Indole-3-Carbinol
Indole-3-Carbinol (I3C)
A compound from cruciferous vegetables that supports healthy estrogen metabolism and may help with hormone-related conditions.
Indole-3-Carbinol (I3C) is a compound found in cruciferous vegetables like broccoli, cabbage, and Brussels sprouts. It's converted in the stomach to DIM (diindolylmethane) and other metabolites that influence estrogen metabolism, shifting it toward more favorable 2-hydroxy estrogen metabolites. It's used for hormonal balance, particularly in conditions related to estrogen dominance, and is studied for potential cancer-preventive effects.
Mechanisms of Action
Estrogen Metabolism
Shifts estrogen to favorable metabolites
DIM Conversion
Converts to DIM in stomach
Detox Enzymes
Induces detoxification enzymes
Recommended Dose
200-400mg daily
Loading: Not required
Optimal Timing
- With food (reduces GI upset)
- Divided into 2 doses
Take with food
Best Form
I3C capsules or DIM (more stable)
Alternatives: DIM (diindolylmethane) - the active metabolite
I3C must be converted in stomach; DIM is the active metabolite and may be more predictable. Some use both.
Duration
Minimum: 4 weeks
Optimal: 12 weeks
Cycling: Not required
Note: Taking with food improves tolerance and allows acid conversion to DIM. Some prefer DIM directly for more predictable metabolism.
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Hormone Balance
Improved estrogen metabolism ratio
PMS Support
May reduce estrogen-related symptoms
Detox Support
Enhanced liver detoxification
GI Issues
Can cause digestive upset
Consult doctor; may help but needs monitoring
Who Should NOT Take This
- Hormone-sensitive conditions (consult doctor)
- CYP450-metabolized medications
Drug Interactions
May increase metabolism of some drugs
May affect hormone therapy; consult doctor
Possible Side Effects
Tip: Take with food; consider DIM instead
Tip: Discontinue if occurs
Warnings
- Affects estrogen metabolism significantly
- May interact with many medications
- Those with hormone-sensitive conditions should consult doctor
Top studies from 40+ peer-reviewed papers
Simões AC et al. • Journal of lower genital tract disease (2025)
“Imiquimod 5% is an effective treatment for uVIN with comparable results to surgery.”
Key Findings:
- A meta-analysis of 2 studies comparing imiquimod 5% to placebo found that 55.3% of women in the imiquimod group experienced total lesion resolution, compared to 0% in the placebo group (risk ratio = 18.21, 95% CI = 2.60-127.69).
- Cidofovir 1% had a complete response rate of 41%, while imiquimod 5% showed a 42% response.
- Imiquimod 5% was well-tolerated and showed a trend toward noninferiority to surgical treatments.
- Sinecatechins 10% showed lesion improvement in the best observed clinical response compared to those in the placebo group ( p = .002), while indole-3-carbinol and Omiganan were ineffective despite adherence to treatment protocols.
Galanty A et al. • International journal of molecular sciences (2024)
“Instead, they indicate that including brassica vegetables in the daily diet, particularly when accompanied by adequate iodine intake, poses no adverse effects on thyroid function.”
Key Findings:
- We analyzed the results of 123 articles of in vitro, animal, and human studies, describing the impact of brassica plants and extracts on thyroid mass and histology, blood levels of TSH, T3, T4, iodine uptake, and the effect on thyroid cancer cells.
- We also presented the mechanisms of the goitrogenic potential of GLSs and ITCs, the limitations of the studies included, as well as further research directions.
- The vast majority of the results cast doubt on previous assumptions claiming that brassica plants have antithyroid effects in humans.
- Instead, they indicate that including brassica vegetables in the daily diet, particularly when accompanied by adequate iodine intake, poses no adverse effects on thyroid function.
Amarakoon D et al. • Annual review of food science and technology (2023)
“This article reviews current knowledge of the occurrence of I3C in nature and foods, along with the beneficial effects of I3C and DIM concerning prevention and treatment of human chronic diseases, focusing on preclinical studies and their mechanisms of action at cellular and molecular levels.”
Key Findings:
- One of its main in vivo metabolites is 3,3'-diindolylmethane (DIM), formed by the condensation of two molecules of I3C.
- Both I3C and DIM alter multiple signaling pathways and related molecules controlling diverse cellular events, including oxidation, inflammation, proliferation, differentiation, apoptosis, angiogenesis, and immunity.
- There is a growing body of evidence from both in vitro and in vivo models that these compounds possess strong potential to prevent several forms of chronic disease such as inflammation, obesity, diabetes, cardiovascular disease, cancer, hypertension, neurodegenerative diseases, and osteoporosis.
- This article reviews current knowledge of the occurrence of I3C in nature and foods, along with the beneficial effects of I3C and DIM concerning prevention and treatment of human chronic diseases, focusing on preclinical studies and their mechanisms of action at cellular and molecular levels.
Behera A et al. • Cell death & disease (2023)
“This systematic-review examined the effects of Indole-3-Carbinol.”
Key Findings:
- In this review, we discuss the evolutionary perspective, structure, and functions of WWP1 and its multilevel regulation by various regulators.
- We also examine its emerging roles in cancer progression and its therapeutic potential.
- Finally, we highlight WWP1's role in normal physiology, contribution to pathological conditions, and therapeutic potential for cancer and other diseases.© 2023.
Lawrie TA et al. • The Cochrane database of systematic reviews (2016)
“Topical treatment (imiquimod or cidofovir) may effectively treat about half of uVIN cases after a 16-week course of treatment, but the evidence on whether this effect is sustained is limited.”
Key Findings:
- Medical interventions: Topical imiquimod was more effective than placebo in achieving a response (complete or partial) to treatment at five to six months post-randomisation (three RCTs, 104 women; risk ratio (RR) 11.95, 95% confidence interval (CI) 3.21 to 44.51; high-quality evidence).
- At five to six months, a complete response occurred in 36/62 (58%) and 0/42 (0%) women in the imiquimod and placebo groups, respectively (RR 14.40, 95% CI 2.97 to 69.80).
- Moderate-quality evidence suggested that the complete response was sustained at one year (one RCT, nine complete responses out of 52 women (38%)) and beyond, particularly in women with smaller VIN lesions.
- Histologically confirmed complete response rates with imiquimod versus cidofovir at six months were 45% (41/91) and 46% (41/89), respectively (one RCT, 180 women; RR 1.00, 95% CI 0.73 to 1.37; moderate-quality evidence).
Study Type Distribution
Goals This Supplement Supports
Related Goals
This information is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider before starting any supplement.