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Magnesium L-threonate

Magnesium L-threonate suppliers and sourcing guide

Magnesium L-threonate is the magnesium salt of L-threonic acid, a four-carbon sugar acid. L-threonic acid is typically produced by oxidizing ascorbic acid, and the acid is then reacted with a magnesium base such as magnesium carbonate or hydroxide, purified and dried to a white powder. It carries a low share of magnesium by weight (well under 10%), so doses are large relative to other magnesium salts; brands buy it as powder for capsules and drink mixes, often as a branded, patented ingredient.

Also known as
Magnesium threonate · Magnesium L-threonate hydrate · L-threonic acid magnesium salt
Facts checked
November 2026

Forms and grades of magnesium L-threonate

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

  • Branded powder

    Patented ingredient supplied under a trade name with its own specification and use terms.

  • Generic powder

    Magnesium L-threonate from other manufacturers, where stereochemistry and purity data deserve close review.

  • Granulated grades

    Agglomerated powder for better flow in capsule filling and tableting.

What to check on the COA

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

Magnesium assay
Magnesium by EDTA titration or ICP-OES.
L-threonate assay and identity
L-threonate by HPLC or ion chromatography, with specific optical rotation to confirm the L-form.
Related substances
Residual ascorbic acid, oxalate and other by-products of the oxidation route, where the supplier's specification lists them.
Loss on drying or water
Moisture or Karl Fischer water, since the salt is supplied as a hydrate.
Heavy metals and microbiology
Lead, arsenic, cadmium and mercury by ICP-MS, plus total plate count, yeast and mold.

Storage, lots and expiry

Storage and shelf life

Keep magnesium L-threonate in sealed containers in a cool, dry place away from light; it is hygroscopic and cakes when exposed to humid air. Reseal opened packs immediately. Shelf life is set by the supplier's stability data and specification, and older lots are retested for water and assay.

Lots and expiry dates

Record magnesium and L-threonate assays and water content for each lot. Because branded and generic material are both sold, keep supplier documentation on file and do not swap sources without a new specification review.

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.

Magnesium L-threonate suppliers

Manufacturers and distributors whose own websites say they sell it.

  • AIDP

    Distributor · City of Industry, CA

    Sells it as Magtein

    California ingredient supplier that sources branded and commodity ingredients for supplement and food makers, from amino acids and vitamins to magnesium L-threonate and a plant-based vitamin D3.

  • 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 magnesium L-threonate can brands buy?

Common forms include branded powder, generic powder and granulated grades. Ask each supplier for the specification sheet of the exact grade they quote.

What should the COA for magnesium L-threonate include?

Expect magnesium assay, l-threonate assay and identity, related substances, loss on drying or water and heavy metals and microbiology, each with its method, specification and result for that lot.

How should magnesium L-threonate be stored?

Keep magnesium L-threonate in sealed containers in a cool, dry place away from light; it is hygroscopic and cakes when exposed to humid air. Reseal opened packs immediately. Shelf life is set by the supplier's stability data and specification, and older lots are retested for water and assay.

What is the regulatory status of magnesium L-threonate?

GRN 499, for magnesium L-threonate hydrate notified by Magceutics, Inc. as a source of dietary magnesium in certain food categories, closed on September 3, 2014 with FDA having no questions. Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists magnesium L-threonate among the source ingredients for magnesium (Table 2).

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