Oncology

Animal Protein as a Carcinogen

Answer to a Reader’s Question:

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

Further, over the years, this research required a lot of funding and our applications for funding 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 very best cancer research journals. Among the people who know the most about cancer, our work was entirely convincing.

Very simply, normal adjustment of protein intake was capable of enormously influencing the ability of a chemical carcinogen’s ability to promote cancer. Dietary protein trumped a very powerful carcinogen in a species that was exceptionally sensitive to this carcinogen.

Then we did much the same thing with a cancer caused by a virus, the hepatitis B virus.

If we follow the criteria of determining what is a [...]

Animal Rights in Research

As an animal rights activist, I am very curious about your rat studies. My question is hypothetical. If the politics of research funding were not so animal model dependent, and you would have been funded for the China Study without first doing the rat research, do you feel your conclusions would have been significant enough without the rat work to have come to the same conclusions in your book?

In other words, you say there was no way that you could have done the work without the rats, but the massive epidemiological study, to me, seems so much more significant and applicable to human health, that I wonder if the rat work was truly necessary?

This is a question that I have long thought about. The answer is “No”, the China Study would not have been so clear, although I say this because of somewhat indirect considerations. It is true that the rat and mice studies illustrated something about animal protein that had never before been demonstrated, especially with the depth, completeness and convincing nature of the observation. That is, it directly proved the carcinogenic nature of animal based protein, something that would never have been seen in human studies. In human studies, we only have correlation or observational findings and other researchers would have dispelled such associations as not being real. Indeed, such associations were previously seen in earlier human studies and no one made anything of them–indeed refused to believe that they were reliable.

What we did in the rat and mice studies, in effect, was to use the experimental criteria routinely used in science to establish whether a chemical is carcinogenic, a procedure widely accepted by almost everyone. Indeed, this is wherefrom the public [...]

Prostate Cancer

The toll from prostate cancer is immense. In the U.S., one out of every ten men will be diagnosed with this devastating disease.
  • American Medical Association
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    Letter to the Editor: Journal of the American Medical Association

Letter to the Editor: Journal of the American Medical Association

Re: Holmes DH, Hunter DJ, Colditz GA, et al. Association of dietary intake of fat and fatty acids with risk of breast cancer. JAMA 1999; 281:914-920.

Holmes et al1, using data from the Nurses’ Health Study, report no significant association between breast cancer risk and type of dietary fat consumed, a finding mostly (but not entirely) consistent with earlier reports2-3 on this important study. This and earlier reports have shown that lower fat diets are not associated with lower risks for breast cancer, as originally hypothesized by this group2.

Although this observation is important and, by now, well documented, it may be even more important to note the shortcomings of the underlying hypothesis for this study. Namely, the original hypothesis was rather narrowly focused on the proposition that dietary fat was an independent and perhaps major cause of breast cancer. This hypothesis was based on findings of international correlation4 and migrant5-6 studies, on experimental animal studies7-8 and, at that time, on some recently published dietary goals by an expert panel of the National Academy of Sciences9. One of these recommendations one was to limit dietary fat to 30% of calories as a means of reducing cancer incidence.

However, an alternative explanation of this earlier evidence was that dietary fat was a biomarker of a type of diet, not a major and independent cause of the disease. For example, prior evidence had shown that the association of total dietary fat with breast cancer risk was more likely explained by diets enriched in animal-based foods at the expense of plant-based foods. For example, 1) correlation studies showed that breast cancer risk was associated with diets rich in animal fat, but not in plant fat10; 2) the correlation of breast [...]

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    What Does Research Indicate About Animal Protein and “Reproductive” Cancers?

What Does Research Indicate About Animal Protein and “Reproductive” Cancers?

Answer to a Reader’s Question:

“In ecologic data, correlations exist between per capita meat…consumption and prostate cancer mortality rate [1 study cited]. In case control and prospective studies, the major contributors of animal protein, meat, dairy products and eggs have frequently been associated with a higher rate of prostate cancer…[23 studies cited].” (quoted from Giovannucci, E. Dietary influences of 1,25 (OH)2 vitamin D in relation to prostate cancer: a hypothesis. Cancer Causes and Control, 9: 567-582, 1998).

Here is a quote from my book (Campbell, TC and Campbell TM II, The China Study, Startling Implications of Diet, Weight Loss and Long-Term Health, 2005, 417 pp.):

“Under unhealthy conditions…IGF-1 becomes more active, increasing the birth and growth of new cells while simultaneously inhibiting the removal of old cells, both of which favor the development of cancer [7 studies cited]. …consuming animal-based foods increases the blood levels of this growth hormone, IGF-1 [3 studies cited].

With regard to prostate cancer, people with higher than normal blood levels of IGF-1 have been shown to have 5.1 times the risk of advanced-stage prostate cancer…when men also have low blood levels of a protein that binds and inactivates IGF-1 [1 study cited], they will have 9.5 times the risk of advanced stage prostate cancer….fundamental to this finding is the fact that we make more IGF-1 when we consume animal-based food like meat…[3 studies cited].”

In effect, these data, summarized from multiple studies and including BOTH observational data AND mechanistic explanations is far more reliable than citing an occasional study. This kind of analysis also becomes much more impressive because it refers to a general property of a group of foods, in this case animal-based foods of which meat is a major component. And [...]

Food vs. Chemical Carcinogens

Answer to a Reader’s Question:

Chemicals as carcinogens are widely believed to be the main cause of human cancer. However, when directly compared, nutrient imbalances are far, far more substantial in their effect than chemicals. I have taken this argument, as a seminar, directly to the two major chemical carcinogen testing organizations in the world (the International Agency for Research on Cancer in Lyon, France (a WHO organization) and the National Toxicology Testing Program (once in Research Triangle Park and once in Jefferson, Arkansas (an FDA/ NIH program) in order to get their critical comment. I only get comments that validate our work — almost all of which was supported by NIH funding. I also have been on 3 expert panels of the National Academy of Sciences where this topic was considered and have published extensively on the topic in professional peer-reviewed journals.

The China Study mentions a small fraction of the evidence that supports my argument.

I am confident that there is an extraordinary amount of hype on the chemical carcinogen hypothesis and, although well intended by many who make this argument, I also am confident that this hypothesis has been extensively used to discredit the nutritional imbalance hypothesis primarily to protect the animal foods industry. I say this because when I was invited by Senator John Glenn to testify before his committee as to why the public is so confused about diet and health, his staff had received — in advance of my testimony — a crescendo of mail to the contrary and, upon a little snooping around by Glenn’s staff, discovered that almost all of it was generated by the animal and livestock lobbying groups!

This prejudice also is responsible for the $30 million [...]