I3C

Indole-3-carbinol (I3C) is an organic compound produced when cruciferous vegetables are chewed or processed. It is derived from glucosinolates, particularly glucobrassicin, and occurs naturally in broccoli, Brussels sprouts, cabbage, kale, cauliflower, and related vegetables. I3C is unstable in stomach acid and rapidly condenses to several products; the most studied is 3,3'-diindolylmethane (DIM), which is absorbed and biologically active.

In vitro and animal studies have shown that I3C and its metabolites can modulate cell growth, differentiation, and apoptosis, and may influence inflammatory pathways. A major proposed mechanism involves alteration of estrogen metabolism: I3C and DIM can induce enzymes that metabolize estrogens, increasing formation of 2-hydroxyestrogens that are considered less estrogenic, and reducing activation of estrogen receptors. I3C and DIM also act as ligands for the aryl hydrocarbon receptor (AhR) and may affect cellular signaling and phase I/II metabolism.

Dietary sources and supplementation: A diet rich in cruciferous vegetables provides I3C and related compounds. I3C is also marketed as a dietary supplement; many products provide DIM rather than I3C itself due to stability concerns. Clinical evidence for cancer prevention or treatment remains limited and inconclusive.

Safety and regulation: I3C/DIM supplements are not approved as medicines. Side effects are generally mild but can include digestive upset; high doses may have adverse effects and could interact with hormonal therapies or other medications. Pregnant or breastfeeding individuals should avoid use without medical advice.