“BGH [Bovine Growth Hormone] causes an increase in an insulin-like growth factor (IGF-1) in the milk of treated cows. IGF-1 survives milk pasteurization and human intestinal digestion. It can be directly absorbed into the human bloodstream, particularly in infants.
It is highly likely that IGF-1 promotes the transformation of human breast cells to cancerous forms. IGF-1 is also a growth factor for already cancerous breast and colon cancer cells, promoting their progression and invasiveness.”Sep. 17, 2007