|The China Study Myth|
|Written by Denise Minger|
|Saturday, 24 March 2012 20:55|
Flaws in the Vegan Bible
The year 2006 marked an event that rocked the world of nutrition (as well as the walls of Whole Foods): the release of The China Study by T. Colin Campbell. Printed by a small publishing company known for other scientific masterpieces such as The Psychology of the Simpsons and You Do Not Talk About Fight Club, Campbellâ€™s book quickly hit the word-of-mouth circuit and skyrocketed towards bestseller status, with sales exceeding half a million copies to date.
The premise is that all animal foodsâ€”ranging from Chicken McNuggets to a fillet of wild-caught salmonâ€”are responsible for modern ailments like heart disease and cancer. Such diseases, the book claims, can generally be prevented or even cured by shunning animal products and eating a diet of whole, unprocessed plant foods instead.
Although this startling thesis was hard for some to swallow, the book appeared credible due to its exhaustive references and the authorâ€™s laundry list of credentialsâ€”including a PhD from Cornell, authorship of over three hundred scientific papers, and decades of direct research experience. Perhaps not surprisingly, The China Study was quickly absorbed into the vegan community as a bible of sortsâ€”the final word on the harmfulness of animal foods, and indisputable proof that a plant-only diet is best for mankind. To the exasperation of meat lovers everywhere (especially those who enjoy arguing for sport), once lively debates with vegans were now extinguished with one simple phrase: Just read The China Study!
But despite the bookâ€™s black-and-white declarations about animal productsâ€”and its seemingly well-referenced argumentsâ€”The China Study is not a work of scientific vigor. As weâ€™ll see in this article, the bookâ€™s most widely repeated claims, particularly involving Campbellâ€™s cancer research and the results of the China-Cornell-Oxford Project, are victims of selection bias, cherry picking, and woefully misrepresented data.
Does Animal Protein Cause Cancer?
The seeds of animal-food doubt were first planted early in Campbellâ€™s career, while he was working in the Philippines on a project to help combat malnutrition. A colleague informed him of a startling trend: liver cancer was plaguing affluent Filipinos at a much higher rate than their less-wealthy counterpartsâ€”a phenomenon that, despite a slew of other lifestyle differences, Campbell believed was linked to their higher intake of animal protein.1 Bolstering his suspicions, Campbell also learned of a recent study from India showing that a high protein intake spurred liver cancer in rats, while a low protein intake seemed to prevent it.2 Intrigued by this gem of little-known research, Campbell decided to investigate the role of nutrition in cancer growth himselfâ€”an endeavor that ended up lasting several decades and producing over one hundred publications (none of which pertained to Fight Club).3
The China Study relayed Campbellâ€™s findings with powerful simplicity. In a series of experiments, Campbell and his team exposed rats to very high levels of aflatoxinâ€”a carcinogen produced by mold that grows on peanuts and cornâ€”and then fed them a diet containing varying levels of the milk protein casein. In study after study, the rats eating only 5 percent of their total calories as casein remained tumor-free, while the rats eating 20 percent of their calories as casein developed abnormal growths that marked the beginning of liver cancer. As Campbell described, he could control cancer in those rodents â€ślike flipping a light switch on and off,â€ť simply by altering the amount of casein they consumed.4
Despite these provocative findings, Campbell wasnâ€™t ready to declare all protein a threat to public health and stamp the peanut butter aisle with Mr. Yuk stickers. Animal protein, it turned out, seemed to be uniquely villainous. In several of his experiments, when the aflatoxin-exposed rats were fed wheat protein or soy protein in place of casein, they didnâ€™t develop any cancerâ€”even at the 20 percent level that proved so detrimental with casein.5 It seemed that those plant proteins were not only PETA-approved, but also the least likely to turn rat livers into tumor factories.
These findings led Campbell to his firm and famous conclusion: that all animal proteinâ€”but not plant proteinâ€”could uniquely promote cancer growth. Out with the steak, in with the tofu! But as several critics have pointed out,6,7 that proclamation required a few somersaults of logic (and maybe some cartwheels of delusion). The effects of caseinâ€”particularly isolated casein, separated from other components of dairy that often work synergisticallyâ€”canâ€™t be generalized to all forms of milk protein, much less all forms of animal protein. An impressive number of studies shows that the other major milk protein, whey, consistently suppresses tumor growth rather than promoting it, likely due to its ability to raise glutathione levels.8,9 Another of Campbellâ€™s own studies suggests that fish protein acts as a cancer-promoter when paired with corn oil, but not when paired with fish oilâ€”highlighting the importance of dietary context (and the neverending terribleness of vegetable oils).10
And the kicker: one of Campbellâ€™s most relevant experimentsâ€”which sadly received no mention in The China Studyâ€”showed that when wheat gluten is supplemented with lysine to make a complete protein, it behaves exactly like casein to promote tumor growth.11 This means that animal protein doesnâ€™t have some mystical ability to spur cancer by mere virtue of its origin in a sentient creatureâ€”just that a full spectrum of amino acids provide the right building blocks for growth, whether it be of malignant cells or healthy ones. And as any vegan whoâ€™s been asked â€śWhere do you get your protein?â€ť for the eight hundredth time will answer, even a plant-only diet supplies complete protein through various mixtures of legumes, grains, nuts, vegetables, and other approved vegan fare. Theoretically, a meal of rice and beans would provide the same so-called cancer-promoting amino acids that animal protein does. Indeed, Campbellâ€™s experiments lose their relevance in the context of a normal, real-world diet opposed to the purified menu of casein, sugar, and corn oil his rats received.
