The China Study (54 page)

THE CHINA STUDY
356
of comprehensiveness, quality and uniqueness greatly improved the
credibility and reliability of the findings-by far. Indeed, the New York
Times, in a lead story in its Science Section, called the study "The Grand
Prix" of epidemiological studies.
COMPREHENSIVENESS OF DATA
This survey was, and still is, the most comprehensive of its kind ever
undertaken. After all the blood, urine and food samples were collected,
stored and analyzed, and after the final results were tabulated and evalu-
ated for quality (a few suspect results were not included in the final
publication), we were able to study 367 variables. These represented
a wide variety of dietary, lifestyle and disease characteristics, now in-
c l u d e d in a dense 896-page monograph. l There were:
• disease mortality rates on more than forty-eight different kinds of
disease 2 ;
• 109 nutritional, viral, hormonal and other indicators in blood;
• over twenty-four urinary factors ;
• almost thirty-six food constituents (nutrients, pesticides , heavy
metals) ;
• more than thirty-six specific nutrient and food intakes measured in
the household survey;
• sixty diet and lifestyle factors obtained from questionnaires;
• and seventeen geographic and climatic factors .
The study was comprehensive, not only because of the sheer number
of variables, but also because most of these variables varied over broad
ranges, as with the cancer mortality rates. Broad ranges strengthened
our ability to detect important preViously undiscovered associations of
variables.
QUALITY OF DATA
A number of features added quality to this study.
• The adults chosen for this survey were limited to those who were
thirty-five to sixty-four years of age. This is the age range in which
the diseases being investigated are more common. Information on
death certificates of people older than sixty-four years was not in-
c l u d e d in the survey because this information was considered less
reliable.

357
EXPERIMENTAL DESIGN OF THE CHINA STUDY
• In each of the sixty-five counties in the study, two villages were
selected for the collection of the information. Having two villages
in each county rather than one gives a more reliable county av-
erage . When the values of two villages are more similar to each
other than to all the other counties, then this means higher-quality
data. 3
• When possible, variables were measured by more than one kind
of method. For example, iron status was measured in six different
ways, riboflavin (vitamin B2 ) in three ways, and so forth . Also , in
many cases, we could assess the quality and reliability of data by
comparing variables known to have plausible biological relation-
ships.
• The populations under study proved to be very stable. An average
of 93-94% of the men in the survey were born in the county where
they lived at the time of the survey; for women it was 89%. Also,
according to data published by the World Bank,4 the diets at the
time of our survey were very similar to those consumed in earlier
years. This was ideal because those earlier years represented the
time when the diseases were initially forming.
UNIQUENESS OF DATA
One idea that makes our study unique is our use of the ecologic study
design. Critics of the ecologic study design correctly assume that it is a
weak design for determining cause-and-effect associations when one is
interested in the effects of Single causes acting on Single outcomes. But
this is not the way that nutrition works. Rather, nutrition causes or pre-
vents disease by multiple nutrients and other chemicals acting together,
as in foods . An ecologic study is almost ideal if we wish to learn how
an array of dietary factors act together to cause disease. It is the com-
prehenSive effects of nutrients and other factors on disease occurrence
where the most important lessons are to be learned. To investigate these
comprehensive causes of disease, it was therefore necessary to record
as many dietary and other lifestyle factors as pOSSible, then formulate
hypotheses and interpret data that represent comprehenSiveness.
Perhaps the most unique characteristic that set this study apart con-
c e r n e d the nutritional characteristics of the diets consumed in rural
China. Virtually every other human study on diet and health, of what-
ever deSign, has involved subjects who were consuming a rich Western

