Magnesium Glycinate vs L-Threonate: The Sleep Form, the Brain Form, and Less Magnesium Than You Think
Threonate is sold as the magnesium that reaches the brain; glycinate as the calm bedtime form. Each has a couple of small trials, and the label math shows threonate carries a little over half the magnesium per gram.
By Kymata Health Editorial Published Last checked
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Momentous Magnesium L-Threonate, 90 capsules
from Momentous
Its name matches magnesium L-threonate, one of the forms compared in our Forms table.
Label: 3 capsules: 2 g Magtein magnesium L-threonate (145 mg elemental magnesium).
Best for regular use: $37.49 on subscription vs $49.99 one-time (checked Oct 15, 2026).
Key takeaways
From 10 sources- By weight, magnesium L-threonate is about 8.3% magnesium and glycinate about 14.1%, so 2 g of threonate carries roughly 165 mg of magnesium12.
- For sleep, a 4-week trial of 250 mg/day of magnesium as bisglycinate in 155 poor sleepers cut insomnia scores slightly more than placebo (3.9 vs 2.3 points)3.
- Threonate's sleep results are mixed: better ring-measured deep and REM sleep scores at 1 g/day for 21 days, but no ring-measured difference at 2 g/day for 6 weeks45.
- For focus, a 6-week trial of 2 g/day of threonate in 100 adults improved a composite cognition score more than placebo, in a study funded by the ingredient's maker5.
- The idea that threonate reaches the brain better comes from rat studies; no human trial has compared brain magnesium between the two forms6.
What this article covers
3 evidence profilesThe evidence, graded
Pulled from the trial tables in our evidence profiles. Grades follow our evidence-grading policy.
Graded findings
4 rows- CGrade CInsomnia severityImproved Insomnia Severity Index fell 3.9 points versus 2.3 with placebo (p = 0.049); a small effect (Cohen's d = 0.2). No differences in other psychological outcomes.Magnesium glycinate · RCT · n=155 · 2025 · PMID 40918053
- CGrade CSleep qualityMixed Ring-measured deep and REM sleep scores and several self-rated daytime measures improved versus placebo. In a 6-week trial of 2 g/day (n=100), ring-measured sleep did not differ and only some self-rated measures improved, so results are mixed.Magnesium L-threonate · RCT · n=80 · 2024 · PMID 39252819
- CGrade COverall cognitive performanceImproved Greater improvement than placebo on the NIH Toolbox total cognition composite (p = 0.043) and reaction time; no difference on Raven's matrices.Magnesium L-threonate · RCT · n=100 · 2025 · PMID 41601871
- CGrade CTime to fall asleep (older adults)Improved Sleep onset latency was 17.4 minutes shorter than placebo; total sleep time rose 16 minutes but not significantly. Trials were at moderate-to-high risk of bias; evidence quality low to very low.Magnesium · Meta-analysis · n=151 · 2021 · PMID 33865376
Safety at a glance
From our Magnesium L-threonate evidence profilePublished interactions and cautions only. Each one is cited on our Magnesium L-threonate evidence profile, with its own numbered sources.
Interactions
- Oral bisphosphonates
- L-threonate supplies magnesium like any salt; NIH ODS advises a 2-hour gap from bisphosphonates.
- Tetracycline and quinolone antibiotics
- Magnesium latches onto these drugs. Take them 2 hours before your threonate dose or 4–6 hours after it.
- Levothyroxine
- In a crossover study of 15 healthy adults, a 1 mg dose of levothyroxine given together with 243–301 mg of magnesium cut thyroxine absorption by 12% with magnesium aspartate and by 7% (not significant) with magnesium citrate. The authors advise spacing levothyroxine apart from magnesium products. Threonate itself was not tested.
- Potassium-sparing diuretics
- Reduce kidney excretion of magnesium.
Who should be careful
- Kidney problems
- Threonate's magnesium is still cleared by the kidneys, so impaired function means a toxicity risk.
- High intakes and digestive effects
- At high doses expect diarrhea, nausea or abdominal cramps. Only the elemental magnesium in threonate counts toward 350 mg/day; laxative or antacid doses over about 5,000 mg/day have caused toxicity.
- Pregnancy and breastfeeding
- No threonate-specific pregnancy data. EFSA's 2024 safety opinion covered adults except pregnant and lactating women. ODS RDAs are 350–400 mg/day pregnant and 310–360 mg/day lactating, with pill magnesium capped at 350 mg.
- Children
- For children, supplement magnesium is capped at 65 mg/day (1–3) and 110 mg/day (4–8).
First, the label math
Magnesium is always bound to a partner molecule. US Supplement Facts panels declare elemental magnesium, the magnesium itself, rather than the weight of the whole compound7.
