Two years ago, 27-year-old Tricia Mangan, a U.S. Ski Team Member, had her blood tested. The Dartmouth College 2021 graduate and two-time Olympian was deficient in magnesium. After talking with her training team, Mangan started taking a magnesium supplement. The result was an improvement in her sleep quality and heart rate variability (HRV), both of which she monitors with wearable technology to optimize her athletic performance.
“The two things I look at most in terms of performance are HRV and my deep sleep, what is called NREM (non-rapid eye movement) sleep. The magnesium had an immediate impact on both,” she says.
Like Mangan, many now champion the benefits of magnesium as consumer demand for magnesium supplements grows, along with demand for supplements overall.
But while nutritionists and other medical professionals recognize the vital but not yet fully understood role that magnesium plays in our health, they also advise that you talk to your healthcare practitioner before taking any supplements, including those that contain magnesium.
Possible benefits of magnesium supplements
Women’s health
Donelan recommends magnesium supplements to her female patients for a number of conditions. “I use magnesium not infrequently,” she says. She finds it a safe option for pregnant women experiencing recurrent migraines and sometimes for women with other ailments who have trouble sleeping. “I would say the data is not great on sleep, but if I have a patient who has headaches, constipation and sleep disturbances–which a lot of women in menopause or perimenopause do–it can sometimes help with all of those things. There's also some data to suggest that magnesium can help with dysmenorrhea, or painful periods, which I have used it for.”
Gut health
Magnesium is the main ingredient in many antacids and laxatives. For patients who suffer from chronic idiopathic constipation, Michael A. Curley, MD, FRCPC, first introduces basic measures such as increasing dietary fiber and fluids per 2023 guidelines, but he will suggest magnesium supplements or polyethylene glycol-based preparations such as Miralax as first-line stool softeners. “Many of our patients are interested in holistic and natural preparations and therefore prefer magnesium supplementation,” he says, cautioning that there is limited medical evidence to support that preference, which is still considered an off-label recommendation. “Magnesium is generally considered safe although caution should be used in patients with kidney disease due to the risk of developing high magnesium levels. Magnesium has also been reported to have benefits for a variety of health issues such as insomnia and migraines which many of our patients also suffer from,” he says.
Children’s health
Magnesium is one of the most common supplements that parents ask Hand about and hand is supportive of the use of magnesium supplements in several instances. These include headaches, GI issues like constipation and irregularity, and sometimes sleep and anxiety, though he says the studies are not definitive. Again, he recommends parents talk to their provider first.
Heart health
Min says there is a lot to learn about magnesium and heart health. Among possible benefits of magnesium are decreased LDL (bad cholesterol) and an improvement among patients with ventricular tachycardia (the opposite of atrial fibrillation or AFib). But while low magnesium levels have been associated with fatigue, muscle spasms, weakness, and other symptoms, Min remains cautious about prescribing magnesium, stressing that studies on the relationship between heart conditions and magnesium are often nuanced and inconclusive. “A lot of those symptoms can also be other things,” he says. Still, he says magnesium definitely has a role in cardiac rhythms and how our heart contracts. “I do think that clinicians when they have patients with a constellation of symptoms should consider checking magnesium levels, which isn't a typical part of our standard metabolic panel.” In addition, a number of medications used to treat AFib or heart disease are associated with the depletion of some minerals, including magnesium.
Magnesium is an essential nutrient and mineral in our body
Dartmouth Health Obstetrician Gynecologist Emily A. Donelan, MD, explains: “The reality is magnesium is involved in so many important reactions that if you are deficient, all kinds of bodily functions do not operate as well.”
Among the 300-plus reactions involving magnesium are those associated with energy production, muscle and nerve function, blood pressure regulation, and heart rhythm. Magnesium also plays a role in bone structure.
We don’t get enough magnesium
There is a lot we do not know about how magnesium works in our body. What we do know is that most people are deficient in it.
