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Solid Science™ about Magnesium and Your Heart
By Terry Dunkle, DietPower Founder and Editor-In-Chief*
“Magnesium heart” is a popular search term these days, because supplement sellers have peppered the Web with claims that magnesium fights heart disease. In this article, Solid Science™ separates the truth from the hype. All of the following rests on peer-reviewed studies in leading scientific journals.
(You will notice the phrase “magnesium heart” repeated throughout this article. That’s because Solid Science™ wants Google and other search engines to prefer reliable information instead of self-serving ads masquerading as journalism. You can help by linking to this article in your website, blog, Facebook account, etc.)
Key Facts About Magnesium
Magnesium is a silvery white metal comprising 2 percent of the earth’s crust. Certain foods are unusually rich in magnesium: nuts, fish, peanut butter, beans, potatoes, fortified cereals, and leafy vegetables such as spinach.
Magnesium is also the fourth most abundant mineral in your body, comprising about one ounce of your weight. More than half of your magnesium is stored in your bones.
Magnesium plays a role in more than 300 chemical reactions in your body. One of the most important is helping to deliver nerve signals to your muscles. That’s one reason why, without magnesium, you would instantly die.
What "Magnesium Heart" Searchers Need to Know
Because magnesium mediates the delivery of nerve signals to your heart muscles, it is vital to maintaining normal heart rhythm. By following thousands of patients over several decades, medical researchers have concluded that people with a chronic magnesium deficiency are more likely to develop cardiac arrhythmia, making them more vulnerable to heart attack.
In addition, magnesium helps to control the tensing of muscles in your artery walls. As a consequence, a magnesium shortage can elevate your blood pressure. As most people know, high blood pressure “hardens” arteries and invites plaque deposits that may narrow or block the arteries feeding your heart, triggering a coronary episode and/or requiring you to have a bypass or a stent.
Do Magnesium Supplements Prevent Heart Disease?
This is a major reason people search the Web for “magnesium heart.” The answer is “yes and no.”
Scientists have found plenty of evidence that a magnesium deficiency may increase your risk of arrhythmia, hypertension, and heart attack. They also know that roughly one-third of Americans do not get enough magnesium in their diets.
Nevertheless, direct evidence that taking magnesium supplements will lower these risks is scarce and debatable. More studies are needed. (To see the latest research, keep an eye on Medline or check your favorite search engine for “magnesium heart” every few months.)
What’s more, it is possible to overdose on magnesium. And ironically, the symptoms of overdose (heart palpitations, fatigue, anxiety) are similar to those of magnesium deficiency—which means that someone taking dangerous amounts of magnesium could misinterpret the signs, take even more, and end up damaging the heart. (We might call such an ailment Magnesium Heart, although that is not yet a recognized medical term.)
How Much Magnesium Do You Need?
Once again, this is an important question for “magnesium heart” searchers. Measured in milligrams, the U.S. Food and Nutrition Board’s (FNB’s) official Recommended Dietary Allowance (RDA) for magnesium depends on your age, sex, and reproductive status.
- For males: 410 milligrams from age 14 to 18, 400 from age 19 to 30, and 420 after age 30.
- For females: 360 milligrams from age 14 to 18, 310 from age 19 to 30, and 320 after age 30.
- For pregnancy: 400 milligrams for women 18 or younger, 350 for those 19 to 30, and 360 for those 31 through 50.
- For lactation: 360 milligrams for mothers 18 or younger, 310 for those 19 to 30, and 320 for those 31 through 50.
Especially if you are over 50 or have heart disease, kidney disease, or certain other ailments, your doctor or dietitian may prescribe an allowance higher or lower than the RDA.
Where Can You Get Your Magnesium?
This is another big reason people search for “magnesium heart.”
Getting your RDA from a single food would have you eating about two cups of cooked spinach, one and a half cups of 100% bran cereal, five cups of beans, or nine ounces of peanut butter. Obviously, your best course is to get it from multiple foods. To find other magnesium-rich foods, one excellent tool is DietPower nutrition software (download a free trial).
You can also get magnesium from supplements, but most experts advise doing this only if you are unable to get your entire RDA from foods. (A typical multivitamin tablet, such as Centrum Silver, provides 50 milligrams.)
One problem is that some of the magnesium in supplements passes through the body instead of being absorbed. That’s why the RDA for magnesium is predicated on food sources, not supplements.
How Much Is Too Much?
For teenagers and adults, the FNB’s Tolerable Upper Intake Level (UL) of magnesium from supplements is 350 milligrams. Supplements exceeding this level may harm your health, but getting the same amount from food may be safe.
Because excess magnesium is excreted by the kidneys, the UL for people with kidney disease may be lower. Ask your doctor or dietitian.
Finally, anyone who is considering magnesium supplements for a heart ailment should seek the opinion of a reputable physician, preferably one who is also expert in nutrition. Don’t rely solely on Web searchers for “magnesium heart.” Many of the sites that you find are only trying to sell you something.