Compound or practice · Supplement
Magnesium
A cofactor in 300+ reactions that a large fraction of adults under-consume — real, modest benefits for sleep, blood pressure, and migraine.
- Overall grade
- Grade B
- Last revised
- 4
- graded outcomes
- 0
- references listed
A structured monograph in Prometheus's bundled library. Its grades are the monograph's own reading of the evidence, not a peer-reviewed review.
1 at grade A · 5 at grade B · 1 at grade C — 7 graded rows
What is known
Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.
- Correcting low statusEvidence grade A
Common dietary shortfall
Moderatehigh
- Blood pressureEvidence grade B
~2–3 mmHg in meta-analysis
Smallhigh
- Migraine prophylaxisEvidence grade B
Recommended by some guidelines
Moderatemixed
- Subjective sleepEvidence grade B
Modest, larger if deficient
Smallmixed
Conditions
How the entry reads its effect on diagnosed conditions: the direction first, then the grade. Never a substitute for the person who treats you.
- Migraine May improveEvidence grade BProphylactic; 400–600 mgGrade B
- Hypertension May improveEvidence grade BSmall additive loweringGrade B
- Insomnia May improveEvidence grade CSubjective improvementGrade C
What is uncertain
Read off the same rows as above. Nothing here is added that the entry does not itself record.
- Studies disagree: Migraine prophylaxis (mixed agreement); Subjective sleep (mixed agreement).
- Caution with Blood-pressure medications: Mild additive blood-pressure lowering.
Interactions
Documented pairings with supplements and medicines. A medicine on this list is a conversation for whoever prescribes it.
Blood-pressure medicationsCaution
Mild additive blood-pressure lowering.
PPIsDepletes a nutrient
Prolonged PPI use can drive magnesium clinically low.
LevothyroxineMind the timing
Binds thyroid hormone in the gut — separate by 4 hours.
AntibioticsMind the timing
Chelates quinolones/tetracyclines — separate by 2+ hours.
Vitamin DWorks together
Required cofactor for activating vitamin D.
GlycineWorks together
The evening sleep-onset pairing.
The evidence in words
What it is
Magnesium is an essential mineral concentrated in bone and inside cells, where it is a cofactor for over 300 enzymes including every reaction that uses ATP. Intakes below the requirement are common on Western diets. Forms differ mainly in absorption and bowel tolerance: glycinate and citrate absorb well, oxide is mostly a laxative, and L-threonate is marketed for the brain.
How it works
As a counter-ion to ATP and a gate on NMDA receptors and calcium channels, magnesium tunes neuromuscular excitability, vascular tone, and insulin signaling. Low status nudges all of these toward over-excitation — cramps, higher blood pressure, poorer sleep.
What the evidence shows
Correcting low status is grade A. On top of that, meta-analyses support small reductions in blood pressure, a modest improvement in subjective sleep, and genuine prophylactic benefit in migraine. Effects are real but not dramatic, and larger in people who started deficient. It is cheap, safe, and one of the more defensible everyday supplements.
How to use it
200–400 mg elemental magnesium in the evening from glycinate (gentle) or citrate (also helps regularity). Avoid oxide unless a laxative effect is the goal. Threonate is dosed for CNS uptake and costs more per milligram.
Safety & interactions
Very safe with normal kidneys; excess is excreted, with loose stools the main sign of too much. In kidney impairment it can accumulate dangerously. It binds several drugs in the gut (see timing interactions). Vitamin D — Required cofactor for activating vitamin D. Glycine — The evening sleep-onset pairing. levothyroxine — Binds thyroid hormone in the gut — separate by 4 hours. antibiotics — Chelates quinolones/tetracyclines — separate by 2+ hours. ppi — Prolonged PPI use can drive magnesium clinically low. antihypertensives — Mild additive blood-pressure lowering.
Bottom line
One of the better-value supplements: 200–400 mg glycinate or citrate in the evening. Expect modest help with sleep, blood pressure, and migraine — most in those who were low to begin with.
How it is used
As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.
- Sleep / general
- 200–400 mg elemental as glycinate, evening.
- Regularity
- Citrate; oxide is laxative-forward.
Goes with
Questions people ask
Which form?
Glycinate for calm/sleep and gentleness; citrate if you also want regularity; skip oxide except as a laxative; threonate only if you specifically want the CNS-uptake angle and accept the cost.
Related reading
Entries that share this one's tags or conditions.
- Magnesium for Blood pressureEvidence grade B — ~2–3 mmHg in meta-analysisEvidence grade B
- Magnesium for MigraineEvidence grade B — Prophylactic; 400–600 mgEvidence grade B
- Magnesium for Correcting low statusEvidence grade A — Common dietary shortfallEvidence grade A
- Magnesium for HypertensionEvidence grade B — Small additive loweringEvidence grade B
Sources
This entry lists no references of its own.
Last revised . A grade is this entry's reading of the evidence, not medical advice.