Magnesium
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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 healthful range. And since magnesium is plentiful in vegetables, legumes, and whole grains, it is easy to consume enough if you are eating a healthful diet.

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)
MaleFemale
0-6 months Adequate intake
(AI) = 30
AI = 30
7-12 monthsAI = 75AI = 75
1-3 years8080
4-8 years130130
9-13 years240240
14-18 years410360
19-30 years400310
31-50 years420320
50-70 years420320
>70 years420320
Pregnancy (18 years or younger)n/a400
Pregnancy 19-30 yearsn/a350
Pregnancy 31-50 yearsn/a360
Lactation (18 years or younger)n/a360
Lactation 19-30 yearsn/a310
Lactation 31-50 yearsn/a320

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 medications 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 medications 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, which 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 ( type 1 or 2 ), which can increase the loss of magnesium through urine
  • Alcoholism: Alcohol increases urinary excretion of magnesium; also, alcoholics 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.

Magnesium Toxicity

Magnesium toxicity 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. Symptoms of magnesium toxicity include:

  • Weakness
  • Nausea
  • Malaise (general discomfort or an "out-of-sorts" feeling)

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.

FoodServing sizeMagnesium content (mg)
Artichoke, boiled1 medium180
Pumpkin & squash seeds, roasted1 ounce151
Tofu, raw, firm½ cup118
Navy beans, boiled1 cup107
Almonds, dry roasted, unsalted1 ounce91
Black-eyed peas, boiled1 cup86
Lima beans, boiled1 cup81
Chickpeas (garbanzo beans), boiled1 cup79
Spinach, boiled½ cup78
Swiss chard, boiled½ cup76
Cashews, dry roasted1 ounce74
Avocado, raw, California1 medium71
Lentils, boiled1 cup71
Sweet potato, canned, mashed1 cup61
Potato, microwaved with skin1 medium55
Peanut butter2 tablespoons51
Acorn squash, baked½ cup cubes44
Whole wheat spaghetti, cooked1 cup42
Wheat germ, toasted2 tablespoons41
Sunflower seeds, dry roasted1 ounce37
1% milk1 cup (8 fluid ounces)34
Whole wheat bread1 slice24

Health Implications

Blood Pressure

A 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, the findings are still not clear, and 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.

Liver Disease

It has been known for years that there is a strong association between liver disease in alcoholism and magnesium deficiency. In fact, alcoholic liver disease is the most common clinical condition associated with low serum magnesium. While most experts think that low magnesium is a result of alcoholic liver disease, rather than a cause, there is some evidence from Mexico and Slovakia that magnesium may be part of the process that leads to another common liver disorder called nonalcoholic steatosis.

This condition occurs most commonly in people who are obsese and, on occasion, may become so severe that it requires liver transplant. Further studies will be necessary, but it is possible that screening for and correction of low magnesium levels in those at risk could improve long-term outcomes.

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're 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:

American Dietetic Association
http://www.eatright.org/

International Food Information Council
http://ific.org/

CANADIAN RESOURCES:

Canada's Food Guide
http://www.hc-sc.gc.ca/

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

References:

Elisaf M, Merkouropoulos M, Tsianos EV, Siamopoulos KC. Pathogenetic mechanisms of hypomagnesemia in alcoholic patients. J Trace Elem Med Biol. 1995;9:210-214.

Facts about dietary supplements—magnesium. NIH Clinical Center, National Institutes of Health website. Available at: http://www.cc.nih.gov/.

Larson Duyff R, American Dietetic Association. The American Dietetic Association's Complete Food & Nutrition Guide . Minneapolis, MN; Chronimed Publishing; 1998.

Rodriguez-Hernandez H, Gonzalez JL, Rodriguez-Moran M, Guerrero-Romero F. Hypomagnesemia, insulin resistance, and non-alcoholic Steatohepatitis in obese subjects. Arch Med Res. 2005;36:362-366.

Turecky L, Kupcova V, Szantova M, Uhlikova E, Viktorinova A, Czirfusz A. Serum magnesium levels in patients with alcoholic and non-alcoholic fatty liver. Bratisl Lek Listy. 2006;107:58-61.

Wardlaw G, Insel PM. Perspectives in Nutrition. 2nd ed. St. Louis, MO: Mosby; 1993.



Last reviewed June 2008 by Marcin Chwistek, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.


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