A naturally occurring, orally available cleavage product of the glucosinolate glucobrassicanin, a natural compound present in a wide variety of plant food substances including members of the family Cruciferae with antioxidant and potential chemopreventive properties. Indole-3-carbinol scavenges free radicals and induces various hepatic cytochrome P450 monooxygenases. Specifically, this agent induces the hepatic monooxygenase cytochrome P4501A1 (CYP1A1), resulting in increased 2-hydroxylation of estrogens and increased production of the chemoprotective estrogen 2-hydroxyestrone.