Magnesium supplements: what you should look for

When we look at the pyramids, we think of the pharaohs who built them—except they didn’t. Sure, they probably approved the plans and issued orders, but the work was done by thousands of others.

Similarly, your body doesn’t just build strong bones or keep a perfect heart rhythm on its own. There’s a range of underappreciated minerals that are critical to these processes, without which they wouldn’t and couldn’t happen. One of those essential minerals instrumental in building and maintaining your healthy body is magnesium.

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Calling magnesium a hard worker would be an understatement. This mineral, which we cannot produce on our own, is required for over 600 chemical reactions in the body (Baaij, 2015).

You name it, and magnesium is probably involved. It helps with protein synthesis and muscle function. One of the main effects of magnesium is a strong, regular heartbeat because of how it works in tandem with calcium.

This mineral plays an integral part in energy production and possibly blood sugar regulation for people with type 2 diabetes. It may lower blood pressure, decrease the risk of heart disease, and improve sleep quality (Wienecke, 2016; Reffelmann, 2011).

Magnesium may even prevent inflammation that’s associated with certain cancers, a 2017 study found. As you can see, it more than deserves to be called essential (Chen, 2017).

With that many functions influenced by the presence or lack of this mineral, you obviously want the best supplement out there. But a quick scan of the supplement section of your local drugstore reveals it’s not that simple. Unlike some vitamins and minerals like vitamin C, there are what feels like countless forms of this supplement.

When the role of magnesium in your body is so large, you want to make sure you’re getting a good supplement. Yes, research can be needed to make sure you’re choosing the right one—but we did it for you. 

Unlike zinc, which also has multiple forms that tend to be used to treat different conditions, most forms of magnesium treat a whole host of conditions.

The two biggest differences in the various forms of this essential mineral are cost and likelihood of causing side effects such as loose stool. Some forms are generally better tolerated than others, and we’ll tell you which those are later on.

Overall, the best supplement for you is going to be one from a trusted source, that you can take consistently. Magnesium is a promising treatment for a wide range of conditions, including heart disease, migraines, and fibromyalgia, but it’s not an overnight solution (Shahrami, 2015; Kim, 2011).

Subjects of many studies see health benefits after six to eight weeks of a consistent supplement routine. A lifestyle that includes both consistently taking a supplement and eating foods with high magnesium content is probably your best bet for avoiding a deficiency. And that should be taken seriously because it can take a while to diagnose low magnesium levels since the symptoms tend to be nonspecific.

Marked magnesium deficiency can cause bone loss by acting directly on your bones or affecting how your body uses calcium, which is especially serious for older adults. One of the roles of magnesium is regulating your heartbeat, so a deficiency can cause an irregular heartbeat, called arrhythmia (Castiglioni, 2013).

Unfortunately, that’s only the start. Not getting enough magnesium may also contribute to high blood pressure (which, in turn, increases your risk of stroke and heart attack), a higher risk of depression, and general fatigue and muscle weakness (Cheungpasitporn, 2015).

The first signs you’ll likely notice are a loss of appetite and nausea, which is why it can be hard to diagnose. These symptoms could be signs of any number of conditions, so a medical professional will likely use a combination of methods to diagnose your condition. And, clearly, the best option is to act early to prevent these low magnesium levels from happening.

When you take a supplement, not all of it can be absorbed. Though some of this is affected by the form of magnesium you choose, it’s also affected by your body. Some people have malabsorption issues because of health conditions.

Gut issues like Crohn’s disease can block your body from taking in as much of the mineral from supplements. Talking to your healthcare provider is always a good idea for pointing you in the right direction, but here’s a quick guide to what you need to know about each form of magnesium.

• Magnesium citrate: This is one of the better-absorbed forms of magnesium, but it can cause a laxative effect at higher doses. Aside from oral magnesium intended to boost daily intake, the most common use of this particular form of the mineral is as stool cleaning preparation for surgery or bowel procedures such as colonoscopies.

• Magnesium lactate: This common form is used for general treatment to correct or prevent magnesium deficiency.

