The China Study: An Evening with Dr. T. Colin Campbell
On Wednesday, June 22nd, 2005, the Pine Street
Foundation was pleased to welcome Dr. T.
Colin Campbell to Marin County to speak
about his landmark China Study, one of
the most comprehensive studies of nutrition
ever conducted. Dr. Campbell’s research
findings have startling implications for
diet, weight loss, and long-term health. The
lecture was facilitated by Dr. Lawrence H.
Kushi, Associate Director for Etiology and
Prevention Research at Kaiser Permanente.
» Read the Transcript
from the Interview
» About the China
Study
» Scientific
Justification
» Why China?
» About Dr. Campbell
and Dr. Kushi
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The Interview - Wednesday, June 22nd
Dr. Lawrence H. Kushi: You are a strong advocate of
essentially vegetarian or even vegan dietary choices. One of the things
that I find
interesting is that you actually grew up on a dairy farm in Virginia.
Dr. T. Colin Campbell: As a youth, I was a meat and potatoes
kind of guy. I was raised on a farm and milked cows until I went away to
school. I was the first member in my family on either side to even
go to college, let alone graduate school, so I really went into the
whole scientific profession rather naïvely. My initial graduate work
at Cornell University was on how to grow cows more efficiently so
we could eat more of them and drink more of their milk. My doctoral dissertation
was specifically focused on making sure we all got enough protein, especially
so-called “high quality” animal protein.
I would have preferred to have continued on that path, but as I got
involved in the Philippines working with malnourished children and
then in the laboratory doing a lot of basic research, I started to get
some results that began to question my whole upbringing, especially
what I believed about protein.
LK: Can you give an example of your work in the Philippines
that triggered this?
CC: My job in the 1970s was to coordinate a nationwide program
to feed malnourished children in the Philippines. In those days, and still
to some extent today, the notion was that malnourishment largely resulted
either from not enough calories, not enough protein, or some
combination of the two. The protein issue was one of my principal
interests when I first got involved.
One day, I was playing golf with a medical advisor to President
Marcos who told me that he and some other doctors had recently
been operating on children four years old and younger for primary
liver cancer, which I thought was very interesting. I then started
investigating where these children were likely to come from and they
seemed to be from families who were the best fed and who were getting the
most protein. All of a sudden, I began to question what I was
doing there; I was trying to get more protein to the kids and, in some
cases, they were ending up worse off. It was exactly the opposite of
what I thought I was going there to do.
LK: How did you then take this observation into your work?
CC: I first told one of my senior colleagues back at MIT
about this and he thought it was crazy. Then I saw a paper in the Indian journal
Pathology that showed that when rats were exposed to a carcinogen
and then fed two different levels of animal-based protein, the animals
fed the regular levels of protein essentially all got tumors whereas the
animals fed the lower level – the so-called “inadequate level” – did
not. That was essentially what I thought I was seeing in the children,
too. The interesting thing about that study was that the level of protein being
fed that caused tumors to develop was not exorbitant; it
was well within the range of what humans might ordinarily consume
(the protein requirements of rats and humans, as a percentage of total
calories, are fairly identical).
LK: The type of protein used in that study was casein, the
principal protein found in milk.
CC: In the beginning, I didn’t pay a lot of attention
to the kind of protein we were using in our research, but eventually had to
come to
terms with the fact that the type of protein I was using all along – as
everyone else was doing in those days – was casein. So I then tried
soy protein and wheat protein and they didn’t have the same tumor
growth effect. I also found that the casein effect only existed when
the level of protein in the diet was above 10% of total calories. In
other words, once the animal satisfied its need for protein and then
started consuming excess of that as casein, tumors started to grow.
In the case of plant proteins, however, exceeding 10% and even up
to 20% of total calories as protein, tumors did not grow. So, suddenly
there emerged this dichotomy between the two kinds of protein,
animal and plant.
