The China Study (43 page)

282                         THE CHINA STUDY
their share of positive press these days. If you've heard anything about
omega-3 fatty acids, it's that you need more of them to be healthy. Again,
more Harvard findings :
• " ... contrary to the predominant hypothesis, we found an in-
creased risk of breast cancer associated with omega-3 fat from fish"
(This increased risk was statistically significant and was associated
with an increase of only 0.1% of the total dietary energy.)l0
• "our findings suggest that eating fish once per month or more can
reduce the risk of ischemic stroke in men"34
• "data suggest that consumption of fish at least once per week may
reduce the risk of sudden cardiac death in men [but not reduce
the] risk of total myocardial infarction, non-sudden cardiac death
or total cardiovascular mortality"35 (In other words, fish may pre-
v e n t some aspects of heart disease but ultimately has no effect on
mortality from heart disease, or even heart attack risk.)
Is this yet another question of deciding which disease you fear the
least? Or is this another man versus woman difference?
Here's an even older story: We have been warned for a long time to
cut down on our cholesterol intake, and it was largely for this reason
that consumption of eggs was brought into question. One egg has a
whopping 200 mg or more of cholesterol,36 which takes up a large pro-
p o r t i o n of our 300 mg recommended daily limit. So, what do the Har-
vard studies tell us on this timeworn issue?
... consumption of up to one egg per day is unlikely to have sub-
stantial overall impact on the risk of CHD or stroke among healthy
men and women3?
But, for breast cancer,
Our findings [representing eight prospective studies] suggest a possi-
ble modest increase in [breast cancer] risk with egg consumption....
breast cancer risk was found to increase by 22% with every 100-g
per day increment of egg consumption [about 2 eggsJ26 [There was
a 67% increase in risk for the Nurses' Health 5tudy.J26
But earlier, the Harvard researchers took a slightly different position:
... among healthy men and women, moderate egg consumption
can be part of a nutritious and balanced diet38

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SCIENTIFIC REDUCTIONISM
Most recently, the Nurses' Health Study is cited as having come up
with an even more powerful endorsement for eggs. A recent news item
stated:
Eating eggs during adolescence could protect women against
breast cancer. . . . 39
The article goes on to quote a Harvard researcher as saying:
Women who had, during adolescence, a higher consumption of
eggs ... had a lower risk of breast cancer.... 39
Most people who read this news article will likely say that eggs are
back in favor-even when they don't know how many eggs per day are
okay or whether there are exceptions to this generalization. Eggs will
only seem to be more healthful when the henhouse industry adds their
words of wisdom. But wait a minute-evidence says egg consumption
for teenage girls is okay, maybe even good, but evidence also says more
egg consumption overall increases breast cancer risk. By the way, here's
something else to think about. Multiple studies have rather conSistently
shown that egg consumption can increase colon cancer risk, more so for
women than for men.w
What are we to believe? One minute alcohol intake can reduce our
disease risks, the next minute it can increase them. One minute fish
consumption can help to reduce our disease risks, the next minute it
can hurt. One minute eggs are bad, the next minute they can be healthy.
It seems to me that what is missing here is the larger context. What you
have without that context is just a lot of confusion.
UNRAVELING DIET AND CANCER
In addition to stating that diet and exercise are unrelated to breast can-
cer, the Harvard researchers have been chipping away at other popular
notions regarding diet and cancer. For example, the Harvard studies
have not been able to detect any association between colorectal cancer
and fiber or fruit and vegetable intake. 4 • 4 1, 42
Dietary fiber, of course, only comes from plant-based foods, thus
these findings put a dent in the idea that fiber or fruits , vegetables and
cereals prevent large bowel cancer. Keep in mind that the Harvard stud-
ies are dealing with uniformly carnivorous populations, almost none
of which are using a whole foods, plant-based diet that is naturally low
,.   in fat and high in fiber. It is likely that the potential protective effect of

284                            THE CHINA STUDY
fiber or fruits and vegetables does not kick in against colorectal cancer
until there is a complete dietary shift away from an animal-based diet.
Between the colon cancer and breast cancer findings, the Nurses'
Health Study has done much to confuse, if not discredit, the idea that
diet is related to cancer. After these decades of work, Professor Walt
Willett says:
... increasing fruits and vegetables overall appears to be less prom-
ising as a way to substantially reduce cancer risk. ... the benefits
[of these foods] appear greater for cardiovascular disease than for
cancer4
This statement sounds a bit ominous. Colon cancer, historically one
of the first cancers said to be prevented by a plant-based diet,43-45 now is
being said to be unrelated to diet? And low-fat diets don't prevent breast
cancer? With results like these, it's only a matter of time before the hy-
p o t h e s i s of a dietary connection to cancer starts falling apart. In fact, I
have already heard people within the scientific community beginning to
say that diet may have no effect on cancer.
These are the reasons that I believe that the Nurses' Health Study has
done considerable damage to the nutrition landscape. It has virtually
nullified many of the advances that have been made over the past fifty
years without actually posing a scientifically reliable challenge to earlier
findings regarding diet and cancer.
This problem of studying a population that uniformly consumes a
high-risk diet and looking at the differences in consumption of one nu-
t r i e n t at a time is not unique to the Nurses' Health Study. It is common
to virtually all studies using Western subjects. Furthermore, there is
little or no value to pooling the results of many large studies for analysis
in order to get a more reliable result if all the studies have the same flaw.
A pooling strategy is often used for identifying cause-and-effect associa-
tions that are more subtle and uncertain within single studies. This is a
reliable assumption when each study is properly done, but obviously it
is not when all the studies are similarly flawed. The combined results
only give a more reliable picture of the flaw.
The Harvard researchers have done several of these multi-study
pooled analyses. One such pooled analysis concerned the question of
whether meat and dairy foods had any effect on breast cancer.26 A previ-
o u s 1993 pooling of nineteen studies46 had shown a modest, statistically
significant 18% increase in breast cancer risk with increased meat intake

