Indole-3-carbinol or I3C is a breakdown product of the glucosinolate glucobrassicin, also known as indole-3-glucosinolate. Glucosinolates are beta-thioglucoside N-hydroxy-sulfates,  which are primarily found in cruciferous vagetables.

Indole-3-carbinol may have cancer chemopreventive activity. Indole-3-carbinol is produced from indole-3-glucosinolate via the action of the enzyme myrosinase, an enzyme which is present in cruciferous vegetables and activated upon maceration of the vegetables.

Indole-3-carbinol may modulate estrogen metabolism. It may also have anticarcinogenic, antioxidant and anti-atherogenic activities.

Indole-3-carbinol is contraindicated in those hypersensitive to this substance or to any component of an indole-3-carbinol-containing product.