Product Comparison
Compare the three magnesium forms head-to-head — absorption, tolerance, elemental dose per dollar, and honest context for each. The form decision is a tolerability-and-budget decision, not a mechanism decision: all three deliver the same Mg²⁺ ion.
At a glance
Thorne Magnesium Bisglycinate
NOW Magnesium Citrate
Magtein Magnesium L-Threonate
Multi-dimensional comparison
Multi-dimensional Comparison
| Metric | 🏆Thorne Magnesium Bisglycinate Thorne | NOW Magnesium Citrate NOW Foods | Magtein Magnesium L-Threonate Magtein (various licensees) |
|---|---|---|---|
| Delivery Form | Capsule | Capsule | Capsule |
| Strength | 200 mg elemental | 200 mg elemental | 144 mg elemental (2 g Magtein) |
| Servings / Container | 120 | 180 | 90 |
| Retail Price | $24.00 | $11.99 | $39.95 |
| Cost / Serving | $0.20 | $0.07BEST 💰 | $0.44 |
| Overall Score | 85/100 | 84/100 | 72/100 |
| 3rd-Party Testing | None | None | None |
| Vegan Friendly | ✓ Yes | ✓ Yes | — No |
Did you know?
Glycinate absorption
The best-tolerated form at higher doses — the one that makes 400–600 mg/day achievable without GI revolt. The glycine chelate protects the mineral through the gut and contributes its own calming neurotransmitter.
Citrate value
The best absorption-to-cost ratio — ~30% bioavailable at a fraction of the glycinate price. Mild laxative effect at 400+ mg/day, tolerable at 200–400 mg. The budget workhorse.
L-Threonate's elemental dose
The brain-penetrant form's honest weakness: 3 capsules deliver only 144 mg elemental — the lowest per-dollar magnesium on this page. Interesting science, premium price, thin outcomes.
Oxide absorption
The form to avoid: 4% absorbed, 96% stays in the gut as a laxative. High elemental weight per pill makes labels look impressive — the label trick this page teaches you to read through.
The supplemental ceiling
The FDA's unsupervised upper limit from ALL supplement sources — set by the laxative effect, not toxicity. The migraine-prevention range (600 mg) is a physician-conversation dose, deliberately above it.
The right blood test
Serum magnesium reflects only ~1% of body stores and misses chronic marginal deficiency. The RBC (red blood cell) magnesium test is the better gauge of tissue status — ask for it by name.