The China Study

In Chapter 1, the authors describe worsening epidemics of cancer, obesity and diabetes in the United States. They note that the medical system is the third highest cause of death. It is also the most expensive in the world and rapidly becoming more expensive. While good nutrition can solve many of these problems, the American public is getting a lot of contradictory advice on nutrition and is harmed by a series of diet fads. The authors introduce their recommendation, which is to avoid animal-based foods and eat whole, plant-based foods.[13]^{:Chapter 1}

Chapter 2 examines the history of protein research and the emphasis on protein in dietary recommendations. In particular, animal protein is described as "high quality" because it comes close to matching the balance of amino acids in human protein, while vegetarians believe that they must carefully match ingredients to get all the amino acids they need. However, the authors state that the human body can synthesize all the amino acids it needs from a varied plant diet. Colin Campbell describes how he began with a traditional view of the importance of protein, but some research changed his mind. A study of nutrition in the Philippines found that fungus in peanuts and corn was producing aflatoxin, a potent carcinogen; and the highest rates of liver cancer were in affluent families where the children had abundant protein. He also found a research paper from India that showed a strong association between protein consumption and liver cancer in rats. The rest of the chapter describes topics in research methodology, including the difference between correlation and causation, statistical significance, mechanisms of action and meta-analysis.[13]^{:Chapter 2}

Chapter 3 begins with a description of the deep public interest in carcinogens. An example is nitrites, chemicals found in foods such as hot dogs, bacon and canned meat. In the rats, these were "anticipated to be human carcinogens" based on laboratory studies with rats. The authors emphasize that these studies exposed the rats to enormous quantities of nitrites, and the effect on cancer rates was modest (in one study, rising from 5% to 10%). Colin Campbell then describes coming across an Indian research paper in which lowering the intake of protein reduced cancer from 100% to 0%.[13]^{:Chapter 3}

The rest of the chapter discusses research that Campbell and colleagues did on the relationship between diet and cancer. He describes three stages of cancer. In the initiation phase, a carcinogen enters a cell and is metabolized by an enzyme called mixed-function oxidase (MFO). Although the products of this metabolism are mostly safe, there are some toxic byproducts that can damage DNA. In the promotion phase, tumors grow from tiny clusters of cells called foci. This phase is reversible, depending on the balance between promoters that feed growth and anti-promoters that inhibit it. Finally, progression is the spreading of the cancer from its source to neighboring parts of the body, at which point it is considered malignant.[13]^{:Chapter 3}

Rats were fed aflatoxin and varying amounts of protein (between 5% and 20% of their diet). A low-protein diet greatly reduced tumor initiation by several mechanisms; for example, enzyme activity dropped and fewer toxins binded to DNA.[13]^:44–45 In the promotion phase, the development of foci was "almost entirely dependent on how much protein was consumed, regardless of how much aflatoxin was consumed."[13]^:46 They developed if the protein content exceeded the amount (12%) that their bodies required to grow, and focal growth could be switched on or off by varying the protein.[13]^:48 Finally, a population of several hundred rats were studied over 100 weeks, close to the normal lifetime of a rat. At the end of this period, all rats on the 5% diet were "alive and active, with sleek hair coats"[13]^:52 while all those on the 20% diet were dead.[13]^:52 Much the same results were obtained in studies of liver cancer and diet in mice.[13]^:54

In the above experiments, the rats were fed casein, the dominant protein in cow's milk. However, plant proteins such as gluten (from wheat) and soy protein did not promote the growth of tumors, even at the higher levels.[13]^:51 The conclusion is that animal-based foods increase tumor development while plant-based foods decrease it. However, the chapter ends by noting that experiments involving rats do not provide quantitative information on the effect of diet on humans. This serves as an introduction to the next chapter.[13]^{:Chapter 3}

Chapter 4 discusses the China–Cornell–Oxford Project, a massive epidemiological study conducted in the 1980s, also referred to as the China Study. The book takes its title from this study.[15] It built on a national survey in the 1970s that collected data on mortality for 96% of Chinese citizens and produced an atlas of rates for each kind of disease (of which there were more than four dozen)[13]^:65 cancer by region. Rates for some cancers varied by a factor of over 100, a far greater variation than in the United States.[13]^:60–61

