Review of The China Study

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http://www.westonaprice.org/bookreviews/chinastudy.html

 

The China Study:

Startling Implications for Diet, Weight Loss, and Long-Term Health

by T. Colin Campbell

BenBella Books

 

It was growing up on one of the many dairy farms of the rural American

landscape that the young T. Colin Campbell formed the views that would

shape the early portion of his career. Cow's milk,

" Nature's most

perfect food, " was central to the existence of his family and

community. Most of the food that Campbell's family ate they

produced

themselves. Campbell milked cows from the age of five through his

college years. He studied animal nutrition at Cornell, and did his PhD

research on ways to make cows and sheep grow faster so the American

food supply could be pumped up with more and more protein.1

 

Fast forward to the present. Campbell is now on the advisory board of

the Physicians' Committee for Responsible Medicine,2 which

describes

itself as " a nonprofit organization that promotes preventive

medicine,

conducts clinical research, and encourages higher standards for ethics

and effectiveness in research, " 3 but whose pro-vegan agenda

reflects

its ties to People for the Ethical Treatment of Animals (PETA) and

other animal rights groups, including, according to Newsweek, Stop

Hunting and Animal Cruelty, which the Department of Justice calls a

" domestic terrorist threat. " 4

 

Campbell's new book The China Study: Startling Implications for

Diet,

Weight Loss, and Long-Term Health hit the bookstores in January 2005

and details the turning points in his post-graduate research that led

Campbell to become a famed opponent of animal foods and an advocate of

the vegan diet. It takes the reader on a tour through Campbell's

early

animal experiments, which he interpreted to implicate animal protein

as a primary cause of cancer, through the massive epidemiological

study after which the book was named. Only 39 of 350 pages are

actually devoted to the China Study. The bold statement on page 132

that " eating foods that contain any cholesterol above 0 mg is

unhealthy, " 5 is drawn from a broad—and highly

selective—pool of

research. Yet chapter after chapter reveals a heavy bias and

selectivity with which Campbell conducted, interpreted, and presents

his research.

 

Protein and Cancer

 

The first strike against the pro-protein mantra Campbell had inherited

from his nutritional forbears came while he was studying the

relationship between aflatoxin (AF), a mold-related contaminant often

found in peanut butter, and cancer in the Philippines. Campbell was

informed by a colleague that, although the areas with the highest

consumption of peanut butter had the highest incidence of liver

cancer, it was the children of the " best-fed families, " who

consumed

the most protein, who were getting liver cancer. Whether the best-fed

Philippino families ate the many staples of modern affluent diets like

refined breads and sugars isn't mentioned.6

 

This observation was corroborated by a study published in " an

obscure

medical journal, " that fed AF to two groups of rats, one

consuming a 5

percent protein diet, one consuming a 20 percent protein diet, in

which every rat in the latter group got liver cancer or its precursor

lesions, and none in the former group got liver cancer or precursor

lesions.7

 

Campbell went on to investigate the possible relationship between

nutritional factors, including protein, and cancer, a study that

proceeded for 19 years with NIH funding.8 His conclusion was

revolutionary and provocative: while chemical carcinogens may initiate

the cancer process, dietary promoters and anti-promoters control the

promotion of cancer foci,9 and it is nutritional factors, not chemical

carcinogens, that are the ultimate deciding factors in the development

of cancer.10 Yet the 19 years of research into this project leave us

with more questions than answers, and have left T. Colin Campbell with

a foundation of unsupported conclusions upon which he has built his

tower of vegan propaganda.

 

Campbell began his studies using AF as an initiator of cancer foci and

the milk protein casein as the promoter protein of study. His results

corroborated the earlier results of other researchers: a dose-response

curve existed for AF and cancer on a 20 percent casein diet, but

disappeared on a 5 percent protein diet.11 He found that adjusting the

protein intake of the same rats could turn cancer promotion on and off

as if with a switch,12 and found casein to have the same effect when

other cancer initiators, such as the hepatitis B virus, were used.13

 

Rather than throwing a blanket accusation at all protein, Campbell

acknowledged that the study of other proteins would be required before

generalizing, just as the study of other cancer initiators would be

required before generalizing to them. Wheat and soy protein were both

studied in lieu of casein, and both were found not to have the

cancer-promoting effect of casein.14 Amazingly, Campbell's

reluctance

to make unwarranted generalizations ends here. After briefly

describing some research finding a protective effect of carotenoids

against cancer, Campbell concludes the chapter on his animal research

by noting the following overarching pattern: " nutrients from

animal-based foods increased tumor development while nutrients from

plant-based foods decreased tumor development. " 15 (His italics.)