• Magnesium aspartate: You’ve absolutely seen this form on drugstore shelves before. It’s used not only to prevent low levels of magnesium but also to treat upset stomach, heartburn, and acid indigestion. It’s one of the forms your body absorbs the best. You’ll also find it in health stores as ZMA, a supplement popular with athletes which contains zinc monomethionin, magnesium aspartate, and vitamin B6. Studies on this particular supplement and its effect on performance and strength, however, are mixed (Wilborn, 2004).

• Magnesium chloride: This is another form of magnesium that you’ll see both as a supplement to treat or prevent deficiency and as an antacid. It’s one of the better absorbing types of magnesium. You may also see it in some spray formulas designed to absorb through your skin.

• Magnesium malate: This is a combination of magnesium and malic acid, and it absorbs relatively well while generally costing less than some other forms of magnesium. Bioavailability studies on magnesium malate were done in animals, though (Uysal, 2018). Since it’s believed to absorb well, it’s used to treat a range of conditions magnesium may help, such as migraines, anxiety, depression, and chronic pain in an oral or spray form. One small study even suggests the combination of magnesium and malic acid may be an effective long-term treatment to manage the pain associated with fibromyalgia.

• Magnesium taurate: This combination of magnesium and taurine may be beneficial for those seeking the heart health-boosting benefits. Taurine’s health benefits reportedly parallel those of magnesium, so you’re potentially getting two ingredients that impact cardiovascular health.

• Magnesium oxide: Also called magnesia, this supplement can be used to boost magnesium intake and treat deficiency but is better known as an antacid that can relieve heartburn or indigestion.

• Magnesium sulfate: This form of magnesium is more commonly used in a medical setting by healthcare professionals and is generally administered as an injection or IV. It’s used to treat kidney problems in kids, prevent preterm labor and seizures in some cases of severe pregnancy complications. It’s also used by medical professionals to treat hypomagnesemia, or low magnesium levels, in a hospital setting. But you might also know this form as Epsom salt, which athletes and habitual gym-goers use to ease aching muscles and muscle cramps.

• Magnesium glycinate: One of the most readily absorbed forms of magnesium, it’s also one of the least likely to cause a laxative effect. It can be used to treat or prevent low mineral levels but is also potentially effective at treating chronic pain, according to one case report. Since it is more effectively absorbed by the body than other forms, it may also confer more of the mineral’s potential health benefits like easing premenstrual syndrome symptoms, alleviating anxiety, protecting against insulin resistance, and lowering blood pressure.

We’re all most familiar with oral magnesium, but these supplements come in other forms. Healthcare professionals may use IV drips or injections of magnesium to treat patients with severe deficiency or administer high doses of the mineral.

But there are also forms that support absorption through the skin, bypassing your digestive system. Magnesium sulfate, specifically, is found as Epsom salt, which you use in the bath. But other forms of magnesium are now being used in topical sprays meant to help with muscle cramps and sleep issues.

The best plan for treatment and prevention of deficiency is likely a combination of supplementation and dietary magnesium, though. Magnesium supplementation was more effective in subjects when paired with a lifestyle that included intake from magnesium-rich foods, one study found (Kass, 2013).

Luckily, if you’re enjoying a diet low in processed foods, you’re likely already well on your way to meeting your recommended dietary allowance (RDA) of 400–420 mg of magnesium for adult men and 310–360 mg for adult women. The amount of magnesium considered the upper limit for supplements is 350 mg, which means the rest is supposed to come from the diet (Office of Dietary Supplements, 2019).

High doses above this mark may lead to side effects (more on that below), but large doses may be given in the short term under medical supervision to correct a deficiency quickly. Magnesium toxicity may happen with doses in excess of 5,000 mg.

Although side effects are less likely under 350 mg per day through dietary supplements, they may affect certain people differently.

A diet rich in sources of magnesium like green leafy vegetables, cashews, whole grains, and dark chocolate paired with supplements is likely most people’s best bet for meeting their RDA. This combination method ensures you’re getting enough magnesium without risking side effects such as diarrhea, nausea, and abdominal pain.

Those with kidney issues have a higher risk of developing side effects. Talk to a healthcare professional about which form is best for you, given your medical history, and follow medical advice to avoid any adverse effects.

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

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Current version

December 03, 2019

Written by

Linnea Zielinski

Fact checked by

Mike Bohl, MD, MPH, ALM

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About the medical reviewer

Mike Bohl, MD, MPH, ALM

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.