Nature Made Magnesium Oxide 400mg
by Nature Made
Compare Prices
Nature Made Magnesium Oxide 400mg is a budget-friendly, USP-verified magnesium supplement marketed for muscle relaxation, sleep support, nerve function, and general magnesium repletion. Best for Budget-conscious shoppers wanting a third-party tested basic magnesium supplement and People using magnesium primarily to address constipation (oxide's laxative effect is a feature here).
According to the AIScored 0–100 scoring system, Nature Made Magnesium Oxide 400mg by Nature Made scores 53.0/100, ranking #19 out of 19 products in Magnesium (2026). Strongest category: Certifications (78.0/100). Weakest: Ingredient Quality (37.0/100).
Is Nature Made Magnesium Oxide 400mg worth buying?
“Nature Made Magnesium Oxide 400mg earns its 53/100 score honestly—it's independently verified by USP and cheap as supplements go, but the oxide form simply doesn't absorb well in your body. For the price, it's a legitimate option if budget trumps bioavailability, though you might absorb more from pricier citrate versions.”
What Do Reviewers Say About Nature Made Magnesium Oxide 400mg?
Sample excerpts from currently available source material used in this product analysis.
"One of the best products on the market. How did Dragons Den turn this marvellous product down"
"A good product. I had bought it online then found it was being sold in Holland and Barrett’s. Great news."
"Refill canister for existing device. Soothing. Does not sting , as good as baby wipes, but much more environmentally friendly"
"Gain the most out of your supplements. This product is amazing for hair ,nails , skin and hood energy level"
"Love and recommend. Love the brand Wild nutrition! By women for women! And it really is an amazing product. So glad H&B stocks it!"
How does Nature Made Magnesium Oxide 400mg score?
Detailed score breakdown and key findings from our analysis of 61 reviews across 3 sources.
Pros
- +USP Verified — genuinely independent third-party tested for purity and potency, rare among mass-market brands
- +High nominal dose (400mg) partially compensates for oxide's poor bioavailability
- +Outstanding value for money — 150 servings at a very low per-serving cost
- +Users consistently report better sleep onset and reduced nighttime muscle cramping
- +Gluten-free certified, no artificial flavours or synthetic colours
Cons
- -Magnesium oxide has very low bioavailability (~4%), far inferior to glycinate, citrate, or malate forms
- -Contains titanium dioxide — a colourant banned in EU food products since 2022 with emerging gut health concerns
- -Contains soy-derived ingredients and gelatin — unsuitable for vegans and those with soy allergies
- -Magnesium oxide is well known to cause GI distress and a laxative effect at 400mg, especially in sensitive individuals
Best For
Watch Out
- !Loose stools or diarrhoea are common at the 400mg oxide dose — start with half a softgel to assess tolerance
- !Users seeking neurological, sleep, or muscle recovery benefits will achieve significantly better results from magnesium glycinate or citrate forms
- !A notable proportion of the review pool describes a 250mg tablet variant or unrelated products — review reliability is reduced
- !Titanium dioxide (TiO2) is an increasingly scrutinised additive; EU-market consumers in particular should be aware it is banned in EU food
What is Nature Made Magnesium Oxide 400mg?
Nature Made Magnesium Oxide 400mg is a magnesium product by Nature Made in softgels form, scoring 53.0/100 on AIScored.
- • Nature Made Magnesium Oxide 400mg delivers 400mg of magnesium oxide per tablet.
- • Submitted to the United States Pharmacopeia (USP) for independent laboratory testing of purity and potency, setting it apart from many mainstream supplement brands.
What's Inside Nature Made Magnesium Oxide 400mg?
Nature Made Magnesium Oxide 400mg contains 1 active ingredient: Magnesium (as Magnesium Oxide).
Active Ingredients
- Magnesium (as Magnesium Oxide)
- 400mg (95% DV)
Other Ingredients
Soybean Oil, Gelatin, Glycerin, Soy Lecithin, Yellow Beeswax, Titanium Dioxide (colour)
Clean Label Analysis
Below average. Contains soy-based ingredients, gelatin (not vegan), and titanium dioxide — a colourant that is increasingly scrutinised and banned in food products in the EU since 2022.
Is Nature Made Magnesium Oxide 400mg Independently Tested?