 

The generalization from the milk protein casein to all " nutrients

from

animal-based foods " is clearly unwarranted. If Campbell took

caution

to study the issue further before generalizing from casein to all

proteins, why didn't he take the same caution before generalizing

from

casein to all animal proteins or all animal nutrients? Indeed,

Campbell later acknowledges that he is making this generalization:

" .

.. . casein, and very likely all animal proteins, may be the most

relevant cancer-causing substances that we consume. " 16 Why this

generalization is " very likely " to be true is left

unexplained.

 

Campbell is aware that casein has been uniquely implicated in health

problems, and dedicates an entire chapter to casein's capacity to

generate autoimmune diseases.17 Whey protein appears to have a

protective effect against colon cancer that casein does not have.18

Any effect of casein, then, cannot be generalized to other milk

proteins, let alone all animal proteins. Other questions, such as what

effect different types of processing have on casein's capacity to

promote tumor growth, remain unanswered. Pasteurization,

low-temperature dehydration, high-temperature spray-drying (which

creates carcinogens), and fermentation all affect the structure of

casein differently and thereby could affect its physiological

behavior. What powdered, isolated casein does to rats tells us little

about what traditionally consumed forms of milk will do to humans and

tells us nothing that we can generalize to all " animal

nutrients. "

Furthermore, Campbell fails to address the problems of vitamin A

depletion from excess isolated protein, unsupported by the

nutrient-dense fats which accompany protein foods in nature.

Lessons from China

 

In the early 1980s, along with Chen Junshi, Li Junyao, and Richard

Peto, T. Colin Campbell presided over the mammoth epidemiological

study referred to as the China Project, or China Study. The New York

Times called it " the Grand Prix of epidemiology, " and it

gathered data

on 367 variables across sixty-five counties and 6,500 adults.

Amazingly, from over 8,000 statistically significant associations,

Campbell was able to draw a single unifying principle: " People

who ate

the most animal-based foods got the most chronic disease. . . . People

who ate the most plant-based foods were the healthiest and tended to

avoid chronic disease. " 19

 

The study utilized recall questionnaires, direct observation and

measurement of intakes over a three-day period, and blood samples.20

The blood samples were combined into large pools for each village and

each sex.21 This had the drawback of dramatically decreasing the

number of data points relative to the enormous number of correlations

being generated, and the advantage of allowing the blood to be tested

for many, many more variables than would be testable using individual

samples.

 

One of the benefits of the China Study's design was that the

genetic

stock of the study subjects had little variation, while there was wide

variation among cancer and other disease rates. While the dietary

surveys were conducted in the autumn of 1983,22 the mortality rates

were taken a decade earlier in 1973 through 1975.23 Rural areas were

thus deliberately selected to ensure that the people in the area had

for the most part lived in the area all their lives and had been

eating the same foods native and traditional to that area, so that the

mortality data would reliably match the dietary data.

 

One of the drawbacks of the study was that nutrient intakes were

determined from food composition tables, rather than measured directly

from foods.24 This disallowed any consideration of differences in

nutrient composition of foods within the area due to soil quality,

which was a primary theme of Weston Price's research. Another

drawback

was that the questionnaire did not adequately account for the

diversity of animal foods in the Chinese diet. Questions about the

frequency of consumption of sea food, meat, eggs, and milk were

included, but questions about organ meats and insects were not

included on the questionnaire, nor was fish differentiated from shell

fish, despite the very different nutrient profiles of these foods.25

Additionally, the autumn dietary survey could not take into account

foods that were not in season at the time.

 

What is most shocking about the China Study is not what it found, but

the contrast between Campbell's representation of its findings in

The

China Study, and the data contained within the original monograph.

Campbell summarizes the 8,000 statistically significant correlations

found in the China Study in the following statement: " people who

ate

the most animal-based foods got the most chronic disease. " 26 He

also

claims that, although it is " somewhat difficult " to " show

that

animal-based food intake relates to overall cancer rates, " that

nevertheless, " animal protein intake was convincingly associated

in

the China Study with the prevalence of cancer in families. " 27

 

But the actual data from the original publication paints a different

picture. Figure 1 shows selected correlations between macronutrients

and cancer mortality. Most of them are not statistically significant,

which means that the probability the correlation is due to chance is

greater than five percent. It is interesting to see, however, the

general picture that emerges. Sugar, soluble carbohydrates, and fiber

all have correlations with cancer mortality about seven times the

magnitude of that of animal protein, and total fat and fat as a

percentage of calories were both negatively correlated with cancer

mortality. The only statistically significant association between

intake of a macronutrient and cancer mortality was a large protective

effect of total oil and fat intake as measured on the questionnaire.

