Magnesium is an essential mineral many adults under-consume. The strongest case is correcting a shortfall — those starting low see the clearest gains, while the already well-supplied gain little. Best-supported benefits are modest lowering of blood pressure and better blood-sugar control. It is inexpensive, widely available, and well tolerated, with loose stools the most common complaint. (Full Review)

Protocol

Dose

200–400 mg/day

Elemental magnesium from a well-absorbed organic salt

Form

Glycinate

Citrate for repletion, malate for daytime, L-Threonate for cognitive aims

Timing

Evening, with food

Split into two doses to improve absorption and reduce laxative effect

Time to effect

Blood pressure & metabolic

Weeks–months

Includes repletion of tissue stores

Relaxation

Days

Calming effects can appear early

Laxative effect

Hours

At higher doses of poorly absorbed salts

Benefits

High: Blood pressure reduction, correction of magnesium deficiency

Medium: Improved glycemic control & insulin sensitivity, migraine prophylaxis, lower risk of type 2 diabetes

Low: Improved sleep quality, constipation relief, mood & depressive symptoms, bone mineral density support, cardiovascular & all-cause mortality

Speculative: Cognitive protection & brain aging, exercise performance & recovery

Contraindications

Severe kidney impairment (eGFR < 30 mL/min/1.73m²)

High-degree heart block

Myasthenia gravis

Pregnancy (high doses, supervised only)

Key Interactions

Quinolone/tetracycline antibiotics, bisphosphonates, levothyroxine

Magnesium-containing antacids and laxatives

High-dose calcium and zinc, vitamin D

Blood-pressure-lowering supplements (potassium, taurine, fish oil), relaxants (glycine, L-Theanine)

Proton pump inhibitors, loop/thiazide diuretics

Risk & Side Effects

High: Gastrointestinal effects

Medium: Hypermagnesemia & toxicity in renal impairment

Low: Reduced absorption of co-administered drugs, additive hypotension & sedation

Speculative: Cardiac conduction effects at extreme intake

Monitoring

Marker	Target	Why
Serum magnesium	2.0–2.6 mg/dL	Detects overt deficiency or excess
Red blood cell magnesium	5.5–6.5 mg/dL	Better reflects tissue stores
Serum potassium	4.0–4.5 mEq/L	Low magnesium drives stubborn low potassium
Serum calcium	9.2–10.0 mg/dL	Magnesium affects calcium and its regulating hormone
Kidney function (eGFR)	≥ 90 mL/min/1.73m²	Determines safety of supplementation
HbA1c	< 5.4%	Tracks any metabolic benefit
25-hydroxy vitamin D	40–60 ng/mL	Vitamin D and magnesium are interdependent

Cadence: Retest at 8–12 weeks after starting, then every 6–12 months

Qualitative Assessment

Sleep quality and time taken to fall asleep
Frequency of muscle cramps, twitches, or restless legs
Daytime energy and exercise recovery
Mood and resilience to stress
Bowel regularity (and any loose stools signaling too high a dose)
Frequency and severity of migraine, where relevant

Magnesium for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment