Calcium & Magnesium

Two-mineral calcium and magnesium reference formula at an example 500 mg calcium and 250 mg magnesium per serving, developed as a tablet, capsule or powder, with amounts set by the brand.

Calcium & Magnesium is a reference formula for brands building a two-mineral product with calcium and magnesium as the only active ingredients. The amounts of 500 mg calcium and 250 mg magnesium per serving are examples from a labeled product, and the brand sets the final pair of amounts for its market.

Development centers on two salts in one serving: the combined salt weight decides the number of tablets or capsules, and the choice of calcium and magnesium salt sets the texture of a powder. Tablet is the lead format, with capsule and powder versions built on the same elemental amounts.

Ingredient Composition

IngredientPer ServingRaw Material FormAlternative Form (same amount of active)
Calcium500 mg (example amount)Calcium carbonate for tablets and capsules, specified on elemental calcium; 500 mg calcium per servingCalcium citrate for powders, with the input recalculated to 500 mg of elemental calcium
Magnesium250 mg (example amount)Magnesium oxide for tablets and capsules, specified on elemental magnesium; 250 mg magnesium per servingMagnesium citrate for powders, or magnesium glycinate (bisglycinate), each recalculated to 250 mg of elemental magnesium

Amounts are stated as mg of elemental calcium (Ca, 40.08 g/mol; PubChem CID 5460341) and elemental magnesium (Mg, 24.305 g/mol; PubChem CID 5462224). Elemental content by weight follows from the anhydrous molecular weights: calcium carbonate 40.0% (CID 10112, 100.09 g/mol), calcium citrate 24.1% (CID 13136, 498.4 g/mol, three calcium atoms), magnesium oxide 60.3% (CID 14792, 40.305 g/mol), magnesium citrate 16.2% (CID 6099959, 451.12 g/mol, three magnesium atoms) and magnesium glycinate 14.1% (CID 84645, 172.42 g/mol). Hydrate state and assay of each purchased salt are set with the supplier.

Intended Benefits & Formula Rationale

This formula is designed for products positioned around daily mineral intake and bone nutrition. Calcium and magnesium are included as the only actives so that the pair of amounts, the salts and the unit count can be set together.

Intended Benefit DirectionKey IngredientsFormulation Rationale
Daily mineral intakeCalcium, MagnesiumIncluded as two minerals that a narrative review links to skeletal health: magnesium appears to be involved in bone metabolism, and magnesium deficiency could negatively influence bone and muscle health [1]. Evidence: Referenced
Bone nutritionCalcium, MagnesiumPositioned around skeletal nutrition, with the evidence mixed: the same review reports that calcium alone is not recommended for fracture prevention in the general postmenopausal population and that data on magnesium supplementation and bone are inconclusive [1], and a later review of trials concluded that calcium supplements do not prevent fractures in community-dwelling adults [2]. Evidence: Contested
Magnesium salt selectionMagnesium oxide, citrate, glycinateIn a randomized, double-blind study the organic forms (citrate and amino-acid chelate) showed greater absorption at 60 days than oxide [3]; a separate study measured fractional absorption of oxide at 4% [4]. Evidence: Referenced

The reviews do not agree on what supplemental calcium and magnesium do for the skeleton, so the pair of amounts, the claims and the target market are brand decisions reviewed per market.

Available Formats

The reference formula is built for tablet, capsule and powder versions; the unit count per serving is a design choice that the brand can adjust.

FormatUnitPer ServingPack SizeOther Ingredients (typical)Suitability
Tablet2 tabletsCalcium 500 mg + Magnesium 250 mg120 tablets (60 servings)Microcrystalline cellulose, croscarmellose sodium, stearic acid, magnesium stearate, aqueous coatingLead format; both salts shared across two tablets
Capsule4 capsulesCalcium 500 mg + Magnesium 250 mg240 capsules (60 servings)Capsule shell, flow agent, magnesium stearateFour-capsule serving for brands that avoid tablets
Powder1 stick packCalcium 500 mg + Magnesium 250 mg30 stick packsDiluent, acidulant, sweetener, flavorCitrate salts for a drink mix

Raw Material Input & Fill (Design Estimate)

Design estimates. Each input is the elemental amount divided by the elemental share of the salt at an assumed 100% assay: calcium carbonate 40.0% and magnesium oxide 60.3% for tablets and capsules (about 1,249 mg + 415 mg of salt per serving), calcium citrate 24.1% and magnesium citrate 16.2% for powder (about 2,073 mg + 1,547 mg).

