So, what's the best magnesium supplement for your health? Well, there are lots of forms to choose from, and the best one really depends on what you're trying to achieve, or on your underlying conditions. Some people may benefit from taking several forms of magnesium together to optimize their health.
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It's important to get this right because adequate magnesium stores are crucial for nearly every aspect of health, from neurological and heart health to metabolism, digestion, sleep, anti-aging, and even cancer prevention. In this article, I'll go over exactly which forms of magnesium are best for different individual needs, the biggest mistakes people make with magnesium and how to avoid them, and which brands I personally take and recommend to my patients.
I'm Dr. Leonid Kim. I am board-certified in Internal Medicine and Obesity Medicine, and I discuss the most up-to-date, evidence-based information on weight loss, metabolic health, and longevity. Let's get into it.
Magnesium Glycinate
Let's start with one of the most popular forms of magnesium: magnesium glycinate. It's formulated by binding elemental magnesium to the amino acid glycine. Amino acids like glycine are the building blocks of protein and are usually found in meats, bone broth, fish, and dairy.
The reason magnesium glycinate is so popular is that it's very bioavailable, meaning it's easily absorbed, with a large portion entering the bloodstream and being utilized by the body. Because it's absorbed across many areas of the intestine, it doesn't cause as many gastrointestinal side effects, such as diarrhea, as other forms of magnesium, like magnesium oxide or sulfate, which we'll cover later.
Magnesium glycinate has been associated with several health benefits, most notably improvements in depression, anxiety, and sleep. Unfortunately, I couldn't find many high-quality studies specifically testing magnesium glycinate. However, there was a small case study showing that magnesium glycinate could help improve symptoms of depression, which makes sense mechanistically, since magnesium deficiency is very common among people with depression.
Another important reason I usually recommend magnesium glycinate is that it helps with vitamin D absorption. Magnesium is a crucial cofactor for enzymes involved in vitamin D metabolism, playing a key role in converting the inactive form of vitamin D we get from food or supplements into the more biologically active form, 25-hydroxyvitamin D, which is the form typically measured in a blood test. A double-masked randomized controlled trial showed that in people with overweight or obesity, adding magnesium glycinate to vitamin D was more effective at raising vitamin D levels than vitamin D supplementation alone.
One important thing to note when choosing a magnesium glycinate supplement is to look for a brand that offers a chelated form of magnesium, meaning the magnesium and glycine are chemically bonded together. This transforms the inorganic metallic element into a form more readily absorbed by the body. Many brands use misleading or inaccurate labeling; instead of a true chelated form, they sell a blend of glycine with a cheaper form of magnesium, such as magnesium oxide or magnesium carbonate, which is less well absorbed and more likely to cause diarrhea.
A quality test conducted by NOW, published in December 2022, found that most magnesium glycinate products sold on Amazon did not actually provide a truly chelated form of magnesium, but rather a cheaper, blended (non-chemically bonded) form. Not surprisingly, NOW's own magnesium supplement performed well in their own funded study, so take that for what it's worth.
Magnesium Citrate
Next, let's talk about magnesium citrate. Like magnesium glycinate, magnesium citrate is also fairly well absorbed by the body, but at higher doses it can become a laxative. At very high doses, it's often used for bowel preparation before colonoscopies. Magnesium citrate is formed by binding magnesium with citric acid ions, and citric acid is commonly found in citrus fruits like lemons and limes.
Like other forms of magnesium, magnesium citrate is reported to help with anxiety. We also have studies showing it can help with metabolic syndrome, specifically blood pressure and insulin resistance. A small pilot double-masked randomized controlled trial, published in 2021, showed that supplementing with 400 milligrams of magnesium citrate daily for 12 weeks led to a significant decrease in blood pressure and a significant improvement in hemoglobin A1c.
Magnesium L-Threonate
Next, we need to talk about magnesium L-threonate, which has been getting a lot of attention lately for its potential impact on brain function, especially memory and cognition, as well as its potential use in chronic pain.
Magnesium levels are tightly regulated in the body, and very little of the magnesium in our blood can cross the blood-brain barrier, the membrane separating the blood from the brain. So, in general, very little ingested magnesium is transported to the brain or cerebrospinal fluid. This is where magnesium L-threonate comes in. Animal data suggest that magnesium L-threonate can more readily cross the blood-brain barrier due to its unique chemical structure, in which magnesium is bound to threonic acid, a metabolite of vitamin C. This structure is thought to enable it to cross the barrier and reach higher concentrations of magnesium in the brain.
Much of the excitement is based on small-animal studies in mice and rats, with some showing improved memory and motor function in Parkinson's disease models and others showing reduced brain inflammation. However, it's hard to draw firm conclusions from animal studies, as many findings don't translate well to human trials.
We do have small human studies that offer a bit more insight. The initial study that put magnesium L-threonate on the map was a small, randomized, double-masked, placebo-controlled trial with only 44 participants aged 50 to 70 who had self-reported complaints of impaired memory or concentration. The group that took magnesium L-threonate showed a small, possibly clinically significant improvement in executive function and working memory.
A more recent study, published in 2022, was larger, with 109 participants, and was also double-masked and placebo-controlled. It showed that treatment with 400 milligrams of magnesium L-threonate, along with vitamin B6, vitamin C, vitamin D3, and phosphatidylserine, significantly improved cognition and memory performance, with older participants showing more improvement than younger ones. That said, it's hard to draw firm conclusions from this study, since we don't know whether it was the magnesium L-threonate, the other vitamins, the phosphatidylserine, or some combination that was responsible for the improvement. Another important caveat for both studies is that they were industry-funded, which may introduce conflicts of interest.
