BANOO PARPIA: Now, let's move from the purely descriptive results and the comparisons of US and China values to the more analytical results and start beginning to look at what the relationship is between, let's say, plasma total cholesterol and heart disease risk, green vegetable intake and colon cancer risk, and so on.
All these relationships have been looked at in depth in several manuscripts and scientific articles that have been published in the peer reviewed literature. Each one of these papers or articles would require a separate study room or a separate presentation to, in fact, go into some of the technical details and describe to you the findings and build a story, as it were, for each of these outcomes. Professor Campbell now will comment more generally on the overall findings and the implications of these findings for our own dietary and lifestyle choices.
T. COLIN CAMPBELL: Basically, in the study of China, we were measuring a large number of different things that characterized dietary and lifestyle characteristics. Namely, we were measuring blood cholesterol, dietary fat intake, dietary fiber intake, animal protein intake, and a number of other things to give us some sense of the kind of diet they were consuming. And they were, of course, consuming a low fat, high fiber diet. And as a result, they experienced much lower levels of cholesterol than we had here in the West.
For example, we explored the relationship between breast cancer and dietary fat was in that very low range of fat intake. In this case, I should point out, incidentally, that fat intake represents the intake of animal-based foods. But in any case, what we found was that as fat intake goes up, or I should say, animal-based food intake goes up, breast cancer goes up.
At the same time, as animal food intake goes up in China from very low levels, age of menarche begins to come down. The average age of menarche among young Chinese women is 17 years. The range was from 15 to 19 years. In the West, it's around 11 to 12 years. And we've known for a long time that the earlier the age of menarche, the higher the risk for breast cancer. That's a well-established fact.
And so what we discovered in China was that as animal food intake goes up, especially among young women-- and I'm sure the same would happen with young boys or young men, as well, for other reproductive cancers-- but in any case, as animal food intake goes up, the age of menarche begins to decline. That triggers a series of events that go on. Subsequently, it leads to breast cancer later in life.
We looked at the relationship between dietary fiber and colon cancer. The higher the fiber intake, the lower the rates of colon cancer.
We considered the relationship, let's say, between plasma Vitamin C, or I should say, Vitamin C in the blood as it related to stomach cancer. And what we found there was that Vitamin C, which comes exclusively from plant-based foods, the higher the Vitamin C level in the blood the lower was the rate of stomach cancer.
Beta carotene is yet another vitamin that is an antioxidant that we now know about, but exclusively found in plant-based foods. It turns out that the beta carotene level that is in the blood, as well as the level that's consumed, the higher the consumption or the higher levels of beta carotene in the blood, the lower was the rates of various and sundry cancers.
After we completed this study and went back and looked at it in a very comprehensive way, it turned out that every time we looked for a specific relationship between something specific about the diet or lifestyle on the one hand and disease outcome on the other that these versus and sundry relationships that we studied in some depth pointed in the same direction. The richer the diet was in plant-based foods, the lower was the risk of the kind of diseases that most of us in this country succumb to before our time, namely heart disease, cancers, diabetes, and so forth.
And so what this really recommended to us or showed us, I should say, is this idea that the relationship between diet and disease is not a function of a specific nutrient intake, as many of us are wanting to think about, such as with dietary supplements. Instead, what this study showed us from really a broad point of view, as well as from a relatively in depth point of view, particularly when we consider the data relative to other studies, what this showed us was that it was a dietary pattern really that made the difference as far as these diseases are concerned. Diets that just started to include animal-based foods were problematic.
And in the China Study, what was really quite remarkable was it only took a small amount of these foods to start being associated with increasing levels of blood cholesterol from very low levels. And as the range went from, let's say, 90 milligrams per deciliter up to about 170, we could see statistically significant relationships with various cancers and other diseases begin to emerge.
In any case, getting that information together with the information that we had in the beginning, focused primarily on animal protein versus plant protein, it began to describe for us the notion that consuming a diet that had animal-based foods in it was really a problem.
