MAGNESIUM
Citrate vs Oxide
The best-studied pair of magnesium forms, side by side.
Compare →Magnesium form
Magnesium Oxide
In short
A compact, inexpensive form with a high percentage of elemental magnesium by weight but low water solubility. It’s common in budget tablets, multivitamins and antacids.
At a glance
- Compound
General reference - Magnesium oxide (MgO)
- Approx. elemental magnesium
SuppScout calculation - ~60% by weight
- Typical formats
General reference - Tablets, multivitamins, antacids
- Absorption research
Published research - Lower fractional absorption than citrate in comparative studies
- Price
General reference - Usually lowest cost per 100 mg elemental
SuppScout calculation About 60% elemental magnesium by weight.
About magnesium oxide
What it is
Magnesium oxide packs the most elemental magnesium into the smallest tablet, which is why it appears in many multivitamins and low-cost products.
What the research says
Comparative studies show oxide dissolves poorly and is absorbed to a lesser extent than citrate. The NIH lists oxide among the forms most associated with diarrhea at higher doses. Lower fractional absorption doesn’t mean zero absorption — but it does mean a milligram-for-milligram comparison with citrate or glycinate isn’t the whole story.
Label tip
Oxide often appears inside “buffered” glycinate or “magnesium complex” products. If a product lists several forms in parentheses, the amounts of each usually aren’t disclosed.
Compare Oxide
MAGNESIUM
Glycinate vs Oxide
Elemental content, solubility and cost per 100 mg.
Compare →Magnesium Oxide products
Cost comparison
| Product | Format | Per serving | Servings | Price | Cost / serving | Cost per 100 mg elemental magnesium | Other ingredients |
|---|---|---|---|---|---|---|---|
| Harbor & Pine Magnesium Oxide 250 mg Harbor & Pine · demo |
Tablets 1 tablet |
250 mg elemental magnesium | 100 | $8.99* | $0.09 | $0.04 | 4 |
| Harbor & Pine Magnesium Glycinate (Buffered) 240 mg Harbor & Pine · demo |
Capsules 2 capsules |
240 mg elemental magnesium | 90 | $19.49* | $0.22 | $0.09 | 2 |
SuppScout calculation Sorted by cost per 100 mg elemental magnesium. * Demonstration prices from fictional listings, used to show the calculation — not current market prices.
Products
Harbor & Pine Magnesium Glycinate (Buffered) 240 mg
Harbor & Pine · Demo
- Primary ingredient
- Magnesium Glycinate
- Per serving
- 240 mg elemental magnesium
- Servings
- 90
- Format
- Capsules
- Price
- $19.49*
- Per serving cost
- $0.22
Not verified
Harbor & Pine Magnesium Oxide 250 mg
Harbor & Pine · Demo
- Primary ingredient
- Magnesium Oxide
- Per serving
- 250 mg elemental magnesium
- Servings
- 100
- Format
- Tablets
- Price
- $8.99*
- Per serving cost
- $0.09
Not verified
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Other magnesium forms
Sources & references
- Magnesium: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.govGovernment
- Lindberg JS, Zobitz MM, Poindexter JR, Pak CY (1990). Magnesium bioavailability from magnesium citrate and magnesium oxide. Journal of the American College of Nutrition 9(1). pubmed.ncbi.nlm.nih.govStudy
- Walker AF, Marakis G, Christie S, Byng M (2003). Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnesium Research 16(3). pubmed.ncbi.nlm.nih.govRandomized trial
SuppScout links to primary and authoritative sources wherever possible. See our editorial policy for how sources are selected and how corrections are handled.
This page is educational and is not medical advice. Talk to a healthcare professional before starting a supplement, especially if you have a medical condition, take medications, or are pregnant or breastfeeding.