358                              THE CHINA STUDY
diet. This is true even when vegetarians are included in the study be-
cause 90% of vegetarians still consume rather large amounts of milk,
cheese and eggs, while a significant number still consume some fish
and poultry. As is shown in the accompanying chart (Chart B.1),5 there
is only a small difference in the nutritional properties of non-vegetarian
and vegetarian diets as consumed in Western countries.
CHART B.l: VEGETARIAN AND NON-VEGETARIAN DIET
COMPARISONS AMONG WESTERNERS
Nutrient                Vegetarian      Non-vegetarian
30-36             34-38
Fat (% of calories)
150-300           300-500
Cholesterol (g/day)
50-55              <50
Carbohydrates (% of calories)
12-14             14-18
Total protein (% of calories)
40-60             60-70
Animal protein (% of total protein)
A strikingly different dietary situation existed in China. In America,
15-17% of our total calories is provided by protein, and upwards of 80%
of this amount is animal-based. In other words, we gorge on protein and
we get most of it from meat and dairy products. But in rural China, they
consume less protein overall (9-10% of total calories), and only 10%
of it comes from animal-based foods. This means that there are many
other major nutritional differences in the Chinese and American diets,
as shown in Chart B.2.l
CHART B.2: CHINESE AND AMERICAN DIETARY INTAKES
Nutrient                   China      United States
40.6           30.6
Calories (kcal/kg body wt./day)
14.5          34-38
Total fat (% of calories)
33             12
Dietary fiber (g/day)
64             91
Total protein (g/day)
0.8*          10-11
Animal protein (% of total calories)
34             18
Total iron (mg/day)
"Non·fish animal protein

359
EXPERIMENTAL DESIGN OF THE (HINA STUDY
This was the first and only large study that investigated this range of
dietary experience and its health consequences. Chinese diets ranged
from rich to very rich in plant-based foods. In all other studies done on
Western subjects, diets ranged from rich to very rich in animal-based
foods. It was this distinction that made the China Study so different
from other studies.
MAKING IT HAPPEN
Organization and conduct of a study of this size, scope and quality was
possible because of the exceptional skills of Dr. Junshi Chen. Survey
sites were scattered across the far reaches of China. In American travel
distances, they ranged from the Florida Keys to Seattle, Washington,
and from San Diego, California, to Bangor, Maine. Travel between these
places was more difficult than in the United States, and supplies and
instructions for the survey had to be in place and standardized for all
collection sites. And this was done before e-mails, fax machines and cel-
lular phones were available.
It was important that the twenty-four provincial health teams, each
comprised of twelve to fifteen health workers, be trained to carry out
the blood, food and urine collections and complete the questionnaires
in a systematic and standardized manner. To standardize the collection
of information, Dr. Chen divided the country into regions. Each region
sent trainers to Beijing for the senior training session. They, in tum, re-
t u r n e d to their home provinces to train the provincial health teams.
Although the U.s. National Cancer Institute (NCI) of the National
Institutes of Health (NIH) provided the initial funding for this project,
the Chinese Ministry of Health paid the salaries of the approximately
350 health workers. It is my estimate that the Chinese contribution to
the project was approximately $5-6 million. This compares with the
U.s. contribution of about $2.9 million over a ten-year period. Were
the U.S. government to have paid for this service in a similar project in
the U.S., it would have cost at least ten times this amount, or $50-60
million.

__ ~ ~. END IX __C__
__ A                _
The "Vitamin" DConnection
THE MOST IMPRESSIVE EVIDENCE favoring plant-based diets is the way that
so many food factors and biological events are integrated to maximize
health and minimize disease. Although the biological processes are ex-
ceptionally complex, these factors still work together as a beautifully
choreographed, self-correcting network. It is exceptionally impressive,
especially the coordination and control of this network.
Perhaps a couple of analogies might help to illustrate such a process.
Flocks of birds in flight or schools of fish darting about are able to shift
direction in a microsecond without bumping into each other. They
seem to have a collective consciousness that knows where they are go-
i n g and when they will rest. Colonies of ants and swarms of bees also
integrate varying labor chores with great proficiency: But as amazing
as these animal activities are, have you ever thought about how their
behaviors are coordinated with such finesse? I see these same charac-
teristics, and more, in the way that the countless factors of plant-based
foods work their magic to create health at all levels within our body,
among our organs and between our cells and among the enzymes and
other sub-cellular particles within our cells.
For those unfamiliar with biomedical research laboratories, the walls
of these labs are often covered with large posters showing thousands of
biochemical reactions operating within our bodies. These are reactions
that are known; far more remain to be discovered. The interdependence
of these reactions with each other is especially informative, even awe-
s o m e in its implications.
361