As an interesting aside, there was a highly significant negative

correlation between cancer mortality and home-made cigarettes!28

 

Campbell's case for the association between animal foods and

cancer

within the China Study is embedded within an endnote. Campbell states:

" Every single animal protein-related blood biomarker is

significantly

associated with the amount of cancer in a family. " 29 Following the

associated endnote, these biomarkers were " plasma copper, urea

nitrogen, estradiol, prolactin, testosterone, and, inversely, sex

hormone binding globulin, each of which has been known to be

associated with animal protein intake from previous studies. " 30

 

Since Campbell does not cite these " previous studies, " the

reader is

left in the dark regarding the reliability of his assumptions. Blood

biomarkers are generally associated with food intake patterns, rather

than specific foods. Since food intake patterns differ in different

populations, an association found between a biomarker in one

population cannot be necessarily generalized to another.31 For

example, people who eat more whole grains might have higher levels of

vitamin C, even though whole grains do not contain vitamin C. This

might be true in one population where people who eat whole grains tend

to eat more fruits and vegetables, but untrue in another population.

It isn't at all clear why this roundabout way of measuring animal

protein consumption is superior to the direct methods of the study,

such as the food questionnaire and the dietary observations.

 

Additionally, of the biomarkers measured, estradiol only had a

statistically significant relationship with animal protein in women

under 45, as is true for sex hormone-binding globulin, both of which

had negative correlations in women aged 55-64. There was no

statistically significant relationship between animal protein and

testosterone in men of any age, which were negatively correlated in

all age groups, nor in females except those aged 55-64. Plasma

prolactin was only statistically significantly related to animal

protein consumption in the oldest group of females, and was negatively

correlated in other age groups.32 Only urea nitrogen and copper were

consistent and significant indicators of animal protein consumption,

and of these two only copper was significantly related to cancer

mortality.33

 

It is difficult to see how Campbell can so emphatically draw the

conclusion that animal foods are the cause of most diseases from this

data.

Only Half the Story?

 

By the title, one would expect The China Study to contain objective

and complete information derived from the China Study. Page one touts

" real science " above " junk science " and " fad

diets. " Yet Campbell

consistently presents only half the story at best through the duration

of the book. In Part II, Campbell presents the evidence incriminating

animal products as the cause of nearly every disease. He cites several

health care practitioners, including Dr. Caldwell Esselstyn Jr. and

Dr. Dean Ornish, who claim to have been able to reverse heart disease

with plant-based diets,34 and cites the Papua New Guinea Highlanders

as an example of a traditional society without the occurrence of heart

disease, but makes no mention of George Mann's and other

researcherS'

extensive study of the Masai or the healthy primitives of Weston

Price. That the programs of Ornish and Esselstyn involved more than

abstention from animal foods—especially the program of Ornish, of

which diet is only a small part—is not seen as a confounding

factor

that detracts from our ability to incriminate animal foods in heart

disease. Nor does he bother to mention the cannibalism or the swollen

bellies of children that accompanies the protein-starved diet of the

New Guinea Highlanders.35

 

In Campbell's discussion of diabetes, he concludes that

" high-fiber,

whole, plant-based foods protect against diabetes, and high-fat,

high-protein, animal-based foods promote diabetes. " 36 He

discusses the

possible role of cow's milk in causing Type 1 diabetes via an

autoimmune reaction,37 but makes no mention that wheat gluten has been

implicated in Type 1 diabetes by a similar process.38 He similarly

fails to mention the role of fructose consumption in causing insulin

resistance,39,40 and the increase in high fructose corn syrup

consumption that has paralleled the increase in diabetes.

 

Campbell discusses the role of animal foods in causing prostate

cancer,41 but makes no mention of the potent preventative role current

research is attributing to vitamin A, a nutrient found in animal

foods.42 He devotes 19 pages to discussing the role of cow's milk

in

causing autoimmune diseases,43 but zero pages to the role of wheat

gluten in causing autoimmune diseases.44 Campbell suggests that

dietary fat and cholesterol contribute to Alzheimer's and

discusses

the potential protective effects of plant foods,45 but makes no

mention of the protective effect of DHA, an animal-based nutrient,

currently under investigation.46

 

The China Study frequently ignores the contribution of animal foods to

certain classes of nutrients, such as B vitamins and carotenes. Both

classes of nutrients are assumed to come from plant foods, despite egg

yolks and milk from pastured animals being a good source of carotenes,

and the high B vitamin content of liver. But the most curious of such

statements is one found on page 220, where Campbell declares,

" Folic

acid is a compound derived exclusively from plant-based foods such as

green and leafy vegetables. " 47 This is a fascinating statement,

considering that chicken liver contains 5.76 mcg/g of folate, compared

to 1.46 mcg/g for spinach!48 A cursory look through the USDA database

reveals that the most folate-dense foods are organ meats.

