Magnesium Types
Not all magnesium is the same. The form determines what it does — sleep, stress, cognition, or just bowel movements. Here's a quick guide.
Magnesium comes in many forms, and each one is absorbed differently and targets different benefits. Choosing the wrong form means you either don't absorb enough or get the wrong effect. The form matters more than most people realise.
This guide is for you if: You know you need magnesium but aren't sure which form to buy, have tried magnesium oxide and it didn't seem to do anything (or just gave you diarrhoea), or want to match the form to your specific goal.
See the evidenceAll magnesium forms compared
| Form | Best for | Absorption | Notes |
|---|---|---|---|
| Glycinate | Sleep, anxiety, overall | Excellent | Best all-rounder; glycine has calming effects |
| L-Threonate | Brain, cognition, memory | Excellent | Crosses blood-brain barrier; Magtein brand |
| Taurate | Heart, blood pressure | Good | Taurine adds cardiovascular benefits |
| Citrate | Muscle cramps, general | Good | Can be slightly laxative at higher doses |
| Malate | Energy, muscle pain | Good | Malic acid supports energy production |
| Oxide | Constipation relief | Poor (4%) | Cheap but barely absorbed; laxative effect |
Which form for your goal?
- Better sleep: Magnesium glycinate (200–400 mg before bed). The glycine component adds its own sleep-promoting effects via NMDA receptors and core body temperature regulation.
- Brain fog / cognitive support: Magnesium L-threonate (Magtein, 144 mg elemental Mg or ~2,000 mg threonate). It's the only form shown to increase brain magnesium levels in animal studies.
- Heart health / blood pressure: Magnesium taurate (200–400 mg). Taurine and magnesium both support cardiovascular function.
- Muscle cramps / general deficiency: Magnesium citrate (200–400 mg). Well-absorbed, affordable, and effective.
- Constipation: Magnesium oxide or citrate (400–800 mg). The osmotic effect draws water into the intestines.
Magnesium glycinate is the best all-rounder. It's well-absorbed, gentle on the stomach, supports sleep and stress, and corrects deficiency effectively. Start here unless you have a specific reason to choose another form.
How much to take
The RDA for magnesium is 310–420 mg/day for adults. Most Indians get about 200–250 mg from diet. A supplement dose of 200–400 mg of elemental magnesium (from any well-absorbed form) will cover the gap.
Note: the label may show the total compound weight (e.g., 2,000 mg magnesium glycinate) but the elemental magnesium is what matters — that same 2,000 mg of glycinate contains about 200 mg of elemental Mg.
Check your magnesium status with RBC Magnesium
eterni includes RBC magnesium (not just serum) in your panels — the more accurate way to assess magnesium status.
Get early accessFrequently Asked Questions
Why is magnesium oxide so popular if it is poorly absorbed?
It's cheap and has the highest elemental magnesium percentage by weight (~60%), so it looks good on labels. But only about 4% is actually absorbed — the rest acts as an osmotic laxative. It's fine if you want constipation relief, but for correcting deficiency or getting health benefits, glycinate, citrate, or threonate are far superior.
Can I take multiple forms of magnesium?
Yes — many people take glycinate at night for sleep and threonate in the morning for cognition. Just keep total elemental magnesium at 200–400 mg/day unless advised otherwise. Taking too much can cause loose stools.
How do I know if I am magnesium deficient?
Standard serum magnesium tests are unreliable — only 1% of body magnesium is in the blood. RBC (red blood cell) magnesium is more accurate. Symptoms of deficiency include muscle cramps, poor sleep, anxiety, fatigue, and eyelid twitching. Given that most Indians don't get enough from diet, supplementing 200–400 mg of a well-absorbed form is a reasonable default.
Does magnesium interfere with any medications?
Magnesium can reduce absorption of certain antibiotics (tetracyclines, fluoroquinolones), thyroid medications (levothyroxine), and bisphosphonates. Space magnesium at least 2 hours away from these medications. Magnesium is generally safe alongside most other supplements and medications.
Why the form matters: bioavailability data
Bioavailability studies consistently show that chelated forms (glycinate, taurate, malate) and organic salts (citrate) are absorbed 2–4x better than inorganic forms (oxide, carbonate). A 2019 comparison found: glycinate ~80% absorption, citrate ~25–30%, oxide ~4%.
Magnesium L-threonate is unique because it's the only form demonstrated to cross the blood-brain barrier and increase cerebrospinal fluid magnesium levels in animal studies (Bhatt et al., MIT). This is why it's specifically recommended for cognitive benefits, memory, and neurological support — other forms raise serum magnesium but don't significantly increase brain levels.
The glycine advantage: Magnesium glycinate provides a dual benefit because glycine itself is a neurotransmitter that activates NMDA receptors and lowers core body temperature — both of which promote sleep. This is why magnesium glycinate is specifically effective for sleep, beyond what other magnesium forms provide.
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