362                          THE CHINA STUDY
An example of a very small portion of this enormous network of re-
actions is the effect of vitamin D and its metabolites on several of the
diseases discussed in this book. This particular network illustrates a com-
plex interconnection between the inner workings of our cells, the food we
eat and the environment in which we live (Chart Cl). Although some of
the vitamin D present in our bodies may come from food, we can usually
get all that we need from a few hours of sunshine each week. In fact, it
is our ability to make our vitamin D that leads to the idea that it is not a
vitamin; it is a hormone (i.e., made in one part of our body but function-
ing in another part). The sun's UV rays make vitamin D from a precursor
chemical located in our skin. Provided we get adequate sunshine, this is
all the vitamin D we need. I We can, of course, also get vitamin D from
fortified milk, certain fish oils and some vitamin supplements.
The vitamin D made in our skin then travels to our liver, where it is
converted by an enzyme to a vitamin D metabolite. This metabolite's
main function is to serve as the body's storage form of vitamin D (while
remaining mostly in the liver but also in body fat).
The next step is the crucial one. When needed, some of the stor-
age form of vitamin D in the liver is transported to the kidney, where
another enzyme converts it into a supercharged vitamin D metabolite,
which is called 1,25 D. The rate at which the storage form of vitamin
D is converted to the supercharged 1,25 D is a crucial reaction in this
network. The 1,25 D metabolite does most of the important work of
vitamin D in our bodies.
This supercharged 1,25 D is about 1,000 times more active than the
storage vitamin D. Supercharged 1,25 D only survives for six to eight
hours once it is made. In contrast, our storage vitamin D survives for
twenty days or more. 2, 3 This demonstrates an important principle typi-
cally found in networks like this: the far greater activity, the far shorter
lifetime and the far lower amounts of the 1,25 D end product provide a
very responsive system wherein the 1,25 D can quickly adjust its activi-
ty minute-by-minute and microsecond-by-microsecond as long as there
is sufficient storage vitamin D to draw from. Small changes, making a
big difference, can occur quickly.
The relationship between the storage form of vitamin D and the
supercharged 1,25 D is like having a large tank of natural gas buried
in our yard (storage vitamin D) but carefully using only a very tiny
amount of gas to light the burner at our stovetop. It is critical that the
amount and timing of gas (1,25 D) coming to our stove top be carefully

THE ·VITAMIN" 0 CONNECTION                         363
CHART C.l: THE VITAMIN D NETWORK
Supercllilrged
125 D
(i" li ••• ,)
Iii D~ I
regulated, regardless of how much there may be in the tank, whether it
is low or whether it is full. However, it is also useful that we maintain
an adequate supply in our storage tank. In the same way, it is critical
that the kidney enzyme in this reaction has a soft, sensitive touch, so to
speak, as it produces the right amount of the 1,25 D at the right time for
its very important work.
One of the more important things that vitamin D does, mostly
through its conversion to supercharged 1,25 D, is to control the devel-
o p m e n t of a wide variety of serious diseases. For the sake of simplicity,
this is schematically represented by showing the inhibition of the con-
version of healthy tissue to diseased tissue by 1,25 D. 4-12
So far, we can see how adequate sunshine exposure, by ensuring
enough storage form of vitamin D, helps to prevent cells from becom-
i n g diseased. This suggests that certain diseases might be more common
in areas of the world where there is less sunshine, in countries nearer
the North and South Poles. Indeed there is such evidence. To be more
specific: in the northern hemisphere, communities that are farther north
tend to have more Type 1 diabetes, multiple sclerosis, rheumatoid arthritis,
osteoporosis, breast cancer, prostate cancer and colon cancer, in addition to
other diseases.
Researchers have known for eighty years that multiple sclerosis,
for example, is associated with increasing latitude.13 As you can see in
Chart C.2, there is a huge difference in MS prevalence as one goes away
from the equator, being over 100 times more prevalent in the far north
than at the equator. 14 Similarly, in Australia, there is less sunshine and