Magnesium Threonate vs Glycinate: Which to Take?

Pick magnesium glycinate for sleep or to correct a low intake: it is about 14% magnesium by weight, and a 4-week trial in 155 adults found it modestly eased insomnia¹. Pick magnesium L-threonate only if memory is the goal: two small placebo-controlled trials found cognitive gains^{2, 3}, but it carries about half as much magnesium per gram³.

No trial has compared the two forms head to head, so every verdict here rests on separate studies of each. For what magnesium does in general, see its evidence page.

The difference is the molecule the magnesium is bound to. Magnesium glycinate (also sold as bisglycinate) pairs magnesium with glycine, an amino acid; magnesium L-threonate pairs it with threonic acid, a breakdown product of vitamin C.

That partner sets how much magnesium each capsule holds:

• Glycinate: in a 2025 sleep trial, each 893 mg capsule supplied 125 mg of magnesium and 761.5 mg of glycine, about 14% magnesium by weight¹.
• Threonate: in a 2025 cognition trial, 2 g a day supplied 145 mg of magnesium, about 7% by weight³. The European Food Safety Authority (EFSA) puts 3,000 mg of threonate at about 250 mg of magnesium⁴.

Check the Supplement Facts panel: it declares elemental magnesium, not the weight of the whole compound⁵. A "2,000 mg" threonate serving is not 2,000 mg of magnesium.

Threonate's selling point is the brain. A 2010 rat study found it raised brain magnesium and improved learning and memory⁶. That brain-uptake advantage has not been measured directly in people.

Neither form has been shown to beat the other in humans, because no study has measured both. Forms that dissolve well in liquid are generally absorbed more completely than poorly soluble ones such as oxide⁵.

• Glycinate, positive: in a 1994 crossover trial in 12 people with part of their small intestine removed, overall absorption was about the same as oxide (23.5% vs 22.8%). In the 4 worst absorbers, glycinate did better (23.5% vs 11.8%), and it was better tolerated⁷.
• Glycinate, null: in a 2024 crossover study in 40 healthy adults on a low-magnesium diet, a single bisglycinate dose produced no significant rise in blood magnesium over 6 hours⁸.
• Threonate: EFSA reviewed a dissociation study, two rat studies and one human trial and concluded that magnesium from threonate is bioavailable⁴. It made no claim that threonate is better absorbed than other forms.

For a gentle form that is well tolerated, both work. If you want to compare glycinate with the cheaper forms, see magnesium glycinate vs citrate and magnesium oxide vs glycinate.

Glycinate has the more convincing sleep trial; threonate's results are mixed. Neither effect is large.

Glycinate for sleep

A 2025 randomized trial gave 155 adults with poor sleep 250 mg of magnesium as bisglycinate, 30-60 minutes before bed, or placebo for 4 weeks. Insomnia Severity Index scores fell by 3.9 points on glycinate and 2.3 on placebo (p = 0.049), a small effect (d = 0.2). People with low dietary magnesium seemed to benefit most¹.

The glycine may add something. It is an amino acid with both inhibitory and excitatory signalling roles in the nervous system⁹. Taking 3 g of glycine before bed improved subjective sleep and shortened the time to fall asleep in a small study¹⁰, and reduced next-day fatigue after 3 nights of restricted sleep¹¹. In rats, glycine lowers core body temperature, one proposed route to sleep onset⁹. A 250 mg glycinate dose supplies about 1.5 g of glycine, half the amount in those studies¹.

Threonate for sleep

• Positive: a 2024 trial gave 80 adults aged 35-55 with sleep problems 1 g of threonate a day or placebo for 21 days. Ring-tracked deep and REM sleep scores improved versus placebo, mostly because the placebo group declined¹².
• Mixed: a 2025 trial gave 100 adults 2 g a day for 6 weeks. Self-rated sleep-related impairment improved (p = 0.043), but sleep disturbance and restorative sleep did not, and the sleep ring found no difference in any sleep outcome³.

Magnesium for sleep in general

The wider evidence is weak. A 2021 meta-analysis of 3 trials in 151 older adults found people fell asleep 17.36 minutes sooner on magnesium, with low to very low quality evidence¹³. A 2026 review of 12 trials concluded that magnesium is not supported as a routine insomnia treatment¹⁴. Our magnesium for sleep quality and magnesium for insomnia pages grade that evidence, and glycine has its own page.

Supplements in this guide

• Magnesium
• Glycine

Threonate is the only one of the two tested for cognition, with small positive trials. Nobody has run a cognition trial of glycinate.

