Magnesium is an essential mineral that has a hand in many vital body functions, for example releasing energy, regulating body temperature, building protein, and stabilizing bone. It is also one of several nutrients that helps keep blood pressure within a healthy range. And since magnesium is plentiful in vegetables, legumes, and whole grains, it is easy to consume enough if you are eating healthy food.
Magnesium's functions include:
Magnesium deficiency is rare because most people have large stores of this mineral in their body. However, it can be caused by diseases or medicines that interfere with the body's ability to absorb magnesium. Symptoms of a magnesium deficiency include: irregular heartbeat, nausea, confusion, depression, tingling, weakness, loss of appetite, and muscle contractions and cramps.
Conditions and medicines that may lead to a magnesium deficiency include:
Tolerable Upper Intake
It's also possible to get too much magnesium. The Office of Dietary Supplements publishes tolerable upper intake levels for magnesium.
Magnesium toxicity through food intake is not a concern for most healthy people. However, people with kidney disease may develop toxicity because the kidneys are responsible for regulating the level of magnesium in the blood. Also it is possible to take too much magnesium in supplements. Symptoms of magnesium toxicity include:
Major Food Sources
Magnesium is found in a variety of foods. The best sources are legumes, nuts, whole grains, and certain vegetables. "Hard" water (which is high in dissolved minerals, specifically calcium and magnesium) is also a source of magnesium.
Foods that provide high levels of magnesium include:
Greater magnesium intake is associated with a lower incidence of high blood pressure. This is the finding of a few large clinical studies. One of these, the DASH (Dietary Approaches to Stop Hypertension) study found that a diet high in magnesium, potassium, and calcium and low in sodium and fat can significantly lower blood pressure. You can get these nutrients by eating a diet rich in fresh fruits and vegetables, legumes, whole grains, and low-fat dairy foods. Another group of researchers studied 30,000 US male health professionals over several years. The study found a greater magnesium intake was significantly associated with a lower risk of hypertension.
Based on the growing number of studies showing a positive role for magnesium in managing blood pressure, the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends maintaining an adequate magnesium intake to prevent and manage high blood pressure.
Several studies have found links between magnesium status and heart health. Many of these suggest that an adequate intake of magnesium is protective of the heart. However, further study needs to be done to clarify magnesium's role.
Since a significant amount of magnesium is stored in the bones and one of magnesium's roles is to help keep bones healthy, it would make sense that magnesium would help protect bones from the thinning of osteoporosis. Several studies have suggested just that—magnesium supplementation may improve bone mineral density. However it is still not clear, and more study needs to be done.
Tips For Increasing Your Magnesium Intake
It is easy to meet your magnesium needs through foods. To increase your intake, try some of the following:
Academy of Nutrition and Dietetics
International Food Information Council
Canada's Food Guide
Dietitians of Canada
Appel L, Moore T, et al. A clinical trial of the effects of dietary patterns on blood pressure. N Engl J Med. 1997;336:1117-1124.
Larson Duyff R, American Dietetic Association. The American Dietetic Association's Complete Food & Nutrition Guide . Minneapolis, MN; Chronimed Publishing; 1998.
Magnesium. Office of Dietary Supplements website. Available at: http://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/. Accessed July 29, 2012.
Osteoporosis. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated May 25, 2012. Accessed July 29, 2012.
The seventh report of the Joint National Committee on Prevention, Detection, and Treatment of High Blood Pressure. Hypertension.2003;42:1206. National Heart Lung and Blood Institute website. Available at: http://www.nhlbi.nih.gov/guidelines/hypertension/. Published December 2003. Accessed July 29, 2012.
Wardlaw G, Insel PM. Perspectives in Nutrition . 2nd ed. St. Louis, MO: Mosby; 1993.
Last reviewed July 2012 by Brian Randall, MD