“Indole-3-Carbinol (I3C)?”Here!I3C
Hasn’t appeared in a scanned product yet.
As a supplement
Talk to your doctor or pharmacist.
Roll Call does not check drug interactions or assess personal safety.
A compound formed when cruciferous vegetables like broccoli, cabbage, and Brussels sprouts are chewed or digested. Supplements provide a concentrated, isolated form rather than the whole vegetable.
Why it’s used
Taken by some with an interest in hormone metabolism, particularly estrogen breakdown, and marketed toward general cellular health support.
What the evidence says
Human clinical evidence is limited and mixed. Some small trials have looked at I3C's effect on estrogen metabolite ratios and in specific gynecological contexts, but results are not consistent enough to establish a reliable effect, and NIH ODS does not maintain a fact sheet on this ingredient. Most robust data comes from laboratory and animal studies, which do not reliably predict human outcomes at supplement doses.
Where we looked
There was no paper to cite here, so this is the search instead — run it yourself and see what we saw.
- PubMed: 267 records · searched September 2026
"Indole-3-Carbinol"[Title/Abstract] AND (review[pt] OR "safety assessment"[Title/Abstract] OR "risk assessment"[Title/Abstract] OR toxicology[Title/Abstract] OR toxicity[Title/Abstract] OR characterization[Title/Abstract] OR characterisation[Title/Abstract]) - PubMed: 8 records · searched September 2026
"Indole-3-Carbinol"[Title/Abstract] AND ("dietary supplements"[MeSH] OR supplementation[Title/Abstract] OR supplement[Title/Abstract] OR supplements[Title/Abstract] OR "oral administration"[Title/Abstract]) AND (randomized controlled trial[pt] OR clinical trial[pt] OR meta-analysis[pt] OR systematic review[pt]) AND humans[MeSH] - PubMed: 1199 records · searched September 2026
"Indole-3-Carbinol"[Title/Abstract]
This says what this database holds under these terms. It is not a finding that no research exists.
Context
Human studies have used a range of doses and durations, often in small, short-term trials focused on biomarkers like the 2-hydroxyestrone to 16-alpha-hydroxyestrone ratio rather than clinical outcomes. Findings have not been consistently replicated, and the compound is unstable, breaking down into other byproducts (including diindolylmethane, DIM) once ingested, which complicates interpreting what is actually being measured in these trials.
Rumors
Indole-3-carbinol supplements help prevent cancer.
Supports — suggestivehealth and safety evidence
Studied in: women with biopsy-proven cervical intraepithelial neoplasia (CIN II-III).
Measured as an outcome.
- Placebo-controlled trial of indole-3-carbinol in the treatment of CIN (Peer-reviewed) · Funding not checked
- Abstract for TR-584 (Regulatory) · Funding not checked
Who’s saying this
- iherb.com — we couldn’t open the site to see who runs it
Indole-3-carbinol blocks testosterone.
Not gradedhealth and safety evidence
Sources cited — no verdict reached.
What was measured is not yet noted.
- Indole-3-carbinol inhibition of androgen receptor expression and downregulation of androgen responsiveness in human prostate cancer cells (Peer-reviewed) · Funding not checked
- Effects of indole-3-carbinol on steroid hormone profile and tumor progression in a mice model of canine inflammatory mammarycancer (Peer-reviewed) · Funded by Spanish Ministry of Science and Education (government) · No conflicts declared
Who’s saying this
- bioenergetic.forum — the site doesn’t say who runs it
Indole-3-carbinol supplements support healthy estrogen metabolism and hormonal balance.
We haven’t found evidence strong enough to support this or rule it out.
What was measured is not yet noted.
Who’s saying this
- iherb.com — we couldn’t open the site to see who runs it
High doses of indole-3-carbinol cause gastrointestinal distress, nausea, and neurological symptoms such as tremors and balance problems.
We haven’t found evidence strong enough to support this or rule it out.
What was measured is not yet noted.
Who’s saying this
- RTHM — a brand: sells cash-pay medication prescriptions, consultations and clinic care for chronic conditions
How we know who this is
- “RTHM is an intelligent care platform that makes it easy to gather all your health data in one place, connect the dots with AI, and affordably access the diagnostic testing, treatments, and support you need—so healing is finally within reach” (their page)
- “Pay a $49-59 consultation fee + the cost of medication at the pharmacy only if your prescription is approved.” (their page)
- RTHM — a brand: sells cash-pay medication prescriptions, consultations and clinic care for chronic conditions
Indole-3-carbinol clears hormonal acne by correcting estrogen imbalance.
We haven’t found evidence strong enough to support this or rule it out.
What was measured is not yet noted.
Who’s saying this
- Amazon.com, Inc. — a retailer: online store selling products across many departments
How we know who this is
- “© 1996-2026, Amazon.com, Inc. or its affiliates” (their page)
- Amazon.com, Inc. — a retailer: online store selling products across many departments