In experimental animal testing with mice and rats, Indole-3-Carbinol and brussels sprouts, respectively, have
demonstrated an ability to reduce mammary cancer incidence in animals exposed to carcinogens that are known to
promote mammary cancer in these species.21,22 In human studies, the ingestion of Indole-3-Carbinol has been
shown to increase the metabolism of estrone hormone to 2-hydroxyestrone rather than the16-alpha-hydroxyestrone
metabolite. Studies indicate that 16-alpha-hydroxyestrone is associated with an increased risk of breast cancer in
women and, conversely, 2-hydroxyestrone is associated with a reduction in breast cancer risk. Thus, Indole-3-
Carbinol influences the body’s enzyme systems in a fashion that favorably influences the 2-hydroxyestrone to 16-
alpha-hydroxyestrone ratio, helping to reduce risk of breast cancer.20,21,23,24 A large prospective study involving
5,000 Italian women and a second study of patients with either benign or malignant breast lesions highlighted the
ability of a higher 2/16 hydroxyestrone ratio to predict which women were less prone to breast cancer development.
a. Breast Cancer: Epidemiological studies and experimental evidence strongly suggests that Indole-3-Carbinol may
reduce breast cancer risk through the above-cited mechanisms.25,26,27,28 To date there are no human intervention
trials that have tested Indole-3-Carbinol as a preventive or therapeutic agent against breast cancer.
b. Cervical Cancer: In a 12-week double-blind study, 8 of 17 patients with early-stage cervical cancer given 200 or
400 mg of Indole-3-Carbinol per day experienced a complete reversal of their condition.29 Animal studies have also
shown that indole-3-carbinol can help prevent cervical cancer in the presence of various carcinogens.30,31