We Looked Into Whether It's Worth Taking Magnesium Supplements

Maybe you’re among the seven percent of Americans who experienced depression in the past year or the one in three who has trouble sleeping, and you’re looking for a solution that doesn’t involve a prescription. Magnesium has been touted as a treatment for everything from insomnia and depression to high blood pressure and glucose levels. And about 50 percent of Americans aren’t getting enough magnesium, due in part to declining soil quality, poor diet, and depleted levels from chronic diseases and medications, says Melissa Majumdar, a dietitian at Brigham and Women's Hospital in Boston. Does that mean most of us should be popping a magnesium supplement?

Magnesium is a mineral in foods that’s sometimes added to antacids and is the main ingredient in laxatives. It’s involved in tons of processes throughout the body, including converting food into energy, blood glucose control, blood pressure regulation, bone development, DNA synthesis, muscle and nerve function, blood vessel contraction, and the regulation of enzymes and hormones. The heart, in particular, needs magnesium to maintain a normal rhythm, says Philip Muskin, a professor of psychiatry at Columbia University and secretary of the American Psychiatric Association. “Magnesium is important, as are sodium, calcium, and potassium," he says. "The brain, heart, and neurons all need all of the ions for healthy function."

While there is a link between magnesium levels and high blood pressure, cardiovascular disease, and type 2 diabetes, according to the National Institutes of Health (NIH), issues are mostly among people who are deficient over a long period of time—and it’s hard to tell which is the chicken and which is the egg. “Both cardiovascular disease and type 2 diabetes cause further decreases in magnesium levels,” Majumdar says.

Among people with high blood pressure, a risk factor for heart disease, a 2006 study found people who took magnesium supplements for two to six months slightly reduced their blood pressure; another 2012 meta-analysis of 22 studies had similar findings. A 2010 study in the American Heart Journal found people with the highest concentrations of magnesium in their blood had a 38 percent reduced risk of sudden cardiac death, and another 2012 meta-analysis of seven studies found that adding 100 mg of magnesium per day to people’s diets decreased risk of stroke by eight percent.

As for blood sugar, one big study found that upping magnesium intake by 100 mg daily decreased diabetes risk by 15 percent. The problem is, most studies that have looked at magnesium intake are only observational, meaning their findings could be due to other factors, like a person’s overall diet and lifestyle habits. The American Diabetes Association doesn’t recommend magnesium supplementation to control glucose in people with diabetes.

Furthermore, Haitham Ahmed, a preventive cardiologist at Cleveland Clinic, says that magnesium supplementation has not been proven helpful for most people. “No large clinical trials have shown routine supplementation to significantly improve blood pressure, reduce heart disease risk, or reduce diabetes risk,” he says.

A couple of small studies have found that magnesium supplementation improved sleep quality in older people, possibly because magnesium binds to GABA receptors similar to Ambien. The research, however, is not enough to lead most psychiatrists to recommend it to their patients.

Still, plenty of people have found magnesium has helped them to sleep. Gary Leake, 44, a lifestyle and business coach in Los Angeles, says in his thirties he started having problems falling and staying asleep. He tried Tylenol PM, which didn’t make him feel rested. He didn’t want to take a prescription sleep med because of “nightmare stories” about sleep walking, so he visited a naturopathic doctor, who recommended magnesium to help with sleep as well as the leg cramps Leake had experienced most of his life.

“He told me that most people are deficient and never know it, and that people who had reported restless leg syndrome had success with magnesium and it would probably help me as well,” he says. Leake started taking 150 mg in 2008 and says that’s all he needs to fall asleep and sleep soundly without leg cramps. “I noticed a marked improvement in sleep quality on the first night I took it. Even today I notice a relaxed calm feeling and can drift off to sleep with ease, typically within 30 to 45 minutes. But I don’t take them every night because I don’t like taking pills,” he says.

Magnesium is essential for brain function, and signs of a deficiency can include anxiety, depression, irritability, and sleep disorders, says Jerome Sarris, a professor of integrative mental health and the deputy director of the National Institute of Complementary Medicine Integrative Medicine Research Institute at Western Sydney University, Australia.

A large 2015 study found people who had the lowest magnesium intakes were at 22 percent increased risk of depression. There have been other studies linking magnesium to depression, but Muskin says they weren’t blinded—meaning the researchers and participants knew what they were being tested for, which can bias the results. For now, studies only offer weak evidence for a relationship between magnesium and depression but may “tentatively support” magnesium supplements for people with depression, Sarris says.

