Can You Take A Magnesium Supplement Every Day? We Asked A Dietitian

Peek into any medicine cabinet, and there's a good chance you'll find at least one vitamin or supplement bottle. That wasn't the case a decade ago. According to recent industry statistics, household spending on nonprescription vitamins has nearly doubled since 2007—with mineral supplements such as calcium and magnesium leading the way.

That raises the question: Are these supplements safe to take day after day? And how much is too much? We asked a dietitian for her take on magnesium, specifically.

First, a recap on why someone might want to take a magnesium supplement in the first place: Magnesium is a really important mineral.

If you're an avid mindbodygreen reader, you've probably heard us wax poetic about it before: It facilitates hundreds of chemical reactions in the body, helping to regulate blood sugar, blood pressure, muscle and nerve function, protein building, and more, registered dietitian and spokesperson for the Academy of Nutrition and Dietetics Amy Kimberlain, RDN, CDCES, explains.* "Additionally," she says, "magnesium plays a vital role in helping maintain a healthy heart and healthy bones."*

When we eat whole foods that contain magnesium (plants need the mineral to grow, too, so leafy greens tend to be high in it), about half of it is stored in bones, and the rest goes to other body tissues or is excreted by the kidneys. In addition to greens, beans, nuts, seeds, and whole grains are also good food sources of magnesium. Kimberlain explains that if a food is high in dietary fiber, chances are it contains magnesium, too.

Even though a number of healthy foods are high in magnesium, nationally representative research estimates that nearly half of Americans don't get enough of it through diet alone. On an episode of the mbg podcast, immunologist Heather Moday, MD, said that magnesium is one of the most common deficiencies1 she sees with patients.

This is likely due in part to the rise in processed, nutrient-poor food. But even for those who eat a mostly unprocessed diet, industrial farming practices are increasingly stripping soil—and in turn, crops—of essential nutrients like magnesium. Magnesium levels also tend to decline with age, and there are racial and gender disparities2 in intake as well.

Taking a magnesium supplement is a way to make sure your body has enough of the mineral, regardless of diet or other factors.

If you are getting your magnesium exclusively from food sources, you don't really need to worry about overdoing it. But when taking the mineral in supplement form, Kimberlain says that it's important to stay below what's known as the Tolerable Upper Limit. "The Tolerable Upper Limit is the maximum daily intake that would be unlikely to cause any harmful effects on health," she explains. For magnesium, that's 350 mg for adults.

In doses lower than 350 mg, then, magnesium supplements should be safe to take daily. It totally depends on the individual, but doses above that could lead to uncomfortable side effects; mostly loose stools, but some people also experience nausea and cramping.

Where this rule of thumb gets slightly confusing is that magnesium, when taken on its own, can be difficult for us to absorb. To make it easier for the body to distribute, it's often paired with another organic compound that's more palatable. This is why there are so many different types of magnesium supplements available—each one matches the mineral with a unique partner.

"Because there are so many forms, the amount that you absorb from the supplement will vary," Kimberlain says. "Some magnesium supplements will dissolve in liquid and therefore absorb better in the gut than ones that are less soluble."

Less absorbable forms of magnesium (such as magnesium carbonate, gluconate, and oxide) might also cause more side effects—even if in doses that fall under that 350 mg mark. So any time you're taking a magnesium supplement with low bioavailability, you'll want to pay extra attention to how it's affecting digestion.

Magnesium is an essential mineral in the body that you might not be getting enough of through diet alone. Taking a magnesium supplement daily is generally considered safe—as long as the dose isn't regularly higher than 350 mg. Keep in mind that taking less bioavailable magnesium supplements might cause uncomfortable side effects like loose stools, so finding the right one for your body is key if you're going to be taking it daily.