When it comes to essential nutrients, it doesn’t get much more essential than magnesium. At the most basic level, mitochondria can’t make ATP—the body’s energy currency—without magnesium. No ATP, no energy, no life. Magnesium regulates the electrical activity of the heart, helps maintain healthy vitamin D levels, and allows nerves to fire and muscles to contract. Low magnesium is associated with everything from PCOS to type 2 diabetes, depression, migraines, and cataracts, to name just a few.
This is just a snippet of magnesium’s impressive resume, which is why it’s so important to get enough. Unfortunately, the majority of adults don’t hit the recommended daily intake of 310 to 320 mg for females and 400 to 420 mg for males.1 Why is magnesium deficiency so widespread?
The list of reasons is long, and magnesium supplementation is almost necessary just to close the gap. Perusing the magnesium section of your local health food store is intimidating, though, to say the least. So many different types and formulations. How do you pick? What’s the best form of magnesium?
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Pure elemental magnesium is unsafe to handle. It can catch fire upon contact with water. It’s caustic and you can’t eat it. To make it safe, you have to bind it to another substance like an oxygen molecule, an organic acid (citric acid, malic acid), or an amino acid (glycine, taurine). That’s why supplemental magnesium comes in different forms. The differences between various forms of magnesium come down to the properties of the compounds and the chemical bonds, not the magnesium itself. Once the compounds are cleaved apart, magnesium is magnesium. However, different forms offer different amounts of elemental magnesium per gram, and they are absorbed at different rates in different parts of the body depending on what compound it’s bound to. Each one also brings along a “sidekick”—oxygen, citric acid, glycine—that can have unique benefits once it enters the body.
To answer that, we have to look at the individual forms of magnesium. It’s one of the best-studied mineral supplements on the planet, with hundreds of papers devoted to teasing out this exact question. Magnesium can be taken alone or as part of a multivitamin/multimineral complex. Let’s look at the
Magnesium bound to oxygen is magnesium oxide, the most common form of magnesium supplement. You’ll usually find oxide in your basic drug store brand of magnesium or multivitamin. When it mixes with water, it becomes magnesium hydroxide, the active ingredient in many over-the-counter antacids.
Magnesium oxide gets a bad rap for supposedly being useless for actual magnesium needs in the body, but that’s exaggerated. While it’s not the most bioavailable, it has been shown to improve magnesium status, even excessively so.3
Magnesium oxide is often used to treat digestive ailments like indigestion and heartburn. It can pull water into the intestines and cause diarrhea if you’re not careful, but that also makes it an effective laxative if constipation is your issue. Whatever your reason for using, start small and work your way up.
Magnesium citrate is magnesium plus citrate. Magnesium citrate is usually more bioavailable than magnesium oxide.6 Magnesium oxide delivers more elemental magnesium per dose, though, so it may balance out somewhat.7
Magnesium lactate comprises magnesium and lactic acid. It’s used in much the same manner as citrate and oxide.
The citrate and oxide forms are more common, but if your goal is to increase magnesium levels, consider magnesium lactate instead. Compared to other forms, magnesium lactate scores well in terms of bioavailability,11 and it may be better tolerated.12
Magnesium glycinate or bisglycinate (the terms are interchangeable) is magnesium bound to the amino acid glycine. You might already know that I’m a big fan of glycine, the primary amino acid in collagen. Among its many benefits, glycine improves sleep. Adding some glycine before bed via bone broth or collagen is one of my favorite sleep hacks.
Glycine and taurine also act as neurotransmitters with properties similar to GABA.15 16 GABA is colloquially called the “calming neurotransmitter.” Glycine and taurine can have analogous effects. There is limited evidence that magnesium glycinate and taurate might relieve symptoms of anxiety and depression.17 However, it’s not clear how much those effects are due to the magnesium per se.
Glycinate scores well in terms of bioavailability and is less likely than oxide or citrate to cause digestive distress.
Magnesium taurate is magnesium and taurine, another amino acid. This form is primarily recommended for heart health since magnesium and taurine both exert cardioprotective effects. Low magnesium can lead to arrhythmia (irregular heartbeat) and hypertension; taurine can prevent arrhythmia and lower blood pressure.20 It’s perfect, on paper.
