Full profile
| Also known as | Magnesium bisglycinate, Chelated magnesium |
|---|---|
| Best for | Sleep-onset support (evening use) · Stress and relaxation · Gentle magnesium repletion in a non-laxative form |
| Evidence grade | Grade C — Limited — early or small human trials |
| Studied dose range | ~200–350 mg elemental magnesium/day (the key sleep RCT used 250 mg). Watch the compound-weight trap: bisglycinate is only ~14% elemental magnesium, so ~250 mg elemental is ~1,800 mg of the salt — studies and labels must state elemental. The supplemental upper limit is 350 mg/day elemental (food magnesium is not counted). |
| Time to effect | Not acute; sleep/stress benefits in trials appeared over roughly 1–4 weeks of daily use. |
| Best form | Magnesium bisglycinate (glycinate) — better GI tolerance and far less laxative effect than magnesium oxide. For a cognition-specific claim, magnesium L-threonate is the differentiated form, but its evidence is only Emerging. |
| Food sources | Leafy greens, Nuts and seeds (pumpkin, almonds), Legumes, Whole grains, Dark chocolate |
Evidence, honestly graded
Limited but real. A 2025 RCT of magnesium bisglycinate in adults with poor sleep (Schuster 2025, n=155) found a statistically significant but small reduction in insomnia severity — larger in people with low dietary intake — and one author is tied to a nutraceutical-funded CRO, so it is sponsor-adjacent. A meta-analysis of oral magnesium for insomnia in older adults (Mah 2021) found sleep onset roughly 17 minutes shorter than placebo but rated the evidence low-to-very-low quality, and a systematic review of magnesium for anxiety/stress (Boyle 2017) found only a suggestive benefit in anxiety-prone groups on poor-quality trials. Graded C. General-magnesium cognition evidence is weaker still — the crisp line versus L-threonate is claim architecture, not magnesium content.
See the full grading rubric — study type, replication, population match, and dose adequacy — in The Evidence Standard.
Side effects
- Diarrhea, nausea, or abdominal cramping (dose-dependent; less than oxide or citrate)
Who should avoid it or check first
- Kidney impairment or chronic kidney disease without medical supervision (risk of magnesium build-up)
- Heart block or bradycardia at high intakes without review
Interactions
- Reduces absorption of oral bisphosphonates, tetracycline and quinolone antibiotics, and levothyroxine — separate doses by a few hours
- PPIs and loop/thiazide diuretics alter magnesium status — discuss with a clinician
Stacks well with
- Glycine (evening slot)
- Melatonin (evening slot)
Use caution stacking with
- Daytime stimulant-free focus actives — this is an evening ingredient
What to look for on a label
- Declare elemental magnesium, not compound weight — Health Canada specifically flags magnesium for dosing-error risk.
- Honest regulatory note: Health Canada's multi-vitamin/mineral monograph does NOT permit sleep, stress, or cognition claims for magnesium — only structural/functional ones (e.g. normal nervous-system and muscle function). A sleep/calm positioning needs its own product-specific evidence dossier. Products above 350 mg/day elemental must carry a "may experience diarrhea" statement.
References
- Schuster J, Cycelskij I, Lopresti A, Hahn A (2025). Nature and Science of Sleep, 17:2027–2040Small but significant reduction in insomnia severity versus placebo; larger in people with low dietary magnesium.
- Mah J, Pitre T (2021). BMC Complementary Medicine and Therapies, 21(1):125Modest reduction in sleep-onset latency on a low-quality evidence base.
- Boyle NB, Lawton C, Dye L (2017). Nutrients, 9(5):429Suggestive reduction in subjective anxiety in vulnerable groups only; low-quality evidence.
Grades and studied doses are our conservative reading of the human research, shown for education. They are not product claims, and a studied dose is not a recommended dose.
See how Magnesium Glycinate compares on grade, dose, and goal in the Evidence Explorer.
