Dr. Campbell Responds to Dr. Mercola
by T. Colin Campbell, PhD.

For background, it should be noted that Dr. Mercola's views, when he says that the China Study is "seriously flawed", parallel very closely those of the Weston A Price Foundation (WAPF), a Washington-based agricultural lobbying group. They assert, among other claims, that high cholesterol diets are healthy even beneficial thus supporting their advocacy for the consumption of raw un-pasteurized, un-homogenized grass-fed beef and other animal-based food products. They also, perhaps to be politically correct, recommend the consumption of fruits and vegetables but in a way that is virtually meaningless. They rely heavily on a personal survey that a dentist, Weston Price, did during the 1920s and 1930s when he visited a total of 14 indigenous peoples in various parts of the world to examine and photograph their dental health (dental caries and dental arch formation). However, the WAPF, by principally relying on Price's findings, go far beyond what Price actually did. They would have us believe that he published extensive data to support the health value of cow's milk and high cholesterol animal based foods and, further, that he 'discovered' a fat soluble factor in milk that is likely responsible for these healthy effects of cow's milk. I read his book and there are no data that Price accumulated, tabulated and interpreted to support this view. Indeed, the so-called fat soluble factor mentioned by Price was noted at a time during the early days of vitamin discoveries when little was known about their metabolism and biochemical effects, except that they divided into water and fat soluble substances. The most oft-quoted criticism of The China Study promoted by the WAPF and their allies is that written by Chris Masterjohn, a 24-year old man who, not being either in the profession or trained in the subject, viewed research from a very limited perspective. I previously replied to his and related remarks in a comment posted on the Internet at


Although I find it difficult at times to 'debate' people whose professional views are aligned with their commercial interests and who have no experience in peer-reviewed original research (except for a few letters to the editor, I find no evidence that Dr. Mercola, for example, has successfully submitted his findings to the critical review of peers), I must turn my attention to the substance of Dr. Mercola's criticisms. His critical views are quite general and far ranging but the main points seem to be as follows.

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 the amino acid composition is altered by these treatments.

This focus on amino acid composition of proteins is important because animal based protein will be the same regardless whether it is provided by grass-fed or feed lot fed animals. Moreover, the casein that we used in our extensive experiments was produced before hormones were introduced and before factory farming became the norm, thus it represented mostly animals that were grass fed.

There have been many different kinds of studies for well over a half century showing that the nutritional responses of different proteins are attributed to their differing amino acid compositions that have nothing to do with pasteurization, homogenization or contamination with foreign chemicals. These differences in nutritional response disappear when any limiting amino acids are restored.

In our case, for example, we found that casein was a powerful promoter of experimental cancer (in dozens of experiments over a period of more than 30 years) and that this effect was attributed to a large number of highly integrated reactions within the cell and well as within the body. Two of the more prominent of these biochemical/physiological responses result from increased production of growth hormones and an elevation in body acid load (metabolic acidosis) that impacts a number of critical enzyme activities. Wheat protein, unlike casein for example, did not stimulate cancer development but when its limiting amino acid, lysine, was restored, it acted just like casein. There have been literally thousands of studies going back many decades showing a similar effect on body growth and other events associated with body growth--all resulting from differences in amino acid composition of different proteins. These differences have long been described by the concept of "biological value" or, perhaps, "protein efficiency ratio", which served as a starting point for my own research career that started with my doctoral dissertation program more than 50 years ago.

I should also mention that my experimental research extended well beyond the singular effects of animal protein and, as we proceeded through the years (all supported by NIH funding and documented in several hundred publications in well known professional journals) it included experimental studies on other nutrients, other mechanisms and other health/disease outcomes. These additional findings only became more provocative and convincing that a diet comprised of plant-based foods created the best health on what seems to be all accounts. The effects in humans, as shown by my physician colleagues are profound, broad and fast.

I mostly reject what Dr. Mercola and his WAPF colleagues are claiming. While it may seem reasonable to assume that grass-fed animal products compared with feed lot animal products are somewhat healthier on some accounts (perhaps due to a more favorable fatty acid composition, slightly more--but still minimal--tissue antioxidants derived from the plants being consumed), they do not come close to the health value of plant based products. But even if this slight advantage of organic, grass fed animals were shown to be true, this hardly justifies its being of interest for the general public.

There is no possibility that their is enough land, water and other resources to meet the current and future demand for these products. Because this is so obvious, I have often wondered what motivates this argument for grass fed animal agriculture. When I find people vigorously making this argument (and some do!) at the same time that they have a monetary incentives, I can't help but wonder if these thoughts are not connected. In any event, I know of no convincing evidence that consuming grass-fed animal products are really better health-wise than feedlot animal products.

On one final point, those who lament a "serious flaw" in The China Study mostly limit their arguments to the China project itself, as if this is all there is in our book. It is not. It is only one of the eighteen chapters. These critics fail to note what Tom and I tried to do in writing the book. It was simply to tell the story in a way that I myself learned it, by using as much as possible my own first hand research and policy experiences that persuaded me, then let readers decide for themselves. We simply asked that the reader to "try it" before making his/her final opinions. If my long years in research have told me anything that's really important it is that we should be interpreting scientific evidence not as an absolute truth but as a component of a wider message within context. Deciding what is supposedly absolutely true is great for making money but it is not for making health.

There is far more that I could say that refutes the scientific basis for advocating the diet promoted by Dr. Mercola and his colleagues associated with WAPF. But time intercedes.

T. Colin Campbell

Jacob Gould Schurman Professor Emeritus
of Nutritional Biochemistry

Cornell University
Ithaca, NY