Magnesium is the super mineral of the moment, touted as a sleep aid, muscle soother, anxiety easer and constipation cure.
An essential mineral involved in hundreds of biochemical reactions in the body, magnesium helps convert food into energy, supports muscle and nerve function, and helps regulate blood pressure and maintain brain health.
Yet nearly half of U.S. adults aren’t meeting the recommended dietary allowance (RDA) for magnesium, which is about 320 milligrams for women and 420 milligrams for men ages 31 and older daily, says Yasi Ansari, MS, RDN, senior dietitian at UCLA Santa Monica Medical Center.
“The RDA is what's recommended to help prevent a deficiency,” Ansari says, “but it fails to consider how much is needed for targeted needs like sleep, relaxation, digestion, muscle pain, migraines and more.”
People with digestive issues or metabolic disorders may be at higher risk of magnesium deficiency, she says. People with alcohol dependence, malnutrition and those who consume diets higher in ultra-processed foods may also be at higher risk.
A simple blood test can assess whether you’re low on magnesium. However, it’s not typically part of the regular bloodwork done during an annual physical. The test can detect severe magnesium deficiency, but it doesn’t tell the whole story since most of the body’s magnesium is stored in bones and cells, Ansari says.
Do you need a magnesium supplement?
Before considering taking a magnesium supplement, Ansari recommends trying a “food-first” approach. Foods high in magnesium include pumpkin and chia seeds, dry roasted almonds, spinach and legumes such as black beans and edamame.
One benefit to the food-first approach is there’s no limit for how much magnesium one can consume as there is with supplementation. People should not take more than 350 milligrams of magnesium supplements, Ansari says.
Magnesium can interfere with calcium absorption, and it also can interact with anesthesia: “Let your physician know if you’re taking magnesium,” she says.
Which form of magnesium is right for you?
If you do opt for magnesium supplements, choosing which one to take can be confusing, as there are at least five common varieties: citrate, glycinate, oxide, sulfate and malate. Each is absorbed differently and has different effects, Ansari says.
Magnesium citrate is generally well-absorbed and has a mild laxative effect, so it’s often used for constipation. Magnesium glycinate is also well-absorbed and used to support relaxation and sleep, she says.
Magnesium oxide, on the other hand, isn’t as well absorbed. It’s often used as a laxative or antacid. Magnesium sulfate, also known as Epsom salt, can be absorbed through the skin. It’s used for relaxation and to alleviate muscle soreness, but research on its efficacy is limited, Ansari says. Magnesium malate, which supports energy production, is sometimes used for muscle fatigue.
“The best type of magnesium depends on your goal and your tolerance,” she says, “which is why individual guidance is supportive, and working with a registered dietitian or your physician.”
