Magnesium oxide

Studies in people

• No harm found

  Blood pressure and artery stiffness²

  In people, magnesium oxide taken for 24 weeks did not change blood pressure or artery stiffness.

• Benefit

  Night-time leg cramps³

  In people with night leg cramps, magnesium oxide monohydrate cut how often and how long cramps lasted, and improved sleep.

• Benefit

  Kidney stone risk⁴

  In people, magnesium oxide lowered oxalate in urine, which matters for kidney stones, though less than magnesium citrate did.

• Open question

  Artery stiffness⁵

  Scientists do not yet know whether magnesium oxide affects artery stiffness, blood pressure or gut bacteria in people.

• Benefit

  Bone strength in girls⁶

  In girls with low magnesium diets, taking magnesium oxide daily led to slightly better hip bone buildup.

How it’s made and used

• Diet and blood minerals⁷

  In men, six days of high-magnesium diets raised ionized magnesium in the blood, but magnesium oxide did not.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least one finding in people. When most findings in people point one way, the page leans that way (“Mostly”), and every finding is still shown. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.

Expert panels that weigh all the research. Shown for context: the signal at the top does not count them.

• UN and WHO food additive experts (JECFA), 1965

  No daily limit needed (“ADI not specified”, JECFA’s term for very low toxicity).