The China Study is one of the most famous and comprehensive studies of human diets ever undertaken. Proponents of this study often use it to vindicate pro-vegetarian or vegan views. So here is my analysis of the study. It’s a little dry, but hopefully imformative.
The China Study was an epidemiological study, one of the largest of its kind.It was conducted by four professors representing well known institutions and a number of their colleagues. They were Dr. Chen Junshi of the Chiense Academy of Preventive Medicine, Professor T. Colin Campbell of Cornell University, Professor Richard Peto of the University of Oxford, and Dr. Li Junyao of the Chinese Academy of Medical Sciences (http://webarchive.human.cornell.edu/chinaproject/).
The funding came from two American nonprofit organizations, the US National Cancer Institute and the American Institute for Cancer Research, as well as from The Imperial Cancer Research fund of England (http://webarchive.human.cornell.edu/chinaproject/).
Was the study biased? The variety and quality of institutions from which the scholars came should create an appropriate setting for a bias-free study. Also, because there was no profit motive—the only motive being to prevent cancer—the funding should not have contributed to bias in the results.
The China Study took place with the goal of learning about the dietary causes of cancer. The study looked at sixty five randomly chosen counties of China, predominately rural. The differences in climate, lifestyle, urbanization, socioeconomics, etc. among the different counties provided adequate groups to test various controls and variables. County mortality rates and causes of death were surveyed from 1973 to 1975 and from 1986 to 1988. In 1983 and 1989, detailed surveys of biochemistry profiles, diet, and lifestyle were undertaken. Within each location, individuals from 50-60 households were surveyed. Blood and urine sample analyses, three day dietary surveys, lifestyle questionnaires, and county geographic characteristics were noted in the study. Blood samples were pooled among males and females within counties, preventing complete individualization of results, but individual samples were also saved. Household food consumption was measured by subtracting the weight of the food at the end of the three days from the weight at the beginning. Some of this information was resurveyed in 1993 (http://www.ctsu.ox.ac.uk/~china/monograph/).
This methodology was of utility in gathering a wild amount of facts, and I don’t want to diminish the value in this. But in my view there were a couple of problematic elements in the methodology. Generally speaking, the survey is limited in that unlike other surveys of traditional diets, the China Study only surveyed one ethnic group. This precludes any use of the ideas behind biochemical individuality. Not everyone will respond to the same diet in the same way. Also, by reducing all food values to their macro and micro nutrient values, the quality of the food is not accounted for. The idea that macronutrients can be good or bad for us seems silly, if the carbohydrate could be either organic broccoli or pure sugar. Additionally, because of the pooled blood samples, outliers cannot be accounted for and may sway results significantly. Finally, there was no accounting for exposure to toxic chemicals, which in my view should be of primary concern in a cancer study.
Results and Conclusions
Altogether, the China Study yielded an impressive amount of data. It was found that the Chinese consume 30% more total calories, yet have significantly lower rates of obesity. The Chinese had healthier levels of certain beneficial minerals including iron. Plant protein consumption was colerated with lower levels of both total and LDL cholesterol, with positive implications for heart health. Only 10% of protein came from animal foods; the rest came from plant sources. Chinese consumption of fat (14% of total calories) was much lower than American consumption (36%). Calcium intake in China were lower, but so were osteoporosis incidences. Liver cancer was found to be much more common in China, mainly due to hepatitis, and higher cholesterol levels were also correlated with the cancer. Stomach cancer were found to be much more common in China, perhaps because of H. Pylori infections, and plant consumption was negatively correlated with the cancer. High dietary fat intake and elevated estrogen and testosterone levels were correlated with breast cancer. Compared to the US, China was found to have significantly higher consumption of fiber, starches, plant protein, and vitamin C (http://webarchive.human.cornell.edu/chinaproject/).
The data concluded undeniably that the Chinese people were subsisting comparatively very healthfully on a diet comparatively very low in animal protein. The researches thus concluded that Americans would do well to eat less animal protein in their diet. To use a quote, “The major comprehensive dietary factor responsible for disease rates of pre-industrialized societies changing to those of post-industrialized societies is the decision to consume much larger quantities of animal based foods” (http://webarchive.human.cornell.edu/chinaproject/results.html).
To me, that seems like a problematic assertion to focus on. While the researchers also concluded that degenerative diseases concentrated in urban areas, the need to live in a rural environment did not emerge as a recommendation. While animal protein is an important part of the results, it is by no means the sum of all of the results of the study. Numerous lifestyle factors were surveyed, but none of them seem to come through in the results. Clearly, people in rural China were living more active lives. Also, some analysts point out the negative correlation in the study between fat consumption intake and cancer and the fact that in one measure carbohydrates were more closely correlated with cancer than animal protein (http://www.cholesterol-and-health.com/China-Study.html). Campbell seems to ignore these results. Taken together with my methodology criticisms above—namely regarding the lack of variable ethnic groups and the lack of discourse on the quality of the food—the detracting elements of the China Study make it hard to whole heartedly endorse.
What I gather from the China Study is that Americans need to reconsider the way we choose to lead our modernized, urbanized lifestyles and the way we choose to eat so much processed food and to be sedentary. Indeed, many of us will not do well on the meat and fat heavy Western diet, and I don’t mean to say that the diet described in the China Study is not a very healthful one for many people. It certainly is. To me, this study is one more survey of a traditional society thriving on a traditional diet, fitting in suitably with the works of Weston A. Price and others.