And this kind of observation really hadn't been noted that much before. Or the extent to which it had been noticed wasn't too much discussed int the scientific community in part, in my view, because the studies that are done in the West are not designed in a way in which we can really look at that question. As I pointed out in the beginning, the studies done in the West are focused on cohorts of people who are consuming diets already rich in animal-based foods. And so we all tend to do that. And therefore, we can't study these broad dietary patterns quite in that fashion.
I was particularly interested in exploring the observations that had been done elsewhere in the literature. And it turned out that basically, going back many years, in some cases, the observations that we were making in the China Study were, in fact, supported by a large number of observations elsewhere.
These results also had some important implications about Ken Carroll, or the Professor Carroll studies, where he showed a high intake of dietary fat being associated with a high risk of breast cancer and other sorts of diseases like that. He focused on fat. And it was that observation, actually, that led to much of the interest in our society to decrease fat intake because obviously, these studies did, in fact, specify fat has being a problem. However, if we go back and look at those studies, it turns out that the relationship between fat intake and breast cancer, for example, as well as other diseases was primarily a relationship not just of total fat, it was specifically a relationship for animal fat, but not plant fat.
What we learned from the China Study, and together with many other kinds of evidence, was that as animal protein intake is increased, in particular animal protein intake-- as it's increased from 10% to 20% and higher, that's when the cancers begin to appear. That's when heart disease occurs. That's when blood cholesterol goes up. And that's when all these other diseases begin to occur. So in other words, we're consuming diets much too high in protein, specifically animal protein.
What do we get in the most recent recommendations? Unfortunately, the Food Nutrition Board, which is responsible for setting national nutrition policy on this question, recently came out with a recommendation that we could consume protein as high as 35% of total energy. That would supposedly be consistent with the reduction of these diseases. In my own personal view, this is really one of the most tragic findings that we've seen in our community in many, many years. And I have to say that I'm troubled by the fact that these recommendations came as a result of support from the industry that would benefit from these recommendations.
So in addition to the inferences of the China Study findings for nutrition policy recommendations and for the way we should be eating, it also raises some very provocative considerations and provocative questions, particularly regarding that sort of sacred nutrient, animal protein. I mean, most of us have been asking for years, where do we get our protein from. And by inference, people tend to want to consume more animal-based foods in order to get that protein.
We're going to have to go back and revisit that question. We have to go back and revisit a lot of questions that we have taken for major assumptions in our society. It turns out that these kinds of observation really do become controversial, quite intensively so at times. And the public gets very confused about what's going on.
And I'm troubled by that because we have major medical problems in this country that need to be resolved. And one of the reasons we have these problems in this country is because we simply don't eat right. And our data show very clearly that we need to make some major changes in the way we eat if we're going to solve the medical problems that we now have, particularly in a sense of preventing these diseases.
In order to take that step, we've got to figure out ways of being able to do it. And my own personal view on this is that one of the best ways to do this is to organize more opportunities for discourse, transparent discourse with integrity, to include many communities from our society, not just the professionals, but also the public, as well. And so I'm particularly interested in seeing something developed along the lines of organizing more workshops and symposia and the give and take of classroom debate, seminar debate, on these tough questions, and making it all very transparent.
I think the results that we've gotten from the China Study are really quite remarkable in the sense of pointing the way to where we ought to be going. But in order to get there, we've got to figure out some mechanisms to be able to do that. And I think having more discourse, more public discussion, and a little bit less interference from the food industry and the way we think about things, I think would all be very helpful.
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This study room provides a general overview and introduction to the Cornell-China-Oxford project. The project is a large and comprehensive epidemiologic study designed to explore and investigate the relationship between diet and disease.
In addition to the general descriptive findings of the study, the implications of this body of research evidence for prevention of chronic diseases such as heart disease and cancer are discussed.
This video is part 7 of 8 in the The China Project: Studying the Link Between Diet and Disease series.