Why Magnesium is Good for Brain Health

The fourth most abundant mineral in your body, magnesium is essential for hundreds of enzyme reactions that affect everything from bones and blood sugar to nerves and brain cells. Yet most Americans don't think about magnesium and routinely skimp on the foods that are the best sources of it. And eating a balanced diet is the ideal way to get what you need. Magnesium may also help ease migraine and lower blood pressure.

Low levels of magnesium in the bloodstream—due to stress, diet, genetics, or other medical problems—may contribute to inflammation, which could result in chronic migraine headaches. Low magnesium may also spread pain signals by allowing calcium to dock on certain receptors in the brain. A 2016 study in International Clinical Psychopharmacology showed that low serum concentration of magnesium was an independent risk factor in migraine attacks.

People with migraine have lower levels of magnesium in the brain compared to migraine-free people. Up to 50 percent are deficient at the time of an attack. Some people may have inherited absorption problems or have irritable bowel syndrome. Alcohol also can reduce magnesium levels, which may explain why it can be a migraine trigger.

What The Research Says
Several small, older studies suggest that magnesium supplements reduce the number and pain of migraines. More recent studies, including a 2015 review in Cephalalgia and a 2018 review in the journal Headache, found limited evidence and concluded that getting magnesium from food was sufficient.

Should You Try It?
Extra magnesium won't help with migraine if your levels are in the normal range. If you have a poor diet, increasing your consumption of healthy foods that contain magnesium may help, he adds, but may not be enough if you have migraines. 

For people with chronic migraines and low magnesium levels, the recommendation is 400 milligrams of supplemental magnesium daily (in one dose or split into two doses, taken morning and evening). It helps about one-quarter of the people who try it, and if the supplement works, you probably have a magnesium deficiency. Magnesium supplements are safe for most people; the most common side effect of taking too much is diarrhea. But don't take magnesium if you have kidney disease.

High Blood Pressure
Overall, people with the highest magnesium intake have a 10 percent lower risk for stroke than those who consume the least in observational studies. These studies don't prove cause and effect, but some researchers speculate that magnesium might offer some stroke protection by helping to control blood pressure and blood sugar and by discouraging the formation of blood clots, he says.

What the Research Says
A 2016 Chinese meta-analysis of 34 magnesium/blood pressure studies, published in Hypertension, showed that taking a 368 mg magnesium supplement daily for three months lowers systolic blood pressure by two points and diastolic pressure by 1.7 points.

But magnesium doesn't work alone. It may contribute by relaxing coronary blood vessels. But it works best in a diet that is also rich in calcium and potassium and low in sodium. This combination can lower systolic blood pressure by about 11 mm Hg—as good as a pill.

Should You Try It?
It's better not to rely on any supplement to fix unhealthy food choices. Switching to a DASH diet and getting away from high-sodium, low-nutrient processed food may itself be an important part of controlling blood pressure and lowering your risk for stroke. Following a DASH or Mediterranean-type diet is optimal. Exercise, weight control, not smoking, moderate alcohol consumption, and getting treatment for conditions like high blood pressure, diabetes, and atrial fibrillation are also key.

How to Get the Magnesium You Need
The Academy of Nutrition & Dietetics and the US Department of Agriculture both recommend getting magnesium from food before relying on supplements. Magnesium-rich foods also deliver fiber and other important nutrients. And supplements can interact with other medications you may be taking, such as bone-protecting bisphosphonates as well as tetracyclines and quinolone antibiotics.