Summer Tomato Book Review: The China Study

by | May 6, 2009

the-china-studyIn the first official book review at Summer Tomato I examine Dr. Colin Campbell’s The China Study. Several readers have asked about this book since I wrote last week about who you can trust for diet advice, so I think it is a perfect subject for my first review.

The China Study was published in 2006 and branded itself as “The most comprehensive study of nutrition ever conducted.” It is written by Colin Campbell, PhD, a highly accomplished scientist that has worked for decades in the fields of nutrition and disease research. It was co-authored by his own son, Thomas Campbell.

Clearly both these men care deeply about health and nutrition and believe the information they provide can relieve a huge proportion of the world’s suffering. Their sincerity is apparent and, given the current dietary trends in Western culture, I am sure their recommendations would help the vast majority of people become healthier. Yet there are several logical flaws in The China Study that prevent me from giving it an A grade. Overall, however, The China Study offers a compelling view of nutrition and health from one of the leaders in the field and is worth reading.

gradebMy biggest disappointment with The China Study is how little of the book is devoted to the study itself–a large ecological-style research project, conducted by Dr. Campbell and his colleagues, examining the relationship between diet and health in rural China. As a scientist, I am a bit of a data junkie and always most impressed by strong statistics and rigorous logic.

UPDATE: [Denis Minger has taken it upon herself to re-analyzed the data from The China Study, and makes it pretty clear that Campbell vastly overstates his case. I agree with everything Denise writes, and every educated person who cares about these findings should read her analysis.]

Only a single chapter in the book is specifically dedicated to the work done in China (Chapter 4), and it conveys little new information. Most of Chapter 4 is spent reiterating the links between diet and chronic diseases such as cancer, heart disease and diabetes, discoveries that did not surprise me in the least. The two most important novel findings reported in the China study are discussed below.

The China Study is divided into four major sections. The first section describes Dr. Campbell’s original research and is the part I enjoyed most. It begins by discussing his work in the Philippines where he discovered a tight link between animal protein consumption and a specific kind of liver cancer induced by aflatoxin, a dangerous poison that is sometimes found in contaminated peanuts. He follows up this work with extensive studies in his U.S. laboratory elucidating the mechanisms of cancer promotion by the main protein found in cow’s milk, casein. Dr. Campbell makes a compelling case that this protein can influence cancer development in the presence of an extremely potent carcinogen, and his work should be taken very seriously in this regard. However,  he goes on to argue that this finding can be generalized to support the view that all animal proteins promote cancer and he recommends they be completely eliminated from your diet.

This was a logical leap I was not able to make after reading through his evidence. What about the benefits of fish for the heart and brain?

As mentioned above, the final chapter of the first section describes the China study. According to the book, the Chinese consume much less fat and protein than Americans, but more fiber and iron. Nothing too surprising there. It also reports that rural Chinese have substantially less heart disease, cancer and diabetes than Americans, but in more urban areas where diets follow more Western patterns the incidences of these diseases are higher. Again, not surprising.

Two pieces of information out of the China study did pique my interest. The first is that participants in the China study reportedly consume more, not fewer calories than Westerners. This was true even for Chinese office workers who consume 30% more calories but weigh 20% less than average Americans.

Part of this difference was accounted for by differences in physical activity (even office workers in China get more exercise than we do), but not all of it. Data in the China study suggests that Chinese have a more active metabolism and burn more calories than typical Americans. Dr. Campbell argues that this is because they eat less animal protein and fat, but the China study is observational (non-intervention) and cannot prove cause and effect.

Isn’t it possible that the Chinese metabolize their food differently because it is less processed than Western food (no matter the source)? From the literature I have read, this seems like a more plausible explanation. But regardless of the reason, the data from China suggests that all calories are not created equal in terms of both health and metabolism. This argues against the dogma offered by most nutrition experts that a calorie is a calorie.

The other surprising finding from the China study is the degree to which blood cholesterol levels predict heart disease. Although most Americans assume there is some connection between blood cholesterol and heart disease, there is still debate regarding how strong this connection is. Data from the China study suggests lower total cholesterol levels decrease risk of heart disease and death. Moreover, the data suggests that optimal cholesterol levels are far below what are recommended by Western medicine (150 mg/dL to 180 mg/dL). The healthiest Chinese had total cholesterol levels from 170 mg/dL to as low as 90 mg/dL. In the China study, lower cholesterol levels were also linked to decreased rates of several cancers. However, some scientists question the validity of this data.

