Indole-3-carbinol, also known as I3C, is a breakdown product of the glucosinolate glucobrassicin found in cruciferous vegetables.

Research shows that indole-3-carbinol modulates estrogen metabolism. When added to breast cancer and prostate cancer cells in culture, I3C caused cell cycle arrest. Indole-3-carbinol has also been found to stop the formation of new blood vessels that feed tumors and fuel their growth --a process known as angiogenesis.

References

Chinni SR, Li Y, Upadhyay S, Koppolu PK, Sarkar FH. Indole-3-carbinol (I3C) induced cell growth inhibition, G1 cell cycle arrest and apoptosis in prostate cancer cells. Oncogene. 2001;20(23):2927-2936.Meng Q, Goldberg ID, Rosen EM, Fan S. Inhibitory effects of Indole-3-carbinol on invasion and migration in human breast cancer cells. Breast Cancer Res Treat. 2000;63(2):147-152. Chang X, Tou JC, Hong C, et al. 3,3'-Diindolylmethane inhibits angiogenesis and the growth of transplantable human breast carcinoma in athymic mice. Carcinogenesis. 2005;26(4):771-778.