When T. Colin Campbell wrote in his book The China Study:
We were finding that high protein intake, in excess of the amount needed for growth, promotes cancer. Like flipping a light switch on and off, we could control cancer promotion merely by changing levels of protein.
The effects of protein feeding on tumor development were nothing less than spectacular. … [In one experiment] all animals that were administered [the carcinogen] aflatoxin and fed the regular 20% levels of casein either were dead or near death from liver tumors at 100 weeks. All animals administered the same level of aflatoxin but fed the low 5% protein diet were alive, active and thrifty, with sleek hair coats at 100 weeks. This was a virtual 100 to 0 score, something almost never seen in research.”
I would never have dreamed that our results up to this point would be so incredibly consistent, biologically plausible and statistically significant.
Let there be no doubt: cows milk protein is an exceptionally potent cancer promoter.
He was criticized for not discussing aspects of cow’s milk and other animal foods which could confound the relationship between animal protein and cancer. Here’s an excerpt from an article by Campbell addressing this concern:
“The adverse effects of animal protein, as illustrated in our laboratory by the effects of casein, are related to their amino acid composition, not to the effects of pasteurization, homogenization, or of the presence of hormones, pesticides, etc. Even though pasteurization and homogenization may cause slight changes in the physical characteristics of proteins, I know of no evidence where amino acid contents are altered by these treatments. This is important because it shows that there will be no difference in the biological effects of animal based protein from grass-fed or feed lot fed animals. Moreover, the casein that we used in our extensive experiments was before hormones were introduced and before factory farming became the norm, thus it mostly represented animals that were grass fed.”
– Grass-Fed Animal Agriculture, T. Colin Campbell Foundation
Here’s Campbell in his own words, arguing that “casein (cows milk protein) is the most relevant chemical carcinogen ever tested.”
Dr. Campbell is not extremist or fringe. He spent his career as a biochemist, professor, and research scientist working within mainstream institutions … MIT, Virginia Tech, Cornell. He has “received over 70 grant-years of peer-reviewed research funding (mostly NIH), served on several grant review panels, lectured extensively, and authored over 300 research papers.” He doesn’t just talk about research, he conducts his own, and has had it published in professional, peer-reviewed journals. He has sat on boards and panels and has “actively participated in the development of national and international nutrition policy.”
And after all this, one of his primary messages is … Consumption of animal protein promotes development of cancer. Consumption of plant protein does not:
Wheat and soy proteins for example did not stimulate cancer development and when wheat protein, which is deficient in the amino acid lysine, was replenished with lysine, it acted just like casein. There have been literally thousands of studies going back many decades showing a similar effect of animal and plant based proteins on body growth and other events associated with body growth–all resulting from their differences in amino acid compositions.
A problem with eating a low-carb diet is that, by default, it has you eating more fat and protein, and that protein is primarily derived from animal foods.