The China Study (53 page)

349
REPEATING HISTORIES
gen products to bind to DNA, which allow more mutagenic reactions
that give rise to cancer cells, which allow more rapid growth of tumors
once they are initially formed. Data show that a diet based on animal-
based foods increases a female's production of reproductive hormones
over her lifetime, which may lead to breast cancer. We now have a deep
and broad range of evidence showing that a whole foods , plant-based diet is
best for cancer.
Never before have we had technology to measure the biomarkers
associated with diabetes, and the evidence to show that blood sugar,
blood cholesterol and insulin levels improve more with a whole foods,
plant-based diet than with any other treatment. Intervention studies
show that Type 2 diabetics treated with a whole foods, plant-based diet
may reverse their disease and go off their medications. A broad range of
international studies shows that Type 1 diabetes, a serious autoimmune
disease, is related to cow's milk consumption and premature weaning.
We now know how our autoimmune system can attack our own bod-
ies through a process of molecular mimicry induced by animal proteins
that find their way into our bloodstream. We also have tantalizing
evidence linking multiple sclerosis with animal food consumption, and
especially dairy consumption. Dietary intervention studies have shown
that diet can help slow, and perhaps even halt, multiple sclerosis. We
now have a deep and broad range of evidence showing that a whole foods,
plant-based diet is best for diabetes and autoimmune diseases.
Never before have we had such a broad range of evidence showing that
diets containing excess animal protein can destroy our kidneys. Kidney
stones arise because the consumption of animal protein creates excessive
calcium and oxalate in the kidney. We know now that cataracts and age-
related macular degeneration can be prevented by foods containing large
amounts of antioxidants. In addition, research has shown that cognitive
dysfunction, vascular dementia caused by small strokes and Alzheimer's
are all related to the food we eat. Investigations of human populations
show that our risk of hip fracture and osteoporosis is made worse by di-
ets high in animal-based foods. Animal protein leeches calcium from the
bones by creating an acidic environment in the blood. We now have a deep
and broad range of evidence showing that a whole foods, plant-based diet is
best for our kidneys, bones, eyes and brains.
More research can and should be done, but the idea that whole foods ,
plant-based diets can protect against and even treat a wide variety of
chronic diseases can no longer be denied. No longer are there just a few
people making claims about a plant-based diet based on their personal

350                          THE CHINA STUDY
experience, philosophy or the occasional supporting scientific study.
Now there are hundreds of detailed, comprehensive, well-done research
studies that point in the same direction.
Furthermore, 1 have hope for the future because of our new abil-
ity to exchange information across the country and around the world.
A much greater proportion of the world population is literate, and a
much greater proportion of that population has the luxury of choosing
what they eat from a wide variety of readily accessible foods . People can
make a whole foods, plant-based diet varied, interesting, tasty and con-
venient. 1 have hope because people in small towns and in previously
isolated parts of the country can now readily access cutting edge health
information and put it into practice.
All of these things together create an atmosphere unlike any other,
an atmosphere that demands change. Contrary to the situation in 1982,
when a few colleagues tried to destroy the reputations of scientists who
suggested that diet had anything to do with cancer, it is now more com-
monly accepted that what you eat can determine your risk of multiple
cancers. 1 have also seen the public image of vegetarianism emerge from
being considered a dangerous, passing fad to a healthful, endUring life-
style choice. The popularity of plant-based diets has been increasing,
and both the variety and availability of convenient vegetarian foods have
been skyrocketing. 14 Restaurants around the country now regularly offer
meat-free and dairy-free options. 15 Scientists are publishing more articles
about vegetarianism and writing more about the health potential of a
plant-based diet. 16 Now, over 150 years after my great-great uncle George
Macilwain wrote books about diet and disease, 1 am writing a book about
diet and disease with the help of my youngest son Tom. Tom's middle
name is McIlwain (the family changed the spelling over the past couple
of generations), which means that not only am 1 writing about many of
the same ideas Macilwain wrote about, but a relative bearing his name is
the co-author. History can repeat itself. This time, however, instead of the
message being forgotten and confined to library stacks, 1 believe that the
world is finally ready to accept it. More than that, 1 believe the world is
finally ready to change. We have reached a point in our history where our
bad habits can no longer be tolerated. We, as a society, are on the edge of
a great precipice: we can fall to sickness, poverty and degradation, or we
can embrace health, longevity and bounty. And all it takes is the courage
to change. How will our grandchildren find themselves in 100 years?
Only time will tell, but I hope that the history we are witnessing and the
future that lies ahead will be to the benefit of us all.

