Last updated: October 2026
Magnesium L-threonate is magnesium bound to threonic acid, a form developed to raise magnesium levels in the brain. Small, mostly industry-funded trials suggest it may help memory and sleep quality, but the evidence is early. It provides little magnesium per capsule, typically around 144mg from a 2g daily dose, and costs more than other forms.
This guide covers what the research actually shows, how much to take and when, how long it takes to work, side effects, and how it compares with glycinate and citrate.
What is magnesium L-threonate?
It’s a magnesium salt of L-threonic acid, which is a breakdown product of vitamin C. It was developed by researchers at MIT and is sold under the trade name Magtein. In rat studies, it raised magnesium levels in the brain more than other forms and was linked with better learning and memory. That’s where its reputation as the “brain magnesium” comes from.
The catch is that threonate is a large molecule, so only about 7 to 8% of the compound is actual (elemental) magnesium. Compare that with roughly 14% for glycinate and 16% for citrate.
Benefits: what the research shows
There are only a handful of human trials, and all of the main ones were funded by companies that make or sell Magtein. They’re promising, but small.
| Trial | Who and how much | What it found |
|---|---|---|
| Memory in older adults (2016) | 44 adults aged 50 to 70 with memory complaints, 12 weeks | Better overall cognitive scores than placebo |
| Memory in healthy adults (2022) | 109 adults aged 18 to 65, 2g a day of a threonate and phosphatidylserine formula | Better memory and cognition scores than placebo, especially in older participants |
| Sleep (2024) | 80 adults aged 35 to 55 with sleep problems, 1g a day for 3 weeks | Better deep and REM sleep scores on a sleep-tracking ring, and better mood and energy on questionnaires |
| Cognition and sleep (2025) | 100 adults aged 18 to 45 unhappy with their sleep, 2g a day for 6 weeks | Better cognition and reaction time than placebo; the overall sleep score wasn’t significantly better |
| Adult ADHD (2021) | 15 adults, open-label (no placebo) | About half improved, but with no control group this can’t show cause |
Our take: threonate is one of the more interesting magnesium forms, but it hasn’t been compared head to head with cheaper forms in people, and independent trials are still missing. Whatever the form, magnesium contributes to the normal functioning of the nervous system, normal psychological function and the reduction of tiredness and fatigue.
Does magnesium L-threonate get into the brain?
That’s the main idea behind it. In a 2010 study at MIT, rats given magnesium L-threonate had higher magnesium levels in the fluid around the brain and performed better on learning and memory tests than rats given other forms. It’s an important finding, but it was in animals. In people, nobody has directly measured brain magnesium after taking threonate; the human trials measured memory, sleep and mood scores instead.
Magnesium L-threonate for focus, mood and anxiety
- Focus and memory: the 2025 trial in adults aged 18 to 45 found better overall cognitive scores, especially working and episodic memory, and faster reaction times than placebo after 6 weeks.
- Mood and energy: in the 2024 sleep trial, people taking 1g a day for 3 weeks also reported better mood, energy, alertness and productivity on questionnaires.
- Anxiety: there are no trials of magnesium L-threonate specifically for anxiety. Research on magnesium and anxiety in general is covered in magnesium for anxiety.
All of these trials were small and funded by the makers of Magtein, so treat them as early signals. If you’re struggling with concentration or low mood, see how to focus better, brain fog and, if it’s affecting daily life, speak to your GP.
Dosage: how much to take
Trials used 1 to 2g of magnesium L-threonate a day, which provides roughly 72 to 144mg of elemental magnesium. Most products split this into two or three capsules. Always follow the label.
For context, the NHS says adults need 300mg (men) or 270mg (women) of magnesium a day, and most can get it from food. Taking 400mg or less a day from supplements is unlikely to cause harm. If you take more than one magnesium product, add up the elemental magnesium from each. See magnesium for sleep for dose by goal.
When to take it
In the trials, people often took part of the dose in the morning and the rest in the evening, or all of it in the evening when sleep was the focus. Take it with food if it upsets your stomach. Consistency matters more than the exact time. See best time to take magnesium.
How long does it take to work?
Trial effects were measured after 3 to 12 weeks: sleep changes at 3 weeks, memory changes at 6 to 12 weeks. So give it at least a month before judging it. Magnesium levels in the body build up gradually rather than working like a sleeping tablet. See how long magnesium takes to work and how long magnesium stays in your body.
Side effects and who should avoid it
- It was well tolerated in trials. Possible side effects include headache, drowsiness and, less often than with other forms, loose stools.
- Speak to your GP first if you have kidney disease, because magnesium can build up.
- Magnesium can affect how some medicines are absorbed, including some antibiotics and bisphosphonates for osteoporosis. Ask your pharmacist about timing.
