What 65 Counties Can — and Can't — Tell Us
One of the largest snapshots of diet and disease ever taken. A brilliant curiosity engine, and a perfect lesson in what observational research can and cannot say.
Across counties, do diet and cholesterol patterns travel with disease patterns?
- Each dot = a county average
- The tilt = an association researchers noticed
- County averages are not individual proof
- County-level diet patterns may travel with county-level disease patterns.
- That can generate hypotheses worth testing.
- It cannot prove diet caused disease.
- It cannot explain one individual person's outcome.
- Other county-level factors may be involved.
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What it was
In the 1980s, the China–Cornell–Oxford Project surveyed diet, lifestyle, and mortality across roughly 65 rural Chinese counties — a collaboration of Cornell University, the University of Oxford, and the Chinese Academy of Preventive Medicine. It took advantage of unusually wide regional variation, from largely plant-based eating to more animal-food-inclusive patterns, in fairly stable rural populations.
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What showed up
Across regions, more plant-dominant dietary patterns were associated with lower rates of some chronic 'Western' diseases, while higher animal-food intake and higher blood cholesterol tracked with higher rates of some of those diseases. These are population-level associations — patterns across counties, not effects measured within individuals.
What it suggests — and what it doesn't
What it suggests
- When diet patterns vary dramatically across regions, disease patterns vary too — a rich source of hypotheses worth testing more rigorously.
What it does not prove
- Because it is ecological and correlational, it cannot prove diet causes the disease patterns. County-level correlations are vulnerable to confounders (such as hepatitis B or other regional infections) and to the ecological fallacy of reading individual cause from group data.
- The popular 2005 book that drew on this work has been criticized by scientists for causal, diet-prescriptive conclusions that the underlying observational data do not support.
Treat the project as a map of interesting questions, not a verdict. Big associations are where good science starts, not where it ends.
Sources & citations (3)Tap to open
- Diet, Lifestyle, and Mortality in China: A Study of the Characteristics of 65 Chinese CountiesFoundational monograph of the China–Cornell–Oxford Project. Linking to the publisher; bibliographic details corroborated via encyclopedic sources.
- Diet, lifestyle, and the etiology of coronary artery disease: the Cornell China Study
- The China Study Revisited (critical analysis of causal claims)Included for balance: scientists have criticized the popular book's stronger causal claims.
We summarize these sources in our own words and link to the originals. Summaries can simplify nuanced findings — follow the links for the full picture.