The China Study - T. Colin Campbell and Thomas M. Campbell

Lessons from China

A SNAPSHOT IN TIME
Have you ever had the sensation of wanting to permanently capture a moment? Such moments can grip you in a way you will never forget. For some people, those moments center on family, close friends or re- lated activities; for others those moments may center on nature, spiri- tuality or religion. For most of us, I suspect, it can be a little of each. They become the personal moments, both happy and sad, which define our memories. It's these moments in which everything just "comes together." They are the snapshots of time that define much of our life experience.
The value of a snapshot of time is not lost on researchers either. We construct experiments, hoping to preserve and analyze the specific de- tails of a certain moment for years to come. I was fortunate enough to be privy to such an opportunity in the early 1980s, after a distinguished se- nior scientist from China, Dr. Junshi Chen, came to Cornell to work in my lab. He was deputy director of China's premier health research labo- ratory and one of the first handful of Chinese scholars to visit the u.S. following the establishment of relations between our two countries.
THE CANCER ATLAS
In the early 1970s, the premier of China, Chou EnLai, was dying of cancer. In the grips of this terminal disease, Premier Chou initiated a nationwide survey to collect information about a disease that was not well understood. It was to be a monumental survey of death rates for twelve different kinds of cancer for more than 2,400 Chinese counties and 880 million (96%) of their citizens. The survey was remarkable in many ways. It involved 650,000 workers, the most ambitious biomedi- cal 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.1

This atlas made it clear that in China cancer was geographically lo- calized. Some cancers were much more common in some places than in others. Earlier studies had set the stage for this idea, showing that cancer incidence also varies widely between different countries.2-4 But these China data were more remarkable because the geographic varia- tions in cancer rates were much greater (Chart 4.2). They also occurred in a country where 87% of the population is the same ethnic group, the Han people.

Why was there such a massive variation in cancer rates among dif- ferent counties when genetic backgrounds were similar from place to place? Might it be possible that cancer is largely due to environmentalJ lifestyle factors, and not genetics? A few prominent scientists had al- ready reached that conclusion. The authors of a major review on diet and cancer, prepared for the u.s. Congress in 1981, estimated that ge- netics only determines about 2-3% oj the total cancer risk.4
The data behind the China cancer atlas were profound. The coun- ties with the highest rates of some cancers were more than 100 times greater than counties with the lowest rates of these cancers. These are truly remarkable figures. By way of comparison, we in the U.S. see, at most, two to three times the cancer rates from one part of the country to another.
In fact, very small and relatively unimportant differences in cancer rates make big news, big money and big politics. There has been a long- standing story in my state of New York about the increased rates of breast cancer in Long Island. Large amounts of money (about $30 mil- lion5) and years and years of work have been spent examining the issue. What sorts of rates were causing such a furor? Two counties in Long Is- land had rates of breast cancer only 10-20% higher than the state aver- age. This difference was enough to make front-page news, scare people and move politicians to action. Contrast this with the findings in China where some parts of the country had cancer rates 100 times (10,000%) higher than others.
Because China is relatively homogenous genetically, it was clear that these differences had to be explained by environmental causes. This raised a number of critical questions:
• Why was cancer so high in some rural Chinese counties and not in others?
• Why were these differences so incredibly large?
• Why was overall cancer, in the aggregate, less common in China
than in the U.5.?
The more Dr. Chen and I talked, the more we wished that we had a snapshot in time of the dietary and environmental conditions in ru- ral China. If only we could look into these people's lives, note what they eat, how they live, what is in their blood and their urine and how they die. If only we could construct a picture of their experience with unprecedented clarity and detail so that we could study it for years to come. If we could do that, we might be able to offer some answers to our "why" questions.
Occasionally science, politics and financing come together in a way that allows a truly extraordinary study to take place. This happened for us, and we got the opportunity to do everything we wanted, and more. We were able to create the most comprehensive snapshot of diet, life- style and disease ever taken.
PULLING IT TOGETHER
We assembled a world-class scientific team. There was Dr. Chen, who was the deputy director of the most significant government diet and health research laboratory in all of China. We enlisted Dr. Junyao Li, one of the authors of the Cancer Atlas Survey and a key scientist in Chi- na's Academy of Medical Sciences in the Ministry of Health. The third member was Richard Peto of Oxford University. Considered one of the premier epidemiologists in the world, Peto has since been knighted and has received several awards for cancer research. I rounded out the team as the Project Director.
Everything was coming together. It was to be the first major research project between China and the United States. We cleared the necessary funding hurdles, weathering both CIA intrusiveness and Chinese gov- ernment reticence. We were on our way.
We decided to make the study as comprehensive as possible. From the Cancer Atlas, we had access to disease mortality rates on more than four dozen different kinds of disease, including individual cancers, heart diseases and infectious diseases.6 We gathered data on 367 vari- ables and then compared each variable with every other variable. We went into sixty-five counties across China and administered question- naires and blood tests on 6,500 adults. We took urine samples, directly measured everything families ate over a three-day period and analyzed food samples from marketplaces around the country.
The sixty-five counties selected for the study were located in rural to semi-rural parts of China. This was intentionally done because we wanted to study people who mostly lived and ate food in the same area for most of their lives. This was a successful strategy, as we were to learn than an average of 90-94% of the adult subjects in each county still lived in the same county where they were born.
When we were done we had more than 8,000 statistically significant associations between lifestyle, diet and disease variables. We had a study that was unmatched in terms of comprehensiveness, quality and uniqueness. We had what the New York Times termed "the Grand Prix of epidemiology." In short, we had created that revealing snapshot of time that we had Originally envisioned.
This was the perfect opportunity to test the principles that we dis- covered in the animal experiments. Were the findings in the lab going to be consistent with the human experience in the real world? Were our discoveries on aflatoxin-induced liver cancer in rats going to apply to other types of cancer and other types of diseases in humans?
FOR MORE INFORMATION
We take great pride in the comprehensiveness and quality of the China Study. To see why, read Appendix B on page 353. You'll find a more complete discussion of the basic design and characteristics of the study.
visioned.
This was the perfect opportunity to test the principles that we dis- covered in the animal experiments. Were the findings in the lab going to be consistent with the human experience in the real world? Were our discoveries on aflatoxin-induced liver cancer in rats going to apply to other types of cancer and other types of diseases in humans?
FOR MORE INFORMATION
We take great pride in the comprehensiveness and quality of the China Study. To see why, read Appendix B on page 353. You'll find a more complete discussion of the basic design and characteristics of the study.
THE CHINESE DIETARY EXPERIENCE
Critical to the importance of the China Study was the nature of the diet consumed in rural China. It was a rare opportunity to study health-re- lated effects of a mostly plant-based diet.
In America, 15-16% of our total calories comes from protein and upwards of 80% of this amount comes from animal-based foods. But in rural China only 9-10% of total calories comes from protein and only 10% of the protein comes from animal-based foods. This means that there are major nutritional differences in the Chinese and American diets, as shown in Chart 4.3.