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Calcium citrate

Calcium citrate suppliers and sourcing guide

Calcium citrate is the calcium salt of citric acid, made by neutralizing citric acid with calcium hydroxide or calcium carbonate and then drying the precipitate. The common commercial form is the tetrahydrate, a fine white odorless powder with about 21% calcium; anhydrous grades carry somewhat more. Brands buy it as powder for capsules and drink mixes or as granulated grades for tablets.

Also known as
Tricalcium dicitrate · Calcium citrate tetrahydrate · E333
Facts checked
November 2026

Forms and grades of calcium citrate

Suppliers sell different products under the same name. Specify the one you need.

  • Tetrahydrate powder

    The standard form, containing four moles of water per mole, with calcium content reported on the as-is or dried basis.

  • Anhydrous

    Dried to remove the water of hydration, giving more calcium per gram and a lower moisture specification.

  • Directly compressible granules

    Calcium citrate granulated, sometimes with a binder, so it flows and compresses on tablet presses.

  • Micronized and fine powders

    Small-particle grades for fortified beverages and dairy alternatives where grit and settling are a concern.

What to check on the COA

Compare each result with your own specification when the lot arrives.

Assay
Calcium citrate content on the dried basis by complexometric (EDTA) titration, against a USP or Food Chemicals Codex specification.
Loss on drying
Water content, which for the tetrahydrate falls within a defined range and confirms the hydrate you ordered.
Identity
Compendial tests for calcium and citrate.
Lead, arsenic and fluoride
Lead and arsenic by ICP-MS and a fluoride limit test, which can carry over from the calcium raw material.
Acid-insoluble substances
Residue that does not dissolve in dilute acid, often traced to the calcium carbonate used.
Particle size and bulk density
Sieve or laser diffraction data and tapped density for capsule fill and beverage suspension.

Storage, lots and expiry

Storage and shelf life

Store calcium citrate in sealed bags or drums in a cool, dry area; it is stable but can gain or lose water if packs are left open in very humid or very dry conditions. Keep it away from strong odors. Shelf life is set by the supplier's specification, and aged lots are usually retested for moisture and assay.

Lots and expiry dates

Record the hydrate form, assay and loss on drying for each lot so the calcium dose is calculated on the right basis. Keep granulated and powder grades on separate item codes, since swapping them changes tablet weight and flow.

Regulatory status

Facts from regulators and standards bodies, each linked to its source.

This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.

Calcium citrate suppliers

Manufacturers and distributors whose own websites say they sell it.

  • Global Calcium

    Manufacturer · Bengaluru, India

    Indian maker of pharmaceutical ingredients and mineral salts, with plants in Hosur. Its mineral range covers calcium, magnesium, iron, zinc, copper and selenium salts and amino acid chelates.

    • Kosher
    • Halal
    • FSSC 22000
    • cGMP

Suppliers are in alphabetical order and none pays to appear. Each claim is checked against the supplier’s own website on the date shown. Ask for the specification sheet and a recent COA before you order, and confirm details with the supplier.

Frequently asked questions

What forms of calcium citrate can brands buy?

Common forms include tetrahydrate powder, anhydrous, directly compressible granules and micronized and fine powders. Ask each supplier for the specification sheet of the exact grade they quote.

What should the COA for calcium citrate include?

Expect assay, loss on drying, identity, lead, arsenic and fluoride, acid-insoluble substances and particle size and bulk density, each with its method, specification and result for that lot.

How should calcium citrate be stored?

Store calcium citrate in sealed bags or drums in a cool, dry area; it is stable but can gain or lose water if packs are left open in very humid or very dry conditions. Keep it away from strong odors. Shelf life is set by the supplier's specification, and aged lots are usually retested for moisture and assay.

What is the regulatory status of calcium citrate?

21 CFR 184.1195 affirms calcium citrate as GRAS, used in food with no limitation other than current good manufacturing practice, and allows its use in infant formula. 7 CFR 205.605(b) lists calcium citrate among the synthetic substances allowed in or on processed products labeled organic. Health Canada's List of Permitted Acidity Regulators and Acid-Reacting Materials includes calcium citrate for infant formula and unstandardized foods. Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists calcium citrate and calcium citrate tetrahydrate among the source ingredients for calcium (Table 2).

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