But thatâ€™s only the tip of the proteinaceous iceberg. In his September 2010 article, â€śThe Curious Case of Campbellâ€™s Rats,â€ť12 Chris Masterjohn ventured beyond the well lit pages of The China Study to explore the dark alleys of Campbellâ€™s publications firsthand. And what he found regarding the low-protein rats was a far cry from the sunshine-and-lollipops descriptions we read in the book. Although rats consuming a high-casein diet were indeed developing liver cancer as Campbell described, the ones in the low-casein groupsâ€”which were portrayed as downright bright-eyed and shiny-coated in The China Studyâ€”were suffering an even worse fate. Campbellâ€™s research actually showed that a low-protein diet increases the acute toxicity of aflatoxin, resulting in cell genocide and premature death. Because protein deficiency prevents the liver from successfully doing its detoxifying duties, less aflatoxin gets converted into cancer-causing metabolites, but the end result is massive (and eventually deadly) tissue damage.
Even the research from India that jump-started Campbellâ€™s interest in the diet-cancer link showed that rats on a low-casein diet were dying with disturbing frequency, while the high-protein ratsâ€”tumored as they may have beenâ€”were at least staying alive.13 (Itâ€™s surprising, then, that The China Study promotes a plant-based diet to prevent cancer, when death is equally effective and requires fewer shopping trips.)
More clues for understanding the casein-cancer research come from another Indian studyâ€”this one published in the late 1980s, and examining the effects of protein in aflatoxin-exposed monkeys instead of rats.14 As with Campbellâ€™s experiments, the monkeys were fed diets containing either 5 percent or 20 percent casein, but with one important difference: instead of being slammed with an astronomically (and unrealistically) high dose of aflatoxin, the monkeys were exposed to lower, daily dosesâ€”mimicking a real-world situation where aflatoxin is consumed frequently in small amounts from contaminated foods. In a fabulous case of scientific switcheroo, this study showed that it was the low-protein monkeys who got cancer, while the high-protein monkeys rejoiced in their tumorlessness.
This apparent paradox highlights a major problem in Campbellâ€™s rat research: the level of aflatoxin exposure plays a critical role in how protein affects cancer growth. When the aflatoxin dose is sky high, animals eating a low-protein diet donâ€™t get cancer because their cells are too busy dying en masse, while animals eating a higher protein diet are still consuming enough dietary building blocks for the growth of cellsâ€”whether healthy or cancerous. When the aflatoxin dose is more moderate, animals eating a low-protein diet develop cancer while their higher-protein counterparts remain in mighty fine health.
In a nutshell, the animal protein fear-mongering in The China Study stems from wildly misconstrued science. What Campbellâ€™s rat experiments really showed wasnâ€™t that animal protein is a vengeful macronutrient of doom, but the following:
1. High-quality protein promotes cell growth no matter where it comes from;
2. Protein deficiency thwarts the liverâ€™s ability to detoxify dangerous substances; and
3. With more realistic doses of aflatoxin, protein is actually tremendously protective against cancer, while protein-restricted diets prove harmful.
Did the Real China Study Show That Animal Foods Are Associated With Disease?
The China Study only devotes one chapter to its namesake study, but that doesnâ€™t mean itâ€™s not a doozy. Also known as the China-Cornell- Oxford Project, the China Study was an enormous epidemiological endeavor exploring diet and disease patterns in rural Chinaâ€”a project coined â€śthe Prix of epidemiologyâ€ť by the New York Times. Spanning sixty-five counties and collecting data on a whopping three hundred sixty-seven variables, it generated over eight thousand statistically significant correlations between nutrition, lifestyle factors and a variety of diseases.15
Although a project of such magnitude inevitably found some contradictory and non-causal links, Campbell asserts in his book that the data generally pointed in one direction: â€śPeople who ate the most animal-based foods got the most chronic disease,â€ť and â€śPeople who ate the most plant-based foods were the healthiest and tended to avoid chronic disease.â€ť16 Althoughâ€”as echoes through the hearts of statisticians everywhereâ€” correlation doesnâ€™t equal causation, these associations in conjunction with Campbellâ€™s other research are supposed to make a compelling case for animal foods being legitimately harmful.
