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 a mineral your body makes and is vital for your heart health? 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.

Read on to find out why magnesium is important for heart health and good sources of this important nutrient.

How Much Magnesium Is Enough?

According to the National Institutes of Health, the adult body contains 25 grams of magnesium, with 50 to 60 percent of it in the bones, and the rest in soft tissues and cells. The recommended dietary allowance (RDA) for magnesium — meaning the amount you should take in each day — varies depending on your age and sex. “The current RDA of magnesium is 420 milligrams (mg) for men and 320 mg for women ages 31 and older,” notes Kristen Campbell, PharmD, a clinical pharmacist practitioner and Director of the PGY2 Cardiology Residency Program at Duke University Hospital in Durham, North Carolina.

The body uses magnesium for energy production and to break down glucose. Magnesium is also used to synthesize DNA and RNA. “You really cannot have too much magnesium,” says Christopher DeSimone, MD, a cardiac electrophysiologist and associate professor of medicine in the department of cardiovascular medicine at Mayo Clinic. He adds that this is because in healthy individuals the body is good at eliminating magnesium as needed.

How Your Body Regulates Magnesium Levels

According to an overview published in Advanced Chronic Kidney Disease, magnesium levels are regulated primarily by the kidneys and the intestines working together. About half of daily intake of magnesium is absorbed by the intestine. Magnesium levels may, however, go unregulated in people with kidney disease. “The kidney is a major regulator of magnesium levels, so kidney disorders can lead to both depletion and overload,” Dr. Campbell notes. Healthy Individuals with low magnesium levels are uncommon. This is because healthy kidneys will limit the passing of magnesium through the urine if the body is in need of this mineral.

Magnesium Helps Your Heart Keep the Beat

Magnesium also plays a role in cells which respond to electrical activity. “Magnesium is a key electrolyte in the body and is necessary for proper homeostasis. Especially in cells that are electrically excitable, like those in the heart,” Dr. DeSimone explains. 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. Campbell adds that magnesium also helps with muscle contraction or pumping of the heart. Research published in Nutrients showed that magnesium deficiency has clinical features including severe muscle cramps and increases of irregular heartbeats known as arrhythmias. Campbell says that low magnesium levels are commonly found in patients with atrial fibrillation, premature or skipped beats, and even serious life-threatening arrhythmias.

DeSimone adds that low magnesium levels can also put patients at risk of developing bad rhythms in the heart’s lower chambers, known as the ventricles, which could be life threatening. 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?

The amount of magnesium in the body depends on several factors, like diet and a person’s kidney function. As we age, for example, magnesium absorption decreases in the body. One research study published in Nutrients suggests the primary causes of lower magnesium levels in older age include insufficient intake of magnesium, reduced absorption of magnesium, and increased urinary excretion of magnesium. Magnesium deficiencies can also be caused by certain conditions, including alcoholism, burns affecting a large area of the body, malnutrition, preeclampsia (if a woman is pregnant), a digestive disorder like Crohn’s disease or ulcerative colitis, excessive urination, including among those with uncontrolled diabetes, pancreatitis, or chronic diarrhea.

Patients who are on diuretics are also of concern for both Campbell and DeSimone. This includes patients being treated for high blood pressure or heart failure. The reason being that these patients are usually on high dose diuretics. “When they are fluid overloaded and diuresed aggressively these levels can drop into dangerously low levels,” notes DeSimone. Campbell adds, “Patients on diuretics need to have their magnesium followed closely.”

Prolonged use of certain medications can also 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

Low levels of magnesium, when left untreated can lead to complications like cardiac arrest. You should know the symptoms of magnesium, which include:

Unusual eye movement
Muscle cramps or weakness
Fatigue
Convulsions

Experts advise people to get nutrients primarily from food. Campbell suggests getting magnesium from green leafy vegetables, whole grain cereal (bran), quinoa, nuts (almonds, cashews), and beans. 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
Low-fat plain yogurt
Pumpkin or chia seeds
Legumes
Black beans
Avocados
Bananas

When to Reach for Magnesium Supplements

Even though magnesium can be found in food sources, some people still need magnesium from other sources. You may have heard some companies suggesting dietary supplements for your nutritional needs.

Campbell notes, “Supplements can be recommended in people who have low magnesium levels despite dietary changes.” She adds that there are different forms of magnesium available, and each differs in absorption and tolerance by the gastrointestinal tract. “The best forms are magnesium citrate, gluconate, or glycinate,” Campbell says.

You should consult with your provider when using supplements to ensure they do not interfere with any other medications you are on and that they’re not contributing to another medical condition. Too much magnesium from food isn't a danger because the kidneys excrete what the body doesn't need. But extremely high doses of magnesium from supplements can cause diarrhea, nausea, and stomach cramping. Extreme doses of magnesium, over 5,000 mg daily, can cause magnesium toxicity and 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.

Additional reporting by Alexandria Jones-Patten.