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Magnesium: A mineral you might be missing

A healthy diet is the best way to make sure you’re getting enough of this essential element.

magnesium spinach mineral
Image: mamadela /Thinkstock

Magnesium probably isn’t a mineral that comes to mind when you think about heart health. But a recent report showing that magnesium supplements may modestly lower blood pressure may have left some people wondering if they should head to Whole Foods to buy a bottle of magnesium pills.

“That’s what I’m worried about,” says cardiologist Dr. Elliott Antman, professor of medicine at Harvard Medical School. The reason? There’s far stronger evidence that consuming less sodium will help improve your blood pressure. “I don’t want people to think they can stop paying attention to how much salt they’re eating if they’re taking a magnesium supplement,” he says.

No clear benefits

The study, published in the August issue of Hypertension, revealed a very modest drop in blood pressure—about one to two millimeters of mercury (mm Hg)—among people who took magnesium supplements for three months. The magnesium doses ranged from 240 to 940 milligrams (mg) and were taken by people both with and without high blood pressure, some of whom may also have been taking blood pressure medications. As a result, we can’t really draw any firm conclusions about who—if anyone—might benefit from a magnesium supplement, says Dr. Antman.

But don’t underestimate the importance of this essential element, which plays a vital role in nerve and muscle function and keeps your immune system strong. Dietary surveys show that most people in the United States—especially men over age 70—don’t get the recommended amount of magnesium from the foods they eat. Men should get 420 mg a day and women should consume 320 mg of magnesium daily (see table).

Good sources of magnesium

Food (serving size)

Milligrams (mg)

Almonds, dry-roasted (1 ounce)

80

Spinach, boiled (½ cup)

78

Peanuts, oil-roasted (¼ cup)

63

Cereal, shredded wheat (2 large biscuits)

61

Soymilk, plain or vanilla (1 cup)

61

Black beans, cooked (½ cup)

60

Peanut butter, smooth (2 tablespoons)

49

Bread, whole-wheat (2 slices)

46

Avocado, cubed (1 cup)

44

Rice, brown, cooked, ½ cup

42

Yogurt, plain, low-fat, 8 ounces

42

Source: Office of Dietary Supplements, National Institutes of Health.

Following a heart-healthy diet, like the Dietary Approaches to Stop Hypertension (DASH) diet, will help. That’s be-cause the DASH diet recommends eating eight to 10 daily servings of fruits and vegetables, which are naturally low in sodium and high in magnesium as well as potassium, another mineral that seems to help lower blood pressure. And chocolate lovers have a good reason to indulge on occasion: a 1-ounce square of dark chocolate (60%–70% cocoa solids) contains 50 mg of magnesium.

It’s possible, but far from proven, than certain people with high blood pressure might benefit from magnesium supplements—but only if they’ve already made a good effort follow a heart-healthy lifestyle and are taking appropriate blood pressure medications, says Dr. Antman.

Low levels?

Some people with certain medical problems may be more susceptible than others to have lower magnesium levels, such as those with Crohn’s disease, celiac disease, or poorly controlled type 2 diabetes. In addition, two widely used types of drugs can deplete magnesium levels. Long-term use of heartburn drugs known as proton-pump inhibitors—including omeprazole (Prilosec) and lansoprazole (Prevacid)—may interfere with magnesium absorption. Diuretics such as hydrochlorothiazide (Microzide) and furosemide (Lasix), which are prescribed to treat high blood pressure, cause magnesium to be flushed out in the urine.

Assessing a person’s magnesium level is difficult because most of the body’s stores are found inside tissues, not in the blood. So a standard blood test for magnesium may not accurately reflect whether a person is deficient. But people with high blood pressure who are concerned about their magnesium status shouldn’t try supplements except under the advice of a physician. There are no known adverse affects of magnesium intake from food. But high doses from supplements or magnesium-containing drugs (for example, laxatives like Phillips’ Milk of Magnesia) may cause diarrhea.

Posted by: Dr.Health

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