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Magnesium threonate, also called magnesium L-threonate, is magnesium bound to threonic acid, a breakdown product of vitamin C. It was developed by researchers who wanted a form that raises magnesium levels in the brain, and it is sold under the brand name Magtein in supplements marketed for memory and focus. The evidence is early: the strongest findings come from rats, and the human trials so far are small, short and mostly linked to companies that develop or sell the ingredient. Here is what the research shows, what is known about safety and how to read a label.
Peptide Labs sells no magnesium threonate supplement, and this article does not recommend any product. It is general information, not medical advice.
Key Takeaways
- Magnesium threonate is magnesium bound to L-threonic acid, a vitamin C metabolite.
- It contains the least magnesium by weight of the common forms, about 8%.
- Memory findings come from rat studies and a few small human trials of weeks to months.
- Most human trials were funded by, or used products from, companies behind the ingredient.
- Side effects in trials were mostly mild, and general magnesium cautions still apply.
What is magnesium threonate?
Like every magnesium supplement, magnesium threonate pairs the mineral with a partner molecule. Here the partner is L-threonic acid. A 2022 paper in Nutrients describes it as a metabolite of vitamin C (ascorbic acid) found naturally in human blood, urine and the brain, and in small amounts in some foods.
Magtein is the trademarked ingredient behind most magnesium threonate products. Because threonic acid is a fairly large molecule, magnesium makes up only about 8% of the compound by weight, calculated from its formula; a 2024 trial reported about 7.5% for the commercial ingredient. That is far less than in citrate or oxide, so a product needs more powder to supply the same magnesium. The Supplement Facts panel should list the magnesium itself, which is the number to compare across products.
Why researchers studied it: the brain magnesium question
Magnesium in the blood does not pass easily into the fluid around the brain. The developers of the compound noted, in a 2016 paper, that raising blood magnesium in humans by up to 300% changes magnesium in the cerebrospinal fluid by less than 19%. They designed magnesium threonate to raise brain magnesium when taken by mouth.
The founding study, published in Neuron in 2010 by a team at the Massachusetts Institute of Technology, reported that magnesium threonate raised brain magnesium in rats and improved their performance on learning and memory tests. Rats given the compound also had more synaptic markers, signs of connections between nerve cells, in the hippocampus, a brain region involved in memory. These were animal experiments, and they do not show that the same happens in people.
Magnesium threonate benefits: what human trials found
Claims about magnesium threonate benefits for memory, focus and sleep rest on a handful of small human studies. The table summarizes the main ones; none is large or long, and they used different people, products and measures.
| Study | Who and how long | Main finding | Funding or company link |
|---|---|---|---|
| Liu 2016 | 44 adults aged 50 to 70 with memory complaints, 12 weeks | Composite thinking score improved vs placebo | Funded by the developer, Neurocentria |
| Surman 2021 | 15 adults with ADHD, up to 12 weeks | About half met response criteria | Open label, no placebo group |
| Zhang 2022 | 109 healthy adults aged 18 to 65, 30 days | Higher memory test scores with a combination formula | Product supplied by Magceutics |
| Hausenblas 2024 | 80 adults aged 35 to 55 with sleep complaints, 21 days | Some sleep scores better vs placebo | Funded by AIDP |
Memory and thinking
In the 2016 trial, published in the Journal of Alzheimer’s Disease, 51 adults aged 50 to 70 with self-reported memory and concentration problems, plus sleep trouble and anxiety, were randomly assigned to a magnesium threonate product or placebo; 44 finished the 12 weeks. A composite score of thinking skills improved more with the product than with placebo. Effects on sleep and anxiety could not be judged because the placebo group improved too. The study was funded and co-designed by Neurocentria, the company developing the product, and its lead author worked there; the authors named the small single-site sample and short length as limitations.
A 2022 trial at Nanjing Medical University gave 109 healthy Chinese adults a capsule combining Magtein with phosphatidylserine and vitamins C, D and B6, or a starch placebo, for 30 days. Scores on a standard Chinese memory test rose more with the formula, especially in older participants. Because the product contained several ingredients, the trial cannot show what magnesium threonate did on its own. The authors reported no competing interests, and the capsules were supplied by Magceutics.
