Magnesium supplements are everywhere, and one form in particular, magnesium L-threonate, is often marketed for memory and brain health. A small study in people with dementia found encouraging changes in brain scans and cognitive tests after 12 weeks. But before you add it to your cart, it helps to know what the study did and didn’t show.
Key Takeaways
- Fifteen people with mild to moderate dementia took magnesium L-threonate for 12 weeks in a pilot study led by researchers at Stanford University, presented in Innovation in Aging in 2017.
- Brain scans showed improved glucose metabolism, a measure of how much energy brain cells are using, and overall cognitive scores improved.
- Patients with higher magnesium levels in their red blood cells tended to have better cognition, though not in every case.
- The study had no placebo group, so it can’t show that the supplement caused the improvements. Larger controlled trials haven’t confirmed the results.
- Magnesium L-threonate isn’t a treatment for dementia. Talk to a doctor before giving supplements to someone with memory problems.
What the study found
Researchers at Stanford University School of Medicine, working with the Banner Alzheimer’s Institute in Arizona, gave magnesium L-threonate to 15 patients with mild to moderate dementia for 12 weeks. They then stopped the supplement for eight weeks and repeated the tests.
The team measured:
- Brain glucose metabolism, using FDG-PET scans. In Alzheimer’s disease, brain regions involved in memory typically use less glucose, so this is one way to track brain health.
- Thinking skills, including memory, attention, processing speed, verbal fluency and executive function (planning and problem-solving).
- Magnesium levels in red blood cells, which reflect the body’s longer-term magnesium status.
After 12 weeks, participants showed significant improvement in metabolism in certain brain regions and in a combined measure of overall cognitive function. Those with higher red blood cell magnesium tended to score better on overall cognition and executive function, though this wasn’t true for everyone.
Why this study needs a closer look
The results are intriguing, but there are important limits:
- It was very small, with just 15 people.
- There was no placebo group. Everyone knew they were taking the supplement. Improvements could reflect the placebo effect, people getting better at tests they’ve taken before, or normal ups and downs in dementia symptoms.
- It was a pilot study reported as a conference abstract, without full details on the dose or effect sizes.
- It hasn’t been confirmed. Nearly a decade later, no large placebo-controlled trial has shown that magnesium L-threonate improves memory or slows decline in people with dementia.
The researchers themselves called for larger, placebo-controlled trials. A 2016 placebo-controlled trial of 44 older adults with memory complaints, though not dementia, found modest improvements in overall cognitive ability with magnesium L-threonate. That study was also small.
Why magnesium L-threonate?
Magnesium plays a role in hundreds of processes in the body, including nerve signaling, memory formation and communication between brain cells. It helps regulate NMDA receptors, which are involved in learning and memory.
Magnesium L-threonate was developed by scientists at MIT, and studies in rats suggested it raises magnesium levels in the brain more effectively than other forms, and improved learning and memory in the animals. Whether it works the same way in people is still being studied.
One thing to know: only a small part of each dose is actual magnesium, so it provides less magnesium than the same amount of other forms such as magnesium glycinate or citrate. It also tends to cost more.
Getting enough magnesium
Many adults don’t get enough magnesium from their diet. Adult women need about 310 to 320 mg a day and adult men need about 400 to 420 mg. Good food sources include:
- Pumpkin seeds, chia seeds and almonds
- Spinach and other leafy greens
- Black beans, edamame and other legumes
- Whole grains like brown rice, oats and whole wheat
- Dark chocolate and avocado
Safety tips
- Talk to a doctor first, especially before giving supplements to someone with dementia, who may already take several medications.
- Stick to recommended doses. For adults, the upper limit for magnesium from supplements is 350 mg a day unless a doctor advises otherwise.
- Watch for side effects, such as diarrhea, nausea and stomach cramps.
- Use caution with kidney problems. People with reduced kidney function can build up dangerous levels of magnesium.
- Check for interactions. Magnesium can interfere with some antibiotics, osteoporosis drugs and thyroid medication if taken at the same time.
- Don’t replace prescribed dementia treatment with supplements.
The best-supported ways to protect brain health include controlling blood pressure, staying physically active, getting good sleep, treating hearing loss and staying socially connected.
This isn’t a substitute for medical advice. Talk to your doctor about what’s right for you or your loved one.
Sources:
- Wroolie TE, Watson K, Chen K, Balzafiore D, Reiman E, Rasgon N. Open label trial of magnesium L-threonate in patients with dementia. Innovation in Aging, 2017;1(Suppl 1):170. PMCID: PMC6242385
- Liu G, et al. Efficacy and safety of MMFS-01, a synapse density enhancer, for treating cognitive impairment in older adults. Journal of Alzheimer’s Disease, 2016.
- Slutsky I, et al. Enhancement of learning and memory by elevating brain magnesium. Neuron, 2010.
- Alzheimer’s Drug Discovery Foundation: Magnesium.
- National Institutes of Health, Office of Dietary Supplements. Magnesium fact sheet.