Label arithmetic · NIH DSLD 313575
NOW Magnesium Caps 400 mg: 400 mg of magnesium per capsule, 1 capsule a day (salt not resolved)
400 mg of magnesium per capsule, 1 a day. Salt not resolved from the NIH record; no US price matched (Nov 2). Inside: label lines, ingredients.
NOW Magnesium Caps 400 mg declares 400 mg of elemental magnesium per 1 veg capsule(s); the magnesium salt is not resolved from the filed record, Single-salt capacity audit excluded as of 2026-10-17: one salt with a defined elemental fraction is not resolved., as of 2026-11-02. No US retail price matched as of 2026-11-02. NIH DSLD 313575, label dated 2024-10-24.
as filedData release 2026-08-10-f441aa9f · registry snapshot 2026-08-10 · latest price observation 2026-10-19 · chemistry 2026-10-17
Mass: not computable · Price: none matched · % DV: 95% vs 95%
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 400 mg of magnesium actually fit in one capsule, or do I need more than one?
The compound mass behind this label cannot be computed as of 2026-11-02: Single-salt capacity audit excluded as of 2026-10-17: one salt with a defined elemental fraction is not resolved.. The filed amounts are listed in the next block. Lower bound, not a measurement: even if all 400 mg of magnesium per serving came from magnesium oxide (60.3% magnesium), the richest magnesium salt used in supplements, because the label names no form, the single capsule would need at least 663 mg of compound, so at this bound it needs at least a size 00 capsule (about 730 mg at 0.8 g/mL); the actual form, which the label does not name, may need more.
computed with assumption| Measure | Value |
|---|---|
| Elemental magnesium per serving | 400 mg |
| Units per serving | 1 |
| Magnesium salt per serving | Not computable as of 2026-11-02 |
| Magnesium salt per capsule | Not computable as of 2026-11-02 |
| Capsule capacity 0 · 00 · 000 | 545 · 730 · 1,100 mg |
| Verdict | Not computable as of 2026-11-02 |
Source · NIH DSLD 313575 · label 2024-10-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
How much elemental magnesium is actually in this label's filed magnesium lines?
NOW Magnesium Caps 400 mg files 1 magnesium line in NIH DSLD 313575; the selected primary line declares 400 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 |
|---|---|---|
| 400 mg | elemental | Primary serving |
Source · NIH DSLD 313575 · label 2024-10-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Does this label's magnesium claim hold up, or could the magnesium come from another source?
No single magnesium salt is resolved from the filed record as of 2026-11-02, so the source of the declared magnesium cannot be checked against capsule capacity, compared with oxide, the salt richest in magnesium at 60.3%.
computed with assumption| Form named on the label | Elemental fraction | Source |
|---|---|---|
| No form named as of 2026-11-02 | No defined fraction | named on label |
Source · NIH DSLD 313575 · label 2024-10-24; 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, and without a resolved salt there is no same-salt comparison.
computed| Rank | Label | Per 100 mg | Observed |
|---|
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, NOW Magnesium Caps 400 mg lasts 180 days: 180 servings against 1 serving a day in the filed directions.
computed| Measure | Value |
|---|---|
| Net contents as filed | 180 Veg Capsule(s) |
| Serving size as filed | 1 Veg Capsule(s) |
| Servings per container | 180 |
| Servings per day in the directions | 1 |
| Days per bottle | 180 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 313575 · label 2024-10-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What does "95% Daily Value" mean here, and does it recompute?
The label declares 95% Daily Value; 400 mg against the 420 mg reference in 21 CFR 101.9 recomputes to 95%, the same within one point.
computed| Group as filed | Declared | Reference | Recomputed |
|---|---|---|---|
| Adults and children 4 or more years of age | 95% | 420 mg | 95% |
Source · NIH DSLD 313575; 21 CFR 101.9 · label 2024-10-24 · 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?
NOW Magnesium Caps 400 mg files 4 other ingredients and a vegetarian shell.
measured| Entry | Filed ingredient or declaration |
|---|---|
| 1 | Hypromellose |
| 2 | Rice Flour |
| 3 | Silicon Dioxide |
| 4 | Stearic Acid |
| Shell | vegetarian |
| Target group | Vegan |
| Target group | Vegetarian |
| Target group | Adult (18 - 50 Years) |
4 additional rows
| Entry | Filed ingredient or declaration |
|---|---|
| Target group | Kosher |
| Target group | Halal |
| Target group | Gluten Free |
| Target group | Dairy Free |
Source · NIH DSLD 313575 · label 2024-10-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What has research measured about this form, and about side effects?
No study in the registry measured an unresolved salt as of 2026-11-02.
measured| Year | Study | PubMed |
|---|
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?
