What is magnesium?
Magnesium is an essential mineral and electrolyte involved in ATP synthesis, muscle contraction and relaxation, protein synthesis, and nerve function. It is the fourth most abundant mineral in the body. Surveys consistently show inadequate dietary magnesium intake in the general population, with athletes at higher risk due to increased losses through sweat.
How it works
Magnesium acts as a cofactor for enzymes involved in energy metabolism, particularly those required for ATP production. It regulates calcium channels in muscle cells, playing a direct role in muscle relaxation after contraction. It also modulates NMDA receptors and GABA activity in the brain, contributing to its effects on sleep quality and stress response.
What the research says
- Magnesium supplementation improved sleep efficiency and reduced cortisol in older adults with insomnia (Abbasi et al., 2012)
- Athletes supplementing magnesium showed improved performance in swimming, cycling, and running compared to placebo (Matias et al., 2021)
- Reduced muscle cramping and improved recovery in deficient individuals
- Low magnesium status is associated with elevated inflammatory markers and reduced insulin sensitivity
Effective dose
200–400mg elemental magnesium daily, taken in the evening with food. The form matters significantly for absorption — magnesium glycinate and malate have superior bioavailability compared to magnesium oxide, which is cheap, poorly absorbed, and acts as a laxative at higher doses. Check labels for elemental magnesium content, not total compound weight.
What to check on the label
Look for magnesium glycinate, malate, or citrate. Avoid magnesium oxide — it is the most common form in cheap supplements but has poor bioavailability. The label should state elemental magnesium content. 200mg of elemental magnesium from magnesium glycinate requires approximately 1000mg of the compound.
Safety
Safe at recommended doses. Excess magnesium is excreted by healthy kidneys. High doses of poorly absorbed forms (particularly oxide) cause diarrhoea. Individuals with kidney disease should consult a doctor before supplementing as the kidneys regulate magnesium excretion.