" Chapter three delineates the decades-long laboratory work we did with experimental animals, work that passed the requirements to be called “good science.” The finding: casein, and very likely all animal proteins, may be the most relevant cancer-causing substances that we consume. Adjusting the amount of dietary casein has the power to turn on and turn off cancer growth, and to override the cancer-producing effects of aflatoxin, a very potent Class IA carcinogen, but even though these findings were substantially confirmed, they still applied to experimental animals. It "

― T. Colin Campbell , The China Study: The Most Comprehensive Study of Nutrition Ever Conducted and the Startling Implications for Diet, Weight Loss, and Long-term Health