“A lot of people aren't eating enough magnesium in general because magnesium is in foods that are often limited in people's diets,” says Interim Clinical Nutrition Manager at Dartmouth Hitchcock Medical Center and Registered Dietitian Nutritionist, Kelli Boi, MS, RDN, LD, CNSC.
Many blame that deficiency on the over-processing of foods, changing farm practices and altered diets.
Our gut linings are damaged from everything we're doing in our environment and everything we're exposed to, including pesticides,” says Donelan. “One result is our food has much less magnesium than it probably did a hundred years ago, and we're not absorbing it the way we used to.”
What the studies say
Yet, doctors remain cautious about the use of supplements, including magnesium. One reason is the lack of published, peer-reviewed studies on how supplementing can measurably improve health outcomes. Another is the possible negative effects of taking supplements—even if as in the case of magnesium—they are relatively few.
The National Institutes of Health(NIH) points to studies that suggest that high doses of magnesium from dietary supplements or medications can result in diarrhea accompanied by nausea and abdominal cramps. Some medications also have the potential to interact with magnesium supplements in other adverse ways.
David B. Min, MD, Cardiovascular Medicine, Dartmouth Hitchcock Medical Center, points to some studies that suggest that magnesium can impact blood pressure and kidney function.
The safer way to increase magnesium intake
Concerns like these are why food rather than supplements is usually the recommended magnesium source, in part because you can’t get too much of it through diet.
“My preference is good food. I mean you can take magnesium until the cows come home, but if you eat nothing but Doritos and Coke, magnesium is not going to do much for you,” says Pediatric Nephrologist and Pediatric Integrated Medicine Specialist, Dartmouth Health Children’s, Matthew Hand, DO
Foods with the most magnesium tend to contain dietary fiber, Boi says. These include green leafy vegetables such as spinach, legumes, nuts, seeds, and whole grains.
Talk with your provider before beginning any supplement
But because making up for a magnesium deficit through food can be difficult, some doctors support taking supplements in some instances, though with caveats.
“We always have to have a really rational approach when we look at supplements and ask, 'What is the evidence'?” says Donelan, who recently completed a one-year, functional and integrative medicine training program with Aviva Romm, MD. “If there is evidence to support use and very minimal to no harm, then it is incredibly reasonable for a patient to try that supplement. But if there is a supplement that has any concerning risk profile, I'm very anti.”
Donelan and others note, too, that the supplement market is not regulated by the U.S. FDA (Food and Drug Administration). “We don't always know what supplements have in them, and so we have to be really careful about the companies that we're choosing, the products that we're buying, and making sure that they’re third-party tested.”
One of the websites Donelan recommends for looking at data on supplements is examine.com. She says the NIH also has a useful integrative medicine site. Hand adds that it can be helpful to check the label on the supplement bottle to see if the brand has been approved by the United States Pharmacopeia (USP) or Consumer Labs.
If you think magnesium might benefit you
Before recommending magnesium, some providers may do a blood test, with the added caveat that blood carries only a small percentage of your body’s overall magnesium.
Remember, too, that magnesium comes in different forms. How your body absorbs and tolerates these forms can vary.
One supplement form that Donelan commonly recommends is magnesium glycinate because it does not have laxative properties. Magnesium citrate is popular and has a mild laxative effect. Both are highly bioavailable, meaning they are well absorbed and more efficiently used by your body.
Another form is magnesium oxide which, due to poor solubility and bioavailability, is released slowly over time. Magnesium hydroxide, an ingredient in Milk of Magnesia, is popular for its strong laxative quality.
Why has magnesium helped Mangan?
Min does not know Mangan. He cannot say whether the magnesium supplement is decreasing extra heartbeats, helping her recover from lactic acid buildup, allowing her to better metabolize sugars and improve her energy levels, increasing her calcium levels, impacting the ability of her heart muscles to contract, or somehow influencing her heart’s overall electrical system.
“I think that our cells live in such an exquisite balance. Whether or not magnesium is the end-all, be-all solution, I think that story is not yet fully told. But I'm glad she is seeing a benefit and associating that with magnesium,” he says.