Magnesium Oxide
Magnesium Oxide is a tier 3 form of Magnesium, used in 3,296 on-market products and providing 60.3% elemental magnesium by weight.
3,296
on-market products
tier 3
quality tier
60.3%
elemental fraction
Basis: MgO, anhydrous (no stable commercial hydrate)
Why this tier: 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