “heart” supplements.
Just last month, an evidence review from Britain, covering 22 clinical trials, confirmed that magnesium supplements can produce a small but “clinically significant” reduction in blood pressure (Kass L et al. 2012).
Now, the results of a very large epidemiological study from Japan reinforce – and greatly expand – the potential importance of magnesium to cardiovascular health.
This news comes in the context that many American adults do not get the Recommended Dietary Allowance (RDA) for magnesium (Rosanoff A et al. 2012).
For some basic magnesium information, see our sidebars, “Top magnesium sources” and “Why magnesium matters”.
Japanese study supports heart-health value of humble mineral
Starting in the late 1980’s, Japanese people were recruited for a huge epidemiological study designed to identify lifestyle factors that may contribute to risk of death from cancer or cardiovascular disease (Tamakoshi A 2007).
Called the Japan Collaborative Cohort (JACC) Study, it includes more than 100,000 people, and has provided clues that can be used to justify controlled clinical trials … the only kind of study that can prove a cause-effect link between a lifestyle factor and a health risk.
Scientists from the JACC just published a new analysis that indicates a large heart-health benefit from magnesium (Zhang W et al. 2012).
Their analysis suggests that higher intakes of magnesium may halve the risk of dying from cardiovascular disease.
The JACC team analyzed diet and health data collected over a period of 14.7 years from 58,615 healthy Japanese aged between 40 and 79.
In addition to a 50 percent cut in the risk of heart-related death, their results indicate a similarly large reduction in the risk of stroke, coronary heart disease, and other adverse cardiovascular outcomes.
Importantly, as the researchers wrote, magnesium’s heart benefits make sense, given the persuasive evidence of a link between magnesium intake and improved blood pressure (Houston M 2011).
The Japanese team noted that magnesium may also benefit heart health by suppressing irregular heartbeats and/or – as researchers from Case Western Reserve University reported earlier this year – by inhibiting inflammation (Sugimoto J et al. 2012).
Why magnesium matters
Magnesium is the fourth most abundant mineral in the body and is needed for more than 300 biochemical reactions in the body.
It helps maintain normal muscle and nerve function, keeps heart rhythms steady, supports a healthy immune system, and keeps bones strong.
Magnesium also helps regulate blood sugar levels, promotes normal blood pressure, and is involved in energy metabolism and protein synthesis.
The positive outcomes of the studies conducted to date have raised hopes that magnesium may help prevent and manage hypertension, cardiovascular disease, and diabetes.
The evidence suggests that adults can safely take 350mg of supplemental magnesium per day.
Note: Very large doses of magnesium-containing laxatives and antacids can cause magnesium toxicity.
Signs of excess magnesium can be similar to magnesium deficiency: changes in mental status, nausea, diarrhea, appetite loss, muscle weakness, difficulty breathing, extremely low blood pressure, and irregular heartbeat.
Not all patients benefit from magnesium, but it appears to increase the effectiveness of all classes of anti-hypertension drugs (Houston M 2011; Chaumais MC et al. 2012).
When the researchers factored in the known blood-pressure-lowering effects of calcium and potassium – which abound in many magnesium-rich foods – this slightly weakened the link between magnesium and heart health.
“However,” as the researchers wrote, “... [the] reduced mortality from cardiovascular disease associated with dietary magnesium intake was maintained after dietary calcium intake was taken into account” (Zhang W et al. 2012).
The takeaway is that Americans would do well to take magnesium supplements and seek out the best food sources … see our sidebar, “Top magnesium sources”.
Chaumais MC, Lecerf F, Fattal S, Savale L, Günther S, Huertas A, Montani D, Perros F, Humbert M, German-Fattal M. A study of magnesium deficiency in human and experimental pulmonary hypertension. Magnes Res. 2012 Mar 1;25(1):21-7.
Dickinson HO, Nicolson DJ, Campbell F, Cook JV, Beyer FR, Ford GA, Mason J. Magnesium supplementation for the management of essential hypertension in adults. Cochrane Database Syst Rev. 2006 Jul 19;(3):CD004640. Review.
Houston M. The role of magnesium in hypertension and cardiovascular disease. J Clin Hypertens (Greenwich). 2011 Nov;13(11):843-7. doi: 10.1111/j.1751-7176.2011.00538.x. Epub 2011 Sep 26. Review.
Kass L, Weekes J, Carpenter L. Effect of magnesium supplementation on blood pressure: a meta-analysis. Eur J Clin Nutr. 2012 Apr;66(4):411-8. doi: 10.1038/ejcn.2012.4. Epub 2012 Feb 8.
Larsson SC, Orsini N, Wolk A. Dietary magnesium intake and risk of stroke: a meta-analysis of prospective studies. Am J Clin Nutr. 2012 Feb;95(2):362-6. Epub 2011 Dec 28.
Larsson SC, Virtamo J, Wolk A. Potassium, calcium, and magnesium intakes and risk of stroke in women. Am J Epidemiol. 2011 Jul 1;174(1):35-43. Epub 2011 May 3.
Larsson SC, Virtanen MJ, Mars M, Männistö S, Pietinen P, Albanes D, Virtamo J. Magnesium, calcium, potassium, and sodium intakes and risk of stroke in male smokers. Arch Intern Med. 2008 Mar 10;168(5):459-65
Maruyama K, Iso H, Date C, Kikuchi S, Watanabe Y, Wada Y, Inaba Y, Tamakoshi A; JACC Study Group. Dietary patterns and risk of cardiovascular deaths among middle-aged Japanese: JACC Study. Nutr Metab Cardiovasc Dis. 2012 Mar 10. [Epub ahead of print]
Nagura J, Iso H, Watanabe Y, Maruyama K, Date C, Toyoshima H, Yamamoto A, Kikuchi S, Koizumi A, Kondo T, Wada Y, Inaba Y, Tamakoshi A; JACC Study Group. Fruit, vegetable and bean intake and mortality from cardiovascular disease among Japanese men and women: the JACC Study. Br J Nutr. 2009 Jul;102(2):285-92. Epub 2009 Jan 13.
Rosanoff A, Weaver CM, Rude RK. Suboptimal magnesium status in the United States: are the health consequences underestimated? Nutr Rev. 2012 Mar;70(3):153-64. doi: 10.1111/j.1753-4887.2011.00465.x. Epub 2012 Feb 15. Review.
Sugimoto J, Romani AM, Valentin-Torres AM, Luciano AA, Ramirez Kitchen CM, Funderburg N, Mesiano S, Bernstein HB. Magnesium Decreases Inflammatory Cytokine Production: A Novel Innate Immunomodulatory Mechanism. J Immunol. 2012 May 18. [Epub ahead of print]
Tamakoshi A; Japan Collaborative Cohort Study for Evaluation of Cancer. Overview of the Japan Collaborative Cohort Study for Evaluation of Cancer (JACC). Asian Pac J Cancer Prev. 2007;8 Suppl:1-8.
U.S. Office of Dietary Supplements (ODS). Magnesium Fact Sheet. Accessed at http://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
Zhang W, Iso H, Ohira T, Date C, Tamakoshi A; JACC Study Group. Associations of dietary magnesium intake with mortality from cardiovascular disease: the JACC study. Atherosclerosis. 2012 Apr;221(2):587-95. Epub 2012 Jan 28.