Magnesium L-threonate is the new kid on the block. This novel form of magnesium was discovered by MIT researchers and first published in 2010.22 What makes it special is how readily it crosses the blood-brain barrier. It can get magnesium into the brain in much higher concentrations compared to other forms of magnesium. For that reason, L-threonate has uniquely positive effects on measures of brain health and brain aging.
L-threonate is unlikely to cause digestive distress.
Transdermal applications like skin oils and lotions usually contain magnesium chloride. As an oral supplement, it is most often used to treat digestive issues, but it’s also highly absorbable for general magnesium purposes. It too can act as a laxative if you take more than you need. If you take magnesium carbonate, it will convert to magnesium chloride when it reacts with the hydrochloric acid in your stomach.
Chloride is an important electrolyte in its own right, playing a major role in regulating fluid balance in your cells.
Epsom salts are magnesium sulfate, a compound comprising magnesium, sulfur, and oxygen. Although you can take it orally, usually it’s used transdermally. Many people swear by Epsom salt baths to soothe sore muscles and relieve stress, though I prefer chloride baths. If you do take magnesium sulfate internally, be advised that it can be, ahem, very effective as a laxative. I’d stick to citrate or oxide for constipation.
Doctors also use magnesium sulfate to treat preeclampsia and eclampsia in pregnant women.30 Heart disease patients frequently get intravenous magnesium sulfate, to good effect. These are clinical applications, though, so these findings might not directly translate to popping a pill at home.
This is magnesium plus malic acid, an organic acid common in fruits. Malic acid is also integral to the process of ATP production. For that reason, there is interest in malic acid supplementation to fight fatigue and enhance energy and sports performance. Creatine malate is a popular athletic supplement. Much more research is needed, though, to confirm the benefits of malic acid.
When magnesium binds to orotic acid, you get magnesium orotate. Orotic acid is important mainly because it helps the heart maintain a steady energy supply, especially after a cardiac event.33
Questions like these are hard to answer. More often than not, empirical studies focus on the effects of magnesium administration per se, not the specific form. Researchers might choose what magnesium compound to use based on cost, convenience, or the form’s particular properties. In many cases, study authors don’t even report the form of magnesium used in the research, much less explain why a certain form was selected. Furthermore, studies that directly compare two or more forms for a specific use case are uncommon.That’s the “bad news.”
The good news is that pretty much every type of magnesium is good for almost every potential application, assuming it’s absorbed. Just because one form is known to be beneficial in a given circumstance, that doesn’t mean that other forms aren’t helpful. Here’s my best advice based on the available data:
I’d opt for magnesium glycinate or threonate, but other forms work too. Magnesium chloride oil sprayed on the body before bed gives very vivd dreams.
Oxide or citrate.
Unclear. Studies that have shown a benefit of magnesium supplementation for blood pressure, for example, variously used magnesium chloride, aspartate, or unspecified compounds.37 Sulfate is often used in a clinical setting. Orotate shows promise, but more research is needed.
In short, they are all going to be helpful.
L-threonate.
Keto dieters should strongly consider supplementing with magnesium (along with sodium and potassium), but form probably doesn’t matter much.
Despite the conventional wisdom that muscle cramps are due to low electrolytes, especially magnesium, there’s really not a lot of evidence to support this claim, and magnesium supplementation doesn’t consistently alleviate cramping.38 It doesn’t hurt to try, though. Just take whatever you have on hand. For sore, not cramping, muscles, I’m still a fan of Epsom salt baths based on my personal experience.
Magnesium chloride topical. This is purely anecdotal—my own experience.
Given that so many people are deficient in magnesium, and magnesium is generally regarded as safe, I tend to think that most people would do well to supplement at least to get to the desired 300-450 mg per day. For serious conditions like cardiovascular disease, talk to your doctor first, obviously. For things like minor sleep disturbances or muscle cramps, trying a magnesium supplement makes sense.
Stick to the recommended doses, and check for drug interactions—you know, the stuff you should always do whenever you add a new supplement. Experiment with different types and see if one or another works better for you.
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