“GMP”
Evidence →“GMP-certified” describes factory processes, not what is in the bottle. The claim does not name a certifier or public register that a shopper can check.
Exact product checked · GTIN 00810047391630DOCTORS' PREFERRED · checked Aug 1, 2026 · on sale since Jan 18, 2024🇺🇸 USPTO wordmark owner · Doctors' Preferred, Inc. · MARYLAND, USA; DELAWARE, USA
Quick read · DOCTORS' PREFERRED
Doctors' Preferred High Potency Magnesium Glycinate…
Checked against public sources on August 1, 2026 · LookCloser does not sell or recommend supplements.
60capsules · 30 servings
Does the marketing hold up?
Magnesium: 420 mg on the label; adult upper limit 350 mg. This serving is about 1.2× the adult upper limit shown by NIH. The limit applies to SUPPLEMENTAL magnesium only (not from food).
Is the dose real?Panel read — dose not verified1 ingredient listed; no advertised amount we could confirm against them
What a serving costs$0.67per serving, at the checked price
Is it tested?No testing claim made
Who’s behind it?🇺🇸Doctors' Preferred, Inc.corporation; limited liability company · MARYLAND, USA; DELAWARE, USA
Is it the real thing?✓Barcode matches outside records
Trouble on record?✓No recalls found
“Couldn’t verify” means we looked and found no public proof — not a mark against the product. Most supplement claims cannot be independently verified by anyone, so grey is the normal state of this industry.
2◖ partly confirmed1△ support not foundno contradictions · no recalls
The label itself
What the Supplement Facts panel says
| Magnesium [as Magnesium Glycinate Complex (magnesium glycinate, magnesium oxide)] | 420 mg |
|---|
Printed on the package: Gluten Free · GMP · DOCTOR DEVELOPED · PATIENT VERIFIED · REMARKABLE RESULTS
We read only 1 line from this label, but the listing describes several ingredients. Treat this as an incomplete read rather than as the whole label.
Marketing claims, checked
The checks, one by one
1 promise needs a closer look.
◐Partly confirmed2
“YOUR HEART AND ENTIRE CARDIOVASCULAR SYSTEM, AND METABOLIC”
Evidence →Published research exists for ingredients in this formula. Whether this product’s doses match those studies could not be confirmed.
Ingredient research can support context, but it is not a trial of this exact product.
△Claimed without support found1
“DOCTORS’ PREFERRED DIFFERENCE: Helping people live healthier, more active lives for over 30 years through innovative and exclusive…”
Evidence →We found no named, citable study of this product or formula. The claim may rest on ingredient research rather than a trial of this product.
Quick read · 4 useful findings
What is worth knowing.
Headlines first. Open evidence only when you want the source trail.
Needs explanationIs the label honest?
Magnesium: 420 mg on the label; adult upper limit 350 mg.
This serving is about 1.2× the adult upper limit shown by NIH. The limit applies to SUPPLEMENTAL magnesium only (not from food).
Evidence and sources
The panel lists 420 mg magnesium. NIH gives 350 mg as the adult Tolerable Upper Intake Level for SUPPLEMENTAL magnesium only (not from food). That is about 1.2 times the limit.
NIH ODS — Magnesium fact sheetupper-limit and Daily Value contextNIH ODS — Magnesium fact sheetmagnesium context · not product evidencePubMed search: magnesium glycinate supplementationmagnesium context · not product evidence
Locked evidence record →Open the full source-linked findingCheckedIs the label honest?
Every ingredient shows its amount · 1 ingredients listed.
Every ingredient shows its real amount — nothing is hidden in a proprietary blend.
Evidence and sources
The panel gives a per-ingredient amount rather than hiding quantities inside a proprietary blend, so each one can be compared to published research.
Locked evidence record →Open the full source-linked findingCheckedWho is behind it?
Registered in NIH's supplement label database (DSLD)
A government label filing makes the listed formula easier to inspect and compare over time.
Evidence and sources
Label #322430 “Advanced Magnesium Glycinate Complex” (Doctors' Preferred), entered 2025-02-23, with the full Supplement Facts on file. Company on file: Distributor — Healthy Directions, Bethesda, MD.
Locked evidence record →Open the full source-linked findingCheckedCan you trust the review pattern?
We can see 7 of this product’s 45 reviews — the count rose between September 17, 2025 and June 14, 2026. That is too small a slice to say anything about the wider pattern.
A count that moves steadily is ordinary. A sudden burst is what deserves a closer look.
Evidence and sources
Written reviews rose from 38 to 45 between September 17, 2025 and June 14, 2026. The largest rise inside any single 30-day window was about 3, so the count moved in steps rather than in one burst.
Locked evidence record →Open the full source-linked findingWhat remains open 2
- No FDA recall matched this brand in the current search.
- Barcode checksum is valid; no independent product record was found.
These are evidence gaps, not strikes against the product.
Who owns the brand wordmark?
🇺🇸
Doctors' Preferred, Inc.Corporation; Limited Liability Company · exact supplement-class mark for DOCTORS' PREFERRED
Filed address
7811 Montrose Road, Potomac, MARYLAND 208541871, UNITED STATES
USPTO identifies the public owner or applicant behind this brand wordmark. This does not by itself identify the product manufacturer or prove where the product was made. Open USPTO source ↗
Research behind the findings
Dose and research context
We could not match an amount on this product to a studied range for the same ingredient, so these links are ingredient background rather than a measurement of this product.
Background reading
What the research says about these amounts
Not a score. Studies disagree with each other and change over time, so this sits beside the evidence rather than counting toward it — it is here so you can read the sources yourself.
The panel lists 420 mg of magnesium per serving. Studies we found used 200 mg–420 mg a day, so this sits inside that range.
0studied 200 mg–420 mg
Study ranges differ between trials and change as research changes. This is background reading, not a pass, a failure, or a recommendation.
Where it sells
Price check for this exact product
Amazon
Exact UPC/GTIN match$19.99
$0.67 per labeled serving
matching UPC/GTIN · checked Aug 1, 2026
View on Amazon ↗iHerb
Not confirmedNo exact listing saved
We only show a price when the seller publishes the same barcode as the bottle. We haven’t found that match here.
Search iHerb ↗Target
Not confirmedNo exact listing saved
We only show a price when the seller publishes the same barcode as the bottle. We haven’t found that match here.
Search Target ↗Walmart
Not confirmedNo exact listing saved
We only show a price when the seller publishes the same barcode as the bottle. We haven’t found that match here.
Search Walmart ↗Only one exact price was available at build time; prices change by date, seller, and promotion.
Reference prices only · no affiliate links · every compared seller must publish the matching UPC/GTIN.
Want the complete evidence trail?
The summary stops at product-specific facts. The full report preserves every source, calculation, limitation, and unresolved check for review or sharing.
Record built August 02, 2026. Sources: source listing observed at check time · USPTO Trademark Search · Keepa exact-listing history · NIH / published research · certification and regulator records where available. LookCloser publishes evidence and gaps; it does not advise for or against any supplement. Evidence-based corrections welcome.