- If you’re pregnant or breastfeeding, check with your midwife or GP before taking a supplement.
Is it suitable for children?
There’s no good research on magnesium L-threonate in children, so we wouldn’t give it to a child without advice from a GP or paediatric dietitian. Children’s magnesium needs are much lower than adults’ and are usually met by food. See magnesium for kids.
Threonate vs glycinate vs citrate
| L-threonate | Glycinate (bisglycinate) | Citrate | |
|---|---|---|---|
| Elemental magnesium | About 7 to 8% | About 14% | About 16% |
| Main interest | Memory and brain | Evening routine, gentle on the stomach | Good absorption, can loosen stools |
| Cost per mg of magnesium | High | Moderate | Low |
| Evidence | A few small, industry-funded trials | Mostly evidence for magnesium in general | Well studied for absorption |
Our Magnesium Glycinate Sleep Complex doesn’t contain threonate. It combines magnesium bisglycinate and citrate with glycine, L-theanine and botanicals, giving 148mg of magnesium per serving. We chose those forms for an evening drink that’s gentle on the stomach and gives a meaningful amount of magnesium. For a full comparison, see magnesium glycinate vs citrate vs threonate and types of magnesium.
How to choose a magnesium L-threonate supplement (UK)
- Check the elemental magnesium, not just the compound. 2g of magnesium L-threonate gives only about 144mg of magnesium.
- Look for the branded ingredient (Magtein) if you want what was used in the trials.
- Watch the serving size. Trial doses usually mean 3 or 4 capsules a day, which affects how long a tub lasts and the real cost.
- Avoid “proprietary blends” that don’t say how much of each form is inside.
- Add up all your magnesium. If you also take another magnesium product, keep the total from supplements to 400mg a day or less, as the NHS advises.
- Buy from a UK seller who lists the full ingredients and can show test results.
Can you take L-threonate with other forms of magnesium?
Yes. Some people take threonate earlier in the day and glycinate in the evening. There are no trials comparing combinations, so the main rule is to add up the elemental magnesium from every product and stay within 400mg a day from supplements. Combining forms is mainly about cost and how your stomach feels. See magnesium glycinate and magnesium side effects.
FAQs
What is magnesium L-threonate good for?
It was developed to raise brain magnesium levels. Small trials suggest it may help memory and sleep quality, but the research is early and mostly industry funded.
How much magnesium L-threonate should I take?
Trials used 1 to 2g a day, giving roughly 72 to 144mg of elemental magnesium. Follow the label and keep total supplement magnesium to 400mg a day or less.
How long does magnesium L-threonate take to work?
Trials measured changes after 3 to 12 weeks. Give it at least a month of daily use before deciding if it helps.
Is magnesium L-threonate better than glycinate for sleep?
There are no head-to-head trials. Threonate has a couple of small sleep studies; glycinate gives more magnesium per gram and is gentle on the stomach.
Can children take magnesium L-threonate?
There’s no good research in children. Speak to a GP before giving any magnesium supplement to a child.
When should I take magnesium L-threonate?
Many people split it between morning and evening, or take it all in the evening for sleep. Taking it consistently matters more than the time.
Is magnesium L-threonate good for anxiety?
There are no trials of threonate specifically for anxiety. One small sleep trial reported better mood and alertness. Magnesium in general contributes to normal psychological function.
Does magnesium L-threonate cross the blood-brain barrier?
In rats, it raised magnesium in the fluid around the brain more than other forms. This hasn’t been measured directly in people.
Can I take magnesium L-threonate with magnesium glycinate?
Yes, as long as the total elemental magnesium from all your supplements stays at 400mg a day or less.
Does magnesium L-threonate cause headaches?
Headache and drowsiness have been reported as possible side effects. Stop taking it and speak to a pharmacist if they continue.
Sources
- Liu G et al. Efficacy and safety of MMFS-01 for treating cognitive impairment in older adults. J Alzheimers Dis, 2016.
- Zhang C et al. A Magtein, magnesium L-threonate, based formula improves brain cognitive functions in healthy Chinese adults. Nutrients, 2022.
- Hausenblas HA et al. Magnesium L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems. Sleep Med X, 2024.
- Lopresti AL et al. The effects of magnesium L-threonate on cognitive performance and sleep quality in adults. Front Nutr, 2025.
- Surman C et al. L-threonic acid magnesium salt supplementation in ADHD: an open-label pilot study. J Diet Suppl, 2021.
- Slutsky I et al. Enhancement of learning and memory by elevating brain magnesium. Neuron, 2010.
- NHS. Vitamins and minerals: magnesium.
This guide is general information, not medical advice. Evopure makes the Magnesium Glycinate Sleep Complex, which does not contain threonate.
