Does low magnesium lead to muscle cramps?

It’s a widely held belief that imbalances in electrolytes — in particular magnesium — may be involved in the etiology of muscle cramps — sudden involuntary contractions of one or more muscles that lead to sharp pains. However, the theory that muscle cramps are related to electrolyte or water imbalances has been questioned, although some evidence suggests that exercise-associated muscle cramps may have their origin in excessive losses of water and sodium during exercise.^[1]

The idea that low magnesium levels play a role in muscle cramping comes from evidence that reduced magnesium levels are correlated to higher rates of muscle cramping during pregnancy^[2][3] and in people who experience leg cramps at night.^[4] Severe magnesium deficiency has also been associated with a higher incidence of muscle pain and cramping.^[5][6]

However, a meta-analysis published in 2020 concluded that it is unlikely that magnesium supplementation in any form can reduce idiopathic nocturnal or exercise-induced muscle cramps. The available evidence on a reduction in pregnancy-associated muscle cramps was conflicting.^[7]