Magnesium is an essential mineral your body requires for hundreds of biochemical reactions, first isolated as a distinct chemical element by English chemist Humphry Davy in 1808. Its medicinal history predates this scientific isolation, however: magnesium sulfate, commonly known as Epsom salt after the English town where it was discovered in mineral-rich spring water, was used as a folk remedy — taken internally as a laxative and used in baths — since at least the 17th century.
Magnesium's inclusion in this Atlas reflects a similar story to melatonin: a genuinely essential nutrient, well-established in basic physiology, whose supplement-industry marketing for specific uses like sleep and anxiety has expanded well beyond what the current clinical trial evidence for those specific uses actually supports.
Magnesium supplementation has a modest evidence base across several traditionally-claimed uses, with real but consistently small effect sizes. For sleep, a meta-analysis of just 3 randomized controlled trials in 151 older adults with insomnia found magnesium reduced sleep onset latency by about 17 minutes compared to placebo — a genuine, measurable effect, but based on a notably small evidence base limited specifically to older adults. For anxiety, a systematic review found "suggestive" benefits, particularly in populations already prone to magnesium deficiency or stress, rather than a strong, general effect.
For nocturnal leg cramps, the traditional use magnesium is perhaps best known for, the evidence is genuinely mixed: one source described historical evidence as limited despite widespread popular use, while a more recent randomized, placebo-controlled multicenter trial did find a specific magnesium formulation significantly reduced cramp duration and improved sleep quality. Reviewers across these different uses consistently note that benefits appear most pronounced in people who are actually deficient, with less clear benefit in people with normal magnesium levels — making "Limited-Moderate" the honest, uses-vary rating.
Not a traditional herbal preparation — historically used as Epsom salt (magnesium sulfate) dissolved in bathwater or taken orally as a laxative; modern supplements use various magnesium salts (citrate, glycinate, oxide) with different absorption profiles.