With colleagues Junshi Chen and Junyao Li from China and Richard Peto of Oxford University, Colin Campbell led a study that encompassed 65 counties in China with 100 adults per county. This involved questionnaires, blood tests, urine samples and food samples from local marketplaces.[13]^:62 They found that diseases tended to be in one of two groups: diseases of affluence (cancer, diabetes, and heart disease) and diseases of poverty (such as pneumonia, peptic ulcer, and pulmonary tuberculosis).[13]^:65–66

One of the strongest predictors of the diseases of affluence (also referred to as Western diseases) was blood cholesterol. The average level in China was 127 mg/dL (far less than the American average of 215 mg/dL) and the county averages were as low as 94 mg/dL. The death rate from heart disease was 17 times lower than in America, yet still was strongly dependent on cholesterol level. The blood cholesterol was in turn strongly correlated with animal protein intake, even though Chinese consumed about ten time less on average than Americans.[13]^:67–68 In particular, liver cancer was strongly associated with cholesterol level, as well as chronic infection with the hepatitis B virus ("the virus provides the gun, and bad nutrition pulls the trigger.") The association with cholesterol was consistent with the lab studies described in the previous chapter.[13]^:93–94

The chapter examines the role of various components of animal and plant food. Previous international studies had shown a correlation between dietary fat and breast cancer, although only with fat from animals. The China Study found a consistent web of correlations between consumption of animal-based foods and breast cancer as well as a host of risk factors for breast cancer, including age of menarche, estrogen levels and cholesterol.[13]^:71–78 Dietary fiber, which is found only in plants, has benefits including an ability to gather up harmful chemicals from the intestines, but there were claims that it inhibited the uptake of iron. The China Study provided evidence for an increase in iron absorption with an increase in fiber because high-fiber foods are also high in iron. Where iron levels were low, in some rural areas, the problem was associated with parasitic diseases.[13]^:78–80

Another class of chemicals found almost exclusively in plants is the antioxidants such as carotenoids, ascorbic acid (vitamin C) and vitamin E. These provide much of the color in plant food and are designed to combat free radicals, a harmful byproduct of photosynthesis but also present in the human body for a variety of reasons. In the China Study, strong links were seen between increased levels of vitamin C in the blood (mainly due to fruit consumption) and lower risk of several kinds of cancer (by factors of up to 8). Blood levels of other kinds of antioxidant were more difficult to measure, so few correlations were seen.[13]^:81–83

Many fad diets are low-carbohydrate diets that restrict the consumption of carbohydrates. This includes the refined carbohydrates in products like sugar and white flour, but also the complex carbohydrates in fruits, vegetables and whole grains. In their place are increased fat and protein. The authors argue that people who follow these diets lose weight because their calorie intake is restricted. They add that this is unsustainable and cite research that shows adverse health effects.[13]^:83–87 They also argue that one of the main justifications for increasing dietary fat is false: a claim that Americans have had a mania for reducing fat, yet they are fatter than ever. However, Americans have actually increased their consumption of fats, and even more rapidly increased their consumption of refined carbohydrates in junk food.[13]^:84,88 In the China Study, the least active Chinese consumed 30% more calories than their American counterparts yet their body weight was 20% lower. The excess calories were lost as heat rather than being stored as fat.[13]^:88–91

The China Study also found that protein intake is associated with height and body weight, whether the source of protein is animals or plants. They also find strong correlations between low body size and diseases of poverty, which explains why people in developing nations are smaller than people in wealthy nations.[13]^:92–93

Part II looks at the diseases (like heart disease, cancer, stroke, Alzheimer's, obesity and diabetes) that were classified as diseases of affluence in Chapter 4. Each chapter summarizes research on one or more closely related diseases and the role of diet.[13]^:99–100

Chapter 5 looks at heart disease and diet. It begins by noting that heart disease is the leading source of mortality in Americans, killing about 40% of them. It is pervasive even in young, active Americans in the form of plaque buildup that partially blocks arteries. If this occurs slowly, the body can compensate by finding new pathways. However, if a plaque deposit ruptures, this can lead to rapid clotting and sometimes full blockage of an artery downstream, and the body does not have time to compensate. The result is a heart attack.[13]^:102–103