An open-label 2021 pilot study at Massachusetts General Hospital gave magnesium threonate to 15 adults with ADHD; about half met the study’s definition of response. With no placebo group, expectation effects cannot be ruled out, and the authors called for larger double-blind trials. None of these studies shows that magnesium threonate can stop or reverse memory loss or replace care for ADHD. If you notice changes in memory or attention, see your doctor.
Sleep
A 2024 trial gave 80 adults with self-reported sleep problems Magtein or placebo for 21 days. Both groups improved on a standard insomnia questionnaire, with significant differences between groups in weeks 2 and 3, and ring-tracker scores for deep and REM sleep were better with Magtein. The trial was funded by AIDP Inc., and the authors noted a strong placebo effect. Our magnesium and sleep guide compares this study with trials of other forms.
Magnesium threonate vs other forms
We found no human trial that directly compared how well magnesium threonate and other forms raise magnesium in the brain; the brain-specific claim rests on rodent research. For general magnesium intake, forms such as citrate and glycinate deliver more magnesium per gram. Our comparison of magnesium glycinate vs citrate explains those forms, and our magnesium malate guide covers another form with limited human data.
Magnesium threonate side effects and safety
Magnesium threonate side effects in trials were mostly mild. In the 2016 study there were no serious adverse events; stomach and bowel complaints affected 20% of the product group and 15% of the placebo group, a difference that was not statistically significant, and events judged possibly related to the study product were actually more common with placebo. The 2022 trial reported the formula was well tolerated. These studies lasted weeks to months, so long-term safety has not been studied.
- General magnesium limits apply: ODS sets the upper limit for magnesium from supplements and medicines at 350 milligrams a day for ages 9 and older; higher intakes commonly cause diarrhea, nausea and cramps. Our magnesium oxide guide explains the limit.
- Kidney disease: magnesium can build up to dangerous levels when kidneys work poorly; ask your doctor first.
- Medicines: magnesium can interfere with some antibiotics and bisphosphonates, and some diuretics and acid reducers change magnesium levels. Our magnesium timing guide covers spacing; ask your pharmacist.
- Pregnancy, breastfeeding and children: no trials of magnesium threonate have been published in these groups, so ask your clinician.
How to read a magnesium threonate label
- Check the magnesium amount: the label should show magnesium from magnesium L-threonate, not only the weight of the Magtein ingredient.
- Look at the whole formula: many brain-support products add other ingredients, so read the full panel and ask about interactions.
- Read claims carefully: phrases such as “supports memory” are structure and function claims that FDA does not review before sale, and they come with the supplement disclaimer.
- Look for testing: our guide to third-party tested supplements explains what independent seals check.
If you are comparing ingredients marketed for focus, our lion’s mane guide covers a mushroom with similarly early human evidence.
Frequently Asked Questions
What is magnesium threonate?
It is magnesium bound to L-threonic acid, a vitamin C metabolite. It was developed to raise brain magnesium and is sold mainly under the Magtein brand.
What are the proven magnesium threonate benefits?
None are firmly established. Rat studies and a few small human trials of weeks to months reported memory or sleep effects, mostly with company funding or company-supplied products.
What is Magtein?
Magtein is the trademarked magnesium L-threonate ingredient used in most products and in the main human trials. About 7 to 8% of it by weight is magnesium.
Is magnesium L-threonate better absorbed than other forms?
The claim that it reaches the brain better comes from rodent research. No human trial has compared brain magnesium across forms.
What are magnesium threonate side effects?
Trials reported mostly mild stomach and bowel complaints, at rates similar to placebo. General magnesium cautions apply, especially for kidney disease and some medicines.
Can magnesium threonate help with memory loss?
No trial has shown it can stop or reverse memory loss. If you notice memory changes, see your doctor for an evaluation.
Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider before starting any supplement, especially if you take medicines, have kidney disease or are pregnant. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Magnesium Glycinate vs Citrate: How the Types of Magnesium Compare, Magnesium Malate: Benefits, Research, Side Effects and Labels, Magnesium for Sleep: What the Research Shows and Which Forms Were Studied.