Increasing your intake of foods high in indole-3-carbinol (I3C) may reduce risk factors for certain cancers and improve hormone balance.
Indole-3-carbinol is a phytonutrient (plant nutrient) derived from a number of cruciferous vegetables.
Diets rich in cruciferous vegetables have long been associated with overall good health and a decreased risk of developing cancer. Crucifers are known to contain glucosinolates, including glucobrassicin, which is the precursor of I3C.
Indole-3-carbinol foods include vegetables in the Brassica family, such as watercress, kale, spinach, broccoli, cauliflower, chard and Brussels sprouts.
According to research studies, the average diet yields between 20 – 120mg of I3C per day. This dosage level is not associated with side effects, but it may be too low to achieve therapeutic benefits.
In addition to I3C, cruciferous vegetables also contain other phytonutrients that can help support overall good health, including water, fiber, vitamins, minerals, flavonoids, peptides and polysaccharides.
While getting more I3C from food sources can help to promote overall health, supplementation may be necessary to obtain specific benefits.



- Supports healthy estrogen metabolism
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I3C in the Diet
Related Topics
Consumption of indole-3-carbinol foods may help support good health.
Cruciferous vegetables are known to be healthy, well-tolerated foodstuffs.
Routinely including them as part of a balanced diet may support improved I3C levels.
When this compound is digested, it is converted into another compound known as Diindolylmethane (DIM).
This conversion takes place when I3C comes into contact with acids in the mouth and stomach. Some users will take DIM directly, instead of using I3C, as this supplement does not need to be converted first before it becomes active in the body.
I3C is commonly sold as a dietary supplement and taken orally for a number of indications. Natural Medicines notes that I3C is used for:
- Breast, colon, prostate, cervical and other types of cancer;
- Fibromyalgia;
- Recurrent respiratory papillomatosis;
- Systemic lupus erythematosus;
- Cervical dysplasia;
- Hormonal imbalances.
Research continues to determine the efficacy of I3C in the treatment of these conditions. It is not currently approved by the FDA to prevent, cure or treat these other any other medical conditions.
Current research into I3C is being funded by the National Cancer Institute and National Institutes of Health in the United States.
Indole-3-Carbinol Food Sources
How much I3C is found in food? Within food sources, I3C exists in the form of glucobrassicin. Glucobrassicin makes up about 10 percent of the total glucosinolates found in cruciferous vegetables.
The following are the amounts of total glucosinolates found in common crucifers per half-cup serving.
- Garden cress: 97.5 mg
- Mustard greens: 78.4 mg
- Brussels sprouts: 88 mg
- Kale: 33.5 mg
- Turnips: 59 mg
- Broccoli: 27 mg
- Bok choy: 17.5 mg
- Cauliflower: 20 mg
- Savoy cabbage: 36 mg
If you are consuming these vegetables to increase your intake of I3C, it is best to consume them raw and not cooked. The concentration of glucosinolates found in crucifers may be altered by cooking and processing these vegetables.
Glucosinolates like glucobrassicin are water soluble. This means the beneficial phytonutrients contained in these vegetables may be partially dissolved when they are cooked in water.
Crucifers cooked using a gentle boil were observed to have between 18 – 59 percent fewer glucosinolates compared to raw vegetables. Steaming, baking and other cooking methods that use less water may help maintain the nutrient levels in cooked cruciferous vegetables.
Indole-3-Carbinol Supplementation
Some opt to supplement with I3C to increase their daily intake levels.
Natural Medicines rates doses between 120 mg and 200 mg as possibly safe for periods of up to 15 months.
Natural Medicines has also identified doses between 200 mg and 400 mg a day as possibly safe for periods of up to three months. The only side effects reported at these doses are skin rashes and slight increases in liver enzymes.
At doses over 400 mg daily, I3C supplementation may lead to more serious side effects. In some cases, nausea, vomiting, disequilibrium and tremors have been noted.
Be sure to speak with your doctor before beginning any I3C supplement program to determine the best dosage for your needs.
