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 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 such a popular supplement. Foods like leafy greens, nuts and seeds, and dark chocolate all contain magnesium, and drinking water actually provides magnesium, too. However, large epidemiological studies suggest that 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 Heavy alcohol use and certain pharmaceuticals (notably diuretics and proton pump inhibitors like Nexium and Prevacid) also increase the risk of magnesium deficiency. So do gastrointestinal disorders like Chron’s and celiac disease, which interfere with nutrient absorption.
Magnesium supplements can be safe and effective for closing the gaps. 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?
Why Are There So Many Different Forms of Magnesium?
In supplement form, you’ll get magnesium bound chemically to another substance like an oxygen molecule, an organic acid (citric acid, malic acid), or an amino acid (glycine, taurine). 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. Each one also brings along a “sidekick”—oxygen, citric acid, glycine—that can have unique benefits once it enters the body.
Choosing the Right Magnesium Supplement
Magnesium can be taken alone or as part of a multivitamin/multimineral complex. While particular forms are touted for specific use cases, there are only a few instances where the evidence supports using one form over another. I’ll cover those below.
The supplement facts on the label tell you how much elemental magnesium (magnesium by itself) is in each serving, not the magnesium compounds’ total weight. More expensive supplements don’t necessarily deliver more magnesium, so shop wisely.
Transdermal magnesium products like sprays, lotions, oils, and bath salts rely on magnesium absorption through the skin. While some people swear by these products, they aren’t as well studied.2 If you’re worried about magnesium deficiency and want to be sure about bringing your levels up, opt for pills or capsules.
What Are the Different Forms of Magnesium?
Magnesium Oxide Versus Magnesium Citrate
Oxide and citrate are the two most common forms of magnesium supplements. You’ll usually find one of these two in multimineral blends.
Magnesium oxide is magnesium bound to oxygen. When it mixes with water, it becomes magnesium hydroxide, the active ingredient in many over-the-counter antacids.
Magnesium citrate is magnesium plus citrate. Magnesium citrate is more bioavailable than other forms of magnesium, including oxide.3 Magnesium oxide delivers more elemental magnesium per dose, though, so it may balance out somewhat.4
Both forms are used to treat digestive ailments like indigestion and heartburn and, more generally, to raise magnesium levels in the body. They can pull water into the intestines and cause diarrhea if you’re not careful, but that also makes them effective laxatives if constipation is your issue. With either form, start small and work your way up.
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,5 and it may be better tolerated.6
Magnesium Glycinate (Bisglycinate) and Magnesium Taurate
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.
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.7
Glycine and taurine also act as neurotransmitters with properties similar to GABA.89 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.10 However, it’s not clear how much those effects are due to the magnesium per se. Other forms, like magnesium oxide, also show benefits in some studies.11
Both glycinate and taurate score well in terms of bioavailability, and they are less likely than oxide or citrate to cause digestive distress.
Magnesium L-threonate is the new kid on the block. This novel form of magnesium was discovered by MIT researchers and first published in 2010.12 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.
In the original 2010 paper, the researchers found that mice given magnesium L-threonate performed better on learning and memory tasks thanks to stronger synaptic connections between brain neurons.
In another study, adults between the ages of 50 and 70 took a magnesium L-threonate supplement for 12 weeks.13 Their performance on various cognition and memory tests improved significantly from the beginning to the end of the study. Another group given a placebo showed no such improvement. The researchers then used participants’ test scores to quantify their “brain age.” They concluded that by supplementing with L-threonate, the experimental group’s brains got, on average, 9.4 years “younger” in just 12 weeks.
In animals at least, magnesium L-threonate seems to improve anxiety and depression-like symptoms, possibly better than other forms of magnesium.1415
Transdermal applications like skin oils and lotions usually contain magnesium chloride. As an oral supplement, it is most often used to treat digestive issues. It’s generally well-tolerated, but 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 there’s really no research to support its efficacy. 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. 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.
Based on some early, promising data, magnesium malate became popular as a treatment for fibromyalgia. However, a 2019 meta-analysis of 11 studies concluded that there’s no consistent benefit.16
That said, magnesium malate appears to be highly bioavailable, so it still may be worth a shot, at least for increasing magnesium levels for those who are deficient.17
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.18
In studies, the one-year survival rate of patients with severe congestive heart failure was significantly higher with magnesium orotate supplementation, compared to a placebo.19 The magnesium group also reported an improvement in their clinical symptoms, while the placebo group got worse. Magnesium orotate may also improve exercise tolerance in folks with heart disease.20 (Magnesium citrate might do the same.21) A small meta-analysis confirmed that magnesium orotate supplementation shows promise for cardiovascular health.22What Is the Best Form of
Best Magnesium for Constipation, Muscle Cramps, Et Cetera?
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.
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:
Best magnesium for sleep:
I’d opt for magnesium glycinate, but other forms work too.
Best magnesium for constipation:
Oxide or citrate.
Best magnesium for heart health:
Unclear. Studies that have shown a benefit of magnesium supplementation for blood pressure, for example, variously used magnesium chloride, aspartate, or unspecified compounds.23 Sulfate is often used in a clinical setting. Orotate shows promise, but more research is needed.
Best magnesium for memory and cognition:
Best magnesium for keto dieters:
Keto dieters should strongly consider supplementing with magnesium (along with sodium and potassium), but form probably doesn’t matter much.
Best magnesium for muscle cramps:
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.24 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.
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. 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.
Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.