Magnesium
Magnesium doesn't receive as much attention as vitamin D or omega-3s, but it is involved in hundreds of processes throughout the body, including muscle and nerve function, blood pressure, blood sugar regulation and energy production.
Many foods contain magnesium, particularly nuts, seeds, beans, whole grains and leafy green vegetables. Yet many Americans consume less than the recommended amount from food.
Getting enough magnesium may become particularly important as we get older. Dietary intake, absorption, medications and some health conditions can all affect magnesium status. And low magnesium isn't always obvious from routine blood tests.
Magnesium supplements are promoted for everything from sleep and muscle cramps to blood pressure, blood sugar and healthy aging. Some of those claims have considerably better evidence than others.
I wanted to understand whether many of us are getting enough magnesium, who might benefit from supplementation, and whether the form of magnesium matters.
Why Might We Not Be Getting Enough?
Many people simply don't eat enough magnesium-rich foods. Older adults are particularly likely to have lower dietary intake, and the intestine may absorb less magnesium as we age while the kidneys may excrete more.
Certain medications can also affect magnesium levels, including some diuretics and long-term use of proton-pump inhibitors for acid reflux. Diabetes and some gastrointestinal conditions can contribute as well.
One complication is that magnesium status isn't always easy to assess. Most of the body's magnesium is stored in bones and tissues, with less than 1% in the blood. A normal blood magnesium level therefore doesn't necessarily tell the whole story.
This makes magnesium different from vitamin D, where a blood test provides a much more useful measure of nutritional status.
What Can Low Magnesium Feel Like?
Low magnesium can sometimes contribute to muscle cramps or weakness, fatigue, numbness or tingling, and abnormal heart rhythms. Severe deficiency can cause more serious problems.
But these symptoms are not specific to magnesium deficiency. Muscle cramps, fatigue and poor sleep, for example, have many possible causes.
That is why a list of symptoms alone can't tell you whether you need more magnesium. The more useful question is whether your diet, medications, health conditions or other factors make inadequate magnesium more likely.
What Does Magnesium Supplementation Actually Help?
The clearest reason to take magnesium is to correct inadequate intake or deficiency. Beyond that, research suggests possible benefits in several areas.
Magnesium supplementation can produce modest reductions in blood pressure and may help improve glucose regulation in some people, particularly when magnesium status is low.
Magnesium is also widely used for sleep and muscle cramps. The evidence here is less consistent. Some people report meaningful benefits, but clinical trials haven't shown that magnesium is a reliable treatment for everyone.
Low magnesium levels have also been associated with an increased risk of atrial fibrillation (AFib). Although magnesium plays an important role in normal heart rhythm, it remains uncertain whether routine oral supplementation prevents AFib.
Does the Form of Magnesium Matter?
Magnesium supplements come in many forms, and they aren't all absorbed equally.
Magnesium citrate is relatively well absorbed but can have a laxative effect. Magnesium glycinate is also commonly used and is often chosen because it tends to be easier on the digestive system.
Magnesium oxide contains a relatively high amount of elemental magnesium, but it is less readily absorbed and is more likely to cause gastrointestinal effects.
Other forms—including magnesium malate and threonate—are promoted for particular benefits, but evidence that they produce substantially better health outcomes is limited.
The important point is that “magnesium” on the front of the bottle doesn't tell the whole story. The form, the amount of elemental magnesium, and how well you tolerate it all matter.
Learn More
A comprehensive review of magnesium, including food sources, recommended intake, deficiency, supplements, health effects and interactions with medications.
A readable overview of magnesium's role in the body, dietary sources, deficiency and research on magnesium and long-term health.
Videos
Dr. Mark Hyman discusses why some people may not get or absorb enough magnesium, factors that can contribute to low magnesium status, and approaches to improving magnesium intake.
Dr. Sten Ekberg discusses possible signs of inadequate magnesium and explains magnesium's roles in muscles, nerves, energy production and other functions.
Rhonda Patrick. Ph.D. takes an in-depth look at magnesium, why inadequate intake may be common, and the research connecting magnesium with metabolism, cardiovascular health, aging and chronic disease.