• Older adults with cognitive impairment: a 12-week trial in 44 people aged 50-70 found overall cognitive ability improved on threonate versus placebo (p = 0.003, d = 0.91)². The developer of the product funded the study and wrote the paper². See mild cognitive impairment.
• Healthy adults with poor sleep: in the 6-week trial of 100 adults, threonate improved the NIH Toolbox cognition composite (p = 0.043) and reaction time, with no change on a reasoning test³. The manufacturer funded it³.
• A combination product: a 30-day trial in 109 healthy Chinese adults improved memory scores, but the capsules also held phosphatidylserine and vitamins C and D, so the threonate's share is unknown¹⁵.
• ADHD: an open-label pilot in 15 adults found 47% met response criteria over up to 12 weeks, with no placebo group¹⁶. Our magnesium for ADHD page covers the wider evidence.

In 83 people with advanced cancer, threonate also slowed the rise in daily morphine needs over 90 days (21.20 vs 40.44 mg/day)¹⁷. That is a single trial in a specific setting; see magnesium for chronic pain.

Treat the threonate memory evidence as preliminary: 2 small trials of threonate alone, both short^{2, 3}. The cognitive function page lists other options with stronger data.

Neither form has a good anxiety trial, so this is a toss-up. A 2017 systematic review of 18 studies found magnesium may ease subjective anxiety in people already prone to it, but rated the evidence quality as poor¹⁸.

• Glycinate: the 4-week sleep trial found no difference from placebo on its other psychological questionnaires¹.
• Threonate: the 12-week trial in older adults could not tell whether threonate helped anxiety, because the placebo group improved strongly too². The 6-week trial found no difference in general wellbeing³.

For tension that shows up as poor sleep, glycinate's sleep data make it the practical first choice. Our magnesium for anxiety page reviews the trials in detail.

Yes, most healthy adults can take both, as long as the total stays within safe limits. No trial has tested the combination, so there is no evidence it works better than either alone.

The limit that matters is the total. The upper limit for magnesium from supplements is 350 mg a day for adults and children aged 9 and over; food magnesium does not count toward it⁵. Higher supplement doses often cause diarrhea, nausea and abdominal cramping⁵.

Some products already combine both forms; add up the elemental magnesium listed for each on the Supplement Facts panel⁵. A combined routine that stays under the limit uses the threonate trial dose but half the glycinate dose tested:

• Morning: 1 g of threonate, about 72 mg of magnesium, as taken in the 2025 cognition trial³.
• Evening: 1 g of threonate 2 hours before bed (another 72 mg)³, or 1 capsule of glycinate (125 mg)¹.

That totals about 145-200 mg of supplemental magnesium. Adding a full 250 mg glycinate dose on top of 2 g of threonate would reach about 395 mg, over the limit^{3, 1, 5}. For timing around meals and other supplements, see when to take magnesium.

The same groups should be careful with both forms, because the risks come from the magnesium, not the partner molecule.

• Kidney disease: poor kidney function reduces the body's ability to clear magnesium, raising the risk of toxicity⁵. Early toxicity symptoms such as low blood pressure, nausea and flushing usually start once blood levels exceed 1.74-2.61 mmol/L; an irregular heartbeat comes later as levels keep rising⁵. Reported toxicity cases mostly involved laxatives or antacids above 5,000 mg a day⁵. See chronic kidney disease.
• Children: the supplement upper limit is 65 mg a day at ages 1-3 and 110 mg at ages 4-8, so a single 125 mg glycinate capsule exceeds it^{5, 1}. Check with a paediatrician before giving either form.
• Pregnancy and breastfeeding: EFSA's safety assessment of threonate covered adults only and excluded pregnant and breastfeeding women⁴. Glycinate has no specific data either; ask your midwife or doctor.
• Certain medicines: magnesium reduces absorption of oral bisphosphonates for osteoporosis, and binds tetracycline and quinolone antibiotics⁵. Loop and thiazide diuretics and long-term proton pump inhibitors can lower magnesium levels, while potassium-sparing diuretics such as spironolactone reduce how much magnesium you excrete⁵. The fact sheet's interaction list stops there; if you take heart or blood pressure medicines such as diltiazem, ask your pharmacist before adding magnesium⁵.

Timing fixes most interactions. Take bisphosphonates at least 2 hours apart from magnesium, and take these antibiotics 2 hours before or 4-6 hours after it⁵. Our guide on what not to take with magnesium lists more.