NOW has 12 FDA recall records matched by brand name in the enforcement data queried 2026-10-19. NOW 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-1726-2013 | 2013-07-31 | It has been determined that this product contains an undeclared ingredient, licorice extract, which contains glycyrrhizin derived from licorice root. | Terminated |
| F-0770-2014 | 2013-12-25 | Firm is recalling dietary supplements containing a raw material which may contain >0.3 ppb chloramphenicol | Terminated |
| F-1537-2014 | 2014-02-26 | Digestive enzyme capsules manufactured by NOW Foods may contain the antibiotic chloramphenicol. | Terminated |
| F-1484-2017 | 2017-02-22 | Product's supplement fact panel incorrectly states that the product contains 75 mg (milligrams) of Molybdenum, when it actually contains 75 mcg (micrograms). | Terminated |
| F-0682-2019 | 2018-12-12 | NOW Health Group Inc. initiated a voluntary recall of NOW s Vitamin B-50 mg 100 Veg Caps product code 0420 because it is mislabeled as Vitamin B-50 mg 100 Veg Caps. | 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 313575 · label 2024-10-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Which labels are closest to this one, with the same salt and dose?
No other label files the same resolved salt within ±10% of this label's dose per unit as of 2026-11-02.
computed| Label | Elemental per unit | Price | Verdict |
|---|---|---|---|
| No neighbour as of 2026-11-02 |
Source · NIH DSLD 313575 · label 2024-10-24; 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 313575 (label 2024-10-24, snapshot 2026-08-10) and the chemistry model of 2026-09-13. 3 gaps remain: Single-salt capacity audit excluded as of 2026-10-17: one salt with a defined elemental fraction is not resolved.; No US retail price matched as of 2026-11-02 (barcode 7 33739 01283 8); A single salt with a defined elemental fraction is unresolved as of 2026-11-02. The CSV carries the values shown here.
measured| Field | As filed |
|---|---|
| NIH DSLD label | NIH DSLD 313575 |
| Scanned label (PDF) | Label 313575 scan |
| Label date | 2024-10-24 |
| Date entered into DSLD | 2024-10-24 |
| Barcode (UPC) as filed | 7 33739 01283 8 |
| Label version · Image difference, same product | NIH DSLD 51741 |
| Label version · Image difference, same product | NIH DSLD 55223 |
| Label version · Image difference, same product | NIH DSLD 14582 |
27 additional rows
| Field | As filed |
|---|---|
| Label version · Image difference, same product | NIH DSLD 70557 |
| Manufacturer | NOW Foods, Bloomingdale, IL, USA |
| Claim category as filed | Nutrient |
| Claim category as filed | All Other |
| Claim category as filed | Structure/Function |
| Suggested/Recommended/Usage/Directions | Suggested Usage: Take 1 capsule daily. |
| Formula re: Contains | Magnesium is a mineral that is critical for energy production and metabolism, muscle contraction, nerve impulse transmission, and bone mineralization. It is a required cofactor for an estimated 300 enzymes. Among the reactions catalyzed by these enzymes are fatty acid synthesis, protein synthesis, and glucose metabolism. Magnesium status is also important for regulation of calcium balance through its effects on the parathyroid gland. |
| FDA Disclaimer Statement | These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. |
| Precautions re: Children | Caution: For adults only. |
| Precautions re: Pregnant or Nursing or Prescription Medications | Consult physician if pregnant/nursing, taking medication, or have a medical condition. |
| Precautions re: Children | Keep out of reach of children. |
| Formulation re: Other | Natural color variation may occur in this product. |
| Formulation re: Other | Nervous system support Supports energy production Critical for enzyme function |
| Formulation re: Does NOT Contain | Non-GMO |
| FDA Statement of Identity | A Dietary Supplement |
| Formulation re: Vegetarian/Vegan | Vegetarian/Vegan |
| Formula re: Kosher | Triangle K (Kosher) |
| Seals/Symbols | Triangle K (Kosher) |
| General Statements: All Other Content | Minerals Family owned since 1968. |
| Formulation re: Other | Made and quality tested in the USA with globally sourced ingredients. |
| Formulation re: Does NOT Contain | Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish, tree nut or sesame ingredients. |
| Precautions re: Allergies | Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish, tree nut or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens. |
| Storage | Store in a cool, dry place after opening. |
| Formula re: Type | Crescent H Halal |
| Seals/Symbols | Crescent H Halal GMP Quality Assured |
| Physical state | Capsule |
| Registry snapshot | 2026-08-10 |
Source · NIH DSLD 313575 · label 2024-10-24; 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.