Indole-3-Carbinol Drug Interactions
Indole-3-carbinol foods may interact with medications that are broken down by the liver. In particular, pharmaceutical agents metabolized by CYP1A2 liver enzymes may be affected by I3C.
The liver may process these agents too quickly and cause them to exhibit either stronger or weaker therapeutic effects and/or side effects.
Also, I3C supplementation has been observed to cause small increases in CYP3A4 activities, which may increase the risk of serious drug interactions. It is estimated that roughly 50 percent of all therapeutic agents are metabolized (to some degree) by CYP3A4 enzymes.
Conclusion
Consult with your doctor if you are thinking about increasing your intake of indole-3-carbinol foods, or if you are considering I3C supplementation at home.
Be sure to seek medical advice before combining I3C supplements with prescription medications. Also, be aware of the potential for negative interactions with certain herbal agents.
- Natural Medicines. Indole-3-Carbinol: Professional Monograph. Reviewed May 2015.
- Latosi?ska JN, Latosi?ska M, Szafra?ski M, Seliger J, Žagar V, Burchardt DV5. Impact of structural differences in carcinopreventive agents indole-3-carbinol and 3,3'-diindolylmethane on biological activity. An X-ray, (1)H-(14)N NQDR, (13)C CP/MAS NMR, and periodic hybrid DFT study.Eur J Pharm Sci. 2015 Sep 18;77:141-53.
- De Santi M, Galluzzi L, Duranti A, Magnani M, Brandi G. The Indole-3-carbinol cyclic tetrameric derivative CTet synergizes with cisplatin and doxorubicin in triple-negative breast cancer cell lines. Anticancer Res. 2013 May;33(5):1867-72.
- Busbee PB, Nagarkatti M, Nagarkatti PS. Natural indoles, indole-3-carbinol (I3C) and 3,3'-diindolylmethane (DIM), attenuate staphylococcal enterotoxin B-mediated liver injury by downregulating miR-31 expression and promoting caspase-2-mediated apoptosis. Natural indoles, indole-3-carbinol (I3C) and 3,3'-diindolylmethane (DIM), attenuate staphylococcal enterotoxin B-mediated liver injury by downregulating miR-31 expression and promoting caspase-2-mediated apoptosis. Reprod Toxicol. 2014 Jan;43:56-66.
- Perez-Chacon G, Martinez-Laperche C, Rebolleda N, Somovilla-Crespo B, Munoz-Calleja C, Buno I, Zapata JM. Indole-3-carbinol synergizes with and restores fludarabine sensitivity in chronic lymphocytic leukemia cells irrespective of p53 activity and treatment resistances. Clin Cancer Res. 2015 Aug 31. pii: clincanres.0736.2015. [Epub ahead of print]
- Rothman DM, Gao X, George E, Rasmusson T, Bhatia D, Alimov I, Wang L, et al. Metabolic Enzyme Sulfotransferase 1A1 Is the Trigger for N-Benzyl Indole Carbinol Tumor Growth Suppression. Chem Biol. 2015 Sep 17;22(9):1228-37.
- Caruso JA, Campana R, Wei C, Su CH, Hanks AM, Bornmann WG, Keyomarsi K. Indole-3-carbinol and its N-alkoxy derivatives preferentially target ER?-positivebreast cancer cells. Cell Cycle. 2014;13(16):2587-99.
- Hargraves KG, He L, Firestone GL. Phytochemical regulation of the tumor suppressive microRNA, miR-34a, by p53-dependent and independent responses in human breast cancer cells. Mol Carcinog. 2015 Mar 19.
Article last updated on: April 8th, 2018 by Nootriment
2 Comments
the results of this https://www.ncbi.nlm.nih.gov/pubmed/28764036
article show that I3C in broccoli contains more than three times. than you indicated
Hi Dmitry,
Thanks for your feedback! It’s important to note that different cultivars of the plant and different growing conditions can produce different concentrations of active ingredients in those plants. There is a range and some individual plants may develop higher or lower levels.
As per the study you references, “Taking into consideration the differences in cultivar, geography, season and environmental factors, the results agreed with values published in the literature using other techniques.”