Indole-3-Carbinol: Benefits, 200 mg Dose, I3C vs DIM, and Safety

A label-first guide to I3C—what comes from cruciferous-vegetable chemistry, what a 400 mg daily direction means, and why a change in a urine biomarker is not a promise to prevent or treat disease.

Indole-3-carbinol is usually shortened to I3C. It is associated with broccoli, cabbage, kale and other cruciferous vegetables because plant glucosinolates can generate I3C when the plant tissue is cut, chewed and acted on by the enzyme myrosinase. That food story is useful context, but it does not identify the source of every supplement. [11]

Biogénique Indole-3-Carbinol is a licensed Canadian natural health product containing 200 mg of synthetic indole-3-carbinol per capsule. Women 19 years and over are directed to take one capsule twice daily, for a total label-directed intake of 400 mg per day. Its exact authorized purposes are to help support or promote healthy estrogen metabolism/balance and to provide a source of antioxidants. [1,3,4]

Those statements are narrower than many claims attached to I3C online. This product is not licensed to diagnose ‘estrogen dominance,’ normalize a laboratory hormone result, treat menopause symptoms, detoxify the liver, prevent breast or cervical cancer, treat HPV, shrink a lesion or replace medical care. The human research discussed below provides scientific context for the licensed wording; it does not convert a surrogate marker into a clinical guarantee.

What is indole-3-carbinol?

Cruciferous vegetables contain glucosinolates, including glucobrassicin. When plant cells are disrupted, myrosinase can break these compounds down and produce several molecules, one of which is I3C. Cooking method, plant variety, storage and preparation can change that chemistry, so a serving of vegetables cannot be converted reliably into a precise I3C capsule dose. [11]

The medicinal ingredient on this product licence is 3-hydroxymethylindole, another name for indole-3-carbinol, and its source is listed as synthetic. The capsule therefore supplies a measured I3C dose; it is not a powdered vegetable, broccoli extract, cabbage concentrate or standardized serving of cruciferous food. [1]

That distinction matters for both accuracy and expectations. Vegetables provide fibre, vitamins, minerals and many phytochemicals in a food matrix. An I3C capsule isolates one compound at a pharmacologically relevant dose. A supplement should not be used as a reason to reduce vegetable intake, and vegetables should not be described as interchangeable with this exact 200 mg product.

What does ‘supports healthy estrogen metabolism’ mean?

Estrogens are processed through multiple biochemical pathways before their metabolites are eliminated. Human I3C studies have often measured urinary metabolites—especially the relationship between 2-hydroxyestrone and 16α-hydroxyestrone—as an indicator that the route of estrogen metabolism changed after supplementation.

A metabolite pattern is not the same thing as the amount of estrogen circulating in blood, a diagnosis of hormonal imbalance, improvement in a symptom or a reduction in disease risk. In a phase I study of 17 women, I3C changed the urinary metabolite ratio while serum estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone and sex-hormone-binding globulin did not change significantly. [8]

What do human studies actually show?

The most directly relevant controlled study enrolled 60 women at increased breast-cancer risk; 57 completed four weeks of placebo or daily I3C at 50, 100, 200, 300 or 400 mg. The change in the urinary 2-hydroxyestrone/16α-hydroxyestrone ratio was greater in the 300–400 mg groups than in placebo and lower-dose groups. The study was double-blind and dose-ranging, but it was short and used a surrogate biomarker. It did not establish fewer cancers, better symptoms or long-term safety. [7]

A later phase I study followed 17 women through a four-week placebo run-in, four weeks at 400 mg per day and four weeks at 800 mg per day. Both I3C doses increased the same urinary metabolite ratio, with no further increase at 800 mg. The small study reported that the regimens were generally tolerated, but it was designed to assess tolerability and metabolic effects—not to prove a health outcome. [8]

That phase I trial also found a 4.1-fold mean increase in CYP1A2 activity at 800 mg per day, with 94% of participants showing induction. CYP1A2 helps metabolize caffeine and multiple medicines. The result does not predict a specific interaction for every person, but it provides a concrete reason to respect the licence warning to consult a health care practitioner before use with medications or other natural health products. [8]

An earlier metabolic study gave 6–7 mg/kg per day to seven men for one week and ten women for two months. Urinary C-2 estrogen metabolites increased, while several other measured estrogen metabolites decreased. The analytical work was detailed, but the groups were tiny and there was no placebo control. The study supports a metabolic effect; it cannot prove a clinical benefit. [9]

