Guide
Magnesium glycinate vs carbonate: what's actually different
Magnesium carbonate carries nearly three times the elemental magnesium per gram that glycinate does, but a 2022 controlled trial in healthy adults found ionized magnesium actually fell after carbonate supplementation — the opposite of what its elemental content would suggest.
Magnesium carbonate carries nearly three times the elemental magnesium per gram that glycinate does — about 29% versus 11–14% — but a bigger number on paper doesn't automatically mean more magnesium reaches your blood. A 2022 controlled trial in healthy young women found ionized magnesium actually fell after 10 days of carbonate supplementation, while a form usually assumed to be poorly absorbed did better.
The two forms, side by side
| Magnesium glycinate | Magnesium carbonate | |
|---|---|---|
| Formula | C4H8MgN2O4 | CMgO3 |
| Molar mass | 172.42 g/mol (PubChem CID 84645) | 84.31 g/mol (PubChem CID 11029) |
| Elemental magnesium by weight | ~11–14% | ~29% |
| Typically sold for | General daily supplementation | General daily supplementation; also used in antacid formulations and, in a different grade, as climbing/gym chalk |
| 2022 controlled trial result | Not included in this trial | Ionized magnesium decreased over 10 days |
| Watch out for | Marketed as gentler than other forms, without a trial showing that | A higher elemental percentage on the label doesn't guarantee better absorption — the trial below found the opposite direction |
What the 2022 head-to-head trial found
A controlled 10-day supplementation study gave 61 healthy young women one of three magnesium supplements — oxide (powder/granulate), citrate, or carbonate (as effervescent tablets) — and measured ionized and total serum magnesium along with other electrolytes before and after. Carbonate decreased both ionized magnesium concentration and its share of total magnesium, without a detectable change in total serum magnesium. Oxide, by contrast, increased both measures — the researchers concluded oxide showed the highest short-term bioavailability of the three, despite oxide's reputation elsewhere as one of the weaker-absorbed forms (see our glycinate vs oxide comparison). Citrate landed in between, raising the ionized fraction but lowering total serum magnesium.
Glycinate wasn't part of this particular trial, so there's no direct three-way result to report. What the trial does establish is that carbonate's higher elemental content per gram didn't translate into better short-term absorption than the other two forms tested — if anything, it moved in the opposite direction on the measure this study used.
Where carbonate shows up outside supplements
Magnesium carbonate is a common antacid ingredient (it neutralizes stomach acid, chemically similar to why it's included in some heartburn products), and a different, non-food grade of magnesium carbonate is the white powder sold as gym or climbing chalk, used to dry the hands rather than to be swallowed. Neither use tells you anything about how well a supplement-grade carbonate tablet is absorbed — they're different applications of the same base compound.
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 carbonate?
Carbonate carries more elemental magnesium per gram (~29% vs glycinate's ~11–14%), but the one controlled trial that tested carbonate found ionized blood magnesium fell over 10 days of supplementation rather than rose. Glycinate wasn't tested in that same trial.
Is magnesium carbonate better than glycinate?
There's no direct trial comparing the two. What we can say is that carbonate's higher elemental percentage didn't produce a better absorption result than oxide or citrate in the one controlled comparison available — a higher number on the label isn't the same as more magnesium reaching your blood.
Is magnesium carbonate the same thing as gym chalk?
Chemically related, but not the same product. Gym and climbing chalk is a non-food grade of magnesium carbonate meant to dry the hands, not a supplement, and it isn't formulated or tested for ingestion.
Related reading
- Magnesium glycinate vs oxide
- Types of magnesium compared
- Magnesium glycinate vs citrate
- How to choose a magnesium glycinate
Sources
- Ivanovic ND, et al. "Effects of short-term magnesium supplementation on ionized, total magnesium and other relevant electrolytes levels." Biometals. 2022;35(2):267-283. PMID 35041150.
- PubChem CID 84645 (magnesium glycinate) and CID 11029 (magnesium carbonate), National Library of Medicine.
- Electric Tiger Magnesium Glycinate Supplement Facts: product page.
Sources
- Effects of short-term magnesium supplementation on ionized, total magnesium and other relevant electrolytes levels A 2022 controlled 10-day trial in healthy young women found magnesium carbonate (effervescent tablets) decreased ionized blood magnesium, while oxide — often assumed to be poorly absorbed — increased it.
*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.
