Label arithmetic · NIH DSLD 282198
Natural Factors Magnesium Citrate 150 mg: 150 mg of magnesium per capsule, 1–3 capsules a day
150 mg of magnesium per capsule; the label's 1–3 capsules a day give 150–450 mg. No US price matched (Nov 2). Inside: salt weight, capsule size.
Natural Factors Magnesium Citrate 150 mg declares 150 mg of elemental magnesium per serving as citrate, which needs 928–1,327 mg of magnesium citrate in each capsule, 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: it fits only that size. No US retail price matched as of 2026-11-02; 17 of the 135 citrate labels in this registry have a matched price. NIH DSLD 282198, label dated 2023-01-23.
computed from the filed label
Chart data
| Displayed chart text |
|---|
| 545 mg |
| 730 mg |
| 1,100 mg |
| 928–1,327 mg of citrate per capsule |
Data release 2026-08-10-f441aa9f · registry snapshot 2026-08-10 · latest price observation 2026-10-19 · chemistry 2026-10-17
Mass: 928–1,327 mg per capsule · Price: none matched · % DV: 36% vs 36%
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 150 mg of citrate actually fit in one capsule, or do I need more than one?
Estimated salt mass versus assumed capsule capacity: Natural Factors Magnesium Citrate 150 mg implies 928–1,327 mg of magnesium citrate in each capsule to deliver 150 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: needs size 000, read at the most favourable hydration and the most units per serving.
computed with assumption| Measure | Value |
|---|---|
| Elemental magnesium per serving | 150 mg |
| Units per serving | 1 |
| Magnesium citrate per serving | 928–1,327 mg |
| Magnesium citrate per capsule | 928–1,327 mg |
| Capsule capacity 0 · 00 · 000 | 545 · 730 · 1,100 mg |
| Verdict | Needs size 000 |
The filed salt can have more than one hydration state (trimagnesium dicitrate 16.2%; dibasic and hydrated forms as low as 11.3%), so the compound mass is a range.
Source · NIH DSLD 282198 · label 2023-01-23; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
How much elemental magnesium is actually in this label's filed magnesium lines?
Natural Factors Magnesium Citrate 150 mg files 1 magnesium line in NIH DSLD 282198; the selected primary line declares 150 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 |
|---|---|---|
| 150 mg | Salt not named in this row; magnesium citrate is taken from the label text | Primary serving |
Source · NIH DSLD 282198 · label 2023-01-23; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Does this label's citrate claim hold up, or could the magnesium come from another source?
The label names one magnesium form, citrate, resolved from the full NIH DSLD record text; 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 citrate | 11.3–16.2% | full NIH DSLD record text |
Source · NIH DSLD 282198 · label 2023-01-23; 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; 17 of 135 citrate labels have one, against a median of $0.1159 per 100 mg among 12 ranked citrate offers.
computed
Chart data
| Displayed chart text |
|---|
| n=12 |
| P25 $0.0843 |
| P75 $0.1469 |
| median $0.1159 |
| Rank | Label | Per 100 mg | Observed |
|---|---|---|---|
| 1 | Best Naturals Magnesium Citrate 200 mg | $0.0344 | 2026-11-02 |
| 2 | Solgar Magnesium Citrate | $0.0607 | 2026-11-02 |
| 3 | LES Labs Magnesium Citrate | $0.0777 | 2026-11-02 |
| 4 | Bluebonnet Magnesium Citrate | $0.0865 | 2026-11-02 |
| 5 | Solaray Magnesium Citrate 400 mg | $0.0868 | 2026-11-02 |
| Median | 12 ranked citrate offers | $0.1159 | 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, Natural Factors Magnesium Citrate 150 mg lasts 120–360 days: 360 servings against 1–3 servings a day in the filed directions.
computed| Measure | Value |
|---|---|
| Net contents as filed | 360 Capsule(s) |
| Serving size as filed | 1 Capsule(s) |
| Servings per container | 360 |
| Servings per day in the directions | 1–3 |
| Days per bottle | 120–360 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 282198 · label 2023-01-23; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What does "36% Daily Value" mean here, and does it recompute?
The label declares 36% Daily Value; 150 mg against the 420 mg reference in 21 CFR 101.9 recomputes to 36%, the same within one point.
computed| Group as filed | Declared | Reference | Recomputed |
|---|---|---|---|
| Adults and children 4 or more years of age | 36% | 420 mg | 36% |
Source · NIH DSLD 282198; 21 CFR 101.9 · label 2023-01-23 · release 2026-08-10-f441aa9f · CSV · method
Why does this label contain magnesium stearate, what shell is it, and who is it filed for?
Natural Factors Magnesium Citrate 150 mg files 3 other ingredients, including magnesium stearate (reference fraction 4.1% magnesium; no quantity filed, so it is not added to the total) and a gelatin shell, against 43 of 135 citrate labels that list magnesium stearate.
measured| Entry | Filed ingredient or declaration |
|---|---|
| 1 | Gelatin capsule |
| 2 | Microcrystalline Cellulose |
| 3 | Magnesium Stearate |
| Shell | gelatin |
| Target group | Adult (18 - 50 Years) |
| Target group | Gluten Free |
| Target group | Dairy Free |
| Target group | Sugar Free |
Source · NIH DSLD 282198 · label 2023-01-23; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What has research measured about citrate, and about side effects?
