Indole-3-Carbinol

Indole-3-Carbinol (I3C) is a glucosinolate derivative produced by the enzymatic hydrolysis of glucobrassicin, a compound abundant in cruciferous vegetables including broccoli, cauliflower, cabbage, and Brussels sprouts. In the acidic environment of the stomach, I3C undergoes condensation reactions to form a complex mixture of biologically active products, most notably diindolylmethane (DIM), as well as indolo[3,2-b]carbazole (ICZ) and linear and cyclic trimers. I3C and its metabolites modulate Phase I and Phase II detoxification enzymes, primarily through activation of the aryl hydrocarbon receptor (AhR) and induction of CYP1A1 enzymes. This shifts estrogen metabolism toward 2-hydroxylation, producing metabolites associated with reduced breast cancer risk. Clinical studies have demonstrated that I3C supplementation (200–400 mg/day) favorably alters urinary estrogen metabolite ratios. I3C has also shown promise in the treatment of recurrent respiratory papillomatosis (RRP), a virally-induced condition. However, I3C is less stable than DIM and produces multiple active metabolites with varying biological effects, which some researchers view as a disadvantage compared to direct DIM supplementation.