However, there's a good chance you're not getting enough. More than two-thirds of Americans don't, according to data from the U.S. Department of Agriculture. Our collective magnesium deficiency -- which ups our risk of health woes such as osteoporosis, migraines, and heart disease -- is due in part to a lower-than-optimal intake of magnesium-rich foods, such as leafy greens, legumes, and nuts, says Dr. Carolyn Dean, author of "The Miracle of Magnesium." In addition, many of those very foods are grown in soil that's been depleted of minerals by years of unsustainable farming practices, says Dean. What's more, extensive processing of food strips it of minerals, so the more we rely on canned and packaged foods, the less magnesium we receive.
Soil conditions aside, whole unprocessed foods are the best source of all nutrients, including magnesium. But to reach the daily recommended amount of the mineral (310 to 420 mg for adults), most of us would benefit from taking a supplement; a number of experts recommend taking 400 mg daily.
Bone is a matrix of several minerals and protein, and magnesium ranks right up there with calcium in terms of nutritional importance. A recent study found that a high intake of magnesium was associated with stronger bones in both Caucasian men and women. "Magnesium helps the body absorb and regulate calcium levels," says Dean. However, high levels of calcium in the diet without sufficient magnesium may lead to the calcification of soft tissues.
If you take a calcium supplement, combine it with magnesium -- experts recommend two or three parts calcium to one part magnesium -- or look for a combination supplement.
Supplementing with magnesium can help prevent heart disease in a number of ways -- by normalizing the contraction and relaxation rhythm of the heart, reducing blood pressure, and helping to prevent dangerous heart-rhythm abnormalities known as arrhythmias.
Magnesium also helps regulate two key enzymes involved in cholesterol production, and studies suggest that high cholesterol may be linked to magnesium deficiency. In fact, promising new research shows that magnesium may one day serve as a safer alternative to cholesterol-lowering drugs such as the statin Lipitor. In a 2004 study comparing the mineral with statins, magnesium was shown to be more effective.
Magnesium may also help lower dependence on heart medications known as calcium-channel blockers, says Dr. Ron Hunninghake, medical director of the Bright Spot for Health, a nutritionally oriented medical clinic in Wichita, Kansas. Used for treating high blood pressure and chest pain, these drugs prevent too much calcium from entering heart cells, allowing the heart to relax. Magnesium functions as a natural calcium-channel blocker, says Hunninghake.
Muscle and Mind Relaxer
Magnesium is a natural, effective muscle relaxant. "Developing 'charley horses' and restless-legs syndrome are dead giveaways of magnesium deficiency," says Dean. These painful leg-muscle spasms are especially common in the elderly, who have a high risk of magnesium deficiency, and in serious athletes, who lose magnesium through sweat.
By helping your muscles relax, magnesium also helps your mind relax. The body's stress response triggers muscle tension, but when the physical tension is released, mental anxiety is eased as well. (In fact, the same muscle-relaxing principle is at work in anti-anxiety medications such as Xanax and Valium.)
Magnesium can exert a calming effect that goes beyond its role as a muscle relaxant. Your body needs magnesium to make serotonin, one of the body's calming neurotransmitters. Recently, French researchers found that a combination of magnesium and vitamin B6 supplements reduced children's hyperactive symptoms, including poor attention, physical aggressiveness, muscle tension, and spasms. Animal studies have found that magnesium can also help ease symptoms of posttraumatic depression and anxiety.
Low magnesium levels are strongly associated with migraine headaches, especially those that are triggered by menstrual periods, according to research by Dr. Bella Altura, of the State University of New York Health Sciences Center in Brooklyn. And since almost three of every four patients with conventional tension headaches have muscular tightness, magnesium might be helpful for these headaches, too.
Many whole, unprocessed foods are rich in magnesium. The foods below (listed in 100-gram servings, which is about 3.5 ounces) contain the following amounts of the mineral.
-Almonds (raw): 275 mg
-Beef (lean, roasted): 23 mg
-Black beans: 70 mg
-Brown rice: 43 mg
-Cashews (raw): 292 mg
-Cheddar cheese: 28 mg
-Chicken (roasted): 21 mg
-Crab (steamed): 63 mg
-Dates: 54 mg
-Dried figs: 68 mg
-Sardines: 39 mg
-Shrimp (steamed): 34 mg
-Turkey (roasted): 26 mg
Supplements and Other Sources
Magnesium oxide is the most common form of the mineral in supplements, but the body doesn't absorb it well. You'll do much better taking other magnesium compounds, such as magnesium aspartate, magnesium citrate, magnesium glycinate, or magnesium taurate. The best compromise in terms of price and absorption is magnesium citrate, which is available for a reasonable price at natural-foods stores. (Don't confuse this supplement with high-dose magnesium citrate products, which are sold in pharmacies as over-the-counter laxatives.)
You'll have to read labels carefully to identify exactly how much magnesium a supplement contains. Look for 400 mg of magnesium -- sometimes referred to as "elemental" magnesium -- not 400 mg of magnesium citrate (or any other form). The former refers to the amount of magnesium, whereas the latter refers to the entire compound. An accurate label might read something like "400 mg magnesium as magnesium citrate."
Hard tap water, found in many parts of the country, is rich in magnesium, calcium, and other minerals; not coincidentally, drinking hard water is associated with a reduced risk of heart attack. European brands of mineral water, like San Pellegrino and Gerolsteiner, contain appreciable amounts of magnesium and calcium.
You can also absorb magnesium through the skin, in the form of magnesium sulfate, also known as Epsom salts.
Although the body generally tolerates magnesium well, doses of more than 400 mg can soften stools and may lead to diarrhea (hence the main ingredient in Milk of Magnesia, magnesium hydroxide). Dividing up your dose by taking magnesium supplements two or three times daily might reduce the risk of diarrhea. Also keep in mind that diarrhea is most likely to occur with magnesium oxide, less so with the citrate and glycinate forms.
In addition, because the kidneys excrete excess amounts of magnesium, people with kidney disease should not take high doses of the mineral.
by Jack Challem