• Magnesium

    Image for magnesium 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.

    Functions

    Magnesium's functions include:
    • Activating more than 300 enzymes (Enzymes are chemicals that regulate a variety of body functions, including making body proteins and causing muscle contractions.)
    • Aiding in the metabolism of fat and carbohydrate to produce energy
    • Binding with ATP to form "active ATP," which provides energy for almost all metabolic reactions and processes
    • Ensuring proper nerve and muscle function and keeping heart rhythm steady
    • Helping synthesize nucleic acids (DNA and RNA) and proteins, which are the building blocks of body tissue
    • Giving structure to cell membranes
    • Helping keep bones healthy
    • Decreasing the risk of tooth decay by binding calcium to tooth enamel

    Recommended Intake

    Age Group Recommended Dietary Allowance
    (mg/d)
    Male Female
    0-6 months Adequate intake
    (AI) = 30
    AI = 30
    7-12 months AI = 75 AI = 75
    1-3 years 80 80
    4-8 years 130 130
    9-13 years 240 240
    14-18 years 410 360
    19-30 years 400 310
    31-50 years 420 320
    50-70 years 420 320
    >70 years 420 320
    Pregnancy (18 years or younger) n/a 400
    Pregnancy 19-30 years n/a 350
    Pregnancy 31-50 years n/a 360
    Lactation (18 years or younger) n/a 360
    Lactation 19-30 years n/a 310
    Lactation 31-50 years n/a 320

    Magnesium Deficiency

    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:
      Gastrointestinal disorders, such as:
      • Severe diarrhea
      • Chronic or severe vomiting
      • Surgical removal of part of the intestine
      • Intestinal inflammation
      Malabsorption disorders , including:
    • Thiazide diuretics (can increase loss of magnesium in the urine)
    • Cisplatin (a drug used to treat cancer)
    • Certain antibiotics, including gentamicin , amphotericin, and cyclosporin
    • Poorly controlled diabetes (can increase the loss of magnesium through urine)
    • Alcoholism—Alcohol increases urinary excretion of magnesium. People who drink heavily typically have poor diets that are lacking in many essential nutrients, including magnesium.
    • Kidney disease—The kidneys are important for reabsorption and excretion of magnesium.

    Tolerable Upper Intake

    It's also possible to get too much magnesium. The Office of Dietary Supplements publishes tolerable upper intake levels for magnesium.
    Age Group Tolerable Upper Intake Levels
    (mg/d)
    Male Female
    1-3 years 65 65
    4-8 years 110 110
    9-18 years 350 350
    19+ years 350 350
    Pregnancy (18 years or younger) n/a 350
    Pregnancy 19+ n/a 350

    Magnesium Toxicity

    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:
    • Diarrhea
    • Abdominal cramping
    • Nausea and diarrhea
    • muscle weakness
    • irregular heartbeat

    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:
    • Wheat bran
    • Almonds
    • Spinach
    • Raisin brain cereal
    • Cashews, dry roasted
    • Soybeans
    • Wheat germ
    • Nuts
    • Bran flakes cereal
    • Shredded wheat cereal
    • Oatmeal

    Health Implications

    Blood Pressure

    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.

    Heart Disease

    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.

    Osteoporosis

    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:
    • Sprinkle wheat germ over your morning bowl of cereal or oatmeal and on top of casseroles or in baked goods.
    • Throw a handful of nuts into a spinach salad to add a little crunch and some extra nutrition.
    • Wrap beans, rice, sauteed vegetables, and a little bit of cheese in a warm tortilla for lunch.
    • Add beans to dishes like chili, soup, salad, pasta, or rice.
    • Have a bowl of whole grain cereal for breakfast or to snack on; if you are not used to the taste, mix it with your usual cereal.
    • Bake a potato and top it with sauteed spinach, black beans, and salsa.
    • Spread peanut butter on your toast or bagel instead of butter, margarine, or cream cheese.

    RESOURCES

    Academy of Nutrition and Dietetics http://www.eatright.org/

    International Food Information Council http://www.foodinsight.org/

    CANADIAN RESOURCES

    Canada's Food Guide http://www.hc-sc.gc.ca/fn-an/food-guide-aliment/index%5Fe.html

    Dietitians of Canada http://www.dietitians.ca/

    References

    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.

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