What is magnesium?
Magnesium is a mineral your body uses in hundreds of chemical reactions, from making energy and building proteins to letting muscles and nerves relax.
Think of magnesium as a stagehand in a theater. You rarely notice it, but without it, the scenery doesn't move, the lights don't change and the actors can't finish the show.
Why it matters for aging
Over half of US adults don't get enough magnesium from food, largely because processed foods contain little of it. The best sources are seeds, nuts, beans, leafy greens, whole grains and dark chocolate.
Supplements come in many forms that differ mainly in how well they're absorbed and how much they affect the gut. People with kidney disease should avoid magnesium supplements unless their doctor approves, because their kidneys can't clear the excess.
A common myth
Magnesium supplements are a reliable cure for poor sleep.
The evidence for sleep is weak: in a review of trials in older adults, people fell asleep about 17 minutes faster, with low-quality evidence overall. Magnesium helps most when you're actually not getting enough.
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Updated Nov 9, 2026 · All terms