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Indole-3-carbinol

Indole-3-carbinol suppliers and sourcing guide

Indole-3-carbinol (I3C) forms when glucobrassicin, a glucosinolate in cruciferous vegetables such as broccoli and cabbage, is broken down by the plant enzyme myrosinase. Commercial I3C is generally synthetic, made from indole-3-carboxaldehyde and purified to an off-white powder. It is unstable in acid, light and heat, where it condenses into DIM and other oligomers, so purity at receipt and storage conditions matter.

See suppliersWhat to ask for on the COA
Also known as
3-hydroxymethylindole · 1H-indole-3-methanol · I3C · CAS 700-06-1
Facts checked
November 2026

Forms and grades of Indole-3-carbinol

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

  • Synthetic I3C

    High-purity powder, the usual traded form.

  • Plant-isolated I3C

    I3C from Brassica vegetables; Health Canada lists both plant isolate and synthetic sources.

  • Diluted blends

    I3C on a carrier at a stated percentage for even blending.

  • Cruciferous vegetable powders

    Broccoli or cabbage powders that contain the precursor glucobrassicin rather than I3C itself; label them as the vegetable, not as I3C.

What to check on the COA

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

Assay (HPLC)
I3C content by HPLC against a reference standard.
Related substances
DIM and other condensation products by HPLC, which rise as I3C ages or is exposed to acid or heat.
Identity and melting point
IR spectrum and melting range.
Residual solvents
Solvents from synthesis and crystallization, against USP <467> or the buyer's limits.
Heavy metals
Lead, arsenic, cadmium and mercury by ICP-MS, checked against the supplier specification and the buyer's own limits.
Microbiology
Total plate count, yeast and mold, coliforms or E. coli, and Salmonella, against the supplier specification.

Storage, lots and expiry

Storage and shelf life

Store sealed, cool, dry and protected from light; refrigeration is often specified because I3C degrades with heat. Avoid acidic blends in storage. Shelf life and retest date come from the supplier's specification, with assay and related substances repeated at retest.

Lots and expiry dates

Record assay and DIM content for each lot and recheck older stock before use, since I3C converts over time. Rotate first-expiry-first-out.

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.

Indole-3-carbinol suppliers

Manufacturers and distributors whose own websites say they sell it.

We are checking Indole-3-carbinol suppliers now

Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.

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Frequently asked questions

What forms of Indole-3-carbinol can brands buy?

Common forms include synthetic I3C, plant-isolated I3C, diluted blends and cruciferous vegetable powders. Ask each supplier for the specification sheet of the exact grade they quote.

What should the COA for Indole-3-carbinol include?

Expect assay (HPLC), related substances, identity and melting point, residual solvents, heavy metals and microbiology, each with its method, specification and result for that lot.

How should Indole-3-carbinol be stored?

Store sealed, cool, dry and protected from light; refrigeration is often specified because I3C degrades with heat. Avoid acidic blends in storage. Shelf life and retest date come from the supplier's specification, with assay and related substances repeated at retest.

What is the regulatory status of Indole-3-carbinol?

Health Canada's indole-3-carbinol monograph lists it either as an isolate from Brassica oleracea varieties or from a synthetic source. The monograph's doses for adults 18 years and older do not exceed 400 milligrams of indole-3-carbinol per day. The EU Novel Food Catalogue entry for indole-3-carbinol states that it is considered a novel food.

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