NOW Foods Magtein Magnesium L-Threonate Review

Yes — both license verified Magtein from Magceutics, the patent holder. Same molecule, same stereoisomer, same trial-validated form that the Slutsky 2010 and Liu 2016 papers actually measured. Both bottles deliver 2000 mg of Magtein (144 mg elemental magnesium) in a 3-capsule serving — the exact Liu 2016 protocol. The chemistry inside the capsule is identical. What differs between brands is the QC stack around the molecule and the price, not the active itself.

Yes — NOW is one of the most trusted value brands in supplements, and the reason is its in-house testing. NOW runs its own analytical and microbiology labs (a real, documented operation, not outsourced paperwork), tests raw materials and finished products, and operates GMP-certified manufacturing. For a 50+ year family-owned company, that QC infrastructure is unusually deep for the price tier. It's the brand built on value-per-mg and consistency at scale — which is exactly why it earns the 'grab it off the shelf' slot in the Magtein category.

On most substances NOW is the cheapest credible option on the shelf — value-per-mg is the brand's whole identity. On this specific threonate SKU, though, it lands at ~$32/month (~$1.07 per 3-cap serving), slightly above Life Extension Neuro-Mag (~$0.93) and Jarrow MagMind (~$1.00). The reason is mostly the licensed-Magtein raw-material cost, which dominates the price of any threonate and compresses NOW's usual value edge. You're still getting the same licensed form and the same trial dose — just not NOW's typical category-low price.

3 capsules per day = 2000 mg Magtein = 144 mg elemental magnesium. That matches the Liu 2016 trial protocol exactly. Take all 3 caps in the morning, or split 2 AM + 1 mid-afternoon. The 90-capsule bottle is therefore a 30-day supply, not 90 days — divide the cap count by 3 to get the real number of days before you compare prices across brands.

Expect subtle and slow, not a same-day stimulant. Liu 2016 measured improvement on executive-function tests at 12 weeks of consistent 2000 mg Magtein/day. Subjective reports — sharper word recall, less brain fog on demanding mental work — typically land around weeks 4-6. The mechanism is structural (threonate raises brain magnesium, which regulates NMDA glutamate-receptor density and synaptic plasticity), so the benefit accrues over weeks rather than hitting in an hour. If you want acute focus, that's caffeine + L-theanine.

Yes — that's the standard protocol for anyone running L-threonate. Magtein covers central nervous system effects (cognition, memory); it delivers too little elemental magnesium to fix peripheral needs like sleep, cramps, or a deficiency. Run NOW Magtein 3 caps AM for the brain and 200-400 mg magnesium glycinate PM for sleep and general magnesium status. Don't dose threonate at night — its brain-magnesium signal can be mildly activating, the opposite of glycinate's calming effect.

1. [1] Slutsky 2010 PMID 20152124 — Enhancement of learning and memory by elevating brain magnesium. The foundational MIT paper for the L-threonate category: brain-magnesium levels rose only with L-threonate (not other magnesium forms), with downstream increases in NMDA-receptor density and synaptic plasticity. The basis for the BBB-crossing claim.
2. [2] Liu 2016 PMID 26519439 — Efficacy and safety of MMFS-01, a synapse density enhancer, for treating cognitive impairment in older adults. The human RCT anchoring the cognitive evidence: 2000 mg Magtein/day for 12 weeks improved executive function by ~9% on standardized tests vs placebo in older adults. The exact trial dose NOW's 3-cap serving matches.
3. [3] Abumaria 2011 PMID 22016520 — Effects of elevation of brain magnesium on fear conditioning, fear extinction, and synaptic plasticity. Follow-up to Slutsky 2010: L-threonate-driven brain-magnesium elevation enhanced fear extinction and prefrontal synaptic plasticity, extending the mechanistic case beyond memory toward emotional regulation.
4. [4] Held 2002 PMID 12163983 — Oral Mg(2+) supplementation reverses age-related neuroendocrine and sleep EEG changes in humans. Reference trial for peripheral magnesium sleep effects — frames why a bisglycinate is the right form for sleep and the right co-stack with Magtein, which is a different category.
5. [5] Rosanoff 2012 PMID 22364157 — Suboptimal magnesium status in the United States. Population-level evidence that a large share of US adults fall below the magnesium RDA. Context for why threonate users should still ensure peripheral magnesium adequacy via diet or a glycinate co-supplement.
6. [6] Uwitonze 2018 PMID 29480918 — Role of magnesium in vitamin D activation and function. Magnesium is the obligate cofactor for vitamin D activation. Relevant context for Magtein users — peripheral magnesium from diet or a co-supplement is still needed to support D3 utilization.