Magnesium Oxide vs. Magnesium Aspartate
Among 6,062 on-market magnesium products with an identifiable primary form, 52.4% use Magnesium Oxide (3,177 products) and 8.2% use Magnesium Aspartate (500).
| Magnesium Oxide | Magnesium Aspartate | |
|---|---|---|
| Quality tier | Tier 3 | Unrated |
| Magnesium by weight | 60.3% | 8.4% |
| Share of market | 52.4% | 8.2% |
| On-market products | 3,177 | 500 |
| Median declared dose | 100 elemental mg middle half: 47.38–140 | 76 elemental mg middle half: 40–167.5 |
| Most common brands | DC, Wonder Laboratories, GNC Mega Men | Bluebonnet, Douglas Laboratories, PS ProSupps |
Doses are declared per serving in elemental mg. “By weight” is the share of the ingredient that is the nutrient itself (e.g. elemental magnesium in a magnesium salt).
Why Magnesium Oxide is tier 3
Virtually insoluble in water, only ~43% soluble even under peak gastric acid.
Source: Lindberg JS et al. 1990, J Am Coll Nutr 9(1):48-55, PMID 2407766
Why Magnesium Aspartate is unrated
No head-to-head human bioavailability study specific to this salt was found.
Source: uncertain -- needs review
Tiers summarize published comparative bioavailability or outcome evidence for each form (see methodology).
This page describes the market; it is not a recommendation to take either form. Talk to a clinician about what's right for you.
Other magnesium comparisons
- Magnesium Oxide vs. Magnesium Citrate
- Magnesium Oxide vs. Magnesium Glycinate
- Magnesium Oxide vs. Magnesium Amino Acid Chelate
- Magnesium Citrate vs. Magnesium Glycinate
- Magnesium Citrate vs. Magnesium Aspartate
- Magnesium Citrate vs. Magnesium Amino Acid Chelate
- Magnesium Glycinate vs. Magnesium Aspartate
- Magnesium Glycinate vs. Magnesium Amino Acid Chelate
- Magnesium Aspartate vs. Magnesium Amino Acid Chelate