✓ Also buy if…- You value NOW's in-house QC labs and 50+ year manufacturing track record
- You're stacking a glycinate PM and want a reliable threonate for the AM half
✗ Also skip if…- You're a drug-tested athlete — choose an NSF Certified for Sport Magtein (Momentous)
- You expect same-day cognitive sharpening — effects are subtle and slow (4-12 weeks)
NOW Foods Magtein Magnesium L-Threonate is the 'grab it off the shelf' pick in the Magtein category — the easiest licensed-Magtein bottle to find in stock, online or in a US health store, from a brand whose entire reputation is value and consistency at scale. NOW is a 50+ year family-owned manufacturer that runs its own in-house analytical and microbiology labs (a real, documented QC operation, not outsourced paperwork) on top of GMP-certified manufacturing. The Magtein inside is the same patent-verified L-threonate form as Life Extension's Neuro-Mag, delivered at the exact Liu 2016 trial dose: 2000 mg Magtein, 144 mg elemental magnesium, 3 capsules. The one honest catch is price — at ~$32/month (~$1.07 per serving) it runs slightly above Neuro-Mag and Jarrow, because the licensed-Magtein raw material dominates the cost and compresses NOW's usual value edge on this particular SKU.