The second section of the book is titled “Diseases of Affluence” and discusses the role of nutrition in the various chronic diseases that plague Western culture. In the third section Dr. Campbell offers his ideal (i.e. vegan) diet. If you are not familiar with the literature on diet and nutrition Dr. Campbell does a decent job going over it, particularly with respect to the role of dairy in prostate cancer, type 1 diabetes and multiple sclerosis. However, most of this information is available in other books that are easier to follow and less dogmatic about the need to eliminate all animal protein from the diet, which even Dr. Campbell admits “has not been absolutely proven” (p. 242).

In my opinion the most incongruous part of The China Study is the fourth section titled, “Why Haven’t You Heard This Before?” Here Dr. Campbell goes into great detail explaining the ties between food industries, drug companies, our government and, sadly, our education system from K1 through post graduate medical residency. While this section of The China Study is fascinating, it dilutes the primary nutrition message of the book with a disconcerting illustration of the roles money and politics play in our education system. But despite the jumbled message, the facts provided in this final section of The China Study are eye-opening and may be the best reason to read the book. It is shocking to learn how deeply opposed to and uneducated most of the medical community is about the life-saving benefits of dietary intervention for chronic diseases. Personally I would have liked this section to be an entirely separate book, as I would recommend it more often.

To summarize, The China Study provides an interesting but not entirely compelling argument for adopting a vegan diet. It also offers a hefty dose of skepticism about who you can trust for nutrition advice, particularly when it comes to the medical community. Overall I enjoyed reading the book and, despite my criticisms, agree with most of it. I have no doubt that for the vast majority of Americans Dr. Campbell’s advice and recommendations would be immensely beneficial.

Final Grade: B

Please add your thoughts on The China Study in the comments below.

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18 Responses to “Summer Tomato Book Review: The China Study”

  1. Scott says:

    …”consume 30% more calories but weigh 20% less than average Americans…”
    Could this be because they are 20% shorter than average Americans? Did the authors ever address the inherent metabolic differences between Chinese people and westerners?

    • Darya Pino says:

      Yes. They argue that because urban Chinese are markedly different from rural Chinese in terms of weight, health and diet, that genetics only plays a small role. This is one of the benefits of the China study, because genetically they are a very homogeneous society. When Chinese move to Western cultures they adopt Western disease risks within one generation. Clearly lifestyle is the most important factor in health.

      • Scott says:

        Wait a sec; at first you say that rural/urban Chinese are markedly different; then you say that they are genetically homogenous. You say that urban chinese have more western weight, health, and diet, then later you make it sound like they obtain that weight/health/diet when they move to a western country. I’m confused.

      • Darya Pino says:

        Sorry if I confused you, Scott. The Chinese studied are genetically homogeneous, but Dr. Campbell studied 65 different Chinese populations within China. The differences were in the lifestyles of these different populations. ALL were pretty different from American habits, but the Chinese in the suburbs of Shanghai were closer to Western habits than some of the very rural Chinese populations. What I am talking about here is a matter of degree. Rural Chinese were the healthiest, city Chinese are less healthy, but still healthier than Westerners. Make sense?

        The data on immigrants from China shows that they very quickly assume the disease risk of their new country (this is true for most cultures, not just Chinese), though this was not looked at in this particular study. This is how we know genetics are not the biggest factor in most chronic diseases.

      • Scott says:

        Thanks for clarification!

  2. Jeff clark says:

    Two things. Since it was an observational study, how can there be a positive causal relationship between higher cholesterol numbers and heart disease? Couldn’t the resultant heart disease be caused by another factor that was not measured or studied? There have many other cultures that had a high fat diet that didn’t have an increase in heart disease with a higher cholesterol levels.
    Second, homo sapiens are omnivores and have been eating animal protein for thousands of years. Linking eating animal protein to cancer is a leap of faith. The amount eaten, the processing method, the animals diet or any number of factors is probably a more reasonable cause of the cancerous relationship. I have a hard time of justifying a completely vegan diet based on limited testing vs. thousands of years of history.

    Thanks for the review!

    • Darya Pino says:

      Thanks for your reply, Jeff. Just to clarify, there is only a correlation between blood cholesterol and heart disease. When I say “predict” that means correlate, not cause. Sorry, science lingo 😉

      Also, it is very important to understand the difference between blood cholesterol and dietary cholesterol. I was careful not to say that a high fat diet causes heart disease. I do not believe this at all. I did not even say that dietary fat raises blood cholesterol. However, I do think there is a relationship between blood cholesterol and heart disease. This study shows it more profoundly than had been shown before. I am aware that some people contest this idea, but I have not yet been convinced otherwise.

