The China Study - T. Colin Campbell and Thomas M. Campbell

Scientific Reductionism

WHEN OUR NATIONAL ACADEMY OF SCIENCES (NAS) Diet, Nutrition and Cancer Committee was deciding how to summarize the research on diet and cancer, we included chapters on individual nutrients and nutrient groups. This was the way research had been done, one nutrient at a time. For example, the chapter on vitamins included information on the relationships between cancer and vitamins A, C, E and some B vita- mins. However, in the report summary, we recommended getting these nutrients from fbods, not pills or supplements. We explicitly stated that "These recommendations apply only to foods as sources of nutrients- not to dietary supplements of individual nutrients.'"
The report quickly found its way to the corporate world, which saw a major money-making opportunity. They ignored our cautionary mes- sage distinguishing foods from pills and began advertising vitamin pills as products that could prevent cancer, arrogantly citing our report as justification. This was a great opening to a vast new market-commer- cial vitamin supplements.
General Nutrition, Inc., the company with thousands of General Nutrition Centers, started selling a product called "Healthy Greens," a multivitamin supplement of vitamins A, C and E, beta-carotene, se- lenium and a miniscule half-gram of dehydrated vegetables. Then they advertised their product by making the following claims2:
[The Diet, Nutrition and Cancer reportl recommended we increase among other things our amounts of specific vegetables to help safeguard our bodies against the risk of certain forms of cancer.
These vegetables recommended by the [National Academy of Sci- ences reportl ... are the ones we should increase[:l cabbages, Brus- sels sprouts, cauliflower, broccoli, carrots and spinach.... Mom was right!
Research scientists and technicians at General Nutrition Labs, realizing the importance of the research, instantly went to work to harness all of the vegetables and combined all of them into a natural, easy to take potent tablet.
[Tlhe result is Health Greens [sic], a new potent breakthrough in nutrition that millions of people can now help safeguard their well-being with ... the greens that the [National Academy of Sci- ences Committeel recommends we eat more of!
GNC was advertiSing an untested product and improperly using a government document to support its sensational claims. So the Federal Trade Commission went to court to bar the company from making these claims. It was a battle that lasted years, a battle that was rumored to cost General Nutrition, Inc. about $7 million. The National Academy of Sciences recommended me as their expert witness because of my co- authorship of the report in question and because of my harping on this point during our committee deliberations.
A research associate in my group, Dr. Tom O'Connor, and I spent three intellectually stimulating years working on this project, including my three full days on the witness stand. In 1988, General Nutrition, Inc., settled the false advertising charges relating to Healthy Greens and other food supplements by agreeing to pay $600,000, divided equally,
to three different health organizations. This was a small price for the
company to pay, considering the ultimate revenues that were generated by the exploding nutrient supplement market.
FOCUS ON FAT
The focus on individual nutrients instead of whole foods has become commonplace in the past two decades, and part of the blame can be put on our 1982 report. As mentioned before, our committee organized the scientific information on diet and cancer by nutrients, with a separate chapter for each nutrient or class of nutrients. There were individual chapters for fat, protein, carbohydrate, vitamins and minerals. I am convinced it was a great mistake on our part. We did not stress enough that our recommendations were concerned with whole foods because
many people still regarded the report as cataloging the specific effects of individual nutrients.
The nutrient that our committee focused on the most was fat. The first gUideline in the report explicitly stated that high fat consumption is linked to cancer, and recommended reducing our fat intake from 40% to 30% of calories, although this goal of 30% was an arbitrary cutoff point. The accompanying text said, "[Tlhe data could be used to justify an even greater reduction. However, in the judgment of the committee, the suggested reduction is a moderate and practical target, and is likely to be beneficial." One of the committee members, the director of the United States Department of Agriculture (USDA) Nutrition Laboratory; told us that if we went below 30%, consumers would be required to re- duce animal food intake and that would be the death of the report.
At the time of this report, all of the human-based studies showing fat to be related to cancer (mostly breast and large bowel) were actu- ally showing that the populations with more cancer consumed not just more fat, but also more animal-based foods and less plant-based foods (see chapter four). This meant that these cancers could just as easily be caused by animal protein, dietary cholesterol, something else exclUSively found in animal-based foods, or a lack of plant-based foods (discussed in chapters four and eight). But rather than wagging the fin- ger at animal-based foods in these studies, dietary fat was given as the main culprit. I argued against putting the emphaSiS on specific nutrients in the committee meetings, but only with modest success. (It was this point of view that landed me the expert witness opportunity at the FTC hearings.)