_A~~. ENDIX A
__
Q&A: Protein Effect in
Experimental Rat Studies
COULD THE DIETARY PROTEIN EFFECT
BE DUE TO OTHER NUTRIENTS IN THE RAT DIET?
Decreasing dietary protein from 20% to 5% means finding something to
replace the missing 15%. We used a carbohydrate to replace the casein
because it had the same energy content. As dietary protein decreased,
a 1: 1 mixture of starch and glucose increased by the same amount.
The extra starch and glucose in the low-protein diets could not have
been responsible for the lower development of foci because these car-
bohydrates, when tested alone, actually increase foci development.! If
anything, a little extra carbohydrate in the low-protein diet would only
increase cancer incidence and offset the low-protein effect. This makes
prevention of cancer by low-protein diets even more impressive.
MIGHT THE PROTEIN EFFECT BE DUE
TO THE RATS ON A LOW-PROTEIN DIET
EATING LESS FOOD (I.E., LESS CALORIES)?
Many studies done in the 1930s, 1940s and 1950s2 had shown that
decreasing total food intake, or total calories, decreased tumor devel-
o p m e n t . A review of our many experiments, however, showed that
animals fed the low-protein diets did not consume less calories but, on
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352                          THE CHINA STUDY
average, actually consumed more calories. 3, 4 Again, this only reinforced
the tumor-promoting effect observed for casein.
WHAT WAS THE OVERALL HEALTH OF THE RATS
ON A LOW-PROTEIN DIET?
Many researchers have long assumed that animals fed diets this low in
protein would not be healthy. However, the low-protein animals were
healthier by every indication. They lived longer, were more physically
active, were slimmer and had healthy hair coats at 100 weeks while the
high-protein counterpart rats were all dead. Also, animals consuming
less dietary casein not only ate more calories, but they also burned off
more calories. Low-protein animals consumed more oxygen, which is
required for the burning of these calories, and had higher levels of a spe-
cial tissue called brown adipose tissue,5,6 which is especially effective in
burning off calories. This occurs through a process of "thermogenesis,"
i.e., the expenditure of calories as body heat. This phenomenon had
already been demonstrated many years before. 7- 11 Low-protein diets en-
hance the burning off of calories, thus leaving less calories for body weight
gain and perhaps also less for tumor growth as well.
WAS PHYSICAL ACTIVITY RELATED TO THE
CONSUMPTION OF THE LOW-PROTEIN DIET?
To measure the physical activity of each group of rats, we compared
how much they voluntarily operated an exercise wheel attached to their
cages. A monitor recorded the number of times the animals turned
the exercise wheel. The low-casein animals 12 exercised about twice as
much, when measured over a two-week period! This observation seems
to be very similar to how one feels after eating a high-protein meal: slug-
gish and sleepy. I have heard that a side effect of the protein-drenched
Atkins Diet is fatigue. Have you ever noticed this feeling in yourself
after a high-protein meal?

