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Supplements

Magnesium

A mineral needed for muscle and nerve function, blood sugar and blood pressure, and making protein, bone, and DNA. Most people get enough from food; supplements have a daily upper limit and drug interactions.

Traditional use

A nutrient rather than a folk remedy, found in legumes, nuts, seeds, whole grains, leafy greens, fortified cereals, and milk products. Supplements are a modern addition; magnesium is also in some laxatives and heartburn products.

What studies show

  • Limited

    Sleep: very little research. A 2021 review of 3 small, low-quality studies suggested it may help older adults with insomnia fall asleep slightly faster; a 2022 review of 9 studies found conflicting results and called for large, well-designed trials.

  • Limited

    Blood pressure and heart disease: supplements might lower blood pressure, but only slightly. Higher dietary magnesium goes with lower heart disease and stroke risk, though other nutrients may explain part of that.

  • Limited

    Type 2 diabetes: higher dietary magnesium goes with lower risk of developing it; whether supplements help people who already have diabetes is still being studied.

  • Limited

    Bone density: higher intakes go with higher bone mineral density, and more magnesium might help older women's bone density; more research is needed on fractures and osteoporosis.

  • Limited

    Migraine: several small studies found supplements can modestly reduce migraine frequency; ODS says to use magnesium for this only under a health care provider's care.

Be careful of

Cautions

  • AmountFood magnesium needs no limit. Supplement and medication magnesium should stay below the daily upper limit, 350 mg for adults and less for children, unless a provider advises otherwise. High intakes cause diarrhea, nausea, and cramping; extreme intakes can cause irregular heartbeat and cardiac arrest.
  • InteractionBisphosphonates and some antibiotics absorb poorly when taken too close to magnesium; diuretics can raise or lower magnesium loss; long-term prescription reflux and ulcer medicines can lower blood magnesium; very high zinc doses can interfere with magnesium absorption.
  • ConditionPeople with Crohn's or celiac disease, type 2 diabetes, or long-term alcoholism, and older people, are more likely to run low.
  • Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or have a medical condition.

Sources

  1. Magnesium - Consumer (opens in a new tab) · NIH ODS · read September 15, 2026
  2. Sleep Disorders and Complementary Health Approaches: Usefulness and Safety (opens in a new tab) · NCCIH · read September 15, 2026

Reviewed September 15, 2026.