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SCIENTIFIC REDUCTIONISM
and 17% increase with increased milk intake. 46 The Harvard researchers
therefore summarized in 2002 a more recent group of studies, this time
including eight large prospective studies where dietary information was
thought to be more reliable and where a much larger group of women
was included. The researchers concluded:
We found no significant association between intake of meat or
dairy products and risk of breast cancer.26
Most people would say, "Well, that's it. There is no convincing evi-
dence that meat and dairy foods are associated with breast cancer risk."
But let's take another look at this supposedly more sophisticated analy-
sis .
All eight of these studies represented diets that had a high proportion
of animal-based foods. In effect, each study in this pool was subject to
the same flaw from which the Nurses' Health Study suffered. It makes
no sense, and does no good, to combine them. In spite of there being
351,041 women and 7,379 breast cancer cases in this mega-database,
these results cannot detect the true effect of diets rich in meat and dairy
on breast cancer risk. This would be true even if there were a few mil-
l i o n subjects in the study. Like the Nurses' Health Study, these studies
all involved typical Western diets highly skewed toward the consump-
t i o n of animal-based foods, where people are tinkering with the intake
of only one nutrient or one food at a time. Every study failed to take
into account a broader range of dietary choiceS-including those which
demonstrated positive effects on breast cancer risk in the past.
IGNORING MY CRITIQUE
Once, after reading a publication on animal protein and heart disease
in the Nurses' Health Study,9 I published a critique47 summarizing some
of the same points that I am making in this chapter, including the in-
ability of the Nurses' Health Study to advance our understanding of
the original international correlation studies. They responded, and our
exchange is as follows.
First, my comment:
Within a dietary range [so rich in animal-based foods 1, it makes no
sense to me that it is possible to reliably detect the so-called inde-
p e n d e n t associations of the individual constituents of this group
when it can be expected that they share the same disease outcomes

THE CHINA STUDY
286
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-
t i o n 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-
i n g 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.

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SCIENTIFIC REDUCTIONISM
On occasions, when our paths have crossed, Professor Willett and
I have had discussions about the findings on fat as they relate to the
China Study and the Nurses' Health Study. I have always made the same
point: whole foods , plant-based diets, naturally low in fat, are not in-
c l u d e d in the Nurses' Health Study cohort, and that it is these types of
diets that are the most beneficial for our health. Professor Willett has
said to me, in response, on more than one occasion, "You may be right,
Colin, but people don't want to go there." This comment has disturbing
implica tions.
Scientists should not be ignoring ideas just because we perceive that
the public does not want to hear them. Too often during my career, I
have heard comments that seem to be more of an attempt to please the
public than to engage in an open, honest debate, wherever it may take
us. This is wrong. The role of science in a society is to observe, to ask
questions, to form and test hypotheses and to interpret the findings
without bias-not to kowtow to people's perceived desires. Consumers
have the ultimate choice of whether to integrate our findings into their
lifestyles, but we owe it to them to give them the best information pos-
sible with which to make that decision and not decide for them. It is
they who paid for this research and it is only they who have the right to
decide what to do with it.
The perception in the scientific community that the public only
wants magic bullets and simple dietary tinkering is overrated. I have
learned in my public lectures that there is more interest in dietllifestyle
change than the academic community is willing to admit.
This method of investigating details out of context, what I call reduction-
ism, and trying to judge complex relationships from the results is deadly.
It is even more damaging than the misbehavior of the small minority
of scientists I discussed in chapter thirteen. Unfortunately, this flawed
way of investigating nutrition has become the norm. As a consequence,
honest, hardworking, well-intentioned scientists around the world are
forced to make judgments about whole dietary effects on the basis of
narrowly focused studies on individual nutrients. The greatest danger is
that reductionism science, standing naked from its larger environment,
has come to be the gold standard. Indeed, I know many researchers who
would even say that this is what defines "good" science.
These problems are especially egregious in the investigation of vi-
t a m i n supplements. As I noted at the beginning of the chapter, I spent
over three years during the early history of the nutrient supplement