Choose by goal, then by cost per milligram of magnesium:

• Poor sleep, or a low magnesium intake: glycinate. It has a 155-person trial at 250 mg before bed¹ and packs twice the magnesium per gram^{1, 3}.
• Memory or mental sharpness: threonate at the trial dose of 2 g a day split morning and evening³, with modest expectations.
• Both goals: threonate by day and glycinate at night can work, kept under 350 mg of supplemental magnesium in total⁵.
• Muscle cramps or constipation: neither form is the obvious choice; compare them with citrate in our glycinate vs citrate guide.

Food comes first if your diet is low in magnesium. Adults need 310-420 mg a day, and 48% of Americans get less than the average requirement from food⁵. Early signs of deficiency include loss of appetite, nausea, fatigue and weakness, with numbness, cramps and abnormal heart rhythms as it worsens⁵. Our list of magnesium-rich foods shows how to close the gap, and magnesium for deficiency covers when a supplement is warranted.

We searched PubMed for trials and reviews of magnesium L-threonate, magnesium glycinate and bisglycinate, magnesium for sleep and anxiety, and glycine for sleep, and read the NIH Office of Dietary Supplements fact sheet and EFSA's threonate opinion. We read 20 studies and cited 17, prioritising randomized placebo-controlled trials and systematic reviews in adults, and read the full methods of 3 trials for their exact doses and funding.

The main limit: no study compares the two forms directly, and the threonate trials are small and short. Last checked 17 October 2026.

1. Schuster J, et al. Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nat Sci Sleep. 2025;17:2027-2040. doi:10.2147/NSS.S524348 Our study summary.
2. Liu G, et al. Efficacy and Safety of MMFS-01, a Synapse Density Enhancer, for Treating Cognitive Impairment in Older Adults: A Randomized, Double-Blind, Placebo-Controlled Trial. J Alzheimers Dis. 2016;49(4):971-90. doi:10.3233/JAD-150538
3. Lopresti AL, et al. The effects of magnesium L-threonate (Magtein®) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trial. Front Nutr. 2025;12:1729164. doi:10.3389/fnut.2025.1729164
4. EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA), et al. 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 J. 2024;22(3):e8656. doi:10.2903/j.efsa.2024.8656
5. National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
6. Slutsky I, et al. Enhancement of learning and memory by elevating brain magnesium. Neuron. 2010;65(2):165-77. doi:10.1016/j.neuron.2009.12.026
7. Schuette SA, et al. Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection. JPEN J Parenter Enteral Nutr. 1994;18(5):430-5. doi:10.1177/0148607194018005430
8. Pajuelo D, et al. Comparative Clinical Study on Magnesium Absorption and Side Effects After Oral Intake of Microencapsulated Magnesium (MAGSHAPETM Microcapsules) Versus Other Magnesium Sources. Nutrients. 2024;16(24). doi:10.3390/nu16244367
9. Bannai M, et al. New therapeutic strategy for amino acid medicine: glycine improves the quality of sleep. J Pharmacol Sci. 2012;118(2):145-8. doi:10.1254/jphs.11r04fm Our study summary.
10. YAMADERA W, et al. Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. Sleep and Biological Rhythms. 2007;5(2):126-131. doi:10.1111/j.1479-8425.2007.00262.x Our study summary.
11. Bannai M, et al. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Front Neurol. 2012;3:61. doi:10.3389/fneur.2012.00061 Our study summary.
12. Hausenblas HA, et al. Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: A randomized controlled trial. Sleep Med X. 2024;8:100121. doi:10.1016/j.sleepx.2024.100121
13. Mah J, et al. Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis. BMC Complement Med Ther. 2021;21(1):125. doi:10.1186/s12906-021-03297-z Our study summary.
14. Lopresti AL, et al. Magnesium Supplementation for Sleep in Adults: A Systematic Review of Randomized Controlled Trials. J Diet Suppl. 2026;23(5):553-581. doi:10.1080/19390211.2026.2719670
15. Zhang C, et al. A Magtein®, Magnesium L-Threonate, -Based Formula Improves Brain Cognitive Functions in Healthy Chinese Adults. Nutrients. 2022;14(24). doi:10.3390/nu14245235
16. Surman C, et al. L-Threonic Acid Magnesium Salt Supplementation in ADHD: An Open-Label Pilot Study. J Diet Suppl. 2021;18(2):119-131. doi:10.1080/19390211.2020.1731044
17. Wu S, et al. Oral application of magnesium-L-threonate enhances analgesia and reduces the dosage of opioids needed in advanced cancer patients-A randomized, double-blind, placebo-controlled trial. Cancer Med. 2023;12(4):4343-4351. doi:10.1002/cam4.4922
18. Boyle NB, et al. The Effects of Magnesium Supplementation on Subjective Anxiety and Stress-A Systematic Review. Nutrients. 2017;9(5). doi:10.3390/nu9050429 Our study summary.