BioStacks
21st Century

MgO-400

2 Tablets · 90 servings · $0.08/serving

iHerbAmazon

Best for

Heart

Ingredients (2)

elemental Magnesium

100%

Dose

483 mg

Target

100–400 mg

Form

Budget

Calcium

130 mg

Trace amount — not scored

Other Ingredients (8)

TalcAnti-caking

IARC classifies cosmetic-grade talc not containing asbestos as Group 2B (possibly carcinogenic to humans); perineal talc use as Group 2A (probably carcinogenic). Johnson & Johnson voluntarily withdrew talc-based baby powder from US/Canada in 2020 and globally in 2022 after extensive litigation tied to ovarian-cancer and mesothelioma cases. The 2018 FDA contamination survey found asbestos in 9 of 52 cosmetic talc products tested. As a supplement excipient talc is a pure manufacturing convenience — no nutritional or functional benefit to the user — so the asbestos-exposure risk has no offsetting upside. Safer alternatives (silicon dioxide, microcrystalline cellulose, rice hulls) are widely available.

KelpFood

Dried brown seaweed used as a whole-food source of iodine and trace minerals.

Magnesium StearateLubricant

A salt of stearic acid used as a lubricant in tablet and capsule production

Silicon DioxideAnti-caking

Fine silica powder used to prevent clumping

Microcrystalline CelluloseBinder

Plant-derived cellulose used as a binder and filler in supplements

Croscarmellose SodiumDisintegrant

Cross-linked cellulose derivative used as a superdisintegrant

Gum AcaciaBinder

Natural plant gum (acacia) used as a binder, stabilizer, and emulsifier in foods and supplements

Stearic AcidLubricant

Saturated fatty acid used as tablet lubricant

How to Take It

Best taken in the evening

Magnesium oxide is poorly absorbed (~4%) and the most laxative form. Most of a dose stays in the gut, which is why it's mainly used for constipation — a poor pick if you're supplementing for magnesium itself.

With or without food
Space it a couple of hours from Iron and Calcium

On the label

As a mineral supplement, adults take two (2) tablets daily with any meal or as directed by a healthcare provider. Do not exceed recommended dosage.

General guidance based on the ingredients, not a substitute for the label or your doctor.

Price Check

$7.00

$10$20$50

Cheaper than 98% of 579 magnesium supplements

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Sources & Scoring

Nutrient data (RDA, UL, and safety thresholds) sourced from: NIH Office of Dietary Supplements and National Academies Dietary Reference Intakes (DRI).

This is not medical advice. Consult a healthcare provider before making changes to your supplement routine.

The score analyzes what's on the label: ingredient doses vs. clinical ranges, chemical forms, evidence levels, and known interactions. It does not verify label accuracy or test for contaminants — for that, look for third-party certifications like USP or NSF.

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