The China Study: The Most Comprehensive Study of Nutrition Ever Conducted and the Startling Implications for Diet, Weight Loss, and Long-Term Health

by T. Colin Campbell

Both diabetes and obesity are merely symptoms of poor health in general. They rarely exist in isolation of other diseases and often forecast deeper, more serious health problems, such as heart disease, cancer, and stroke.

Perhaps you remember the protein diet fad that gripped the country in the late 1970s. The promise was that you could lose weight by replacing real food with a protein shake.

If you aren’t fatigued, constipated, or half-starved by these quick-fix plans, your head is spinning from counting calories and measuring grams of carbohydrates, protein, and fat. What’s the real problem, anyway? Is it fat? Is it carbohydrates? What’s the ratio of nutrients that provides greatest weight loss? Are cruciferous vegetables good for my blood type? Am I taking the right supplements? How much vitamin C do I need every day? Am I in ketosis? How many grams of protein do I need?

This is not health.

I am appealing to your intelligence, not to your ability to follow a recipe or menu plan.

Many people today still equate protein with animal-based food.

Food proteins of the highest quality are, very simply, those that provide, upon digestion, the right kinds and amounts of amino acids needed to efficiently synthesize our new tissue proteins. This is what that word quality really means: it is the ability of food proteins to provide the right kinds and amounts of amino acids to make our new proteins and to do so efficiently.

Among animal foods, the proteins of milk and eggs represent the best amino acid matches for our proteins, and thus are considered the highest quality. While the “lower quality” plant proteins may be lacking in one or more of the essential amino acids, as a group they do contain all of them.

The concept of quality really means the efficiency with which food proteins are used to promote growth.

if the greatest efficiency equaled the gr...

Slow but steady wins the race.

have oftentimes made the unfortunate leap to thinking that more quality equals more health.

We now know that through enormously complex metabolic systems, the human body can derive all the essential amino acids from the natural variety of plant proteins that we encounter every day.

the enduring concept of protein quality has greatly obscured this information.

I went all the way through my graduate studies with a profound belief that promoting high-quality protein, as in animal-based foods, was a very important task.

peanuts often were contaminated with a fungus-produced toxin called aflatoxin

We learned that peanuts and corn were the foods most contaminated.

Whole peanuts were much less contaminated; none exceeded the AF amounts

disparity between peanut butter and whole peanuts originated at the peanut factory. The best peanuts, which filled “cocktail” jars, were hand-selected from a moving conveyor belt, leaving the worst, moldiest nuts to be delivered to the end of the belt to make peanut butter.

the children who got liver cancer were from the best-fed families.

They consumed more protein than anyone else in the country (high-quality animal protein, at that), and yet they were the ones getting liver cancer!

One group was given AF and then fed diets containing 20% protein. The second group was given the same level of AF and then fed diets containing only 5% protein. Every single rat fed 20% protein got liver cancer or its precursor lesions, but not a single animal fed a 5% protein diet got liver cancer or its precursor lesions. It was not a trivial difference; it was 100% versus 0%. This was very much consistent with my observations for the Philippine children. Those

The primary objective of research investigation is to determine only what is likely to be true.

This is because research into health is inherently statistical.

In nutrition research, untangling the relationship between diet and health is not so straightforward.

Perhaps most importantly, food, lifestyle, and health interact through such complex, multifaceted systems that establishing proof for any one factor and any one disease is nearly impossible, even if you had the perfect set of subjects, unlimited time, and unlimited financial resources.

Because of these difficulties, we do research using many different strategies.

we assess whether a hypothetical cause produces a hypothetical effect by observing and measuring the differences that already exis...

In addition to observing what already exists, we might do an experiment and intentionally intervene with a hypothetical treatment to see what happens.

When the weight of the evidence favors an idea so strongly that it can no longer be plausibly denied, we advance the idea as a likely truth.

In effect, correlation does not equal causation.

if someone wants proof that a single factor causes a single outcome, a correlation is not good enough.

A finding is said to be statistically significant when there is less than 5% probability that it is due to chance. This means, for example, that there is a 95% chance that we will get the same result if the study is repeated.

Another arbitrary cutoff point is 99%. In this case, when the result meets this test, it is said to be highly statistically significant.

Knowing the process by which something works in the body means knowing its “mechanism of action.”

Promotion is reversible, depending on whether the early cancer growth is given the right conditions in which to grow. This is where certain dietary factors become so important. These dietary factors, called promoters, feed cancer growth. Other dietary factors, called anti-promoters, slow cancer growth. Cancer growth flourishes when there are more promoters than anti-promoters; when anti-promoters prevail, cancer growth slows or stops. It is a push-pull process. The profound importance of this reversibility cannot be overemphasized.

Similarly, a developing cancer tumor may wander away from its initial site in the body and invade neighboring or distant tissues. When the cancer takes on these deadly properties, it is considered malignant. When it actually breaks away from its initial home and wanders, it is metastasizing. This final stage of cancer results in death.

Enzyme activity could be easily modified simply by changing the level of protein intake.18–21

Decreasing protein intake like that done in the original research in India (20% to 5%) not only greatly decreased enzyme activity, but did so very quickly.

What does this mean? Decreasing enzyme activity via low-protein diets implied that less aflatoxin was being transformed into the dangerous aflatoxin metabolite that ha...

From our extensive research, one idea seemed to be clear: lower protein intake dramatically decreased tumor initiation.

Foci development was almost entirely dependent on how much protein was consumed, regardless of how much aflatoxin was consumed!

Animals starting with the most cancer initiation (high-aflatoxin dose) developed substantially less foci when fed the 5% protein diet. In contrast, animals initiated with a low-aflatoxin dose actually produced substantially more foci when subsequently fed the 20% protein diet.

Ten percent dietary protein is equivalent to eating about 50–60 grams of protein per day, depending on body weight and total calorie intake.

In the animals fed the 20% level of protein, foci increased in number and size, as expected, when the aflatoxin dose was increased. The dose-response relationship was strong and clear. However, in the animals fed 5% protein, the dose-response curve completely disappeared.

There was no foci response, even when animals were given the maximum tolerated aflatoxin dose. This was yet another result demonstrating

that a low-protein diet could override the cancer-causing effect of a very powerf...

In these experiments, plant protein did not promote cancer growth, even at the higher levels of intake.

Gluten, the protein of wheat, did not produce the same result as casein, even when fed at the same 20% level.