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Spring Valley Magnesium 400mg
SPECIMEN #SPRING-V
Verified
MineralsSpring Valley

Magnesium 400mg

400mg looks impressive until you learn magnesium oxide absorbs at about 4%. That's roughly 16mg of actual magnesium. A banana gives you 32mg. Magnesium oxide is primarily a laxative, not a mineral supplement. Pay $2 more for glycinate.

4.0/10
POOR

Magnesium oxide absorbs at about 4%. So 400mg delivers roughly 16mg of actual magnesium. It's basically a laxative marketed as a mineral supplement. Nature Made's glycinate version exists for a reason.

1 ingredientTablets100 servings
We'd look at alternatives
Evidence
2.0
Dosing
3.0
SynergyN/A (single ingredient)
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Whenbedtime

If you want the laxative effect, take at bedtime.

Foodwith food

Slightly better absorption with food. Still poor.

SafetyAll clear

High dose of poorly absorbed magnesium causes diarrhea.

ResearchStrong evidence

Magnesium oxide bioavailability of ~4% is well-documented in comparison studies.

What We Like

  • 100 tablets for under $4.
  • 400mg on the label looks impressive.
  • Works well as an osmotic laxative.

Watch Out For

  • Magnesium oxide has ~4% bioavailability.
  • 400mg oxide delivers roughly 16mg actual magnesium.
  • Causes diarrhea at this dose.
  • Your body absorbs more magnesium from a banana.

What We Analyzed

Magnesium 400mg Supplement Facts

Verified Supplement Facts

Every dose checked against clinical research

We analyzed the actual supplement facts panel for this product. Every ingredient dose below was cross-referenced with published clinical trials to determine if it matches what studies actually use.

1 ingredients analyzed1 at clinical doses

Source: Official product page

Ingredient Breakdown

1 clinical
Clinical Adequate Underdosed Overdosed|Bar = % of clinical dose
IngredientDoseStatusvs. Clinical
Magnesium10.0

Magnesium Oxide

400 mgCLINICAL
100%
400 mg

of 400mg

CLINICAL
100%
In our database (click to learn more) Not yet reviewed

Our Analysis

Best For

People who want a cheap laxative.Constipated individuals.

Skip This If

Anyone wanting actual magnesium supplementation.

Time to Feel

Laxative effect: 6-8 hours. Magnesium benefits: never at 4% absorption.

Value

POOR

How to take: Switch products instead.

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