Chemoprevention, the chemical prevention of cancer, is an important part of colorectal cancer control. This article reviews a study of the ability of silibinin, a component of milk thistle (Silybum marianum,) to prevent colon cancer in mice.
Mice prone to develop colon cancer, spontaneously, were fed silibinin. The animals were tested after 13 weeks of silibinin use. The dose used in the mice was 750 mg/kg, 5 days a week. This dose in mice was effective in reducing the development of small intestinal cancer, especially in the distal portions. The polyps were smaller in size. Silibinin was especially beneficial in the colon in reducing the size of larger polyps in the mice.
Silibinin has been shown to be effective in treating models of cancer of the prostate, skin, bladder and lung. It is shown to have anti-proliferative, antiangiogenic and pro-apoptotic effects.
Carcinogenesis increases production of eNOS (nitric oxide synthase,) an enzyme which produces nitric oxide. Nitric oxide increases the angiogenesis necessary for cancer growth. Silibinin inhibited angiogenesis. Silibinin has been shown to block COX-2 pathway enzymes. This would, also, give silibinin cancer preventive properties.
Familial adenomatous polyposis (FAP) is a hereditary disease in which the intestine forms excessive colon polyps. Polyps can develop into adenomas, which can become cancerous. The patients develop small intestinal polyps which can become adenomas and cancer even when prophylactic colon removal surgeries are done. The results of the mouse model of this disease suggest that silibinin could be used in the chemoprevention of cancer in FAP.
CONCLUSION: Silibinin is especially useful in mouse intestine and colon in preventing the small polyps from developing into large polyps. This is useful in preventing progression to intestinal and colon cancers. Silibinin could be useful for cancer prevention in people with familial adenomatous polyposis.
NOTE: Read about the improved effectiveness of milk thistle phytosome.
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