FormatRaw Material Input per UnitDesign FillBalance for ExcipientsVerification Before Scale-Up
Tablet624 mg calcium carbonate + 207 mg magnesium oxide per tablet (2 per serving)1000 mg tablet weight169 mgCompression behavior, hardness, disintegration, content assay of both minerals
Capsule312 mg calcium carbonate + 104 mg magnesium oxide per capsule (4 per serving)500 mg per capsule84 mgFill weight variation, powder flow, content assay of both minerals
Powder2073 mg calcium citrate + 1547 mg magnesium citrate per stick5500 mg per stick1880 mgDispersion in water, grittiness, taste, content assay of both minerals

Gummy, softgel and liquid versions are separate projects, because the combined salt load of about 1.7 g or more does not fit those formats without a smaller amount per unit.

Formulation Considerations

Combined salt weight. Carbonate and oxide together come to about 1.66 g per serving, which is why the design uses two tablets or four capsules and why the 1000 mg tablet leaves only 169 mg for excipients. The unit count is fixed together with the brand’s pack and the final pair of amounts.
Two minerals in one unit. Calcium and magnesium share one tablet or capsule blend, so the interaction of the two minerals, including any competition in absorption, and the stability of the combined blend are questions for the pilot run and the stability study, not conclusions of this design.
Magnesium salt and absorption. Oxide is the compact salt, while the cited studies measured lower absorption for oxide than for citrate, chelate, chloride, lactate and aspartate [3][4]. Magnesium salts also differ in gastrointestinal tolerance, so the salt and the amount per serving are chosen together and reviewed per market.
Safety review of the calcium amount. A review of trial evidence reports that calcium supplements commonly produce gastrointestinal side effects, increase the risk of renal calculi, and are associated with a 10–20% higher risk of myocardial infarction in meta-analyses of adverse events [2]. Calcium carbonate is also an insoluble salt that shows as grittiness in a drink mix, so particle size is tested in the powder version.

Customization Options

Brands adjust the pair of amounts, the two salts, the unit count and the format.

ParameterRangeNote
Amount per servingCalcium 250 mg + Magnesium 50 mg, 300 mg + 150 mg or 500 mg + 250 mgOptions for the brand; the total salt weight and unit count move with both numbers
Calcium saltCarbonate or citrateCitrate needs about 1.7 times the salt weight of carbonate for the same elemental calcium
Magnesium saltOxide, citrate or glycinateOxide gives the smallest unit; citrate and glycinate need about 3.7 and 4.3 times the oxide weight
Units per serving1 to 4 tablets or capsulesSet by the amounts and the salts
Add-onsVitamin D, vitamin K2A third active shares the tablet weight already taken by two mineral salts

The pilot run confirms tablet hardness and disintegration with both salts present, capsule fill weight and flow of the blended salts, powder grittiness, and the content assay of calcium and of magnesium in the first units against the labeled amounts.

Flavor Options

FormatSuggested FlavorsWhy
PowderLemon, vanilla, orangeMild citrus and vanilla profiles cover the chalky and salty notes of the two mineral salts

Technical Status & Data Sources

ItemStatusDetails
Reference formulaNIH DSLDThe ingredient and amount come from a labeled product in the NIH DSLD (Calcium 500 mg + Magnesium 250 mg on the label of CF000479, a one-tablet serving; example DSLD labels 3107, 6065, 81238). The label names the ingredients as calcium and magnesium; calcium carbonate and magnesium oxide are set as the forms.
SpecificationSet in formulationCalcium carbonate and magnesium oxide (citrate salts for powders), 500 mg elemental calcium and 250 mg elemental magnesium per serving; assay, particle size and heavy-metal limits and method are fixed with the supplier. Unit size, fill weight and stability are set in formulation.
Data sourceNIH DSLDDSLD v9.4.0, downloaded 2026-01-10: 50,824 reference formulas merged from on-market labels with complete ingredient amounts. Counts show how labels are distributed.
Market reviewPer marketDose limits, labeling and claims are reviewed for each sales market before a finished product is developed.
ReferencesSources[1] Capozzi A, Scambia G, Lello S. Calcium, vitamin D, vitamin K2, and magnesium supplementation and skeletal health. Maturitas. 2020;140:55-63. DOI · PubMed<br>[2] Reid IR. Calcium Supplementation- Efficacy and Safety. Curr Osteoporos Rep. 2025;23(1):8. DOI · PubMed<br>[3] Walker AF, Marakis G, Christie S, et al. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnes Res. 2003;16(3):183-91. PubMed<br>[4] Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnes Res. 2001;14(4):257-62. PubMed

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