A five-person study in healthy overweight premenopausal women used 400 mg per day for two months and also observed an increase in an estrogen 2-hydroxylation ratio. With only five participants and no randomized control group, this is corroborating biomarker evidence, not a basis for broad promises about weight, hormones or disease. [13]

Taken together, the human evidence is consistent with a change in selected estrogen-metabolism biomarkers at approximately 300–400 mg per day. The Biogénique label direction totals 400 mg per day, but dose alignment alone does not prove that the exact finished product reproduces every study result. Ingredient source, study population, duration, adherence, assays and finished-product quality all affect transferability.

I3C vs DIM: related, not interchangeable

Indole-3-carbinol is unstable in an acidic environment. After oral I3C reaches the stomach, it can form several condensation products, including 3,3′-diindolylmethane, commonly called DIM. This is why I3C and DIM appear together in research discussions—but they are not the same ingredient.

In a human pharmacokinetic study, women received single I3C doses from 400 to 1,200 mg. I3C itself was not detected in plasma; DIM was the only I3C-derived product detected. DIM exposure varied substantially among participants and did not increase proportionally at the highest doses. The finding supports conversion after ingestion and shows why a simple milligram-for-milligram conversion is not valid. [10]

A bottle labelled 200 mg I3C therefore cannot be treated as 200 mg DIM. Direct DIM supplements contain a different medicinal ingredient and may use formulations intended to change absorption. Compare each product by its own NPN, medicinal ingredient, dose, directions, warnings and evidence rather than assuming one can substitute for the other.

How much indole-3-carbinol is in this product?

At the licensed dose, a 60-capsule bottle supplies 30 days and a 120-capsule bottle supplies 60 days. That calculation assumes two capsules each day and uninterrupted use; it is not a recommended treatment course. The licence lists no required duration, and a health professional may advise a different decision based on medications, liver health, reproductive plans or symptoms.

Do not take two capsules together merely for convenience unless the current label or a qualified health professional directs that schedule. ‘One capsule, two times per day’ is not the same instruction as ‘two capsules once daily.’ Do not exceed the label to copy an 800 mg trial; the higher dose produced no further biomarker increase in the 17-woman phase I study and increased CYP1A2 activity substantially. [8]

There is no licensed onset claim. Urinary biomarkers in the cited studies were assessed after weeks of use, while the pharmacokinetic study measured DIM in plasma over hours. Neither research window tells an individual when she will feel an effect—or whether the biomarker change will be noticeable at all.

Who should not use it, and who should ask first?

The licence contains a direct contraindication: do not use this product if you are pregnant or breastfeeding. This is not a flexible warning and should appear prominently wherever the product is discussed. [1,3]

Consult a health care practitioner before use if you are attempting to conceive; taking medications or other natural health products; have a liver disorder; or have symptoms of low estrogen such as joint pain, mood changes, changes in libido, hot flashes, night sweats, vaginal dryness or irregular menstruation. The licence also directs users to consult a practitioner to exclude a serious cause of hormonal imbalance. [1,3]

Stop use and consult a health care practitioner if liver-related symptoms develop, including yellowing of the eyes or skin, dark urine, abdominal pain or jaundice, or if symptoms of low estrogen develop. Keep the product out of reach of children. Do not use it if the outer seal is missing or broken, and store it in a cool, dry place. [3]

Can I3C treat menopause symptoms or ‘estrogen dominance’?

No such treatment claim appears on this product licence. ‘Estrogen dominance’ is used inconsistently online and does not identify a single diagnosis, laboratory threshold or treatment plan. Symptoms such as irregular bleeding, hot flashes, mood change, breast symptoms, pelvic pain or fertility difficulty can have multiple causes and deserve an appropriate assessment.

The label is especially careful because I3C affects estrogen metabolism. It requires consultation when low-estrogen symptoms are present and asks users to exclude a serious cause of hormonal imbalance before use. A supplement should not be used to self-diagnose a hormone problem or to delay evaluation of persistent, severe or unexplained symptoms. [1,3]

Does I3C prevent breast or cervical cancer?

