Although there are many arguments favoring the nutritional imbalance explanation of cancer, one of the more striking for me was the experimental animal studies discussed in Chapter 3 of my book, The China Study.

Aflatoxin is a very potent carcinogen for the rat. However, after the Indian researchers showed that decreasing animal protein (casein) intake from the usual level of consumption of 20% to 5% could completely prevent this carcinogen from causing cancer, we began our work (references in our book). We explored that finding in great depth and eventually confirmed their initial observation. That is, a simple adjustment of dietary protein (casein) within very normal ranges of protein intake controlled cancer growth, and this effect worked not by one mechanism but by a large array of mechanisms. In other words, we proved this association beyond any doubt.

Over the years, this research required a lot of funding. Our funding applications were reviewed by other researchers highly experienced in this field. Every time, we got high marks for the quality of the research. Then, when we submitted the results for publication, they were again reviewed by peers, and these papers were published in the best cancer research journals. Among the people who know the most about cancer, our work was entirely convincing.

Very simply, adjustment of protein intake within a normal range was capable of enormously influencing a chemical carcinogen’s ability to promote cancer. Dietary protein trumped the carcinogen even though the species was exceptionally sensitive to the aflatoxin.

We then did much the same thing with a cancer caused by a virus (the hepatitis B virus).
Following the criteria for determining what a carcinogen is, these findings should have shaken up the entire world of cancer research and education because this is the way that other carcinogens (Alar, dioxin, DDT, etc.) also work, except the evidence favoring their carcinogenicity is far less than it is for aflatoxin!

I was not comfortable taking the usual path of declaring that casein is a carcinogen that was far more powerful than aflatoxin (“the most potent carcinogen ever discovered,” according to the people who favor the chemical carcinogen hypothesis). Instead, I was more interested in asking broader questions about the role of animal protein-based foods and their association with human cancer, as well as studying the comparative associations of aflatoxin consumption and protein consumption in humans—this was the China Study.

I have shared this analysis with many of the very best—and most critical audiences—that I can find (Harvard, Berkeley, Cornell, Emory, Yale, Duke, NIH, etc.), and I get no criticism on the grounds of the research. The only comment that seems to surface frequently is that I am taking on some really powerful interests and that they won’t listen, regardless of the evidence. In other words, this issue—first narrowly defined but later expanded into a much larger issue—is mostly about politics, economics, personal bias, etc., and not about rational science. Quite honestly, it depresses me because there is so much at stake for human health. Corporate America, which controls the agenda in this health research business, is more interested in generating wealth than they are in the health of the public!