But were the results of the China Study really a sparkling endorsement for plant-based eating?
It seems this conclusion is based, in large part, on unreliable blood variables rather than actual foods. In his book, Campbell states that he and his research team â€śfound that one of the strongest predictors of Western diseases was blood cholesterol,â€ť17 and proceeds to treat cholesterol as a proxy for animal food consumption. Throughout this chapter, we learn that the China Study data found associations between cholesterol and many cancers, as well as cholesterol and animal protein intakeâ€”implying that animal protein and those same cancers must themselves be intimately linked.
But because blood cholesterol can be affected by a number of non-dietary factors and can even rise or fall as a result of disease, examining the relationship between food itself and health outcomes is likely to be more informative than using cholesterol as an overworked, fickle middleman. But the direct relationship between animal protein and diseases isnâ€™t discussed in The China Study for one monumental reason: that relationship doesnâ€™t exist. An examination of the original China Study data shows virtually no statistically significant correlation between any type of cancer and animal protein intake.18 Only fish protein correlates positively, but probably non-causally, with a small number of cancers: nasopharyngeal cancer, a rare disease that only strikes one out of every seven million people; liver cancer, which shows up in fish-eating regions because aflatoxin proliferates in humid areas near water; and leukemia, which is likely linked to other elements of the industrialized lifestyles associated with coastal regions (and thus fish consumption) in the China Study.19
Ironically, when we look at plant proteinâ€” which The China Study argues so vigorously is cancer-protectiveâ€”we find almost three times as many positive correlations with various cancers as we do with animal protein, including colon cancer, rectal cancer, and esophageal cancer.20 Likewise, for heart disease and stroke, plant protein has a positive correlation while animal protein and fish protein have negative or nearly neutral correlationsâ€”meaning the animal-food eaters in rural China, if anything, are getting less cardiovascular disease than their more vegetarian friends.
But matters get even more interesting when we look at some of the peer-reviewed papers generated by the China Study data, most of which are co-authored by Campbell himself. As with the casein research, the China Study findings as described in Campbellâ€™s book are a hop, skip, and eighteen thousand jumps away from what the original research says. Although wheat gets nary a mention in the China Study chapter, Campbell actually found that wheat consumptionâ€”in stark contrast to riceâ€”was powerfully associated with higher insulin levels, higher triglycerides, coronary heart disease, stroke and hypertensive heart disease within the China Study dataâ€”far more so than any other food.21,22 Likewise, in a paper from 1990, Campbell conceded that â€śneither plasma total cholesterol nor LDL cholesterol was associated with cardiovascular diseaseâ€ť in the China Study data, and that â€śgeographical differences in cardiovascular disease mortality within China are caused primarily by factors other than dietary or plasma cholesterolâ€ťâ€”revealing that not even the beloved cholesterol middleman could live up to its heart-disease-causing accusations. 23
And in the spirit of saving the best for last, another of Campbellâ€™s own papers, published a mere two years before The China Study hit the shelves, states point-blank thatâ€”despite Campbellâ€™s claims about the superior health of the near-vegan rural Chineseâ€”â€śit is the largely vegetarian, inland communities who have the greatest all risk mortalities and morbidities and who have the lowest LDL cholesterols.â€ť24 Maybe the lesson here is the same one we gleaned from Campbellâ€™s rats: itâ€™s pretty tough to get sick when youâ€™re dead!
Despite its increasing popularity (and glowing endorsements by high-profile vegan converts like Bill Clinton), The China Study is, in many ways, more a work of fiction than a nutritional holy grail. The book has spawned a number of myths about the hazards of animal protein and the true results of the China Study itselfâ€”myths that easily crumble under a scrutinizing eye, but nonetheless continue trickling into the mainstream and gaining mounting publicity.
If thereâ€™s anything positive to take away from the bookâ€™s four hundred seventeen pages, itâ€™s the promotion of a whole-food dietâ€”and the resulting elimination of vegetable oils, high fructose corn syrup, refined grains, and other industrial products that tend to displace real food on our modern menus. But for those seeking scientific literature of a higher caliber, The Psychology of the Simpsons is likely to be a more satisfying (and animal-product-friendly) read.
THE PLANT-BASED DIET DOCTOR SQUAD
DEAN ORNISH , MD: Limits sugar, corn syrup, white flour, margarine, vegetable oil, alcohol and any processed food with more than two grams of fat. Program involves smoking cessation, peer support, stress management and exercise.
