Edward Saltzman, the academic dean at the Friedman School of Nutrition Science and Policy and an associate professor at both the Friedman School and Tufts University School of Medicine, explains what scientists understand about magnesium, what remains uncertain, and offers guidance on how to take it responsibly.
Magnesium is an essential mineral found naturally in a variety of foods, including nuts, seeds, legumes, whole grains, and leafy green vegetables. It plays a critical role in supporting healthy muscle and nerve function, as well as maintaining a well-functioning cardiovascular system.
Most people in the U.S. get enough magnesium through their regular diet. When a deficiency does occur, it’s often linked to underlying health conditions, such as gastrointestinal disorders that impair nutrient absorption.
You may have heard that magnesium supplements can offer a wide variety of benefits, from improving bone health to even helping you sleep. But like many vitamins and supplements, some uses of magnesium are strongly supported by scientific evidence, while others are not.
Evidence linking magnesium to improvements in health relies on epidemiologic studies that survey many health indicators for large amounts of people over time. There are far fewer of what researchers call ‘intervention trials,’ which test magnesium as a solution for specific health problems. The available epidemiologic research shows that there are sometimes correlations between magnesium and certain health outcomes, but it can be difficult to prove that magnesium itself is responsible for those health outcomes without many more intervention trials.
Magnesium and Bone Health
Let’s start with the bone health claim. Magnesium is important for bone formation, and some studies have found that both men and women with higher magnesium intake had healthier bones. Plus, there is some evidence that increasing magnesium intake can increase bone density in postmenopausal and elderly women (who are at the highest risk of developing osteoporosis, a bone-weakening disease).
Next, you may have seen magnesium promoted as a sleep aid in drinks, supplements, and even TikTok trends. We know that magnesium has a role to play in neurotransmitter release and muscle relaxation, so there may be some truth to the idea that magnesium can be a sleep aid. But the science surrounding magnesium and sleep is still uncertain.
If you’re struggling to sleep, try trusted sleep hygiene methods, such as maintaining a consistent bedtime and reducing screen time and caffeine, before turning to magnesium supplements. If you want to try magnesium as a sleep aid, stay as close as you can to about 300 milligrams per day, which is a little less than the recommended daily intake for adults.
Magnesium and Heart Health
There is also limited evidence that magnesium can improve cardiovascular health. Studies have found that magnesium supplements can result in small decreases in blood pressure, while adding foods high in magnesium via the DASH diet lowers blood pressure even more. But that may be due to the broad benefits of eating more food such as fruits, vegetables, legumes, and whole grains rather than the benefits of magnesium itself. Multiple observational studies also indicate that higher magnesium intake can reduce the risk of heart disease and stroke.
The risk of taking magnesium supplements is low. Side effects mainly include diarrhea, and there are no known long-term effects of taking magnesium supplements. However, very large doses (around 5,000 milligrams per day) can be fatal. If you’re thinking of giving your child magnesium supplements, discuss it with their pediatrician first.
Supplements are not medications, so dosages aren’t regulated by the Food and Drug Administration. If you want to start taking magnesium supplements, look for brands with a label from United States Pharmacopeial Convention (USP), a trusted third-party organization that certifies supplements.