The China Study - critical summary review

Everybody wants a healthy diet. But do you know where to start? Well, who does? Everyone is saying something different about food these days. The sheer number of available diets and nutrition trends is so overwhelming and confusing that it’s become virtually impossible to know what to eat without guilt. Sugar is definitely bad, of course, but is salt as well? What about carbs? Are proteins good for you? Should you stay away from fats? Too many questions, too few evidence-backed answers.

Fortunately, “The China Study” – one of America’s bestselling books about nutrition – is based on a comprehensive 20-year dietary study conducted by China’s government, Cornell University and the University of Oxford. Moreover, it is written by one of the study’s directors, celebrated nutrition expert T. Colin Campbell, and his son, Thomas M. Campbell II. Their findings sent shockwaves throughout the world of nutrition back when the book was first published. They still do. Get ready to find out why.

An ounce of prevention

Benjamin Franklin wrote so many smart and memorable aphorisms you can quote him on almost any topic. “An ounce of prevention is worth a pound of cure” serves our current purpose. Put more relevantly, a healthier diet is much more beneficial, not to mention less expensive, than modern medicine. It is not even a controversial claim to say that if people only ate better, they would certainly spend far less money on antibiotics and other types of medicines then they do at present.

Speaking of which, as advanced as medicine is, it still hasn’t made us substantially healthier. Especially not in the United States, whose health care system is simultaneously one of the most advanced and one of the worst performing in the developed world. According to the World Health Organization, there are 36 countries in the world with health care systems that perform better than the United States. 

This is scary, especially in view of the fact that the United States spends more than a trillion dollars on health care every single year, ever since the late 1990s. Yet, close to 50 million Americans are uninsured to this day. To make matters even worse, in no country in the developed world do so many people die due to medication errors or adverse effects from drugs or surgery. Believe it or not, the American health care system is the third leading cause of death in the United States, ranking only behind cancer and heart disease. Almost 7% (that is, one out of fifteen) of all hospitalized patients have experienced a serious adverse drug reaction, one that “requires hospitalization, prolongs hospitalization, is permanently disabling or results in death.” 

To sum up, even though the American health care system today, as a percentage of GDP, receives about 300% more in expenditures than it did 40 years ago, the health of the average American has considerably worsened since 1970. Just take diabetes, for example. The rate among those aged between 30 and 39 rose by an astounding 70% during the 1990s, skyrocketing the annual economic diabetes-related costs to $100 billion by 1997! Meanwhile, obesity and cancer increased to such unprecedented proportions that we’ve now almost accepted them as inevitable. The same goes for the most pervasive killer in American culture: heart disease. According to the American Heart Association, heart disease will kill one out of every three Americans. That is, if we allow it to.

The China study

We are, quite literally, what we eat. In other words, if you want to be healthy, you must start taking your eating habits a bit more seriously. Fortunately, the Chinese did it for you about 40 years ago. Partnering with Oxford and Cornell, they decided to conduct a large observational study in rural China, aiming to understand better the correlation between health and diet. Comparing the health consequences of plant-based diets to diets rich in animal-based foods, the study lasted for over two decades and, when it ended, was rightly named “the Grand Prix of epidemiology” by The New York Times. Never before or since, has a more comprehensive and scientific study of food patterns and related health consequences been conducted. 

There are many reasons why the results should be taken seriously. First of all, China is relatively homogenous genetically. In other words, most Chinese share similar genes, so they have pretty much the same chance of getting one disease or another. Therefore, differences in cancer or diabetes rates between different Chinese counties can only be explained by environmental or dietary causes. 

It is these differences that make the story more interesting. As Campbell writes, even “relatively unimportant differences in cancer rates make big news, big money and big politics.” For example, the state of New York spent $30 million and several years analyzing why breast cancer is about 10% more prevalent in one county in Long Island when compared to another. In China, there are some parts of the country where cancer rates are 100 times (that is, 10,000%) higher in comparison to others. Suffice to say, if anything is statistically significant, that must be it.

We know these numbers because of some very smart state strategies. Namely, during the 1970s, Zhou Enlai, China’s first prime minister, initiated a nationwide, monumental survey of death rates for 12 different kinds of cancer for more than 2,400 Chinese counties and more than 880 million (96%) of their citizens. Involving more than 650,000 workers, the survey is considered to this day “the most ambitious research project ever undertaken.” The end result of the survey was “a beautiful, color-coded atlas showing where certain types of cancer were high and where they were almost nonexistent.” The atlas made it clear that cancer incidence varies widely between different counties. In 1980, T. Colin Campbell was one of the Western scientists called upon to make sense of the strange differences. But before we get to his findings – a little history.