LK: Would you say casein is a carcinogen?
CC: Chemicals that cause cancer are called carcinogens and
here we had a situation where casein fed at levels that could be anticipated
in
human diets was, in a sense, having a very strong effect in promoting
tumor growth; 20% protein (as casein) diets generated tumor growth
whereas 5% didn’t. Although we didn’t do the test at the time,
there
was also all sorts of evidence to suggest that this effect was probably
a
property of animal protein in general, not just of casein.
LK: How did the China Study first begin?
CC: At the time, the Chinese government had just released
a study showing that cancer tended to occur more in certain Chinese counties
and much less in others, resulting in great differences in mortality rates.
Intrigued by this, we decided to go to China and measure various factors with
respect to diet and lifestyle experiences and
then
compare those measurements with the disease rates that the Chinese
government had already obtained for the years of 1973 to 1975 to
see
what relationships between the two, if any, existed. We selected
130
villages in rural China, which tended to be a very stable population
(people lived in the same village all their lives) and tended to
produce
and use locally grown foods. From an epidemiological point of view,
it was very nice.
LK: What were some of the major findings from the China
Study?
CC: Essentially that animal-based foods were a problem.
In the China Study, we found that as soon as animal-based proteins started
to appear in the diet in certain Chinese counties, blood cholesterol
levels, which were very low by Western standards (about 80mg per
deciliter) started going up and that various cancers and heart disease
started to appear. The association between the increase in animal-based foods
and the increase in those diseases was highly significant,
so much so that it made me get to a point where I started to question
the way I was raised and made me switch to consuming a purely
plant-based diet.
LK: What is your opinion of the current promotion of low-carbohydrate
diets?
CC: When the promotion of these diets first started, I reacted
in a negative way because the proponents took that term and essentially
confused the public – on purpose – to make their point. The whole
genesis for the notion of low-carbohydrate (and therefore higher in
protein and higher in fat) being better was basically a frontal attack
in a very simplistic, albeit very effective, way on the recommendations
that I have become accustomed to because plant-based diets
are inherently “high carb” diets. In the China Study, it was
the diets
highest in carbohydrates that were associated with the least cancer
and the least heart disease.
LK: What about studies that indicate that
low-carbohydrate diets
do appear to have some short-term health benefits, such as lowering
cholesterol levels and assisting in weight loss?
CC: Low-carbohydrate diets have been shown to cause some
weight loss, especially among those who are substantially overweight. To
some extent, cholesterol levels have also been shown to decrease.
But not all studies have produced those effects, however, and the
weight loss and lower cholesterol benefits are minimal as compared
to what is possible with a plant-based diet. Furthermore, people
who go on low-carbohydrate diets usually consume fewer calories,
at least initially, so we’re talking about a calorie effect there that
can’t
be sustained.
LK: What about the “Mediterranean Diet”?
CC: There was research that showed that people who lived
in various Mediterranean countries – Crete, southern Greece, southern
France, and so forth – tended to have lower rates of breast cancer, colon
cancer, and heart disease as compared to people living in the United
States and England, despite the fact they were consuming diets that
were fairly high in fat, mostly from olive oil. It turns out that
in those Mediterranean countries where the fat intake is quite high,
the proportion of their total food as plant food was very similar to what we
saw in rural china. However, when you compare the rural Chinese to
people in Mediterranean countries, it turns out that the heart disease
rates in the Mediterranean are quite a bit higher than in rural China.
So, really the question you should be asking is, “Why are the disease
rates so high in those Mediterranean countries as compared to rural
China?” Is it because of the consumption of olive oil?
LK: What about soy protein?
CC: Soy is a legume and a good source of protein, as far
as plants are concerned, so it should be part of a healthy diet. But soy has
now
been processed into so many products and this processing can lead to
things that one might raise some questions about.
