What is Indole 3 Carbinol?

Indole-3-carbinol (I3C) is a phytochemical found in high levels in many cruciferous vegetables (e.g., cabbage, mustard, cauliflower). I3C is widely promoted for its antioxidant and potential anticarcinogenic properties.

Chemical Properties

• I3C is produced from the enzymatic degradation of glucobrassicin by myrosinase. This occurs only when glucobrassin-containing vegetables (i.e., cruciferous vegetables) are chopped, crushed or cooked. The effects of I3C on the production of estrogen and metabolic enzymes have led to studies and speculation on its anticarcinogenic and chemopreventive properties.

Potential Benefits

• I3C has been explored as an anticarcinogen primarily due to its effects on estrogen metabolism. Human reproductive cancers (e.g., cervical, breast, endometrial, prostate) may be affected by estrogen levels, and I3C may prevent these by both reducing estrogen levels and blocking estrogen receptors. In addition to cultured cell studies demonstrating that I3C halts the development of human reproductive cancer cells, evidence suggests that I3C may prevent these types of cancer in individuals with precancerous conditions.

Warning

• Limited research exists on the effects of I3C in humans, with some studies suggesting that I3C may promote certain types of cancer. I3C overconsumption has been linked to nausea, tremor and vertigo, and I3C may interfere with certain medications. As cruciferous vegetables have health benefits beyond those of I3C, natural sources of I3C are preferred to nutritional supplements.