This product is not licensed to prevent or treat cancer. The controlled human studies most relevant to estrogen metabolism measured surrogate urinary biomarkers, often in women selected for elevated risk. A favourable change in a proposed biomarker does not demonstrate fewer cancers, slower disease progression or better survival. [7–9]

Laboratory, animal and early clinical research can justify further study, but it should not be converted into a retail prevention claim. Anyone with an abnormal breast or cervical screening result, a cancer diagnosis, a high-risk genetic finding or a history of hormone-sensitive disease should discuss supplements with the clinical team responsible for care.

Food first: where cruciferous vegetables fit

Broccoli, Brussels sprouts, cabbage, kale, cauliflower, bok choy and related vegetables contribute fibre and many nutrients alongside glucosinolates. The National Cancer Institute notes substantial laboratory and animal research on cruciferous compounds, while human research on cancer risk has produced mixed results. [11]

A practical food message is therefore simple: include a variety of vegetables because they are nutritious foods, not because a serving can be advertised as an exact I3C dose or a cancer-prevention prescription. A synthetic 200 mg I3C capsule and a plate of vegetables are different choices with different evidence questions.

How to compare indole-3-carbinol supplements

1. Match the exact NPN. Biogénique’s product is NPN 80133515; a similar front-label name is not enough.

2. Confirm the medicinal ingredient and source. This licence identifies synthetic indole-3-carbinol, not a vegetable extract and not DIM.

3. Read per-capsule and daily totals separately. This product provides 200 mg per capsule and directs two capsules per day in divided doses.

4. Use the exact licensed purpose. Estrogen-metabolism support and a source of antioxidants are not disease-treatment promises.

5. Read the full warning panel. Pregnancy, breastfeeding, conception, medications, other natural health products, liver disorders and low-estrogen symptoms materially change the decision.

6. Verify the current non-medicinal ingredients. Current artwork lists hypromellose and rice flour; check the physical bottle received in case production artwork changes.

7. Demand lot matching for quality claims. A useful COA must identify the finished product and the lot on the bottle; a generic badge or another product’s certificate is not equivalent.

What a Certificate of Analysis can—and cannot—show

A finished-product Certificate of Analysis should identify the product and lot, list specifications and methods, report actual results, and show appropriate review or release. Depending on the specification, it may support identity, quantity, microbial, contaminant, disintegration or other batch-quality conclusions.

No current lot-matched Biogénique Indole-3-Carbinol finished-product COA was located in the searched Drive records. This draft therefore makes no lot-specific purity, potency, heavy-metal, microbial, disintegration or third-party-testing claim. The absence of a located record is not proof that testing did not occur; it means the evidence was not available to support publication.

A COA also cannot prove estrogen balance, symptom relief, cancer prevention or any other clinical outcome. It answers a manufacturing and quality-control question for a particular lot, not whether a person will experience a health benefit.

Frequently asked questions

What are the benefits of indole-3-carbinol?

For this exact product, the authorized benefits are support for healthy estrogen metabolism/balance and a source of antioxidants. Human studies show changes in selected urinary estrogen-metabolism biomarkers, but they do not establish treatment of symptoms or prevention of disease. [1,7–9]

Is Biogénique I3C made from broccoli?

No. The Health Canada product licence lists the medicinal-ingredient source as synthetic. Cruciferous vegetables explain the compound’s biological context; they are not the source declared for this capsule. [1]

Is 200 mg the daily dose?

No. Two hundred milligrams is the amount in one capsule. The licensed direction is one capsule twice daily, for 400 mg total per day. [1,3]

Should I take both capsules at once?

The label says one capsule two times per day, which indicates divided dosing. Follow the current physical label and ask a health professional before changing the schedule. [1,3]

How long should I take I3C?

The product licence does not specify a required duration. That is not proof of benefit or safety for indefinite use. Reassess ongoing use with a health professional when medications, liver health, reproductive plans or hormone-related symptoms are relevant. [1]

Is I3C the same as DIM?

No. I3C can form DIM and other compounds in the stomach, but I3C and DIM are different ingredients. A 200 mg I3C capsule is not equivalent to 200 mg DIM. [10]

Can I take I3C while trying to conceive?

The licence says to consult a health care practitioner before use if attempting to conceive. Do not use during pregnancy or breastfeeding. [1,3]

Can I take I3C with medication?

Consult a health care practitioner first. A human trial found marked CYP1A2 induction at a higher I3C dose, reinforcing the need for a medication review rather than a generic yes-or-no answer. [8]

Does I3C treat HPV or prevent cancer?

