Guide
Magnesium glycinate vs sulfate: what's actually different
Magnesium sulfate — Epsom salt — isn't usually sold as a daily oral capsule the way glycinate is. It's an over-the-counter saline laxative at higher doses, a prescription injectable in medical settings, and a bath-soak product with no controlled human trial establishing that it raises blood magnesium.
Magnesium sulfate — better known as Epsom salt — isn't typically sold as a daily oral capsule the way glycinate is. Its common consumer use is as an over-the-counter saline laxative at doses well above a daily mineral supplement, it's also used as a prescription injectable in specific medical settings under direct supervision, and it's the mineral behind Epsom salt baths, where the evidence for raising blood magnesium is much thinner than the marketing suggests.
The two forms, side by side
| Magnesium glycinate | Magnesium sulfate | |
|---|---|---|
| Formula | C4H8MgN2O4 | MgO4S |
| Molar mass | 172.42 g/mol (PubChem CID 84645) | 120.37 g/mol anhydrous; ~246.5 g/mol as the heptahydrate (Epsom salt), PubChem CID 24083 |
| Elemental magnesium by weight | ~11–14% | ~20% anhydrous; ~10% as Epsom salt (heptahydrate) |
| Typically sold for | Daily oral capsule for general supplementation | OTC oral saline laxative (higher single dose); prescription injectable in specific medical settings; bath salts |
| Daily oral supplement capsule? | Yes — this is glycinate's main consumer use | Uncommon — sulfate's oral consumer use is laxative-dose, not daily-supplement-dose |
| Watch out for | Marketed as gentler than other forms, without a trial showing that | Bath and "transdermal" products are marketed on raising blood magnesium; we found no controlled human trial testing that specific claim |
Why sulfate isn't a typical daily capsule
Taken orally at doses anywhere near what would deliver a meaningful elemental magnesium amount, magnesium sulfate draws water into the bowel and acts as a saline laxative — which is exactly what it's sold for over the counter, at single doses far higher than a daily mineral supplement would use. That's a different product for a different purpose than a magnesium glycinate capsule, even though both ultimately deliver magnesium. It's also given as an injectable prescription medicine in specific medical situations, administered directly into a vein under supervision — a pharmacokinetic reference point researchers actually use: one 2018 bioavailability trial measured a new oral magnesium lactate caplet's absorption by comparing it against an IV magnesium sulfate infusion, since an IV dose is by definition 100% absorbed. That trial illustrates the sulfate form's role in magnesium research generally — as the injectable reference standard — rather than as something people take by mouth every day.
What about Epsom salt baths?
Soaking in Epsom salt is a long-standing home remedy, sold on the idea that magnesium crosses the skin and raises blood levels. We looked for a controlled human trial measuring blood or urine magnesium before and after a bath soak and did not find one. The classic four-way oral bioavailability comparison of US commercial magnesium preparations — oxide, chloride, lactate and aspartate, measured by urinary excretion in healthy volunteers — didn't test a bath or topical route at all; all the human absorption data we found for magnesium, sulfate included, is for oral or injected magnesium, not skin contact.
Our product
Electric Tiger Magnesium Glycinate provides 275 mg of elemental magnesium per three-capsule serving, from 2,500 mg of magnesium glycinate — both numbers on the panel, 30 servings a bottle, as low as $16.31 a bottle on subscription.
Questions people ask
What is the difference between magnesium glycinate and magnesium sulfate?
Glycinate is formulated as a daily oral capsule; sulfate's common consumer forms are a laxative-dose oral solution, bath salts, and (in medical settings) an injectable. They aren't interchangeable products even though both are magnesium compounds.
Can you take magnesium sulfate as a daily supplement like glycinate?
It isn't typically sold or dosed that way. At doses close to a daily elemental-magnesium target, oral sulfate's laxative effect is the dominant thing you'd notice, which is why it's marketed as a laxative rather than a daily mineral capsule.
Does an Epsom salt bath raise your magnesium levels?
We didn't find a controlled human trial that measured this directly. The claim is widely repeated, but the human magnesium-absorption research we reviewed covers oral and injected magnesium, not the skin.
Related reading
- Types of magnesium compared
- Topical magnesium glycinate
- Magnesium glycinate vs citrate
- Elemental magnesium, explained
Sources
- Dogterom P, Fu C, Legg T, Chiou YJ, Brandon S. "The absolute bioavailability and the effect of food on a new magnesium lactate dihydrate extended-release caplet in healthy subjects." Drug Dev Ind Pharm. 2018;44(9):1481-1487. PMID 29638147.
- Firoz M, Graber M. "Bioavailability of US commercial magnesium preparations." Magnes Res. 2001;14(4):257-62. PMID 11794633.
- PubChem CID 84645 (magnesium glycinate) and CID 24083 (magnesium sulfate), National Library of Medicine.
- Electric Tiger Magnesium Glycinate Supplement Facts: product page.
Sources
- The absolute bioavailability and the effect of food on a new magnesium lactate dihydrate extended-release caplet in healthy subjects A 2018 pharmacokinetic trial found a new extended-release magnesium lactate caplet had about 20% absolute bioavailability in blood when taken fasted, measured directly against IV magnesium as the reference.
- Bioavailability of US commercial magnesium preparations In healthy volunteers given about 255 mg of elemental magnesium a day, magnesium aspartate was absorbed as well as chloride and lactate, and all three beat oxide. Glycinate wasn't tested in this particular study.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