Another issue is that we
have people who are quite possibly
consuming too much soy. One element that has been discussed is the
presence of phytoestrogens in soy; these estrogens might be just as
mischievous as people’s own estrogens or estrogens they might consume
from animal foods. At certain consumption levels, these phytoestrogens are
probably beneficial because they are antiestrogens and
tend to diminish the effect of otherwise high levels of mammalian
estrogens. But I think soy protein, if it were fed at high enough levels,
might end up doing some of the same things as animal proteins...it’s
simply a matter of quantity.
Regarding the soy debate itself, I first saw it emerge in the 1970s
when I was living in the Philippines. The Philippines wanted to ship
soy to the West and, almost immediately, there erupted all these news
releases about the hazards of soy that ultimately proved to be coming
from the dairy industry. I know that the dairy industry has not been
happy over the years with the erosion of their territory because of soy
products, so when I see so-called “reports,” I don’t know
how to react
to them because I just have this inherent skepticism as to where it
might really be coming from.
LK: Are there differences between protein from fish and
protein from beef?
CC: In one study, Dr. Kenneth Carroll compared a whole variety
of animal-based proteins, including fish protein, to a whole variety of
different plant proteins in their ability to generate cholesterol levels.
What he found when he examined them in a systematic way in
experimental animals was that animal proteins tended to increased
cholesterol and plant proteins tended to decrease cholesterol. Fish
protein was the one animal protein that was the least effective in
increasing cholesterol levels, but it was still far higher than all the
plant proteins.
LK: Because you advocate a plant-based diet, one of the questions you
are often asked is, “How are you supposed to get enough protein?” It
seems there has been a large fixation on protein, both in the nutrition
science community as well as in the general public. CC: The
Recommended Daily Allowance for protein, ever since 1943 when we were making
such recommendations, is set at 10%
of total calories. This amount allows for some variation among
individuals and is supposed to be enough. This is also about the
level of protein that a good plant-based diet provides. However,
there’s such a fixation on protein in this country that, as a population,
we’re consuming somewhere between 11% and 23% and the
average now is around 17% or 18%. If we listen to the food pyramid recommendations,
we’re being encouraged to go even higher.
LK: Is there an over-emphasis on cholesterol measurements?
CC: Yes. Generally speaking, the higher the cholesterol
levels, the greater the risk for heart disease and stroke. But when reducing
that
to the individual level, we know there are lots of exceptions; some
people with relatively low cholesterol levels have heart disease while
some people with relatively high cholesterol levels don’t have heart
disease.
Cholesterol measurement is a crude instrument. It was refined,
to some extent, when we started measuring HDL and LDL – “good
cholesterol” and “bad cholesterol” – and now has
become more refined by measuring oxidized LDL, but that hasn’t
really been taken
into consideration clinically yet. But I think we should recognize the
limitations, especially for individuals, of measuring cholesterol as
an
indicator of heart disease and recognize that there’s a host of
other factors that, when put together – perhaps as an index – is
eventually going to turn out to be a better estimate of disease risk
than just measuring cholesterol alone.
LK: You have said that “the distinctions between
government, industry, science, and medicine have become blurred and the
distinctions between making a profit and promoting health have
become blurred.”
CC: That’s a view that I think a lot of people share,
too. Unfortunately, I’ve seen things that I find to be deeply, deeply
troubling and I
think it’s getting worse. I think our academic science is being
severely corrupted by commercial interests. Right now, for example, the
most
recent food and nutrition board report from the National Academy
of Sciences is funded, in part, by the food and drug companies.
The food pyramid committee has been similarly corrupted. For
example, when someone requested information as to what conflicts
of interest the panel members on the previous board may have had,
the USDA refused to make that information publicly available, even
though it’s required. So after about eight months, a judge forced
the USDA to release that information, which showed that six of the eleven
members, including the chair, had an association with the dairy industry.
And now in the new food pyramid that was just released,
we’re getting recommendations to increase milk consumption. I find
it deeply troubling that we can’t be honest about the science without
having to worry about who’s paying the bills.
