6 Things to Know Before You Take a Magnesium Supplement

Updated: Feb. 15, 2023

Magnesium can help strengthen your bones, give you a better night's sleep, offer pain relief and even improve heart health, so it's no surprise that some people take this miracle mineral as a supplement—but here's what you need to know before you open that bottle.

A vital mineral

Magnesium is an important mineral when it comes to your health, says Carolyn Dean, MD, ND, author of “The Magnesium Miracle” and a medical advisory board member of the Nutritional Magnesium Association. Magnesium may help lower your risk of heart disease, type 2 diabetes and osteoporosis while also helping to reduce anxiety, insomnia, blood pressure, and migraine headaches. It may even help you age more gracefully, according to research published by the National Institutes of Health (NIH). You can get enough magnesium by eating a variety of foods (more on that later). However, some people may not get enough magnesium from their diet, and men over age 70 and teen girls may be at greater risk of a deficiency than other people, according to the Office of Dietary Supplements at the NIH. However, before you pop a supplement, there are a few things you need to know first.

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How much magnesium do you need?

Magnesium already naturally exists in our bones, muscles and cells. The earth’s crust and seawater also contain the mineral. We need between 310 and 420 milligrams of magnesium a day for optimal functioning and to maintain our body’s reserves, according to the NIH. Not sure if you’re getting enough? Check out these 10 Signs You’re Not Getting Enough Magnesium.

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Why take a magnesium supplement?

“Magnesium is one of the key electrolytes your body needs, affecting nearly every system in your body,” Dr. Dean says. “It activates enzymes that control digestion, absorption, and the utilization of proteins, fats, and carbohydrates.” We can get some or all of your daily allotment from green leafy vegetables, whole grains, beans, and nuts. However, many people choose to take supplements to make sure they are getting enough of this essential mineral, she says. (Breakfast cereals and other foods may be fortified with the mineral, so make sure to read those food labels!)

Some groups of people are also more likely to be magnesium deficient, so if you have a gastrointestinal disease, diabetes, alcohol dependence, or are over age 65 then you may need to supplement with extra magnesium, according to the NIH.

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What type of magnesium supplement should you take?

Not all types of magnesium supplements are created equal, Dr. Dean explains.  Some forms of magnesium are more easily absorbed and used by your body, so you want to make sure you’re choosing the right option.

Magnesium supplements come in aspartate, citrate, lactate, chloride, oxide, sulfate, threonate, malate, and glycinate forms but some are more bioavailable—which means they are easier for your body to use, according to the NIH. Confused? Here’s a tip  from the NIH to make it a little easier: the magnesium supplements that your body will absorb best are the ones that can be dissolved in water, including all forms except oxide and sulfate.

The newer supplements, including magnesium glycinate, threonate, and malate, while more expensive, were found to be better absorbed and cause less stomach discomfort, according to a study published in the Journal of The American College of Nutrition. Dr. Dean prefers magnesium citrate powder, as it is affordable, easy to find, and dissolves quickly in water, making it easy to take.

Other magnesium supplements may double as laxatives or antacids. The skin can also absorb epsom salts, another form of magnesium, during a bath.

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How should you take a magnesium supplement?

For best results, you should take the supplement with food. That will help you absorb it better and will minimize stomach discomfort, says Stephanie Schiff, RDN, a registered dietitian at Northwell Health’s Huntington Hospital in Huntington, New York.

Timing can also be important. “Some studies recommend that magnesium supplements be taken at night, as they help relax the muscles in the body and can help you fall asleep,” she adds.

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Can you overdose on magnesium supplements?

Magnesium supplements in reasonable doses are safe for most people, according to the NIH. Overdosing is rare, but taking over 5,000 mg a day can lead to magnesium toxicity, which may be fatal without treatment, they note. The most common side effects from too much magnesium are diarrhea and stomach pain, so make sure to listen to your body. People with kidney or heart problems should exercise caution, according to the National Magnesium Association.

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Can you take other supplements or medications with magnesium?

Be careful loading up on supplements! Taking magnesium can interfere with the absorption of other minerals, says Tod Cooperman, MD, a supplement expert and president of Consumer Labs, a supplement testing site. “So if you take a multivitamin, calcium, or zinc, take magnesium at a different time of day,” Dr. Cooperman warns. “Magnesium may also reduce the absorption of medications such as blood thinners, anti-diabetes drugs, diuretics, and drugs used to treat osteoporosis. Check with your doctor first if you are on any medications.”

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