Starting in 1948, the Framingham Heart Study followed over 5,000 volunteers and developed the concept of a risk factor. For heart disease, risk factors included cholesterol, blood pressure, physical activity, cigarette smoking and obesity.[13]^:104–105 Multiple studies showed that fat and cholesterol are harmful, although they could be "merely indicators of animal food intake".[13]^:105–109 Others, dating back as far as the beginning of the 20th century, implicated animal protein, but such claims have been very controversial, with detractors mocking plant eaters as effeminate.[13]^:109 The main aim of research has been to develop technology such as coronary bypass surgery, coronary angioplasty, defibrillators, pacemakers and heart transplants. Such methods have lowered the death rate but not the incidence rate of heart disease.[13]^:111–113 They save lives when a heart attack is in progress, but are costly and have dangerous side effects such as stroke.[13]^:111–113 "When used for stable disease, bypass surgery, angioplasty, and stents do not address the cause of heart disease, prevent heart attacks, or extend the lives of any but the sickest heart disease patients."[13]^:114

The remainder of the chapter describes research by two doctors: Caldwell Esselstyn and Dean Ornish. While at the Cleveland Clinic, a center for cardiac care, Esselstyn tested the effect of a WFPB diet on 23 of his patients who had severe heart disease. Over 11 years, one of the 17 who stuck with the diet had any further coronary events and one who strayed from the diet for 2 years had a single event. Several had reduced blockages in their arteries. Meanwhile, five who dropped off the diet had ten new events. In a subsequent study of 198 patients, 177 who adhered to a WFPB diet and stopped taking medicine had a total of only one cardiac event, while 62% of the other 21 patients had events.[13]^:115–119 Dean Ornish conducted a controlled study in which 28 heart disease patients were treated with lifestyle changes only and twenty with a standard approach. The former group had dramatic reductions in cholesterol and a 91% reduction in chest pains, and blockages in their arteries shrank. Members of the control group had a 165% increase in chest pains, their cholesterol levels were worse and their blockages increased.[13]^:119–121

Chapter 6 discusses the problem of obesity in America. For both adults and children, this is associated with reductions in quality of life as well as myriad health problems, including diabetes, sleep apnea and bone problems. Costs of medical treatment rose from $70 billion in 1999 to more than $147 billion in 2006, while weight management treatments cost another $60 billion, yet obesity is on the rise.[13]^:125–127 Multiple intervention studies are cited that show rapid weight loss when a WFPB diet is followed. This is sustainable because there is no need for calorie restriction; vegetarians tend to have a higher metabolic rate, burning more calories.[13]^:128–132

Chapter 7 begins with a description of Types 1 and 2 diabetes, which as of 2012 afflicted 9.3% of adults in the U.S. and is associated with much greater risk of heart, kidney and nervous system diseases as well as blindness and other complications. The economic impact was over $245 billion in 2013.[13]^:135–138 Multiple epidemiological studies showed that high-fiber, plant-based diets protect against diabetes.[13]^:138–141 Experimental studies, particularly those by James Anderson and Nathan Pritikin, also showed that almost all patients on such a diet could stop using insulin medication after a few weeks and stay off it, while less strict diets also showed benefits.[13]^:141–145

Chapter 8, with the full title Common cancers: Breast, prostate, large bowel (colon and rectal) begins by noting that these three cancers represent a broader range of cancers for which similar analyses apply.[13]^:147 Breast cancer is associated with risk factors including early age of menarche, late age of menopause, high levels of female hormones (including estrogen and progesterone), and high blood cholesterol. All these factors are worsened by a diet high in animal proteins and refined carbohydrates.[13]^:148–151 However, the medical establishment has focussed most of its attention on genetic mutations BRCA1 and BRCA2, which are rare; screening, which can lead to earlier treatment but may not improve survival rate; and anti-estrogen drugs such as tamoxifen that do not address the causes of high estrogen.[13]^:152–154 Environmental chemicals that can promote cancer include dioxins and PCB's, which are primarily found in animal-based foods; and Polycyclic aromatic hydrocarbons (PAHs), which are pollution products. Laboratory studies have shown that the rate at which they cause cancer is controlled by diet; but epidemiological studies have not adequately accounted for the role of diet.[13]^:154–158

Colorectal cancer is the fourth most common cancer worldwide and second most common in the U.S. There are large differences in rates between countries, and studies of migrants favor environment over genetics as the reason. A 1975 study of 32 countries found a particularly strong link between colon cancer and meat intake. A study by Denis Burkitt in Africa found that low-fiber diets increased the risk of colon cancer.[13]^:160–162 However, most studies cannot separate the effects of the hundreds of kinds of fiber from each other, from other benefits of eating fiber-rich foods, or from reduced consumption of animal products. A 1985 study in South Africa does show that animal products contribute to the risk.[13]^:162–165