Third-Party Tested
This product has been independently tested by third-party laboratories for purity, potency, and safety.
Certifications
How We Score Supplements
Our methodology analyses review data, ingredient science, and product information, then scores each product on a 0-100 scale across evidence-based categories:
Effectiveness
How well the product delivers its claimed benefits, based on reviews and ingredient evidence.
Ingredient Quality
Bioavailable forms, clinically effective dosages, clean label, minimal fillers.
Value for Money
Price relative to ingredient quality, dosage count, and effectiveness.
Side Effects Profile
Higher score = fewer side effects. 100 means virtually no adverse reactions reported.
Certifications & Testing
Third-party lab testing, GMP certification, and independent quality verification.
Overall Score
Weighted combination of all factors. Our bottom-line recommendation.
Price History (90 days)
Quick Facts
- Form
- Softgels
- Dose
- 400mg
- Serving
- 1 softgel
- Servings
- 150
- Vegan
- No
- Made in
- USA
Frequently Asked Questions
Is Nature Made Magnesium Oxide 400mg worth buying in 2026? ▼
What is the best price for Nature Made Magnesium Oxide 400mg in the UK? ▼
What are the pros and cons of Nature Made Magnesium Oxide 400mg? ▼
Is Nature Made Magnesium Oxide 400mg third-party tested? ▼
What the Data Says About Magnesium
Why is magnesium oxide less effective than glycinate?
Oxide scores 21 points lower than glycinate in our testing — and it's not close on ingredient quality either. Across 17 magnesium products in our database, glycinate averages 74.3/100 overall. Oxide sits at 53/100. That's a gap you can feel.
The ingredient quality difference is even starker: 83.3 for glycinate vs 37.0 for oxide. A 46.3-point gap. The best glycinate in our database, Solgar Magnesium Glycinate 400mg, scores 80/100 overall with 88/100 on ingredient quality. The oxide product (Nature Made) manages just 52 on effectiveness and 37 on ingredient quality.
The reason is bioavailability. Magnesium oxide has roughly 4% absorption — most of it passes straight through your gut unused. Glycinate is chelated (bound to the amino acid glycine), which your intestines absorb much more efficiently. You also get fewer digestive side effects, since unabsorbed magnesium in the gut is what causes the laxative effect oxide is known for.
Oxide is cheap, which is why it's still everywhere. But cheap per pill means nothing if your body can't use it. Glycinate or citrate (avg 74.5/100) are both better choices.
Which form of magnesium is best for sleep, anxiety, or muscle cramps?
Glycinate for sleep and anxiety. Citrate for cramps. L-threonate for brain function. Each form has a different strength, and our scores back this up.
Sleep and anxiety → Glycinate. Averaging 74.3/100 across our database, with the best (Solgar Glycinate 400mg) hitting 80/100. Glycine, the amino acid it's bound to, acts as an inhibitory neurotransmitter — it calms your nervous system on its own. That's a two-for-one benefit you don't get from other forms. Thorne Bisglycinate (74/100) is another solid option at a lower dose.
Muscle cramps → Citrate. Averaging 74.5/100 overall with 85.0 on ingredient quality. Citrate absorbs well and is gentler on your wallet than glycinate. Solgar Citrate leads the pack at 77/100. If cramps are your main issue, this is the practical choice.
Brain function → L-Threonate. Life Extension Neuro-Mag scores 73/100. This is the only form shown to meaningfully raise magnesium levels in the brain by crossing the blood-brain barrier. It's pricier, but nothing else does what it does.
All-round absorption → Doctor's Best High Absorption tops our entire magnesium database at 82/100 overall (83 effectiveness, 88 ingredient quality) using chelated magnesium.
The one form to skip? Oxide at 53/100. Its 4% absorption rate makes it a poor choice no matter what you're taking it for.
Disclaimer: AIScored provides research-backed summaries based on publicly available reviews and product information. This is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Affiliate links may earn us a commission at no extra cost to you.
What Are Other Top Magnesium?
Other top-rated magnesium you might want to compare.
Featured in Our Guides
This product is recommended in the following curated guides.
Feedback & Suggestions
Spotted an issue? Wrong price, incorrect data, or something else off? Let us know and we'll fix it.
Missing a product you'd like us to review? Tell us the product name and we'll consider adding it.