Eight common forms of magnesium compared on bioavailability, clinical evidence and best-use case — so you can pick the right one for your goal.
Last reviewed: June 17, 2026 · Reviewed by the SuppIndex research team (editorial policy)
Magnesium is involved in more than 300 enzymatic reactions, and roughly 50% of adults in industrialized countries fall short of the recommended intake. But "magnesium" on a supplement label can mean very different things — different salts and chelates absorb differently, target different tissues, and have very different side-effect profiles. Picking the wrong form is one of the most common reasons people conclude that "magnesium didn't work for me."
This guide compares the eight forms you'll actually see on shelves, using bioavailability data from human pharmacokinetic studies and outcome data from randomized controlled trials. For deeper evidence ratings on the parent ingredient, see our Magnesium Glycinate ingredient page.
Best pick: Magnesium Glycinate
Glycine + Mg both lower sleep latency; best-studied for insomnia.
Best pick: Magnesium L-Threonate
Only form shown to raise brain Mg in human trials.
Best pick: Magnesium Glycinate or Malate
High bioavailability without GI upset; malate aids ATP production.
Best pick: Magnesium Taurate
Taurine adds independent cardiovascular benefit.
Best pick: Magnesium Citrate or Oxide
Osmotic laxative effect is the goal here.
| Form | Best for | Bioavailability | Typical dose | GI tolerance |
|---|---|---|---|---|
| Magnesium Glycinate (Bisglycinate) | Sleep, anxiety, stress, daily repletion | High | 200–400 mg elemental Mg / day | Excellent |
| Magnesium L-Threonate (Magtein®) | Cognition, memory, age-related cognitive decline | Moderate (CNS-targeted) | 1,000–2,000 mg compound (≈144 mg elemental Mg) | Excellent |
| Magnesium Citrate | Constipation, occasional repletion | High | 200–400 mg elemental Mg / day | Moderate |
| Magnesium Malate | Daytime energy, muscle pain, fibromyalgia | High | 300–600 mg elemental Mg / day | Good |
| Magnesium Taurate | Cardiovascular support, blood pressure | High | 125–500 mg elemental Mg / day | Excellent |
| Magnesium Oxide | Cheapest option, laxative use | Low (~4%) | 250–500 mg elemental Mg / day (poorly absorbed) | Poor |
| Magnesium Chloride | Topical use, broad repletion | High | 200–400 mg elemental Mg / day | Good |
| Magnesium Sulfate (Epsom Salts) | Bath soaks, IV use (clinical only) | Variable | Bath: 1–2 cups in tub | Poor |
Evidence: Multiple RCTs supporting sleep latency and subjective sleep quality; well-tolerated chelate.
Notes: Chelated to glycine, which itself has calming, sleep-promoting effects. The default choice for most adults.
Evidence: Animal and small human trials show elevated brain Mg and cognitive benefits; evidence still emerging.
Notes: The only form with strong data on crossing the blood–brain barrier. Premium price.
Evidence: Strong absorption data; osmotic laxative effect well documented.
Notes: Cheap, effective, but loosens stools at higher doses. Good if you also want regularity.
Evidence: Limited but positive trials in fibromyalgia (malate combined with Mg).
Notes: Malate is a Krebs-cycle intermediate; often chosen for daytime use over glycinate.
Evidence: Preclinical data and small human trials suggest blood pressure and arrhythmia benefits.
Notes: Taurine itself supports cardiovascular and metabolic health. Strong rationale, modest human RCTs.
Evidence: Poor absorption documented in head-to-head trials; mostly used for laxative effect.
Notes: Common in cheap multivitamins. Generally not recommended for repletion.
Evidence: Well-absorbed orally; topical absorption data is weaker than marketing claims suggest.
Notes: Solid all-rounder; transdermal sprays are popular but less evidence-supported than oral.
Evidence: Transdermal Mg absorption from baths is contested; oral use is a strong laxative.
Notes: Pleasant for muscle soreness, but oral systemic repletion is not the right tool.
Magnesium glycinate (bisglycinate) is the best-studied form for sleep. The glycine carrier independently lowers sleep latency and supports sleep quality, while the magnesium is highly bioavailable and gentle on the gut.
Glycinate, citrate, malate, taurate and chloride all show high bioavailability in human studies. Oxide is the cheapest but absorbs at only ~4%.
It is the only form with strong evidence for raising brain magnesium and supporting cognition and memory.
RDA is 310–420 mg of elemental magnesium for adults. Supplemental doses of 200–400 mg are typical; over 350 mg from supplements can loosen stools depending on form.
Yes — within typical supplemental dose ranges (200–400 mg elemental Mg), glycinate is well tolerated for long-term daily use.
Dive into clinical studies, evidence ratings and branded trademarks for magnesium on SuppIndex.
