Magnesium and Your Heart

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Magnesium Can Make or Break Your Heart's Rhythm

A new study reveals that low blood levels of an important mineral can significantly affect the way your heart pumps blood throughout your body. And even if you think you're living a healthy lifestyle, you may not be getting enough of it.

I'm talking about magnesium, a mineral that is naturally present in water and foods in varying amounts. The US RDA for magnesium is about 320 mg per day for women and more than 400 mg per day for men - yet studies show that most people regularly take in about half of that. And now new research reveals that this lack of magnesium may put your heart - and your health - at significant risk.

More evidence that magnesium is key to heart health

In this study, published in the latest issue of the American Journal of Clinical Nutrition, researchers from the US Department of Agriculture tracked the effects of a magnesium-deficient diet on 22 healthy postmenopausal women between the ages of 47 and 78. The women all ate the same meals for six months as they lived together under close supervision, taking in about 130 mg of dietary magnesium each day. But half the women also took in another 280 mg of magnesium in supplement form for the first 81 days while the other half took placebo; for the second half of the study period, the groups crossed over to the other treatment category.

The researchers assessed magnesium levels in urine and blood regularly throughout the study period. They also assessed heartbeat patterns through regular electrocardiograms. And here's what they found: not surprisingly, serum and urine concentrations of magnesium were substantially lower on the controlled diet. But they also discovered that heart rhythms were significantly affected by magnesium deficiency - specifically, a lack of magnesium made the heart beat more frequently than usual.

Scientists have long known that magnesium is a critical player in cell metabolism, helping to transport other minerals across cell membranes and affecting cell mechanisms that control the activity of muscle and nerve cells. But as the authors note, their research suggests "cardiac muscle seems to be more sensitive to [magnesium] intake than skeletal muscle."

How to assess your risk for magnesium deficiency

This throws additional weight behind the developing theory that magnesium can help prevent many of the processes that lead to heart disease. In previous research, scientists found several important connections between magnesium deficiency and the development of heart disease; in fact, one study found that the risk of heart disease is higher in areas with "soft" water compared to those with "hard" water. (Hard water contains much more magnesium than soft.)

But there's more to magnesium intake than the water. You may also be at increased risk for magnesium deficiency if you regularly consume alcohol or diuretics, because both can increase urinary excretion of the mineral. Prescription medications, like the antibiotics Gentamicin, Amphotericin, and Cyclosporin, and the cancer drug Cisplatin, can increase magnesium excretion as well. Diabetics are also at increased risk of magnesium deficiency, as are those with Crohn's disease or other chronic gastrointestinal problems.

If you're concerned, ask your doctor to test your blood for magnesium levels. A normal range is anywhere between .66 and 1.23 mmol/L. Fortunately, it's easy to get more magnesium. The mineral is naturally present in green leafy vegetables, avocados, nuts and seeds, and whole grains, but usually in small amounts; you need to eat a wide variety of these foods regularly to get all you need. To make sure you're getting enough of this important mineral, you can also take magnesium supplements - they are readily available at health food stores and vitamin suppliers.

All of us could probably benefit from increasing our magnesium intake. But there is such a thing as too much. The tolerable upper intake level for supplemental magnesium is 350 mg per day for adults. That means that you shouldn't take any more than that in supplement form; more than that amount, in addition to the magnesium you get from food and water, could cause problems. At very high levels, the mineral can be toxic, causing kidney failure. But within reasonable limits, magnesium is an important part of a complete supplement program - and as this study shows, an important tool in your heart-health regimen.

To Your Good Health

More information about magnesium - calcium balance can be found in an on-line book called, MAGNESIUM, THE NUTRIENT THAT COULD CHANGE YOUR LIFE, ©1968. It's by by J. I. Rodale

Too Much Calcium, Not Enough Magnesium

HEART BECOME IRRITABLE WHEN DEPRIVED OF MAGNESIUM

The Human Nutrition Research Center in Grand Forks, North Dakota has released an alarming report that reveals when humans are deprived of magnesium they may begin to experience abnormal heartbeats. [American Journal Clinical Nutrition 75: 550-54, March 2002]

The heart muscle of people who experience sudden-death heart attack has been found to be low in magnesium. Areas of the world where drinking water is low in magnesium (soft water areas) have higher rates of heart attacks. Magnesium is a muscle relaxant, while calcium is a muscle constrictor. Low magnesium intake is associated with muscle spasm, tremors and convulsions.

Most Americans, particularly women, have been advised to consume 1200-1500 milligrams of calcium daily. Virtually none of these women have been told that calcium in single doses that exceed 500 milligrams are not absorbed and that they only need an additional 400-600 milligrams of supplemental calcium since their diet already provides about 800 milligrams of this mineral.

Since 99 percent of magnesium resides inside living cells, blood serum levels are not a good indicator of magnesium deficiency. In other words, your doctor can't easily tell you by a blood test if your magnesium levels are low. Most Americans, 8 in 10, do not consume enough magnesium.

The countries that have the highest mortality rates in the world are the Scandinavian countries and New Zealand where more calcium is consumed from dairy products, while for comparison the lowest mortality rates in the world are in Portugal and Japan where calcium-rich dairy products are not consumed regularly. Americans consume about 800 milligrams of calcium daily (milk drinkers may get 1200-1500 mgs from their diet alone), but only consume about 275 milligrams of magnesium. Thus the dominance of calcium over magnesium produces symptoms of muscle spasm. Migraines, eyelid twitch, heart flutters, backaches, premenstrual tension, leg cramps and constipation are all linked to calcium overload. Excessive calcium may also result in kidney stones (1 in 11 Americans) and heart valve calcifications (mitral valve, 1 in 12 Americans).

A significant percentage of American adults consume more than 2000 milligrams of daily calcium, the point where side effects of overdosage begin to be reported. More than 300,000 sudden-death heart attacks are reported annually in the US (more than 80 per day), which are believed to be related to excessive calcium and a shortage of magnesium.

Modern medicine's answer to the problem is to prescribe billions of dollars of calcium-blocker drugs. Magnesium is a natural calcium blocker, but this goes unrecognized by most physicians. Researchers warn that adults who consume excessive amounts of caffeine or alcohol, or who take water pills (diuretics), are prone to experience irregular heartbeats and should consume more magnesium. The same is true for diabetics and people with low thyroid. Most Americans consume tap water that has been softened (sodium added) which worsens the problem. American adults need to supplement their diet with 200-400 milligrams of magnesium. The only side effect of too much magnesium is loose stool. Reducing dosage resolves this problem.

Too Little Magnesium
Affects the Postmenopausal Heart

A low magnesium diet puts postmenopausal women at risk for supraventricular ectopy suggests this new clinical trial. In a recent metabolic ward study, 22 women were blindly fed a diet containing less than half the RDA for magnesium or more than the RDA (320 mg/day). Those on the low magnesium regimen were more inclined toward arrhythmias, despite the fact that the diet did not cause hypomagnesemia, the usual marker that clinicians use to diagnose magnesium deficiency. Their research is consistent with previous animal and human data that have shown that magnesium deficiency causes adverse neuromuscular effects like spasm, tremor, tetany, and convulsions.

Klevay LM, Milne DB. Low dietary magnesium increases supraventricular ectopy. Am J Clin Nutr. 2002;75:550-554.

Department editor Paul L. Cerrato, MA, Managing Editor of Contemporary OB/GYN is a guest lecturer at the Institute of Human Nutrition, Columbia University College of Physicians and Surgeons, New York, N.Y.