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Animal studies have linked anxiety-type behaviors and magnesium, Sarris says. A recent 2017 review looking at magnesium supplements was “suggestive of a beneficial effect” on anxiety, but the results were inconclusive. Muskin says ultimately there’s no convincing evidence that magnesium can help with anxiety. “There is just not a lot of good data on magnesium overall,” he says.

“I do not use magnesium in my practice for treatment of mental health conditions and know of little data supporting its use definitively and I see very few practitioners using it,” says Gail Saltz, a professor of psychiatry at the New York Presbyterian Hospital, Weill-Cornell Medical College.

Magnesium is involved in neurotransmitter release and vasoconstriction (or the opening of vessels in brain), both of which can be culprits behind migraine headaches, Majumdar says. Not a lot of research has been done, but one 2008 study found taking 300 mg twice a day helped prevent migraines.

“I’ve dealt with anxiety and poor stress management since college, and chronic migraines since probably high school,” says Ashley Boynes-Shuck, 34, a writer and health coach in Pittsburgh. A translational medicine rheumatologist recommended magnesium supplements in 2012, and her neurologist suggested them again this year. A physical therapist also mentioned using magnesium oil on her skin for joint and muscle pain or spasms.

“Sometimes I think it helps with the migraines, sometimes I’m not sure,” Boynes-Shuck says. “Any time I’ve gone off of it, I’ve noticed more disturbed sleep patterns, muscle pain, and less of a feeling of calm wellbeing. I believe it works for me.”

Although we may not be getting as much magnesium as we should, an actual magnesium deficiency is rare, according to the NIH. People with Crohn’s disease and celiac disease are more at risk due to malabsorption in the small intestine, as are people with type 2 diabetes and older adults. And magnesium deficiency can be a potentially big problem: “Low levels can be dangerous to the neuromuscular, cardiovascular, and metabolic systems,” Ahmed says. Severely low magnesium levels—which are usually only found in people who are extremely sick or hospitalized—can lead to tremors, convulsions, weakness, electrical disturbances in the heart, low calcium, low potassium levels, and even a potentially fatal heart arrhythmia.

If you’re worried you might be deficient, talk to your doctor. Unfortunately, blood tests aren’t an option, since less than 1 percent of magnesium is stored in your blood—and the tests doctors do have are an imperfect science. “Magnesium is tightly regulated in your body, since it can impact heart contraction, so if you’re deficient your body will take from another source. You could have a level that looks good when it’s actually depleted,” Majumdar says. Most doctors use magnesium tolerance tests, she adds, where you’re given a big dose of the mineral and they look at the amount that comes out into your urine.

As with any supplement, taking too much magnesium can cause unpleasant and even dangerous side effects. Too-high doses of magnesium supplements can result in diarrhea, nausea, and abdominal cramping. And super-high doses have rarely resulted in fatal hypermagnesemia, or too-high levels of magnesium in the blood that can stop your heart.

There’s also a risk for drug interactions, Majumdar says, including with proton pump inhibitors (PPIs), antibiotics, bisphosphonates (for osteoporosis), diuretics, birth control, and hormone replacement drugs. So talk to your doctor first about whether and how much magnesium you should take.

Men should get about 400 to 420 mg of magnesium daily; women need around 310 to 320 mg (more if you’re pregnant or breastfeeding).

If you want to supplement, Sarris says most people should take between 100 to 300 mg of amino acid or citrate chelations, which are more easily absorbed by the body; Majumdar says most people take 250 to 400 mg daily. Since the FDA doesn’t regulate supplements, look for one that has the “USP” certification on the label, which means independent labs have verified the safety and levels in the supplement. Ease into it with the lower doses, because taking too much at once may cause the runs, Majumdar says.

If you’re taking a calcium supplement, Majumdar says it’s a good idea to also take magnesium too, since your body needs the right balance of both to be able to use each one. What’s more, a 2018 study found that getting enough magnesium is essential for your body to use vitamin D, so if you’re deficient in D it’s worth talking to your doctor about magnesium.

Otherwise, experts are cautious to recommend magnesium supplements if you’re not actually deficient in the mineral. “Rather than wasting money on supplementation, most Americans would be better served by focusing on a well-balanced diet,” Ahmed says. The best food sources of magnesium include almonds, cashews, spinach, beans, edamame, soymilk, whole wheat, brown rice, fortified cereal, low-fat yogurt, avocados, dark chocolate, peanut butter, potato skins, salmon, chicken, and lean beef.

“A balanced diet is most important. And alcohol use and the use of PPIs for acid reflux reduce magnesium along with other micronutrients. Checking magnesium levels may reveal a low level that will not improve without stopping the PPI,” Muskin says. “So addressing these two factors is more important than anything else.”

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