Magnesium

Magnesium is a cofactor in hundreds of enzymatic reactions, so the supplement literature spans an unusually wide range of physiological systems. The supplement comes in many salt forms with materially different absorption profiles and, in some cases, distinct tissue-distribution claims (threonate for brain penetration, glycinate for tolerability). Most randomized trials test a single form rather than comparing forms head-to-head, which means the literature is broad on outcomes but thin on form-vs-form questions a typical reader is asking.

The outcome dimensions covered most heavily include sleep quality (particularly in older adults and people with subclinical deficiency), blood pressure and other cardiovascular markers, glycemic control in type 2 diabetes and prediabetes, migraine prevention, muscle cramps and restless legs, and anxiety. Bone mineralization sits at the foundational end alongside calcium. Exercise performance and recovery are smaller research streams with moderate-quality evidence.

Demographically, the literature is weighted toward older adults (especially in sleep and bone outcomes) and toward clinical populations such as people with type 2 diabetes or migraine. Healthy young populations and women across reproductive years are less represented. Trials often do not measure baseline magnesium status (a non-trivial assay), so distinguishing a true treatment effect from correction of subclinical deficiency is often impossible from a single study.