T. Colin Campbell with Thomas M. Campbell II (2005, Dallas, Texas: BenBella Books)
by Daniel Kirschenbaum, Ph.D., Clinical Director, Healthy Living Academies and Professor of Psychiatry & Behavioral Sciences, Northwestern Universtiy Medical School
Nutritionist Colin Campbell has spent a lifetime studying protein. Dr. Campbell initially believed that protein lived up to the origins of the word, from the Greek word proteios, meaning “of prime importance.” He and his colleagues at Cornell University and elsewhere began studying the influence of protein on disease in the 1960s and have published more than 350 articles in premier scientific journals on their impressive work. They had expected inadequate amounts of animal protein to cause diseases associated with malnutrition, but their startling findings showed just the opposite. Commonly consumed levels of animal protein in the industrialized countries of the world may greatly increase risk of developing and/or exacerbating cancer, heart disease, and many other disorders. The purpose of this book was to explain to intelligent non-scientists the nature of this research, its implications, and the political/financial barriers to making these findings known.
Dr. Campbell effectively enlisted the help of his immediate family, especially his writer-actor son Thomas Campbell, to create a remarkably clearly written and fascinating account of many very important studies with animals. They also described the process, findings, and implications of the most ambitious nutritional survey every conducted, The China Study. The China Study began because the premier of China, Chou EnLai, contracted cancer and wanted to understand why. Beginning in the early 1980s Dr. Campbell and his associates surveyed 2400 Chinese counties, 880 million people (96% of the population), to examine factors associated with death from 12 different cancers. The findings from this remarkable survey correspond to some degree with the dozens of animal studies conducted in laboratories on the effects of protein on disease.
Current dietary recommendations ( Institute of Medicine) include a level of protein intake ranging from about 40 to 120 grams per day. These numbers are based on the current Dietary Reference Intakes (DRIs). That range varies tremendously based on such factors as activity levels and amounts of muscle being maintained. If we consume about 10% of our total calories from protein, then virtually all of us will supply our bodies with adequate amounts of protein. In the USA, we consume 50% more than that level on average. For many weight controllers who are actively attempting to lose weight, 10% of calories from a total intake of 1200 – 1500 calories per day would equal only 30-40 grams of protein per day.
In our programs at Wellspring Camps and the Academy of the Sierras for overweight teenagers, we target 70 grams of protein per day. This level, about twice the minimal number of protein grams required for nutritional health, has been associated, at least in our experience, with substantial weight loss without much hunger or many complaints about the food.
Protein can help you control your weight in several ways. These include:
A recent review of the effects of protein versus carbohydrates versus fat on appetite led to the following conclusion:
The data derived from a number of sources ranging from diet surveys to whole body calorimetry and nutrient infusion studies suggest that in the short-to-medium term, protein is more satiating that carbohydrate which is more satiating than fat. (R.J. Stubbs)
One simple way of thinking about these findings concerns the complexity of protein molecules. Protein molecules are far more complex than carbohydrate and fat molecules. This complexity causes the body to take more time to digest high protein foods, resulting in a time-release effect on the amount of glucose (sugar) in our blood streams. The specific qualities of protein also trigger the release of chemicals in the brain (neurotransmitters) somewhat similar to Prozac and other anti-depressants. To obtain these effects consistently, it helps to eat protein consistently throughout the day.
Protein exists in a great many foods, but especially rich sources of protein include legumes (seed bearing plants like soybeans, green beans, peas, lentils, and kidney beans), egg whites, and lean meats (white meats of poultry; fish; seafood). For example, ½ cup of legumes and one ounce of lean meat both contain about 10 grams of protein.
A Caveat about Animal versus Plant Protein based on The China Study: Plant Protein is Probably Better for Your Health
In their very important series of studies summarized in the book, Dr. Campbell showed that relatively high levels of animal proteins can increase the development of cancerous cells and tumors in mice and rats. Humans and rats apparently have similar needs for protein. Dr. Campbell used strains of rats and mice which were exposed to a high level of a couple of different types of carcinogens (chemicals that reliably produce cancerous tumors over time). He found that providing these animals with diets that contained 20% of its calories from animal protein caused dramatic increases in both pre-cancerous cells (called “foci”) and actual lethal tumors over time. Quite remarkably, diets containing 5% animal protein and 20% plant protein did not produce these very harmful effects.
Related findings have apparently been obtained for other types of proteins and other types of cancers based on studies by Dr. Campbell’s group and other researchers. However, in this wonderful new book, Dr. Campbell provided the following caution when applying these studies to our lives:
So much consistency [in the animal studies] was impressive, but one aspect of this research demanded that we remain cautious: all this evidence was gathered in experimental animal studies. Although there care strong arguments that these provocative findings are qualitatively relevant to human health, we cannot know the quantitative relevance. In other words, are these principles regarding animal protein and cancer critically important for all humans in all situations, or are they merely marginally important for a minority of people in fairly unique situations (p.66).
When Dr. Campbell and his associates ventured far outside their laboratories in Ithaca New York to survey people in China, they found that a diet very low in fat, high in fiber, and low in animal protein seems clearly associated with very low incidences of heart disease, cancer, and other serious afflictions in affluent cultures like ours. However, even the least active groups of Chinese people who were studied are more active than the vast majority of Americans. So, increased activity was also associated with improved health, as we would expect.
The China Study’s results were consistent with the animal studies, but such survey research doesn’t prove that animal protein at modest levels will prove harmful for most people, most of the time. In fact, many people in China consume a good deal of their protein through fish. However, additional research may show that even in this context, much smaller amounts of animal protein than expected can produce harmful results. The most cautious approach would be to attempt to eliminate as much animal protein (and fat) from you diet as possible. A less stringent approach would be to aim for no more than 40 grams of animal protein per day, which would be less than 10% of calories from protein for most weight controllers. The latter level would provide some protection, as shown by some of Dr. Campbell’s findings. This research indicated that precancerous foci didn’t develop at an accelerated level until a 12% animal protein diet was consumed by the rats in this study.
Following even the least restrictive recommendation (40 g of animal protein per day) will prove quite challenging to many people. You would find yourself eating lots more soy milk, low fat tofu, Seitan (a wheat protein meat substitute), and legumes in order to maximize not only your appetite but your long-term health. Fortunately, these foods are becoming more widely available in very convenient forms, including frozen low-fat soy cheese pizzas and many other products. Sources of animal protein are among the more calorie dense foods weight controllers typically consume. This approach will, therefore, also encourage consumption of foods that are low in caloric density, another good principle for appetite control.
The final one hundred pages in the Campbells’ superb book describe the many barriers faced by scientists when attempting to get people to pay attention to findings such as those described in this book. As noted by the Campbells, “The distinctions between making a profit and promoting health have become blurred.” They argue very persuasively that even intelligent consumers have to struggle to find the truth, often hidden by billion dollar marketing campaigns favoring very profitable but very unhealthy and inaccurate information about eating and health. These influences also affect which studies are published in major journals, funded by health organizations, respected by national groups, and reported in the media. Fortunately, books like The China Study are being published that allow those who find it to get a better understanding of the truth as we now know it. It may take a long time to counter the powerful influences that fight against such knowledge, but at least the struggle to do so took a step forward with the publication of this important book.