_______ A~~. E N DIX __ B_______ _
Experimental
Design of the China Study
SIXTY-FIVE COUNTIES in twenty-four different provinces (out of twenty-
seven) were selected for the survey. They represented the full range
of mortality rates for seven of the more common cancers. They also
provided broad geographic coverage and were within four hours' travel
time of a central laboratory. The survey counties represented:
semitropical coastal areas of southeast China;
•
•   frigid wintry areas in northeast China, near Siberia;
•   areas near the Great Gobi desert and the northern steppes;
•   and areas near or in the Himalaya Mountains ranging from the far
northwest to the far southwest part of the country.
Except for suburban areas near Shanghai, most counties were located
in rural China where people lived in the same place their entire lives
and consumed locally produced food. Population densities varied wide-
ly, from 20,000 nomadic residents for the most remote county near the
Great Gobi desert, to 1.3 million people for the county on the outskirts
of Shanghai.
This survey is referred to as an ecological or correlation study design,
meaning that we are comparing diet, lifestyle and disease characteristics
of a number of sample populations, in this case the sixy-five counties.
We determine how these characteristics, as county averages, correlate
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354                         THE CHINA STUDY
or associate with each other. For example, how does dietary fat relate to
breast cancer rates? Or how does blood cholesterol relate to coronary
heart disease? How does a certain kind of fatty acid in red blood cells
relate to rice consumption? We could also compare blood testosterone
levels or estrogen levels with breast cancer risk. We did thousands of
different comparisons of this type.
In a study of this kind, it is important to note that only the average
values for county populations are being compared. Individuals are not
being compared with individuals (in reality, neither does any other epi-
demiological study design). As ecological studies go, this study, with its
sixy-five counties, was unusually large. Most such studies only have ten
to twenty such population units, at most.
Each of the Sixty-five counties provided 100 adults for the survey.
One-half were male and one-half female, all aged thirty-five to sixty-
four years. The data were collected in the following manner:
• each person volunteered a blood sample and completed a diet and
lifestyle questionnaire;
• one-half of the people provided a urine sample;
• the survey teams went to 30% of the homes to carefully measure
food consumed by the family over a three-day period;
• samples of food representing the typical diets at each survey site
were collected at the local marketplace and were later analyzed for
dietary and nutritional factors.
One of the more important questions during the early planning
stages was how to survey for diet and nutrition information. Estimating
consumption of food and nutrients from memory is a common method,
but this is very imprecise, especially when mixed dishes are consumed.
Can you remember what foods you ate last week, or even yesterday?
Can you remember how much? Another even more crude method of
estimating food intake is to see how much of each food is sold in the
marketplace. These findings can give reasonable estimates of diet trends
over time for whole populations, but they do not account for food waste
or measure individual amounts of consumption.
Although each of these relatively crude methods can be useful for
certain purposes, they still are subject to considerable technical error
and personal bias. And the bigger the technical error, the more difficult
it is to detect significant cause-effect associations.
We wanted to do better than crudely measure which foods and how

EXPERIMENTAL DESIGN OF THE CHINA STUDY                  355
much of these foods were being consumed. Thus we decided to evaluate
nutritional conditions by analyzing blood and urine samples for indica-
tors (biomarkers) of multiple nutrient intakes. These analyses would be
far more objective than haVing people recall what they ate.
Collecting and analyzing blood, however, was not easy to arrange, at
least not in the way that we preferred. The initial problem was getting
enough blood. For cultural reasons, rural Chinese were reluctant to pro-
vide blood samples. A finger prick seemed to be the only possibility but
this was not good enough. A regular vial of blood would give 100 times
as much blood and allow for analyses of many more factors.
Dr. Junshi Chen of our team, at the Institute of Nutrition and Food
Hygiene in the Ministry of Health, had the unenviable task of convinc-
i n g these volunteers to give a regular vial of blood. He succeeded. Sir
Richard Peto at the University of Oxford of our team then made the very
practical suggestion of combining the individual blood samples to make
a big pool of blood for each village for each sex. This strategy gave more
than 1,200-1,300 times more blood when compared with the finger
prick method.
Making big pools of blood had enormous implications and made
possible the China Study, as it later became known. It allowed analyses
of far more indicators of diet and health. This allowed us to consider
relationships in a far more comprehensive manner than would have
otherwise been possible. For more detail on the theoretical and practical
basis for collecting and analyzing blood in this way the reader is referred
to the original monograph of the study.l
After collecting the blood, we then had to decide who would do the
many analyses that were pOSSible. We wanted nothing but the best.
While some analyses were conducted at our Cornell lab and at Dr.
Chen's Beijing lab, the rest of the analyses, especially the more special-
ized types, were done in about two dozen laboratories located in six
countries and in four continents. Laboratories were selected because of
their demonstrated expertise and interest. The laboratory participants
are listed in the original monograph. l
HOW GOOD IS THIS STUDY?
Because this survey was a one-of-a-kind opportunity, we intended that
it be the best of its kind ever undertaken. It was comprehensive; it was
high quality; and its uniqueness allowed new opportunities to inves-
tigate diet and disease that were never before possible. These features