No such claim is authorized for NPN 80133515. Biomarker and early clinical research should not be used to replace screening, diagnosis or treatment. [1,7–9]

Does a COA prove the hormone claim?

No. A COA can document lot-specific quality results against specifications. It cannot prove a biological or clinical outcome.

Bottom line

Biogénique Indole-3-Carbinol under NPN 80133515 provides 200 mg of synthetic I3C per capsule. Women 19 years and over are directed to take one capsule twice daily. The exact licensed purposes are to support healthy estrogen metabolism/balance and to provide a source of antioxidants. Current artwork lists hypromellose and rice flour. [1,3,4]

The human evidence supports a careful mechanism-level story. Small trials at roughly 300–400 mg per day found shifts in selected urinary estrogen-metabolism biomarkers, and pharmacokinetic research shows that oral I3C forms DIM and other products rather than behaving like an interchangeable DIM dose. These findings do not establish symptom relief, disease prevention or treatment. [7–10,13]

The safety decision deserves equal weight. Do not use during pregnancy or breastfeeding. Ask first when attempting to conceive, taking medications or other natural health products, living with a liver disorder or experiencing low-estrogen symptoms. Stop and seek advice for liver-related or low-estrogen symptoms. Before publication, Biogénique should fix the blank NPN display, reconcile expanded claims, review ‘PHARMACEUTICAL GRADE’ artwork and attach a current lot-matched COA to any batch-quality statement.

Related resources

Biogénique Indole-3-Carbinol product page

Biogénique Quality Control

Health Canada Licensed Natural Health Products Database

References

1. Health Canada product licence PL-724996 — Indole-3-carbinol, NPN 80133515 — issued 16 Aug 2024; ingredient, synthetic source, dose, purpose, duration and risk fields

2. Health Canada issuance letter IL-724996 — NPN 80133515 — compendial licence issuance and licence-holder responsibilities

3. Current 60-capsule bilingual label artwork — product 100-2500-256 — 200 mg, dose, warnings, storage, hypromellose and rice flour

4. Internal product record — Indole-3-carbinol, NPN 80133515 — formula, licensed use, adult dose and risk information

5. Biogénique — Indole-3-Carbinol product page — current commerce page; NPN display and expanded-claim review

6. Google Search Console export — biogenique.com Performance on Search, 17 August 2026 — 16-month direct-query and product-page opportunity; internal Drive workbook

7. Wong et al. (1997) — dose-ranging study of indole-3-carbinol — 57 completers; placebo-controlled, double-blind; 50–400 mg/day for four weeks; urinary estrogen-metabolite biomarker

8. Reed et al. (2005) — phase I study of I3C in women — 17 women; 400 and 800 mg/day; tolerability, estrogen metabolites and CYP1A2 induction

9. Michnovicz, Adlercreutz & Bradlow (1997) — urinary estrogen metabolites after oral I3C — seven men and ten women; 6–7 mg/kg/day; detailed urinary metabolite profile

10. Reed et al. (2006) — I3C pharmacokinetics based on DIM — single doses of 400–1,200 mg; I3C not detected in plasma; DIM exposure variable and nonlinear

11. National Cancer Institute — Cruciferous Vegetables and Cancer Prevention — glucosinolate context and mixed human evidence

12. Health Canada — Licensed Natural Health Products Database — database scope and product-specific NPN verification

13. Michnovicz (1998) — estrogen 2-hydroxylation in overweight women using I3C — five healthy overweight premenopausal women; 400 mg/day for two months; biomarker-only corroboration

14. Current 120-capsule bilingual label artwork — product 100-2500-256-1 — variant-count confirmation and matching formula, direction and warnings

15. Current Biogénique Indole-3-Carbinol 60-capsule bottle asset — exact product render for identity and future image generation

Disclaimer

This article is for educational purposes only and is not medical advice. Natural health products are not substitutes for diagnosis, screening or treatment by a qualified health care professional. Follow the current physical product label. Do not use during pregnancy or breastfeeding. Consult a qualified health professional before use when attempting to conceive, taking medications or natural health products, living with a liver disorder, experiencing low-estrogen symptoms or investigating a possible hormonal imbalance. Seek timely assessment for persistent, severe or unexplained symptoms.