The China Study by Thomas Campbell

286 THE CHINA STUDY

and when there are so many difficult-to-measure and interacting

risk factor exposures. When will it be understood that it is the to-

tal diet and the aggregate and comprehensive effects of large food

groups that make the greatest contribution to the maintenance

of health and prevention of disease? The sort of reductionism

embodied in the interpretation of data from this [Nurses' Health

Study J cohort runs the risk of severely misleading discourse on

meaningful public health and public policy programsY

Then the response from Dr. Hu and Professor Willett:

Although we agree that overall dietary patterns are also important

in determining disease risk (ref. cited), we believe that identifica-

tion of associations with individual nutrients should be the first

step because it is the specific compounds or groups of compounds

that are fundamentally related to the [disease process J. Specific

components of diet can be modified, and individuals and the food

industry are actively doing so. Understanding the health effects of

specific dietary changes, which Campbell refers to as "reduction-

ism," is therefore an important undertaking.^48

I agree that studying the independent effects of individual food
substances (their identities, functions, mechanisms) is worthwhile,
but Willett and I sharply disagree with how to interpret and use these
findings.
I strongly reject the implications in Willett's argument that "specific
components of the diet can be modified" to the benefit of one's health.
This is precisely what is wrong with this area of research. In fact, if the
Nurses' Health Study shows nothing else, it demonstrates that modify-
ing the intake of one nutrient at a time, without questioning whole di-
etary patterns, does not confer significant health benefits. Women who
tinker with fat, while maintaining a near-carnivorous diet, do not have
a lower breast cancer risk.
This gets to the heart of reductionism in science. As long as scientists
study highly isolated chemicals and food components, and take the infor-
mation out of context to make sweeping assumptions about complex diet
and disease relationships, confusion will result. Misleading news head-
lines about this or that food chemical and this or that disease will be the
norm. The more impressive message about the benefits of broad dietary
change will be muted as long as we focus on relatively trivial details.