Magnesium supplements: Miracle cure or just hype?

There is limited evidence that magnesium supplements may help with at least some issues - especially if you don’t get enough from your diet. Illustration / Sean Dong, The New York Times

A look into what the mineral can - and can’t - do for sleep, mental health and more.

Magnesium supplements are said to help with a long list of ailments: sleep problems, migraine headaches, depression, high blood pressure, muscle cramps, constipation. One wellness coach on TikTok went so far as to say that “to be a functioning member of society,” everyone should be taking them.

The premise that this essential mineral can treat such a wide range of issues rests on the idea that many people are deficient in it. But is that true? And will replenishing your body’s magnesium solve your health problems?

We asked experts whether the claims hold up to scientific scrutiny.

How common is magnesium deficiency?

Most people in the United States do not have a serious magnesium deficiency, said Dr Edward Saltzman, an associate professor at the Friedman School of Nutrition Science and Policy at Tufts University. If they did, he said, they’d have noticeable symptoms like nausea, vomiting, numbness, tingling, seizures and abnormal heart rhythms.

But national diet surveys do suggest that at least half of people in the United States aren’t meeting federal recommendations – at least 310 or 320mg of magnesium per day for women who are not pregnant (depending on their age); and at least 400 or 420mg for men (also depending on age).

Not consuming enough magnesium could have subtler, slower-burning consequences, Saltzman said. Researchers have found correlations, for instance, between consuming less magnesium and health conditions such as Type 2 diabetes, stroke, cardiovascular disease, bone fractures, migraine headaches and poor sleep – though they haven’t proven causation.

Unfortunately there isn’t a simple way to tell if you are meeting federal guidelines. A blood test, for instance, won’t give you a very accurate assessment, said Katherine L Tucker, a professor emerita of biomedical and nutritional sciences at University of Massachusetts Lowell.

“To me, it’s one of the more important nutrients that we’re missing,” Tucker said.

Magnesium is vital for over 300 biochemical reactions in the body. Photo / 123rf

Can magnesium supplements help with certain conditions?

The relevant clinical trials that have looked into this have been small, with inconsistent results, Saltzman said, so whether they can help with such a long list of ailments is “the million-dollar question”.

We need bigger, better studies before recommending magnesium supplements to most people, he added.

However, some limited evidence does provide hints that magnesium supplements may help with at least some issues – especially if you don’t get enough magnesium from your diet, Tucker said. Here are some areas that offer the best, if imperfect, evidence for their use.

Migraine

According to the American Academy of Neurology and the American Headache Society, magnesium supplements are “probably effective” at preventing migraine headaches in people who get them regularly. This is backed by a handful of small clinical trials, which have suggested that patients who took 600mg of magnesium per day had fewer migraine headaches than those who took a placebo.

Some studies suggest magnesium supplements may help prevent migraines. Photo / 123rf

Sleep

In a 2021 review of studies, researchers summarised the findings of three clinical trials that included 151 people aged 50 or older. They found that on average, those who took between 320 and 729mg of magnesium per day fell asleep about 17 minutes faster than those who took a placebo. It wasn’t clear, however, whether the supplements improved the participants’ sleep quality or helped them sleep longer.

Mental health

In a 2023 review of seven small clinical trials, researchers concluded that taking magnesium supplements can help reduce symptoms of depression (though not all the trials they reviewed found such benefits). A 2017 trial of 126 adults with mild to moderate symptoms of depression found that those who took 248mg of magnesium per day for six weeks began feeling less anxious and depressed within two weeks. However, the researchers reported that this benefit could have partly been explained by a placebo effect.

A 2024 review also found that magnesium supplements may help with anxiety, though those results were also mixed.

Clinical trials have found magnesium may reduce depression and anxiety symptoms. Photo / 123rf

Blood pressure and blood sugar

Studies done over short periods of time have suggested that, in people with high blood pressure, magnesium supplements may lower blood pressure by a small amount. And in people with Type 2 diabetes, it may help reduce blood sugars and measures of insulin resistance, Tucker said.

Those findings jibe with longer studies that have found correlations between lower magnesium consumption and greater risks of Type 2 diabetes and cardiovascular disease, she said – though we don’t have enough evidence to say that a magnesium supplement could prevent those diseases.

Constipation

In 2023, experts from two national gastroenterology associations said that people with chronic constipation (meaning those with certain symptoms that last for three or more months) might benefit from taking magnesium supplements. This was based on two small, short-term trials that found that people with chronic constipation who took magnesium oxide (a type of magnesium supplement) had more bowel movements per week than those who took a placebo.

Magnesium citrate and glycinate are more stomach-friendly forms of the supplement. Photo / 123rf

What’s the bottom line?

Scientists don’t know exactly how magnesium supplements may offer these benefits, or if they may help in other ways such as in preventing muscle cramps or improving bone health. But the mineral plays a role in hundreds of chemical reactions in the body, including brain cell function, muscle contraction, blood glucose control, blood pressure regulation and energy production.

The best way to make sure you’re getting enough magnesium is to consume more magnesium-rich foods like nuts, seeds, leafy greens, beans and whole grains, Tucker said.

If you don’t regularly eat these kinds of foods, a supplement may be worth trying, Tucker added.

Just keep in mind that some types of magnesium supplements can cause unpleasant side effects – like diarrhoea, nausea and abdominal cramping, said Mahtab Jafari, a professor of pharmaceutical sciences at the University of California, Irvine.

Magnesium oxide, magnesium chloride, magnesium gluconate and magnesium sulfate are more likely to cause these issues. Other forms, like magnesium citrate, magnesium glycinate, magnesium bisglycinate and magnesium L-threonate, are better tolerated, Jafari added.

Magnesium supplements may interfere with some medications, including certain antibiotics or osteoporosis drugs, Jafari said, and higher doses can be unsafe if your kidneys aren’t functioning properly. It’s good practice to check with your doctor before taking magnesium (or any) supplements.

And keep in mind that dietary supplements in general aren’t rigorously tested for safety and efficacy as pharmaceutical drugs are. Jafari recommended choosing a supplement with a seal from a trusted third party lab, like NSF or US Pharmacopeia, which independently test supplements for contaminants and to ensure they contain what’s on the label.

This article originally appeared in The New York Times.

Written by: Alice Callahan

Photographs by: Sean Dong

©2024 THE NEW YORK TIMES