This mistake of characterizing whole foods by the health effects of spe- cific nutrients is what I call reductionism. For example, the health effect of a hamburger cannot be simply attributed to the effect of a few grams of saturated fat in the meat. Saturated fat is merely one ingredient. Ham- burgers also include other types of fat, in addition to cholesterol, protein and very small amounts of vitamins and minerals. Even if you change the level of saturated fat in the meat, all of the other nutrients are still present and may still have harmful effects on health. It is a case of the whole (the hamburger) being greater than the sum of its parts (the saturated fat, the cholesterol, etc.).
One scientist especially took note4 of our focused critique of dietary fat, and decided to test the hypothesis that fat causes breast cancer in a large group of American women. He was Dr. Walter Willett of the
Harvard School of Public Health, and the study he used is the famous Nurses' Health Study.
Starting in 1976, researchers at the Harvard School of Public Health had enrolled over 120,000 nurses from around the country for a study that was intended to investigate the relationship between various dis- eases and oral contraceptives, post-menopausal hormones, cigarettes
and other factors, such as hair dyes.
lett added a dietary questionnaire to the study and four years later, in 1984, expanded the dietary questionnaire to include more food items. This expanded dietary questionnaire was mailed to nurses again in 1986 and 1990.
Data now have been collected for over two decades. The Nurses'
Health Study is widely known as the longest-running, premier study 6
on women's health. It has spawned three satellite studies, all together 6
costing$4-5millionperyear. WhenIgivelecturestohealthconscious audiences, upwards of 70% of the people have heard of the Nurses' Health Study.
The scientific community has followed this study closely. The researchers in charge of the study have produced hundreds of scien- tific articles in the best peer-reviewed journals. The design of the study makes it a prospective cohort study, which means it follows a group of people, a cohort, and records information on diets before disease events are diagnosed, making the study "prospective." Many regard a prospec- tive cohort study as the best experimental design for human studies.
The question of whether diets high in fat are linked to breast cancer was a natural outgrowth of the fierce discussion going on in the mid- 1970s and the early 1980s. High-fat diets not only were associated with heart disease (the McGovern dietary goals), but also with cancer (the Diet, Nutrition and Cancer report). What better study to answer this question than the Nurses' Health Study? It has a good deSign, massive numbers of women, top-flight researchers and a long follow-up period. Sounds perfect, right? Wrong.
The Nurses' Health Study suffers from flaws that seriously doom its results. It is the premier example of how reductionism in science can create massive amounts of confusion and misinformation, even when the scientists involved are honest, well intentioned and positioned at the top institutions in the world. Hardly any study has done more dam- age to the nutritional landscape than the Nurses' Health Study, and it should serve as a warning for the rest of science for what not to do.
Beginning in 1980, Professor Wil-
CARNIVOROUS NURSES
In order to understand my rather harsh criticism, it is necessary to ob-
tain some perspective on the American diet itself, especially when compared with the international studies that gave impetus to the dietary fat hypothesis. Americanseatalotofmeatandfatcomparedtodeveloping countries. We eat more total protein, and even more Significantly, 70% of our protein comes from animal sources. The fact that 70% of our total protein comes from animal sources means only one thing: we are con- suming very few fruits and vegetables. To make matters worse, when we do eat plant-based foods , we eat a large amount of highly processed products that often have more added fat, sugar and salt. For example, the United States Department of Agriculture (USDA) national school lunch program counts French fried potatoes as a vegetable!
In contrast, people in rural China eat very little animal foods; they
provide only about 10% of their total protein intake. The striking dif-
ference between the two dietary patterns is shown in two ways in
These distinctions are typical of the dietary differences between
Western cultures and traditional cultures. In general, people in Western countries are mostly meat eaters, and people in traditional countries are mostly plant eaters.
So what about the women in the Nurses' Health Study? As you might guess, virtually all of these women consume a diet very rich in animal- based foods, even richer than the average American. Their average protein intake (as % of calories) is around 19%, compared with a U.S.