Indole-3-carbinol
An indole is an aromatic compound with a 'bicyclic' structure, that is, it looks kind of like a bicycle, with a six sided benzene ring attached to a five sided pyrrole ring containing nitrogen.
Cruciferous vegetables contain a substance called glucobrassicin which is metabolized into indole-3-carbinol, or I3C. The plant cells need to be damaged for this conversion to happen, and this can be accomplished by chopping or other preparation that breaks up the cells, or by chewing. Cruciferous vegetables include watercress, mustard greens, brussels sprouts, horseradish, kale, turnip, cabbage, broccoli, kohlrabi, bok choi and cauliflower. I3C is watersoluble, so it can be lost in cooking water. It is best to cook these vegetables in a small amount of water. Also, cooking at high temperatures can destroy the enzyme that converts glucobrassicin into I3C.
I3C is an antioxidant and has chemopreventative activity. In epidemiological studies, which are done on groups within the population, higher intakes of cruciferous vegetables are associated with lower risks of some types of cancer. However with these studies it is hard to pinpoint exactly what it is in the vegetables that has the preventative effect. I3C has also been administered in animal studies and was shown to inhibit cancers of the breast, uterus, colon, lung and liver. This phytonutrient can stimulate detoxification enzymes in the gut and liver, and start apoptosis, which is the death signal for cancerous cells, in cancer cell lines.
I3C is available as a supplement without a prescription, and doses of 200-400 mg per day have been used to treat cervical intraepithelial neoplasia and respiratory papillomatosis. The normal dietary levels are 20-120 mg. There have been adverse effects from taking high doses of this supplement, including high levels of liver enzymes in the blood, skin rash, disequilibrium and tremor.
The information on this page is not meant to be used in treatment of medical conditions. Please seek the advice of a physician about any medical condition or symptom. Those with medical conditions should consult a medical professional about the appropriateness of taking dietary supplements or diet therapy, and how these methods will interact with their medications.
LINKS
Linus Pauling Institute information on I3C.
Memorial Sloan-Kettering Cancer Center.