 

The China Study contains many excellent points in its criticism of the

health care system, the overemphasis on reductionism in nutritional

research, the influence of industry on research, and the necessity of

obtaining nutrients from foods. But its bias against animal products

and in favor of veganism permeates every chapter and every page. Less

than a page of comments are spent in total discussing the harms of

refined carbohydrate products. Campbell exercises caution when

generalizing from casein to plant proteins, but freely generalizes

from casein to animal protein. He entirely ignores the role of wheat

gluten, a plant product, in autoimmune diseases, so he can emphasize

the role of milk protein, an animal product. The book, while not

entirely without value, is not about the China Study, nor is it a

comprehensive look at the current state of health research. It would

be more aptly titled, A Comprehensive Case for the Vegan Diet, and the

reader should be cautioned that the evidence is selected, presented,

and interpreted with the goal of making that case in mind.

 

Review by Chris Masterjohn, chapter leader in West Brookfield,

Massachusetts.

 

REFERENCES

1. Campbell, T. Colin, PhD, with Thomas M. Campbell II, The China

Study: Startling Implications for Diet, Weight Loss, and Long-Term

Health, Dallas: BenBella Books, 2004, p. 4.

2. http://www.pcrm.org/about

3. http://www.pcrm.org

4. http://www.activistcash.com/organization_overview.cfm/oid/23

5. Campbell, p. 132.

6. Ibid, p. 36.

7. Ibid, pp. 36-37.

8. Ibid, p. 48.

9. Ibid, p. 50.

10. Ibid, p. 56.

11. Ibid, p. 59.

12. Ibid, p. 62.

13. Ibid, p. 63.

14. Ibid, p. 60.

15. Ibid, p. 66.

16. Ibid, p. 104.

17. Ibid, p. 183-201.

18. Hakkak, et al., " Dietary Whey Protein Protects against

Azoxymethane-induced Colon Tumors in Male Rats, " Cancer

Epidemiology

Biomarkers & Prevention, Vol. 10, 555-558, May 2001.

19. Campbell, p 7.

20. Campbell, p. 73.

21. Ibid, p. 355.

22. Junshi, Chen, T. Colin Campbell, Li Junyao, and Richard Peto,

Diet, Life-style and Mortality in China: A Study of the

Characteristics of 65 Chinese Counties, Oxford: Oxford University

Press, 1990, p. 6.

23. Ibid, p 1.

24. Ibid, p. 16.

25. Ibid, p. 850.

26. Campbell, p. 7.

27. Ibid, p. 88.

28. Junshi, p. 106.

29. Campbell, p. 89.

30. Ibid, p. 376.

31. Ness, et al., " Plasma Vitamin C: What Does it Measure? "

Public

Health Nutr., 1999 March 2 (1):51-4.

32. Junshi, p. 572.

33. Ibid, p. 106.

34. Campbell, 125-130.

35. Diamond, Jared, Guns, Germs, and Steel: The Fate of Human

Societies, New York: W. W. Norton & Company, 1999, p 149.

36. Campbell, p 151.

37. Ibid, p. 146.

38. Braly, James, M.D., and Ron Hoggan, M.A., Dangerous Grains, New

York: Penguin Putnam, 2002, p. 124.

39. Mayes, Peter A., " Intermediary Metabolism of Fructose, "

Am J Clin

Nutr 1993;58(suppl):754S-65S.

40. Hollenbeck, Clarie B., " Dietary Fructose Effects on

Lipoprotein

Metabolism and Risk for Coronary Artery Disease, " Am J Clin Nutr

1993;58(suppl):800S-9S.

41. Campbell, p. 177-182.

42. McCormick, et al., " Chemoprevention of rat prostate

carcinogenesis

by 9-cis-retinoic acid, " Cancer Res. 1999 Feb 1;59(3):521-4.

43. Campbell, pp. 183-201.

44. Braly, 117-133.

45. Campbell, p 220.

46. Calon, et. al., " Dohosahexaenoic Acid Protects from Dendritic

Pathology in an Alzheimer's Disease Mouse Model, " Neuron, Vol

43,

633-645, 2 September 2004

47. Campbell, p 220.

48. USDA National Nutrient Database for Standard Reference, Release

17.

 

FIGURE 1: Associations of Selected Variables with Mortality for All

Cancers

Total Protein +12% Carbohydrates +23%

Animal Protein + 3% Total Calories +16%

Fish Protein + 7% Fat % Calories - 17%

Plant Protein +12% Fiber +21%

Total Lipids - 6% Fat (questionnaire) - 29%*

 

 

* statistically significant ** highly significant *** very highly

significant