Overall, the totality of evidence for magnesium L-threonate is pretty underwhelming at this point. Hence, it's not a supplement I generally recommend to my patients, especially given its high cost. It would also be very hard to meet your daily magnesium needs with this supplement alone, since it contains very little elemental magnesium. If you're taking magnesium L-threonate, I would not count it toward your recommended daily magnesium allowance.
Magnesium Taurate
Next up is a form of magnesium that's been getting a lot of excitement: magnesium taurate. This form is also well absorbed and contains the amino acid taurine, a protein-building block usually found in clams, shellfish, and poultry. Taurine has been reported to be beneficial for high blood pressure, obesity, and high cholesterol, and some studies speculate it may even have anti-aging effects.
There are animal studies showing that magnesium taurate can help with high blood pressure and has neuroprotective properties in the setting of traumatic brain injury. Unfortunately, the current evidence is largely based on animal studies, and we need larger human studies before I can recommend it with greater confidence.
Magnesium Sulfate (Epsom Salt)
Next, let's talk about magnesium sulfate, formed by combining magnesium, sulfur, and oxygen. Magnesium sulfate is commonly known as Epsom salt. It's often used as a laxative, and many people take Epsom baths to help with muscle cramps or as a way to relax. However, there's insufficient evidence to conclude that Epsom salt can effectively penetrate the skin or be absorbed transdermally to raise the body's magnesium levels meaningfully. That said, anecdotally, many of my patients find Epsom baths very relaxing, and if that's the case, that could be an added benefit, even if it doesn't raise magnesium levels.
Magnesium Malate
Next up is magnesium malate, a compound made of magnesium and malic acid, which is usually found in fruit or wine. This form of magnesium is very well absorbed and is probably the easiest to tolerate, due to a much less pronounced laxative effect. This is the magnesium I typically recommend to patients who haven't been able to tolerate other forms due to GI upset. There are also studies showing magnesium malate can be helpful in the treatment of fibromyalgia, though that's a big topic for another day.
Magnesium Chloride
Next up is magnesium chloride, another form that is very efficiently and easily absorbed. It's reported to be useful in the treatment of depression. In fact, an open-label, randomized controlled crossover trial showed that treatment with 248 milligrams of magnesium chloride for 6 weeks resulted in clinically significant improvements in depression and anxiety scores. Magnesium chloride is also often used as a topical agent for muscle soreness, but, as with magnesium sulfate, there isn't enough evidence to confirm a clinical benefit or to determine whether it's meaningfully absorbed through the skin.
Magnesium Oxide
And last but not least, there's magnesium oxide, the cheapest and most common form of magnesium available. It's an inorganic form that is poorly absorbed by the GI tract, so it really shouldn't be used to treat magnesium deficiency.
Where magnesium oxide does shine is in the treatment of constipation. A double-blind, randomized, placebo-controlled study published in the American Journal of Gastroenterology showed that magnesium oxide was as effective as Senna, a common constipation medication, at improving bowel movement frequency and constipation-related quality-of-life scores.
There's also some early evidence suggesting magnesium oxide could be effective in preventing migraines. A small 2019 double-masked, randomized, crossover trial showed that treatment with 500 milligrams of magnesium oxide was as effective as valproate sodium (Depakote) for migraine prophylaxis.
Conclusion
There's no single "best" magnesium supplement; the right choice depends on your specific goals, whether that's better sleep and mood support (magnesium glycinate), blood pressure and blood sugar support (magnesium citrate), cognitive support (though the evidence for magnesium L-threonate remains underwhelming), gentle GI tolerability (magnesium malate), or constipation and migraine relief (magnesium oxide). Absorption, tolerability, and the quality of the specific product all matter just as much as which form you choose, and label claims like "chelated" aren't always accurate, so third-party testing and reputable brands are worth prioritizing. As with any supplement, talk to your doctor about which form and dose best fit your individual needs and health history.
FAQ
What is the best form of magnesium overall?
There isn't one universally "best" form. Magnesium glycinate is popular for sleep, mood, and overall absorption, with minimal GI side effects. At the same time, other forms, such as citrate, malate, taurate, oxide, or chloride, are better suited to specific goals, such as blood pressure, digestion, or tolerability.
Which magnesium is best for sleep and anxiety?
Magnesium glycinate and magnesium chloride both have some evidence and reported benefits for mood, anxiety, and sleep, though larger, high-quality studies remain limited for most forms.
Does magnesium L-threonate really improve memory?
The evidence is currently underwhelming. While small human studies have shown modest improvements in memory and cognition, most were industry-funded, often combined with other supplements, and the form contains very little elemental magnesium, making it a costly option with uncertain benefit.
Which magnesium is best for constipation?
Magnesium oxide and magnesium citrate are commonly used for constipation. Magnesium oxide has been shown in trials to be as effective as Senna for improving bowel movement frequency and quality of life.
Can Epsom salt baths raise magnesium levels?
There isn't strong evidence that magnesium from Epsom salt baths is meaningfully absorbed through the skin to raise body magnesium levels. However, many people still find the baths relaxing for other reasons.
Why does the form of magnesium matter for absorption and side effects?
Different forms vary widely in bioavailability and GI tolerability. Forms like magnesium oxide are poorly absorbed and more likely to cause diarrhea, while forms like magnesium glycinate, citrate, and malate tend to be better absorbed and better tolerated.