Proteins and tumors

The word “protein” comes from the Greek word proteios, which means “of prime importance.” Indeed, ever since it was first discovered in 1839 by Dutch chemist Gerhard Mulder, protein has been considered “the most sacred of all nutrients.” There is some truth in this idea, but it doesn’t tell even half of the story. “Nothing has been so well hidden as the untold story of protein,” Campbell points out. “The dogma surrounding protein censures, reproaches and guides, directly or indirectly, almost every thought we have in biomedical research.”

These reproaches and guides go all the way to the beginning of the story when German physiologist Carl von Voit – considered by many to be the father of modern dietetics – discovered that the amount of nitrogen in excreted urea is a measure for protein turnover. Furthermore, he realized – contrary to the pervading opinion at the time – that 48.5 grams of daily protein intake may just be enough for any human being. Ironically, he suggested people take in 2.5 times that amount – a whopping 118 grams to be more precise – mostly because of the cultural bias that existed at the time. For most of the 19th century, protein was synonymous with meat, and nobody wished to be told to eat less meat until just recently. Moreover, Voit thought, too much of a good thing can’t be a bad thing, can it? Well, now we know it can. 

You see, protein intake seems to be directly correlated with the expansion of different types of cancers, all of which move through three basic stages. In the first phase, the initiation phase, a carcinogen enters a cell and is metabolized by one of the enzymes of your body. The products of this process are mostly safe, but there are some toxic by-products that can damage your DNA. These by-products can kickstart the second phase of cancer growth, the promotion phase. During the promotion phase, tumors grow from tiny clusters of enzyme-created cells called foci. 

The fascinating part is that whether these foci will develop into cancer or not – which is the final, progression phase – doesn’t depend on the presence of carcinogens in your body, but on the presence of proteins. And not just any kind of proteins, but strictly those from animal sources. To rephrase, a cancer-causing agent (such as the chemicals found in hot dogs or bacon, for example) can only make a cell cancerous if it’s helped by particular enzymes, whose production is, in turn, stimulated by a high-protein diet and decreased by a diet devoid of animal-based proteins. That’s the main finding of the China study. It’s also probably one of the most important findings in nutritional history as well.

Lessons from China (and Indian rats)

On their own, carcinogens aren’t that much of an issue: most of them are metabolized just fine by your body. Put otherwise, most of them are virtually helpless in their intent to harm you in the absence of certain enzymes. In people on low-protein diets, these enzymes are either rarely produced or completely absent from their metabolism. After 20 years of surveys and research, the China study discovered that animal-based diets help cancerous cells develop, whereas plant-based diets – even when protein-rich (beans, nuts and soy) – don’t. In a nutshell, there is a big difference between animal-based and plant-based proteins. A life-or-death difference.

Since first made public, the findings of the China study have been further backed by many other experiments. Take, for example, one conducted in India, involving rats. The experiment conclusively proved that rats respond differently to the poisonous carcinogen aflatoxin; furthermore, the experiment demonstrated that the responses were diet-dependent. Namely, rats who were fed with animal proteins were more likely to develop cancers than rats on a low-protein diet, after being exposed to the same amount of aflatoxin. Even more frighteningly, rats eating animal proteins were more likely to develop cancers than those not eating them, even when the latter ones received higher doses of aflatoxin.

Remember the striking differences in cancer rates between different Chinese counties? Well, this was the reason. Inhabitants of counties where diets were customarily low-fat and plant-based lived much healthier and longer lives than residents of regions who had traditionally preferred a high-protein, animal-based diet. Moreover, high-fat diets were found to be directly related to the incidence of breast cancers. So, it’s not enough to be a vegetarian – if you want a long, healthy life, you’re better off without milk and butter as well. To put all of this in the simplest terms possible: if you want to escape, reduce and even reverse the development of numerous diseases, then opt for a predominantly whole-food, exclusively vegan diet. “Eating foods that contain any cholesterol above 0 mg is unhealthy,” conclude Colin and Thomas Campbell.

Final notes

Even though the term “vegan” was coined by English animal rights advocate Donald Watson back in 1944, it was “The China Study” that made it popular in the 21st century. If you know a vegan, whether explicitly or subtly, he has probably been influenced by this very book. 

CNN’s Dr. Sanjay Gupta said it best when he wrote in a 2011 review that Campbell’s findings “changed the way people all over the world eat.” They still do! Meaning, regardless of whether you are a vegan or not, “The China Study” is not a book you would want to overlook. 

If even a small part of what it says is scientifically true – the jury is still out on that – then “The China Study” may change your life. Even save it.

12min tip

“The China Study” turned many ordinary people into vegans and vegetarians. Jonathan Safran Foer’s “Eating Animals” had the same effect among celebrities. If you liked Campbell’s book, make Foer’s the next one on your agenda.