CALDWELL ESSELSTYN, MD: Forbids vegetable oils, refined grains, white flour, and products made from enriched flour such as bread, pasta, bagels and baked goods. Uses statins to bring patients' cholesterol levels below 150.
JOHN MCDOUGALL , MD: Limits white flour, refined grains, sugar-coated cereals, soft drinks, processed carbohydrates, fruit juice and vegetable oils.
NEAL BARNA RD, MD: Forbids vegetable oils, high-glycemic foods, high fructose corn syrup, caloric sweeteners and fried starches like potato chips and french fries.
JOEL FUHRMAN , MD: Excludes refined foods, including vegetable oils.
Getting rid of empty and refined foods, especially vegetable oilsâ€”the common denominator in all these plant-based prescriptionsâ€”will make for improvements in almost everyone. But long term, without nutrient-dense animal foods,
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. 36.
2. Ibid, p.36.
3. Ibid, p. 48.
4. Ibid, p. 60.
5. Ibid, p. 59.
6. Masterjohn, Chris. â€śThe Truth About the China Study.â€ť http://www.cholesterol-and-health.com/China-Study.html
7. Colpo, Anthony. â€śThe China Study: More Vegan Nonsense!â€ť http://anthonycolpo.com/?p=129
8. Bounous G., et al. Whey proteins in cancer prevention. Cancer Lett. 1991 May 1;57(2):91-4.
9. Hakkak R., et al. Diets containing whey proteins or soy protein isolate protect against 7,12-dimethylbenz(a)anthracene-induced mammary tumors in female rats. Cancer Epidemiol Biomarkers Prev. 2000 Jan;9(1):113-7.
10. Oâ€™Connor, T.P. et al. Effect of dietary intake of fish oil and fish protein on the development of L-azaserine-induced preneoplastic lesions in the rat pancreas. J Natl Cancer Inst. 1985 Nov;75(5):959-62.
11. Schulsinger, D.A., et al. Effect of dietary protein quality on development of aflatoxin B1- induced hepatic preneoplastic lesions. J Natl Cancer Inst. 1989 Aug 16;81(16):1241-5.
12. Masterjohn, Chris. â€śThe Curious Case of Campbellâ€™s Ratsâ€”Does Protein Deficiency Prevent Cancer?â€ť September 22, 2010. http://www.westonaprice.org/blogs/cmasterjohn/2010/09/22/ the-curious-case-of-campbells-rats-does-protein-deficiency-prevent-cancer/
13. Madhavan, T.V. and C. Gopalan. â€śThe effect of dietary protein on carcinogenesis of aflatoxin.â€ť Arch Pathol. 1968 Feb;85(2):133-7.
14. Mathur, M. and N.C. Nayak. â€śEffect of low protein diet on low dose chronic aflatoxin B1 induced hepatic injury in rhesus monkeys.â€ť Toxin Reviews. 1989;8(1-2):265-273.
15. Campbell, p. 73.
16. Ibid, p. 7.
17. Ibid, p. 77.
18. Junshi C., et al. Life-style and Mortality in China: A Study of the Characteristics of 65 Chinese Counties. Oxford: Oxford University Press, 1990.
19. Minger, Denise. â€śA Closer Look at the China Study: Fish and Disease.â€ť June 9, 2010. http://rawfoodsos.com/2010/06/09/a-closer-look-at-the-china-study-fish-and-disease/
20. Minger, Denise. â€śThe China Study: Fact or Fallacy?â€ť July 7, 2010. http://rawfoodsos.com/2010/07/07/the-china-study-fact-or-fallac/
21. Gates J.R., et al. â€śAssociation of dietary factors and selected plasma variables with sex hormone-binding globulin in rural Chinese women.â€ť Am J Clin Nutr. 1996 Jan;63(1):22-31.
22. Fan W.X., et al. â€śErythrocyte fatty acids, plasma lipids, and cardiovascular disease in rural China.â€ť Am J Clin Nutr. 1990 Dec;52(6):1027-36.
24. Wang Y., et al. â€śFish consumption, blood docosahexaenoic acid and chronic diseases in Chinese rural populations.â€ť Comp Biochem Physiol A Mol Integr Physiol. 2003 Sep;136(1):127- 40.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Spring 2012.
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just another guy
written by Rich, Jun 07 2013
written by healthrevolution, Mar 01 2013
what's lacking in The China Study and this commentary is the importance of sufficient protein...., Low-rated comment [Show]
..., Low-rated comment [Show]
Points taken, Low-rated comment [Show]
The commentary here does have a concensus: this article does not make the point it promises to make.
written by Michael Ryan, Jan 07 2013
Vegan, Low-rated comment [Show]
|Last Updated on Thursday, 29 March 2012 17:14|