Threonate binds magnesium to L-threonic acid and is about 8.3% magnesium by weight1. Glycinate binds it to glycine and is about 14.1%2. So the 2 g/day of threonate used in trials delivers roughly 165 mg of magnesium, while the same 2 g of glycinate would carry about 282 mg12. Only the elemental amount counts toward the 350 mg/day adult upper limit for magnesium from supplements7.
Glycinate: a small, real sleep signal
In a 2025 randomized trial, 155 healthy adults reporting poor sleep took 250 mg/day of magnesium as bisglycinate or placebo3. After 4 weeks, insomnia scores fell 3.9 points versus 2.3 with placebo, a small effect, and other psychological outcomes did not differ3.
Across forms, a meta-analysis of 3 trials in older adults with insomnia found people fell asleep 17.4 minutes faster with magnesium, on low-quality evidence8. In a small study of 12 people who had part of their small intestine removed, glycinate was also better tolerated than magnesium oxide9.
Threonate: the brain pitch, and what trials found
The brain story starts in rats, where magnesium L-threonate raised brain magnesium and improved learning and memory tasks6. That has not been measured directly in people.
In humans, a 6-week trial gave 2 g/day of threonate or placebo to 100 adults aged 18 to 45 who were unhappy with their sleep5. The composite cognition score improved more than with placebo, a modest margin, and the funder supplied the product and helped design the study5. An earlier 12-week trial of a threonate-based formulation in 44 adults aged 50 to 70 with cognitive impairment also reported better composite scores10.
For sleep, a 21-day trial of 1 g/day in 80 adults with sleep problems found better ring-measured deep and REM sleep scores than placebo4. The larger 6-week trial found no difference in ring-measured sleep and gains on only some self-rated measures5.
Which one fits you
- Mainly want help settling at night, on a budget: glycinate has the larger single sleep trial and carries more magnesium per gram23.
- Mainly curious about focus and memory: threonate is the only one of the two with cognition trials, and they are small, with the larger recent one funded by the ingredient's maker510.
- Take both: add up the elemental magnesium from every product and stay within 350 mg/day from supplements unless a clinician advises otherwise7.
- Have kidney problems, or take bisphosphonates or tetracycline or quinolone antibiotics: NIH advises caution with magnesium and spacing the doses, so check with your clinician7.
Quick answers
Common questions
3 answersCan I take magnesium glycinate and L-threonate together?
There are no trials of the combination. If you do, total the elemental magnesium on both labels; supplements should stay within 350 mg/day for adults7.
Is magnesium L-threonate worth choosing over glycinate?
Keep reading
Full evidence profiles
Every graded study, studied doses, interactions and safety- MineralMagnesium L-threonateMagnesium salt of L-threonic acid (about 8% magnesium by weight), studied for cognition and sleep in small RCTs.CGrade C
- MineralMagnesium glycinateMagnesium bound to the amino acid glycine (about 14% magnesium by weight); studied in small trials for sleep, asthma/COPD and mood.AGrade A
- MineralMagnesiumEssential mineral involved in over 300 enzyme systems; sold as glycinate, citrate, threonate, malate, taurate, oxide and other salts.AGrade A
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3 capsules: 2 g Magtein magnesium L-threonate (145 mg elemental magnesium); 30 servings
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3 capsules: 2,000 mg Magtein magnesium L-threonate providing 144 mg elemental magnesium; 30 servings
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References
10 sources. Numbers in the text link here.
Sources cited in this article
10 sources- 1Magnesium L-threonate (CID 45489777): C8H14MgO10, MW 294.50PubChem, NIH, 2026
- 2Magnesium glycinate (CID 84645): C4H8MgN2O4, MW 172.42PubChem, NIH, 2026
- 3Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled TrialNat Sci Sleep, 2025 · PMID 40918053
- 4Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: A randomized controlled trialSleep Med X, 2024 · PMID 39252819
- 5The effects of magnesium L-threonate (Magtein) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trialFront Nutr, 2025 · PMID 41601871
- 6Enhancement of learning and memory by elevating brain magnesiumNeuron, 2010 · PMID 20152124
- 7Magnesium: Fact Sheet for Health Professionals (updated January 6, 2026)NIH Office of Dietary Supplements, 2026
- 8Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-AnalysisBMC Complement Med Ther, 2021 · PMID 33865376
- 9Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resectionJPEN J Parenter Enteral Nutr, 1994 · PMID 7815675
- 10Efficacy and Safety of MMFS-01, a Synapse Density Enhancer, for Treating Cognitive Impairment in Older Adults: A Randomized, Double-Blind, Placebo-Controlled TrialJ Alzheimers Dis, 2016 · PMID 26519439
Magnesium L-threonate and other dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Talk to your clinician or pharmacist before starting a supplement, especially if you take prescription medicines. Product links on this page are paid partner links.