≈2 g/day of L-threonate (which provides only ≈144 mg of elemental magnesium).
Magnesium L-threonate (a form that crosses into the brain) improved global cognition and almost normalized executive function in adults aged 50-70 with cognitive impairment (12-week randomized trial, n=44; large effect). Promising, but a small study funded by the manufacturer.
See the study (trial (small RCT)) →In rats, raising brain magnesium with magnesium L-threonate improved short- and long-term learning and memory, and increased connections in the hippocampus. It is the preclinical study that led to testing it in people; in animals, not directly extrapolable.
View the study (study) →⏱ 2 min read
Magnesium L-threonate is a form of magnesium chelated with L-threonic acid (a metabolite of ascorbic acid), developed specifically to optimize the entry of magnesium into the central nervous system; it is distinguished from other forms of magnesium (citrate, glycinate, oxide, malate) by a particular pharmacokinetic characteristic: in animal studies it produced significantly greater increases in brain magnesium concentrations than the other forms, a property that has motivated its development and marketing specifically for neurological and cognitive indications.
Unlike most forms of magnesium, whose main clinical application is the correction of systemic deficiency or cardiovascular/muscular indications, magnesium L-threonate (Magtein is the original brand name backed by the landmark studies) is positioned specifically as "brain magnesium," with modest but promising clinical data on cognitive function in older adults, anxiety, and sleep modulation with a distinctive cognitive profile.
The most studied indication is improving cognitive function in older adults with subjective impairment: a randomized trial published in 2016 with 44 adults aged 50-70 showed significant improvements in global cognitive function, especially processing speed and working memory, with magnesium L-threonate supplementation at 1,500-2,000 mg/day (corresponding to approximately 144-192 mg of elemental magnesium) for 12 weeks; the effects were equivalent to "rejuvenating" cognitive function by approximately 9 years.
In anxiety and mild sleep disorders with a cognitive component, several small studies have documented subjective improvements with supplementation, an indication consistent with the preferential brain profile.
Magnesium L-threonate is significantly more expensive per milligram of elemental magnesium than other forms (citrate, glycinate, malate), and it supplies relatively small amounts of systemic magnesium; for systemic indications (correcting a nutritional deficiency, muscular and cardiovascular benefits), the cheaper forms are clearly preferable; magnesium L-threonate justifies its higher cost in specifically cognitive or neurological indications where preferential brain entry is the clinical goal.
The dose studied is 1,500-2,000 mg/day of magnesium L-threonate (providing 144-192 mg of elemental magnesium), divided into 1-2 doses with or without food; typical commercial products contain 1,000-2,000 mg of Magtein per dose; the cognitive effect appears gradually and requires at least 8-12 weeks for evaluation.
Generally well tolerated at the doses studied; the adverse effects described are rare and mild (mild digestive discomfort); the general precautions for magnesium apply: people with serious kidney failure should avoid high doses; those taking drugs that may interfere with magnesium absorption or excretion should consult; in pregnancy and breastfeeding, specific data as a supplement are limited, although magnesium in nutritional amounts is safe; commercial products without specific Magtein (generic "magnesium threonate") may not provide exactly the same pharmacokinetic characteristics studied in the landmark clinical trials.
Information, not medical advice. Scientific evidence reflects the quality of the studies.