      I absolutely agree with you on the lameness of claiming all animal protein causes cancer. There is no evidence for this bold claim. One thing to remember about those thousands of years of history though is that your theoretical cavemen (or whatever) lived under very different conditions than we do. For instance, the level of pollution we are exposed to now is many orders of magnitude greater than what any ancient man dealt with. We may therefore have different dietary tolerances than him (he probably didn’t live as long either). I am just speculating here, but I just wanted to bring up the possibility that things could be different now regardless of history. Obviously we do not have data on this.

  3. Healthyliving says:

    Great post, I think I’m going to check this out from the library now!

  4. What I loved about this book is how even not being a science person, I read it cover to cover and it didn’t put me to sleep. I thought it was excellent.

  5. Wow. What a thorough review! Thank you.

    This reminds me of Dr. Ornish’s book, “Eat More, Weigh Less.” He doesn’t tell you until half way through that it is a vegetarian program. That’s not on the front or back cover, or in the intro. With good reason: many fewer copies would sell. What percentage of the population will go vegan or vegetarian, even if we assume (for the sake of argument) it would add five years to average lifespan? Gotta be less than 5%.

    [I have nothing against veganism and vegetarianism. Just tell me up front before I read the book. It’s not on either cover of “China Study.” But Ornish has a blurb on China’s front cover.]


  6. Matt Shook says:

    Holy crap! So I avoid the internet for a month or so and then find that this site just took off with the rest of the springtime goodies growing outside. It’s been awhile for me but, wow, it’s good to be back…

    While the China Study has some flaws and annoyances (like repetition), I really enjoyed reading this book and have recommended it to others. So…thanks again for the recommendation Darya.

    • Darya Pino says:

      Shook! I’m so glad you are back!! I thought I sacred you away with my honey bashing–actually I eat it all the time now 😉 Glad you enjoyed the China Study, I did too.

      You going to start posting books and recipes again?

      I must admit, I’m jealous of your internet break. I’m taking one this weekend…

  7. The China Study is very misleading, and probably confusing to anyone that is not a statistics junkie. First of all, a diet composed of raw vegetables with each meal can be very effective in maintaing proper digestion and elimination. It can also reduce immune stimulation that can result in allergies, chronic inflammation, heart disease, diabetes and cancer. But when small amounts of healthy and lean animal protein is added (along with, seeds, nuts, and berries) you have a variation of the Paleo Diet, which has been shown to maintain the brain, nervous system, and skeletal structures from premature degeneration. A vegan diet may be life-saving when diagnosed with various types of cancer, but animal protein added later can enable the patient to completely recover. The Gonzales and Gerson cancer therapies uses these principles in treating cancer patients. The other reasons to use small amounts of animal proteins and fats are to support the Phase 1 and 2 detoxification systems, which require proteins to support the Cytochrome P450 system. The other thing to remember is that the medical and drug establishment are committed to drug research and not nutritional research, that is up to us to do, using our own bodies. If you decide to change your diet, do a complete blood panel first. Stay on the diet for 4 to 6 weeks and retest your blood. You will see positive or negative effects based on your genetics and your choice of foods. APO e4 genotypes should avoid large amounts of animal fats and proteins, while the APO e 2 and 3 can eat more of these foods will no ill effects. Our genes are triggered by our diet and lifestyle to produce health or disease, that is why I genetically test my patients first, before prescribing ANY diet! I hope this helps.

  8. George G. says:

    There is hardly “science” in the China Study. I love objectivity and neutrality but so many of the conclusions they made from very little science are almost comical. For example, Campbell claims, “Western-type diseases, in the aggregate, are highly significantly correlated with increasing concentrations of plasma cholesterol, which are associated in turn with increasing intakes of animal-based foods.” The first part is easy to support. The animal-based part, though, has nothing to do with his study! He didn’t demonstrate once, with simple, black and white, objective data, that anything animal-based had a remotely detrimental impact on plasma cholesterol.
    These are the same “scientists” who consider pizza as meat.

  9. Tom Utley says:

    I’m surprised or maybe more so confused when you mention …that you don’t believe [at all] that ‘a high fat diet causes heart deisease’…am I missing some essential context?

    “Also, it is very important to understand the difference between blood cholesterol and dietary cholesterol. I was careful not to say that a high fat diet causes heart disease. I do not believe this at all. I did not even say that dietary fat raises blood cholesterol.”

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