Mineral
Magnesium Oxide
Also known as: MgO, Milk of magnesia
High elemental magnesium content but poor absorption (4%). Primarily useful as a laxative; not ideal for Mg repletion.
Daily target & upper limit
420 mg / day · UL 350 mgMagnesium Oxide has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:
Magnesium Oxide dosage reference →Primary uses
- Laxative
- Basic magnesium supplementation
- Constipation
- Strong laxative effect
How it works
- Only 4% absorbed
- Strong osmotic laxative effect
- High elemental content per weight
Dosage
- Typical range
- 400-500 mg (only ~20mg absorbed)
- Timing
- Any
- With food
- Optional
- Duration
- Better forms available
- Special populations
- Primarily as laxative
Forms
- Tablet
- Capsule
- Tablets
- Liquid (milk of magnesia)
- Capsules
Safety
Common side effects
- Diarrhea common
Contraindications
- Kidney disease
Known interactions
- Cautionwith calcium
High calcium can impair magnesium absorption
- Infowith magnesium
High-dose magnesium may slightly reduce zinc absorption
- Synergywith magnesium
Magnesium needed for vitamin D activation
- Synergywith melatonin
Complementary sleep support
- Synergywith glycine
Both support sleep through different mechanisms
- Cautionwith magnesium
Magnesium may enhance BP lowering effect
Evidence notes
Well-established laxative effect
Grade A: Multiple well-designed human trials support the main claims.
Cited research for Magnesium Oxide
Clinical studies referenced across Formulate guides that mention magnesium oxide. Each links to the full study page with PubMed source + the guides that cite it.
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