Magnesium L-threonate occupies a unique niche in the magnesium supplement market. While other forms like glycinate and citrate are taken primarily for general magnesium repletion, threonate is marketed almost exclusively for cognitive support and sleep — driven by research suggesting it crosses the blood-brain barrier more effectively than other magnesium compounds. That positioning comes with a significant price premium: threonate products typically cost 3–5× more per day than glycinate or citrate at equivalent magnesium doses. Whether that premium is justified depends on why you're supplementing.
This page ranks magnesium L-threonate supplements by cost per month at the standard research dose of 2,000mg/day (compound weight — delivering about 144mg of magnesium). Products are ranked using data extracted directly from Supplement Facts label images, not product titles or listing descriptions — which often state dosages differently than what the label shows. All prices are current Amazon prices updated weekly.
Prices as of April 26, 2026. Prices update daily; this page updates monthly. For current prices and full interactive filters, see the Magnesium Threonate compare page.
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Magtein® vs generic magnesium L-threonate. Most products on the market use Magtein®, the patented form developed at MIT. This is the form used in all published clinical trials. A handful of generic alternatives exist, but the research base doesn't extend to them. If brain bioavailability is your reason for choosing threonate over other forms, Magtein is the safer bet. That said, magnesium L-threonate is a defined chemical compound — generics aren't necessarily inferior, just untested independently.
Compound weight vs magnesium content. Labels typically read "Magnesium (as Magnesium L-Threonate) 144mg" — that 144mg is the actual magnesium content (called elemental magnesium: the weight of the magnesium atom itself, stripped of the threonate molecule it's bound to). The standard research dose is 2,000mg of the full compound (magnesium L-threonate), which delivers approximately 144mg of magnesium. This page ranks by compound weight at 2,000mg/day to match the studied dose. Don't compare the 144mg magnesium figure against glycinate or citrate products without accounting for this difference — those forms have different compound-to-magnesium ratios.
Serving size matters more than capsule count. Most threonate products require 3 capsules per serving to reach the 2,000mg dose. A 90-capsule bottle that looks like a 3-month supply is actually only 30 days. Check the serving size before comparing prices — the cost-per-month calculation on this page normalizes for this automatically.
This is not a general magnesium supplement. Threonate delivers only about 144mg of magnesium per day at the standard dose — well below the 300–400mg daily recommended intake. If your goal is correcting a general magnesium deficiency, glycinate or citrate delivers more magnesium at a fraction of the cost. Threonate makes sense specifically for people targeting cognitive support or sleep quality and willing to pay the premium for the brain-bioavailability mechanism.
Third-party testing. Look for NSF, USP, or independent lab verification. Several major threonate brands (NOW, Life Extension, Sports Research) disclose third-party testing. Given the price premium in this category, testing transparency is a reasonable baseline expectation.
Evidence for magnesium L-threonate is moderate and growing. Three randomized controlled trials — all using the Magtein® form — have shown improvements in cognitive performance and sleep quality in healthy adults. A large-scale genetic study has provided additional support for a causal relationship between brain threonate levels and cognitive function. However, the clinical trial evidence is still limited: sample sizes are modest (50–109 participants), study durations are short (3–6 weeks), and all trials to date have been funded by the patent holder. No head-to-head trials compare threonate against other magnesium forms for cognitive outcomes. The standard dose is 2,000mg/day (compound weight), typically split between morning and evening. Side effects are generally mild — occasional drowsiness or headache, especially when starting. There are no known serious safety concerns at standard doses.