Magnesium glycinate vs Magnesium L-threonate
Which is better for sleep?
Short answer
For sleep, pick glycinate, but expect little: both are rated Limited, and glycinate's one trial found a small drop in insomnia scores after four weeks, while L-threonate's main sleep trial missed its primary insomnia measure and two other trials found no difference on sleep questionnaires.
L-threonate is sold on memory, where it is also rated Limited: two small trials funded by companies selling it found modest gains, and an independently funded trial at a lower dose did not. It also carries little magnesium, about 145 mg in a 2 g dose against the 250 mg used in the glycinate trial.
The form with a positive sleep trial: insomnia scores fell 3.9 points on 250 mg against 2.3 on placebo
Sold for memory, with two small company-funded positive trials; its sleep trial missed its main measure
Side by side
| Attribute | Magnesium glycinate | Magnesium L-threonate |
|---|---|---|
| Evidence for sleep | Limited (poor sleep / insomnia symptoms) | Limited (poor sleep / insomnia symptoms) |
| Best for | Poor sleep | Memory and thinking |
| How fast | 4+ weeks | 4+ weeks |
| Typical form | Bisglycinate, 250 mg elemental Mg | L-threonate 1.5–2 g (110–145 mg Mg) |
| Main caution | Loose stools above about 250–350 mg supplemental Mg | Kidney disease: magnesium can build up, ask first |
| Magnesium per daily dose | 250 mg elemental Mg (the trial dose) | About 75 mg (sleep trial); 145 mg from 2 g |
| Who funded the trials | A university; one author has industry ties | Companies selling it (sleep and both memory trials) |
| Memory and thinking | Not covered by our entry | Limited: two small company-funded trials, 6–12 weeks |
Which should you pick?
Choose Magnesium glycinate if
- sleep is your main reason for taking magnesium and you want the form with a small positive trial
- you want a daily dose of about 250 mg elemental magnesium, the amount the glycinate trial used
- you can give it about 4 weeks before judging whether it helps
Choose Magnesium L-threonate if
- memory and thinking are your main concern and you accept the evidence is limited and mostly company-funded
- you can give it at least 6 weeks, the shortest of the memory trials, before judging it
- you are an adult and not pregnant or breastfeeding, the groups the EU safety assessment covered
Questions people ask
Can I take magnesium glycinate and magnesium l-threonate together?
Neither entry tests the two together or records any interaction for either, so whether combining them is safe or more useful is unknown, not cleared.
Both count towards the same supplemental magnesium limits (EU 250 mg, US 350 mg a day, set to avoid diarrhoea): the 250 mg glycinate trial dose already reaches the EU limit and 2 g of L-threonate adds about 145 mg, and people with kidney disease should ask a doctor first because magnesium can build up.
Is magnesium glycinate or L-threonate better for sleep?
Glycinate, narrowly. In its one placebo-controlled trial, 250 mg of magnesium as bisglycinate lowered insomnia scores by 3.9 points against 2.3 on placebo after four weeks, a small effect.
In the main L-threonate sleep trial, 1 g a day for three weeks did not improve the primary insomnia score more than placebo, though some secondary measures favoured it, and two other trials found no difference on sleep questionnaires.
Is magnesium L-threonate better for memory?
It is the form sold for memory, but the evidence is limited. Two small trials funded by companies selling it found modest gains on combined test scores after 6 to 12 weeks, one only just statistically significant, while an independently funded trial at 1.2 g a day found no difference on a cognitive screening test.
The idea that it raises brain magnesium comes from rat studies; we found no human study that measured it.
How much magnesium do you get from each?
Check the elemental magnesium on the label, not the compound weight. The glycinate trial used 250 mg of elemental magnesium a day; L-threonate is only about 7.2–8.3% magnesium, so 2 g gives about 145 mg, and EFSA's adult maximum of 3 g supplies about 250 mg, the EU upper limit for supplemental magnesium.
Sources (6)
- Randomised controlled trial Schuster J, Cycelskij I, Lopresti AL, Hahn A. Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nature and Science of Sleep. 2025.
- Randomised controlled trial Hausenblas HA, Lynch T, Hooper S, Shrestha A, Rosendale D, Gu J. Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: A randomized controlled trial. Sleep Medicine: X. 2024.
- Randomised controlled trial Lopresti AL, Smith SJ. The effects of magnesium L-threonate (Magtein) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trial. Frontiers in Nutrition. 2025.
- Randomised controlled trial Liu G, Weinger JG, Lu ZL, Xue F, Sadeghpour S. Efficacy and Safety of MMFS-01, a Synapse Density Enhancer, for Treating Cognitive Impairment in Older Adults: A Randomized, Double-Blind, Placebo-Controlled Trial. Journal of Alzheimer's Disease. 2016.
- Regulator opinion EFSA Panel on Nutrition, Novel Foods and Food Allergens. Safety of magnesium L-threonate as a novel food pursuant to regulation (EU) 2015/2283 and bioavailability of magnesium from this source in the context of Directive 2002/46/EC. EFSA Journal. 2024.
- Regulator opinion Scientific Committee on Food, European Commission. Opinion of the Scientific Committee on Food on the Tolerable Upper Intake Level of Magnesium. 2001.
Reader notes
Experiences and questions from readers, read by an editor before they appear. They are personal accounts, not evidence, and are not medical advice.