Is magnesium worth supplementing — what does it actually do?

Magnesium deficiency or suboptimal status affects approximately 50–60% of Western men on standard dietary intakes, and magnesium participates in over 300 enzymatic reactions including ATP production, insulin receptor signaling, cardiac rhythm regulation, cortisol metabolism, and NMDA receptor modulation, making suboptimal magnesium status a driver of multiple health problems without most men knowing they have it (DiNicolantonio et al., Open Heart, 2018).

The form matters dramatically. Magnesium oxide (found in most cheap pharmacy supplements) has 4% bioavailability and primarily acts as a laxative. Magnesium glycinate, malate, and threonate have 30%+ bioavailability and cross the blood-brain barrier more effectively. Magnesium's most clinically documented effects in middle-aged men: improved insulin sensitivity (meta-analysis shows BP reduction of 2–3 mmHg in hypertensive patients), improved sleep quality in deficient individuals, and reduction in cardiac arrhythmia risk (magnesium is used intravenously in hospitals for certain arrhythmias). It is one of the few supplements a cardiologist can recommend with a straight face.

Honesty Scale: Solid (1) for magnesium's physiological roles and deficiency prevalence. Promising (2) for magnesium supplementation producing the specific health improvements at standard oral doses.

What to do: 300–400 mg magnesium glycinate or malate daily, taken with dinner or before sleep. Do not take magnesium oxide. If you are on diuretics (any type), magnesium depletion is likely and supplementation is more important.

For the full picture, read The Supplementation Deep Dive