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ABOUT THE CHINA STUDY
The China Study demonstrates the link between nutrition and
heart disease, diabetes, and cancer. Referred to
as the “Grand Prix of epidemiology” by The New York
Times, this study examines more than 350 variables of
health and nutrition with surveys from 6,500 adults in
65 counties, representing 2,500 counties across rural
China and Taiwan. While revealing that proper nutrition
can have a dramatic effect on reducing and reversing
heart disease, diabetes, cancer, and obesity, this study
calls into question the practices of many of the current
dietary programs, such as the Atkins diet, that enjoy
widespread popularity in the West. The impact of the
politics of nutrition and the efforts by food industry
lobbyists on the creation and dissemination of public
information on nutrition is also discussed.
SCIENTIFIC JUSTIFICATION
In the late 1970s and early 1980s, there were two principal observations
suggesting a relationship between
diet and cancer. First, rich Western diets (high in fat and
meat, low in dietary fiber) were strongly associated (correlated) with incidence
of colon and breast cancer. Second, migrants moving to areas of different
cancer risks
acquired the risk of the country to which they moved,
regardless of their ethnic or genetic backgrounds.
WHY CHINA?
In 1981, the Chinese Academy of Medical Science
published an Atlas of Cancer Mortality on the 1973-75
mortality rates for about a dozen different cancers for
2,400 counties in China. These maps showed that cancer was highly localized
in specific geographic regions. Residents of these regions tended to live
in the same
regions all their lives and to consume the same diets
unique to each region each and every year. Their diets
(low in fat and high in dietary fiber and plant material)
also were in stark contrast to the rich diets of the Western countries.
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.................................................................................................................... ABOUT DR. CAMPBELL
Colin Campbell, PhD, is the project director of the China-Oxford-Cornell Diet
and Health Project (the China Study), a 20-year study of nutrition and health.
He is a Jacob Gould Schurman Professor Emeritus of nutritional biochemistry
at Cornell University. In more than 40 years of research, he has received more
than 70 grant-years of peer-reviewed research funding and authored more than
300 research papers. He lives in Ithaca, New York.
ABOUT DR. KUSHI
Lawrence H. Kushi, ScD, is Associate Director for Etiology and Prevention Research,
Division of Research, Kaiser Permanente. Internationally recognized for his
expertise in nutritional epidemiology, Dr. Kushi’s research interests
have focused on the role of food and nutrition in the development and prevention
of coronary artery disease and breast and other cancers. Dr. Kushi is also
is the second son of Michio and Aveline Kushi, the foremost proponents of
macrobiotics and leaders in the development and acceptance of unconventional
and lifestyle approaches to cancer. Dr. Kushi is collaborating with the Pine
Street Foundation on the Pine Street Survival Study, a 10-year follow-up
study of people with breast, lung, and colon cancers treated with an integrative
vitamin/herbal protocol in combination with standard chemotherapy.
This event was made possibly by the generous support of the following
sponsors:
PRESENTING LECTURE SPONSORS: The Blair & Hillary Peterson
Family in partnership
with the Marin Community Foundation, the Marin County Department of Health& Human Services, Alan Bear & Bonnie Frank, Western Athletic Clubs – Bay
Club Marin, the
Pine Street Foundation, and the Pine Street Clinic of San Anselmo.
SUPPORTING SPONSORS: Gerda & Edward Giacomini and Karen
Z Hardesty.
COMMUNITY SPONSORS: Diana Chiarabano, Marcia
Fields, Iris Gold, Linda Hallberg
Donaghue, Anne Hiaring, Joanna Lennon, Robin McKee & Timothy Day, Merrily
Milmoe,
John & Janet Petroni, Steve & Carrie Rosenberg, Johanna Sherlin,
Barbara Shilo, Shannon
Wagner, Rachel Webb Williams, and Richard Wilson.
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