You probably know you need calcium for your bones. You may also know you need potassium for your muscles. But did you know that magnesium is important for your heart health? The mineral magnesium is essential for hundreds of biochemical reactions in your body. It helps keep bones strong, nerves and muscles working properly, and blood sugar under control. Magnesium is also necessary for maintaining a steady heartbeat and normal blood pressure to maintain heart health. Read on to find out why magnesium is important for heart health and good sources of this important nutrient.
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How Much Magnesium Is Enough?
According to the National Institutes of Health, the adult body contains 25 grams of magnesium, mostly in the bones. This amount depends on several factors, like diet and a person’s kidney function. “Many people do not get enough magnesium in their diets,” says Dhanunjaya Lakkireddy, MD, chair of the American College of Cardiology’s Electrophysiology Council.
The recommended dietary allowance (RDA) for magnesium — meaning the amount you should take in each day — varies depending on your age and sex. On average, the RDA is 400 milligrams (mg) for men ages 19 to 30 and is lower, at 310 mg, for women of the same age. For those 31 and older, men should get 420 mg of magnesium daily, and women should get 320 mg daily. If a person's magnesium level is less than 1.8 mg per deciliter, they are considered to have a magnesium deficiency, Dr. Lakkireddy explains.
How Your Body Regulates Magnesium Levels
Less than 1 percent of the body's magnesium is found in the blood. Most magnesium (up to 60 percent) is found in the bones. The rest is inside cells, notes Hugh Calkins, MD, professor of medicine and director of the cardiac arrhythmia service at Johns Hopkins Medicine in Baltimore. In otherwise healthy people, a magnesium deficiency is uncommon, Dr. Calkins says, because the kidneys help control how much magnesium is in the body. For example, when your magnesium level is low, less is excreted in the urine. If your healthcare provider suspects that you have a magnesium deficiency, they might order a blood test to check your level.
Magnesium Helps Your Heart Keep the Beat
Magnesium is central to a healthy heart rhythm because it's involved in transporting other electrolytes, such as calcium and potassium, into cells. Electrolytes are all-important for nerve signals and the muscle contractions of a normal heartbeat. Research shows that magnesium deficiency, or restricted magnesium intake, increases irregular heartbeats known as arrhythmias.
In a review published in May 2019 in Cardiology Research and Practice, researchers found that a low level of magnesium in the blood may increase the risk of developing cardiovascular disease. In addition, the review showed that a low magnesium level is associated with atrial fibrillation (afib), the most common heart rate disorder. Afib occurs when a malfunction in the heart's electrical system causes the upper chambers of the heart to quiver.
Who Is at Risk for Magnesium Deficiency?
With age, magnesium absorption decreases in the body. Magnesium deficiencies can also be caused by certain conditions, including alcoholism, malnutrition, preeclampsia (if a woman is pregnant), a digestive disorder like Crohn’s disease or ulcerative colitis, diabetes, or chronic diarrhea.
Prolonged use of certain medications can cause too much magnesium excretion. These include diuretics like Lasix (furosemide), as well as proton pump inhibitors like Nexium (esomeprazole) and Prevacid (lansoprazole) used to treat gastroesophageal reflux disease. Because older people are more likely to take these medications, they're at greater risk for a magnesium deficiency.
How to Get More Magnesium
Experts advise people to get nutrients primarily from food. “Just 1 ounce of almonds or cashews contains 20 percent of the daily magnesium an adult needs,” says Lakkireddy. Although magnesium is added to some foods, like breakfast cereal, there are several excellent natural sources of this mineral:
- Soy products like tofu or soy milk
- Green leafy vegetables like spinach
- Black beans
When to Reach for Magnesium Supplements
“Patients who do not have normal kidney function should be very careful about taking too much magnesium because it can be toxic at high levels,” says Lakkireddy. The forms of magnesium in dietary supplements, which are more easily absorbed by the body, include magnesium aspartate, magnesium citrate, magnesium lactate, and magnesium chloride, according to Lakkireddy. In most cases though, magnesium supplements aren't necessary, Calkins adds, and generally are not prescribed for heart health.
Too much magnesium from food isn't a danger because the kidneys excrete what the body doesn't need. But high doses of magnesium from supplements can cause diarrhea, nausea, and stomach cramping. Extreme doses of magnesium, over 5,000 mg daily, can be fatal. If you’re concerned about your magnesium level, talk to your doctor to find out how you can get the most of this valuable nutrient.
With additional reporting by Avery Miles.