Mineral
Magnesium Glycinate
Strong EvidenceMagnesium status is causally linked to sleep, neuromuscular and cardiovascular function, and the glycinate form is chosen for tolerability rather than for any demonstrated cognitive advantage over other salts.
Recommended Dose
300–400 mg elemental magnesium daily
Timing
Evening, 30-60 min before bed
Mechanism of Action
Magnesium blocks NMDA receptors and activates GABA-A receptors, reducing neuronal excitability. Glycinate form offers high bioavailability and the amino acid glycine provides additional calming effects.
Side Effects & Safety
Generally very well-tolerated. Loose stools at high doses. Avoid in severe kidney impairment. May interact with antibiotics and bisphosphonates.
Do not use / talk to a doctor first
- Chronic kidney disease or any significant renal impairment - magnesium is cleared renally and accumulates when clearance falls
- Heart block or myasthenia gravis, without medical advice
Interactions
Tetracycline antibiotics (doxycycline, demeclocycline)
Magnesium forms insoluble complexes with them, reducing absorption of the antibiotic. Separate the doses
Source: NIH Office of Dietary Supplements, Magnesium
Quinolone antibiotics (ciprofloxacin, levofloxacin)
Same insoluble-complex problem as tetracyclines. Separate the doses
Source: NIH Office of Dietary Supplements, Magnesium
Oral bisphosphonates (e.g. alendronate)
Magnesium reduces their absorption. Take magnesium at least 2 hours before or after the bisphosphonate
Source: NIH Office of Dietary Supplements, Magnesium
Anything that impairs kidney function
Magnesium is cleared renally. When clearance falls, supplemental magnesium accumulates and hypermagnesemia becomes possible - this, not the upper intake level, is the real hazard
Source: NIH Office of Dietary Supplements, Magnesium
Pregnancy & breastfeeding
Magnesium is used in pregnancy, including medically at much higher doses under supervision. Supplementing at ordinary doses is generally considered acceptable, but agree the dose with a midwife or doctor rather than self-prescribing.
Who should avoid / see a doctor
Anyone with reduced kidney function. This page recommends 300-400 mg elemental magnesium and the tolerable upper intake level for supplemental magnesium is 350 mg/day - but that limit was set on DIARRHEA, not toxicity, and a 2023 review found no significant diarrhea difference at intakes from 128 to 1200 mg/day. So the number is not the thing to worry about: kidney function is. If yours is impaired, this dose is not safe for you regardless.
Synergies
Used in These Stacks
See Magnesium Glycinate inside a full protocol — the stack pages cover when and why to combine it.
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References
- 1.NIH Office of Dietary Supplements, Magnesium - Health Professional Fact Sheet — The tolerable upper intake level for SUPPLEMENTAL magnesium in adults is 350 mg/day. Toxicity risk rises with impaired renal function; signs generally appear once serum concentrations exceed 1.74-2.61 mmol/L. Magnesium forms insoluble complexes with tetracyclines and quinolones and reduces bisphosphonate absorption. (authoritative body)
- 2.Costello 2023, Advances in Nutrition — The 350 mg/day UL was set in 1997 with diarrhea as the limiting factor. Reviewing intervention studies from 1997-2022, seven studies at intakes of 128-1200 mg/day found no significant difference in diarrhea between intervention and control, and an FDA CAERS search found only 40 attributable gastrointestinal adverse-event cases; the authors conclude the UL should be re-evaluated. (perspective / evidence review)
