The Quick Answer
| Form | Best for | Notes |
|---|---|---|
| Glycinate | Sleep, anxiety, muscle relaxation | Highly absorbable, gentle on stomach |
| Citrate | Constipation, general supplementation | Can cause loose stools at higher doses |
| Malate | Energy, fibromyalgia, fatigue | Pairs magnesium with malic acid for ATP support |
| Oxide | Cheap label fluff | Poorly absorbed — about 4% bioavailability |
| L-Threonate | Cognition, brain fog | Crosses the blood-brain barrier; premium price |
The form matters more than the dose. 200 mg of glycinate beats 800 mg of oxide for sleep and muscle relaxation every time.
Why Magnesium Form Matters
Elemental magnesium can't enter cells on its own — it has to be bound to another molecule. That carrier molecule determines two things: how well it's absorbed and what it does inside the body.
Glycinate = magnesium bound to glycine (a calming amino acid). The glycine itself improves sleep, so you get a double effect.
Citrate = bound to citric acid. Cheap, well-absorbed, but draws water into the bowel — which is why it's the form in laxatives.
Malate = bound to malic acid, which is a key player in the cell's energy cycle. Popular with people who deal with fatigue or fibromyalgia.
Oxide = magnesium and oxygen. The cheapest form. The form most generic supplements use because it's high-percentage by weight. But only ~4% is absorbed.
L-Threonate = bound to threonic acid, the only form that meaningfully crosses the blood-brain barrier. Used in the few real cognitive studies on magnesium.
How Much You Need
The RDA is 400 mg for men, 310 mg for women. Realistic supplementation:
- Sleep / anxiety: 200-400 mg glycinate, 1 hour before bed
- Constipation: 200-400 mg citrate, morning
- Energy / fatigue: 300-600 mg malate, morning or with lunch
- Stack: 200 mg glycinate at night + your daily multi/electrolyte mix
How 2THIRTY Handles Magnesium
Each 2THIRTY stick includes 50 mg of magnesium as citrate — enough to support hydration and recovery without pushing into laxative territory. For sleep, we recommend adding 200 mg of dedicated glycinate at night.