10 studies in the PubMed-checked registry measured outcomes involving citrate; 1 mention gastrointestinal or adverse outcomes. They measured the salt, not this label.
measured| Year | Study | PubMed |
|---|---|---|
| 2025 | Comparing the Bioavailability of Two Seawater-Derived Magnesium Preparations. | 40955524 |
| 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?
Natural Factors has 0 FDA recall records matched by brand name in the enforcement data queried 2026-10-19. Natural Factors 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 |
|---|---|---|---|
| No recall record as of 2026-10-19 |
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 282198 · label 2023-01-23; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Which labels are closest to this one, with the same salt and dose?
6 labels use the same resolved citrate within ±10% of this label's 150 mg per unit, compared side by side on price and capsule verdict.
computed| Label | Elemental per unit | Price | Verdict |
|---|---|---|---|
| Douglas Laboratories Magnesium Citrate (DSLD 56862) | 150 mg | No price | Needs size 000 |
| Natural Factors Magnesium Citrate 150 mg Key Lime | 150 mg | No price | Capsule sizes do not apply |
| Natural Factors Magnesium Citrate 150 mg (DSLD 220684) | 150 mg | No price | Needs size 000 |
| Natural Factors Magnesium Citrate 150 mg (DSLD 220688) | 150 mg | No price | Needs size 000 |
| PureFormulas Magnesium Citrate | 150 mg | No price | Needs size 000 |
| Douglas Laboratories Magnesium Citrate (DSLD 232777) | 150 mg | $19.00 · 2026-11-02 | Needs size 000 |
Source · NIH DSLD 282198 · label 2023-01-23; 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 282198 (label 2023-01-23, 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 0 68958 01655 9). The CSV carries the values shown here.
measured| Field | As filed |
|---|---|
| NIH DSLD label | NIH DSLD 282198 |
| Scanned label (PDF) | Label 282198 scan |
| Label date | 2023-01-23 |
| Date entered into DSLD | 2023-01-23 |
| Barcode (UPC) as filed | 0 68958 01655 9 |
| Label version · Package size difference, same product | NIH DSLD 51333 |
| Label version · Package size difference, same product | NIH DSLD 36863 |
| Label version · Package size difference, same product | NIH DSLD 51334 |
31 additional rows
| Field | As filed |
|---|---|
| Label version · Package size difference, same product | NIH DSLD 36862 |
| Label version · Package size difference, same product | NIH DSLD 220688 |
| Label version · Package size difference, same product | NIH DSLD 2273 |
| Label version · Package size difference, same product | NIH DSLD 36878 |
| Label version · Package size difference, same product | NIH DSLD 51332 |
| Label version · Package size difference, same product | NIH DSLD 8386 |
| Label version · Image difference, same product | NIH DSLD 36863 |
| Label version · Image difference, same product | NIH DSLD 51334 |
| Label version · Package size difference, same product | NIH DSLD 220684 |
| Manufactured by | Natural Factors Canada, Monroe, WA |
| Claim category as filed | Nutrient |
| Claim category as filed | All Other |
| Claim category as filed | Structure/Function |
| Seals/Symbols | ISURA Non GMO - Mass Spec Documentation - Lab Tested |
| Suggested/Recommended/Usage/Directions | Suggested usage: 1 capsule 1–3 times per day or as directed by a health professional. |
| Precautions re: Pregnant or Nursing or Prescription Medications | Cautions: As with any supplement, consult your health professional before use if you are pregnant, breastfeeding, or trying to conceive, or if you are taking medication, have a medical condition, or anticipate a surgery. |
| Precautions re: Children | Keep out of the reach of children. |
| Formula re: Contains | Magnesium Citrate is in an easy-to-swallow capsule. The citrate form is extremely well absorbed and well tolerated by the body and magnesium is necessary for hundreds of enzyme reactions in the body and for normal heart function. It is necessary for protein synthesis, carbohydrate metabolism, proper muscle function, and helps to absorb calcium and potassium. |
| Formula re: Contains | Mg True elemental content |
| Formulation re: Does NOT Contain | Contains no artificial colors, preservatives, or sweeteners; no dairy, starch, sugar, wheat, gluten, yeast, soy, corn, egg, fish, shellfish, salt, tree nuts, or GMOs. |
| Precautions re: All Other | Sealed for your protection. Do not use if seal is broken. |
| Storage | For freshness, store in a cool, dry place. |
| FDA Disclaimer Statement | This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. |
| Seals/Symbols | Purity & potency guaranteed |
| General Statements: All Other Content | Recyclable container and label. |
| FDA Statement of Identity | Dietary Supplement |
| Formulation re: Other | Healthy muscle & heart function |
| Brand IP Statement(s) re: (c), (TM), (SM) | Isura is a trademark of ISURA. |
| Formulation re: Other | Manufactured by Natural Factors to ensure safety and potency in accordance with Good Manufacturing Practices (GMP) of the FDA and Health Canada. |
| Physical state | Capsule |
| Registry snapshot | 2026-08-10 |
Source · NIH DSLD 282198 · label 2023-01-23; 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.