Prostate cancer is a slow-growing cancer that is one of the most commonly diagnosed forms of cancer. Reviews of the literature show a strong association with consumption of animal-based foods, with higher consumption of dairy doubling or quadrupling the risk.[13]^:167–169 Animal protein increases the production of insulin-like growth factor 1, disturbing the balance between growth and removal of cells, and suppresses the activated form of Vitamin D, suppressing its multiple health benefits.[13]^:170–171 Research by Dr. Ornish, after the first edition of the book, showing that a WFPB diet could "halt and even reverse" prostate cancer.[13]^:172–173

Autoimmune diseases, which include multiple sclerosis, rheumatoid arthritis, lupus and Type 1 diabetes, afflict 7–10% of the world's population. The highest incidences often occur in the same populations. They occur when the body's immune system, which normally protects the body from foreign cells, attacks the body's own cells. This can occur when the foreign protein cells, or antigens, are difficult to distinguish from the body's proteins. Many such molecular mimics are found in food, particularly cow's milk.[13]^:175–178 In type 1 diabetes, the immune system mistakes cells of the pancreas for improperly digested protein fragments such as bovine serum albumin. This can happen if an infant is switched from breastfeeding to cow's milk prematurely. Multiple studies show a strong association between consumption of cow's milk and type 1 diabetes. However, there are strong commercial interests in cow's milk production, and this (or a prejudice in favor of milk) motivates some scientists to overstate the controversy in these results.[13]^:178–185

Multiple sclerosis (MS) occurs when the immune system attacks the myelin sheathes around nerves. Without the insulation a sheat provides, electric currents go astray and "burn" nearby cells. A long-term study by Roy Swank showed that when MS patients had diets low in saturated fats, about 95% remained only mildly impaired over a period of 30 years. By contrast, 80% of those who consumed more saturated fats died. Milk is high in saturated fat, and subsequent studies have found a strong association of MS with milk consumption. Based on migrant studies, the role of genetics appears small, while attempts to link MS with a virus have not succeeded.[13]^:186–189

Autoimmune diseases have a lot in common, including a strong increasing trend with latitude and consumption of cow's milk, a tendency to affect the same people, and a possible role of viruses as triggers. Many of the factors are linked. Cow's milk consumption increases with latitude, while vitamin D production from exposure to sunlight declines. In experimental models, activated vitamin D prevents many of the autoimmune diseases. Diets high in calcium and acid-producing animal proteints inhibit this activation.[13]^:190–192

At the beginning of Chapter 10, the authors emphasize the breadth and quantity of studies supporting the claim that plant-based foods reduce the rates of a great variety of diseases. To underscore the breadth, they discuss five more seemingly unrelated diseases that are often considered "inevitable consequences of aging".[13]^:193–194

To promote bone strength, health policies often recommend a high calcium intake, and because milk is rich in calcium they recommend drinking a lot of milk. Yet rates of hip fracture are highest in the countries that have the highest milk consumption. Rates of hip fracture are highly correlated with the ratio of animal to plant protein in diets. Nigeria, with a 10% ratio, has only 1% of the fracture rate that the U.S. has. Animal protein increases the body's acid load. The body neutralizes this with calcium, which it pulls from bones, so they are weakened. A high consumption of calcium can also impair the body's ability to regulate the use of calcium.[13]^:194–199

The debate over osteoporosis, or bone disease, is complicated by the influence of the dairy industry. Adding to the confusion, low bone mineral density (BMD) is often used to diagnose osteoporosis, but it is a questionable biomarker. High BMD is associated with higher rates of osteoarthritis, breast cancer, obesity, and even (in some places) higher rates of hip fracture.[13]^:200–201

Kidney stones cause a variety of symptoms, one of which (acute renal colic) is "probably one of the worst pains humans experience."[13]^:201 Most stones are made of calcium or oxalate. When animal protein is consumed, levels of both rise sharply within hours. Extensive research by W. G. Robertson at the University of Toronto has shown that a high meat protein intake is the dominant factor in kidney stone formation.[13]^:200–203

• Campbell, Thomas (2015). The Campbell Plan : the simple way to lose weight and reverse illness, using the China Study's whole-food, plant-based diet. Rodale Books. ISBN 9781623364106.
• Campbell, Thomas (2016). The China study solution : the simple way to lose weight and reverse illness, using a whole-food, plant-based diet. Rodale Books. ISBN 9781623367572.
• Campbell, LeAnne; Campbell, T. Colin; Disla, Steven Campbell (2013). The China study cookbook : over 120 whole-food, plant-based recipes. BenBella Books. ISBN 9781937856762.[19]