Label arithmetic · NIH DSLD 10307
Douglas Laboratories MgO2 (Magnesium Caps): 215 mg of magnesium per capsule, 1 capsule a day
215 mg of magnesium per capsule, 1 a day. No US price matched (Nov 2). Inside: salt weight, capsule size.
Douglas Laboratories MgO2 (Magnesium Caps) declares 215 mg of elemental magnesium per serving as oxide, which needs 356 mg of magnesium oxide in each capsule, against 545 mg in a size 0 capsule at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range: it fits a size 0 capsule, the smallest of the three sizes compared here. No US retail price matched as of 2026-11-02; 10 of the 61 oxide labels in this registry have a matched price. NIH DSLD 10307, label dated 2012-06-25.
computed from the filed label
Chart data
| Displayed chart text |
|---|
| 545 mg |
| 730 mg |
| 1,100 mg |
| 356 mg of oxide per capsule |
Data release 2026-08-10-f441aa9f · registry snapshot 2026-08-10 · latest price observation 2026-10-19 · chemistry 2026-10-17
Mass: 356 mg per capsule · Price: none matched · % DV: 54% vs 51%
Elemental: The magnesium itself; the rest of the compound weight is the partner molecule.
Compound: The whole salt, such as magnesium glycinate, that must physically fit in the capsule.
Size 000: The largest standard capsule, about 1,100 mg of powder at 0.8 g/mL, the top of the usual 0.6–0.8 range; size 00 holds about 730 mg and size 0 about 545 mg.
Recompute with your price
Enter the price you paid; the declared amount and servings of this label are prefilled, so the result is the cost per 100 mg of elemental magnesium for your bottle.
Same-salt comparison appears here.
Will 215 mg of oxide actually fit in one capsule, or do I need more than one?
Estimated salt mass versus assumed capsule capacity: Douglas Laboratories MgO2 (Magnesium Caps) implies 356 mg of magnesium oxide in each capsule to deliver 215 mg of elemental magnesium, against 1,100 mg in the largest standard capsule (size 000) at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range. Verdict: fits size 0, read at the most favourable hydration and the most units per serving.
computed with assumption| Measure | Value |
|---|---|
| Elemental magnesium per serving | 215 mg |
| Units per serving | 1 |
| Magnesium oxide per serving | 356 mg |
| Magnesium oxide per capsule | 356 mg |
| Capsule capacity 0 · 00 · 000 | 545 · 730 · 1,100 mg |
| Verdict | Fits size 0 |
Source · NIH DSLD 10307 · label 2012-06-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
How much elemental magnesium is actually in this label's filed magnesium lines?
Douglas Laboratories MgO2 (Magnesium Caps) files 1 magnesium line in NIH DSLD 10307; the selected primary line declares 215 mg of elemental magnesium per serving, against 0 other rows excluded from the primary amount. A salt named under another nutrient does not turn that nutrient's quantity into elemental magnesium.
measured| Filed amount | Salt or note as filed | Role |
|---|---|---|
| 215 mg | oxide · Magnesium (Form: from 500 mg Magnesium Peroxide) | Primary serving |
Source · NIH DSLD 10307 · label 2012-06-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Does this label's oxide claim hold up, or could the magnesium come from another source?
The label names one magnesium form, oxide, resolved from the filed magnesium line; at that salt the declaration is within the assumed size 000 capacity at powder density 0.8 g/mL, compared with oxide, the salt richest in magnesium at 60.3%.
computed with assumption| Form named on the label | Elemental fraction | Source |
|---|---|---|
| Magnesium oxide | 60.3% | filed magnesium line |
Source · NIH DSLD 10307 · label 2012-06-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Is this a good price for the elemental magnesium I'm actually getting?
No US retail price is matched to this label as of 2026-11-02; 10 of 61 oxide labels have one, against a median of $0.0293 per 100 mg among 5 ranked oxide offers.
computed
Chart data
| Displayed chart text |
|---|
| n=5 |
| P25 $0.0258 |
| P75 $0.0356 |
| median $0.0293 |
| Rank | Label | Per 100 mg | Observed |
|---|---|---|---|
| 1 | Nutricost Magnesium Oxide | $0.0148 | 2026-11-02 |
| 2 | tnvitamins Magnesium Oxide 420 mg | $0.0258 | 2026-11-02 |
| 3 | Douglas Laboratories Magnesium Oxide | $0.0293 | 2026-11-02 |
| 4 | Wonder Labs Magnesium Oxide 400 | $0.0356 | 2026-11-02 |
| 5 | Carlson Magnesium Gels 400 mg | $0.0636 | 2026-11-02 |
| Median | 5 ranked oxide offers | $0.0293 | 2026-11-02 |
Source · Amazon via licensed data provider; NIH DSLD · unique ASIN × date; prices observed 2026-10-26 to 2026-11-02 · release 2026-08-10-f441aa9f · CSV · method
How many days will this bottle last at the label's own serving, and what does a day cost?
At the label's own serving, Douglas Laboratories MgO2 (Magnesium Caps) lasts 90 days: 90 servings against 1 serving a day in the filed directions.
computed| Measure | Value |
|---|---|
| Net contents as filed | 90 Capsule(s) |
| Serving size as filed | 1 Capsule(s) |
| Servings per container | 90 |
| Servings per day in the directions | 1 |
| Days per bottle | 90 days |
| $ per 30 days at one label serving a day | No ranked price as of 2026-11-02 |
| $ per 30 days at 420 mg Daily Value | No ranked price as of 2026-11-02 |
Source · NIH DSLD 10307 · label 2012-06-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What does "54% Daily Value" mean here, and does it recompute?
