Magnesium

Overview

Magnesium is an essential mineral (atomic symbol Mg) required as a cofactor for numerous enzymes, particularly those involved in oxidative phosphorylation¹. It is best known clinically as magnesium sulphate, the standard drug used to prevent and treat eclamptic seizures in women with pre-eclampsia, a use supported by a large Cochrane meta-analysis of 15 trials including over 11,000 women². Beyond obstetric use, magnesium supplementation has been studied for skeletal muscle cramps³, muscle strength and fitness⁴, sleep quality/insomnia in older adults⁵, and cognitive health¹, with mixed and generally modest results across these areas.

Different oral supplement forms (organic salts such as citrate versus inorganic salts such as oxide) differ in bioavailability, with organic formulations generally better absorbed and absorption itself being dose-dependent⁶. Dietary sources include magnesium-set foods such as nigari tofu, which also supplies protein and other nutrients.

Safety

Magnesium sulphate is used medically for pre-eclampsia/eclampsia prevention under clinical supervision, reflecting its status as a potent drug at treatment doses rather than a simple supplement in that context². The insomnia meta-analysis assessed adverse events as an outcome alongside sleep effects, indicating that safety monitoring is a relevant consideration with supplementation in older adults⁵. Documented interactions include calcium supplements, potassium, manganese, insulin, vitamin D, fluorides, magnesium sulfate itself, acetylcholine, and edetic acid (EDTA). Beyond these points, the brief does not provide detailed data on contraindications, specific side-effect rates, or populations who should avoid magnesium supplementation — readers with kidney disease, cardiac conduction problems, or those on interacting medications should seek individualized guidance, as this was not directly assessed in the cited studies.

Dosage

Exact dosage figures are not fully detailed in the abstracts provided, but the cited trials used oral magnesium supplementation across several contexts: for muscle cramps³, for muscle strength/fitness outcomes⁴, for insomnia in older adults⁵, and for cognitive outcomes, where randomized trials and cohort data were pooled using linear and nonlinear models against varying supplement/dietary intake levels¹. Magnesium sulphate for eclampsia prevention was administered as a medical intervention in a hospital/obstetric setting rather than as a self-directed supplement dose². Absorption is dose-dependent, and organic salt forms (e.g., citrate) were generally found more bioavailable than inorganic forms (e.g., oxide)⁶. Because the brief does not specify a single consistent milligram range across studies, no unified "studies used X mg/day" figure can be given; readers should consult the full trial texts for precise doses.

Interactions

Documented interactions from the safety data reviewed include calcium supplements, potassium, adenosine triphosphate, manganese, insulin, vitamin D, fluorides, magnesium sulfate, acetylcholine, and edetic acid (EDTA). No further mechanistic or clinical detail on these interactions is provided in the brief; anyone taking magnesium alongside these substances or medications should discuss timing and dosing with a healthcare provider.

Evidence Strength

Magnesium is one of the more thoroughly studied minerals, backed by six meta-analyses covering distinct areas: eclampsia prevention (a large, well-established use), muscle cramps, muscle strength/fitness, insomnia in older adults, cognitive health, and comparative bioavailability of supplement forms. The strength of evidence varies substantially by indication — the eclampsia-prevention data are robust and clinically established, while findings for cramps, muscle fitness, sleep, and cognition are more mixed or modest, reflecting variability in study design, population, and magnesium form used. Overall, this body of evidence is consistent enough across multiple independent syntheses to be considered strong for magnesium as a nutrient of clinical interest, though effects on specific everyday complaints (like cramps or sleep) remain less definitively proven than its core physiological and obstetric roles.