Can You Take A Magnesium Supplement Every Day? We Asked A Dietitian
Peek into any medicine cabinet these days, 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.
Why take a daily magnesium supplement?
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, the National Institutes of Health 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, M.D., said that it's one of the most common deficiencies she sees, up there with vitamin B and zinc.
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 disparities in uptake as well.
Taking a magnesium supplement is a way to make sure your body has enough of the mineral to protect against conditions like heart disease, high blood pressure, type 2 diabetes, and other blood sugar diseases, etc.
A healthy daily dose.
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. Anything above that could lead to uncomfortable symptoms; mostly diarrhea, 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 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.
The deep and restorative sleep you've always dreamt about*
If you're consuming any magnesium supplement daily (again, under 350 mg!), taking it on a regular schedule is a move. Since different forms of magnesium act differently in the body, they should be taken at different times. mbg's magnesium+ supplement, for example, combines magnesium with the highly bioavailable amino acid glycine and is designed to help promote deeper, more restorative sleep.* (Initial research has found that magnesium glycinate supplementation can improve insomnia and promote better sleep quality.*) It has 120 mg/serving and is best taken one to two hours before bed. If you're taking a higher dose that is less bioavailable, though, consuming the supplement earlier in the day with a meal would help mitigate the chance of uncomfortable side effects.
Finally, Kimberlain says to keep in mind that "magnesium supplements can interact and/or interfere with some medicines, i.e., bisphosphonates (used to treat osteoporosis), antibiotics, and diuretics. It's recommended that you discuss the need for a dietary supplement with your health care provider prior to taking one."
The bottom line.
Magnesium is an essential mineral in the body that many people don't get enough of through diet alone. Taking a magnesium supplement daily is generally considered safe—as long as the dose isn't higher than 350 mg. Keep in mind that taking less bioavailable magnesium supplements might cause uncomfortable side effects like diarrhea, though, so finding the right one for your body is key if you're going to be taking it daily.