The label declares 54% Daily Value; 215 mg against the 420 mg reference in 21 CFR 101.9 recomputes to 51%, a difference of 3 points. Labels filed under the earlier 400 mg reference, or with a different filing basis, show gaps of this kind.
computed
Chart data
| Displayed chart text |
|---|
| Declared vs recomputed % |
| DV |
| 51 · 54 |
| Declared vs |
| recomputed % DV |
| Group as filed | Declared | Reference | Recomputed |
|---|---|---|---|
| Adults and children 4 or more years of age | 54% | 420 mg | 51% |
Source · NIH DSLD 10307; 21 CFR 101.9 · label 2012-06-25 · release 2026-08-10-f441aa9f · CSV · method
Why does this label contain these other ingredients, what shell is it, and who is it filed for?
Douglas Laboratories MgO2 (Magnesium Caps) files 3 other ingredients and a gelatin shell, and no magnesium stearate, against 30 of 61 oxide labels that list magnesium stearate.
measured| Entry | Filed ingredient or declaration |
|---|---|
| 1 | Cellulose |
| 2 | Gelatin |
| 3 | Vegetable Stearate |
| Shell | gelatin |
| Target group | Adult (18 - 50 Years) |
| Target group | Dairy Free |
| Target group | Sugar Free |
Source · NIH DSLD 10307 · label 2012-06-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What has research measured about oxide, and about side effects?
12 studies in the PubMed-checked registry measured outcomes involving oxide; 2 mention gastrointestinal or adverse outcomes. They measured the salt, not this label.
measured| Year | Study | PubMed |
|---|---|---|
| 2026 | Randomized, open-label study of the short-term pharmacokinetics of oral magnesium oxide in healthy volunteers. | 42091979 |
| 2024 | Comparative Clinical Study on Magnesium Absorption and Side Effects After Oral Intake of Microencapsulated Magnesium (MAGSHAPE™ Microcapsules) Versus Other Magnesium Sources. | 39770988 |
| 2022 | Effects of short-term magnesium supplementation on ionized, total magnesium and other relevant electrolytes levels. | 35041150 |
Source · PubMed-checked study registry · registry checked 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Has this brand had FDA recalls or adverse event reports?
Douglas Laboratories has 1 FDA recall record matched by brand name in the enforcement data queried 2026-10-19. Douglas Laboratories has FDA CAERS adverse event reports on record at brand level, as do 143 of 273 brands in this registry; openFDA states that “there is no certainty that the reported event (adverse event) was actually due to the product” and that reports “cannot be used to estimate the incidence of these events.”
measured| Recall | Date | Reason | Status |
|---|---|---|---|
| F-1202-2015 | 2015-02-18 | Bottles contained a vegetarian digestive enzyme dietary supplement instead of melatonin. | Terminated |
Source · openFDA enforcement and CAERS · queried 2026-10-19 · release 2026-08-10-f441aa9f · CSV · method
Is this the same formula as another brand's, and how do their prices differ?
No other brand files the same formulation (ingredients, shell, units and rounded amount) as of 2026-11-02.
computed| Label | Brand | Price per 100 mg |
|---|---|---|
| No cross-brand match as of 2026-11-02 |
Source · NIH DSLD 10307 · label 2012-06-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Which labels are closest to this one, with the same salt and dose?
3 labels use the same resolved oxide within ±10% of this label's 215 mg per unit, compared side by side on price and capsule verdict.
computed| Label | Elemental per unit | Price | Verdict |
|---|---|---|---|
| Douglas Laboratories MgO2 (Magnesium Caps) | 215 mg | No price | Fits size 0 |
| Nutricost Magnesium Oxide 375 mg | 210 mg | $14.95 · 2026-11-02 | Fits size 0 |
| Swanson Magnesium 200 mg | 200 mg | No price | Fits size 0 |
Source · NIH DSLD 10307 · label 2012-06-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Where does this record come from, what is missing, and how do I cite or correct it?
Every value on this page traces to NIH DSLD 10307 (label 2012-06-25, snapshot 2026-08-10) and the chemistry model of 2026-09-13. 1 gap remain: No US retail price matched as of 2026-11-02 (barcode 3 10539 00330 5). The CSV carries the values shown here.
measured| Field | As filed |
|---|---|
| NIH DSLD label | NIH DSLD 10307 |
| Label date | 2012-06-25 |
| Date entered into DSLD | 2012-06-25 |
| Barcode (UPC) as filed | 3 10539 00330 5 |
| Label version · Image difference, same product | NIH DSLD 10308 |
| Manufactured in the USA by | Douglas Laboratories, Pittsburgh, PA, USA |
| Claim category as filed | All Other |
| Formulation re: Does NOT Contain | This product contains NO yeast, wheat gluten, soy protein, milk/dairy, corn, sodium, sugar, starch, artificial coloring, preservatives or flavoring. |
8 additional rows
| Field | As filed |
|---|---|
| Suggested/Recommended/Usage/Directions | Suggested Usage: As a dietary supplement, adults take 1 capsule daily or as directed by your healthcare professional. |
| Precautions re: Children | KEEP OUT OF REACH OF CHILDREN. |
| Storage | For optimal storage conditions, store in a cool, dry place. (59(0)-77(0)F/15(0)-25(0)C) (35-65% relative humidity) |
| Precautions re: All Other | Tamper resistant package, do not use if outer seal is missing. |
| General: Product/Version Code | Formula #85477 |
| FDA Statement of Identity | A Dietary Supplement |
| Physical state | Capsule |
| Registry snapshot | 2026-08-10 |
Source · NIH DSLD 10307 · label 2012-06-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
6 brand pages linked below contain magnesium labels from the NIH DSLD registry snapshot dated 2026-08-10.