Dairy Protein Increases Cancer Growth?

Claim: Cancer grows more rapidly when the protein, casein, found in dairy products is consumed in large quantities. 

This claim is based of a study conducted in India by Madhavan and Gopalan called “The effect of dietary protein on carcinogenesis of aflatoxin”. Aflatoxin is a carcinogen that the lab rats were exposed to in the study. The rats were then divided into two groups; one group was fed five percent casein while the other group was fed twenty percent casein. According to the film, the study found that the rats that were fed twenty percent casein had many cancerous growths and tumors. However, the rats fed only five percent casein either did not have any cancerous growths or they had very limited amount of cancerous growths.

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The Indian study was then replicated by Dr. Campbell. He carried out a similar experiment to the one in the Indian Study. However, he also included another group in which the rats’ diets were changed back and forth from five percent casein to twenty percent casein. The diet was changed at three-week intervals.  According to the study cancer growth in the rats fell when the were on the five percent diet and increased when they were on the twenty percent diet.

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The truth is that the findings in the Indian paper contains more information that was glossed over. The study revealed that after a period of one year all of the lab rats on the twenty percent casein diet survived while only twelve rats on the five percent casein diet survived. The rats who ate twenty percent casein did develop cancer but they lived longer. Those that consumed only five percent casein were at lower risk of developing cancer but they died early. In fact this particular finding can be seen in one of the scenes in the movie.


There was in fact a protein deficiency among the rats that were on a low protein diet. The low protein diet caused the rats to consume less food. Campbell in his studies does not really mention the overall food intake of the rats. He makes it appear in the documentary that the rats that consumed five percent casein were perfectly healthy. The truth however was that while those rats may have avoided cancerous growths they were far from healthy.



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