Magnesium supplements stop muscle cramps
Mostly falseThe Claim
Many people believe that nightly leg cramps are a sign of low magnesium and that a magnesium supplement will prevent them.
Origin
Magnesium is involved in muscle contraction and nerve signalling, and magnesium products are widely marketed for cramp relief.
What Science Says
A 2020 Cochrane review of 11 randomized trials (735 people) found that in older adults with idiopathic nocturnal leg cramps, magnesium did not meaningfully reduce cramp frequency compared with placebo (about -0.18 cramps per week, not significant; moderate-certainty evidence). Evidence for pregnancy-related cramps is conflicting, and no trials have tested exercise-associated cramps. Magnesium was linked to more minor side effects, mainly diarrhoea.
Verdict
Mostly False