From research on the impact of animal protein (specifically casein, the protein in cows milk) on cancers in rats, he gradually widened his research into human nutrition and in a remarkable alliance with researchers in China to an immense epidemiological study of disease in humans.
The conclusions of this work are immense and no short review can give the full flavor of the comprehensive analysis performed. I hope that the following summary of this work might cause you to read the work in its entirety.
Cancer and Animal Protein
In a series of studies over a number of years at Cornell, it was demonstrated that rats susceptible to cancer could have the cancer promoted or stopped merely by controlling the amount of animal protein in their diet. At levels of nourishment where 20% of calories were from casein, cancer advanced and the rats died. Reducing the level of protein to 5% of calories caused the cancers to not start, or if started, to stop. The cancer progression could be turned on and off by manipulating protein content in the diet. Campbell notes that rat metabolisms are very similar to those of humans
Diseases of Affluence and Diet
The China Study was a complex and detailed study of nutrition and disease covering large areas of the rural Chinese population. In a few words the study revealed very high correlation between a number of diseases that plague the western world and which have become known as diseases of affluence: heart disease, cancer, obesity, diabetes and osteoporosis. In those areas of China where the population consumed a plant based diet with little or no animal protein in the diet, the diseases of affluence were almost non-existent. As the proportion of animal protein increased, the incidence of these diseases also increased. A statistically significant biomarker for these diseases was determined to be cholesterol with values of less than 150 effectively removing danger of developing such diseases.
The Pharmaceutical/Government/Medical Alliance
A significant part of the book details the work of the elder Campbell as a member of various government agency studies and boards where he describes the difficulty in getting nutritional standards (namely plant based diets) established which improve the health of Americans. The problem he outlines is the difficulty of overcoming the massive financial clout of the processed and animal food industries who would be effectively wiped out by such standards. Equally such standards would devastate the pharmaceutical industry which has made untold billions out of such drugs as the line of statins. Government itself has huge bureaucracies that interact with these industry sectors and they, too, would not longer be needed.
From this work it is easy to conclude that the most effective way of reducing the incidence of the diseases of affluence is to restrict one’s diet to a plant based one with little or no reliance on the consumption of animal protein. This diet has been adopted by the Campbells. It is also the diet that I am on, although my initial motivation derived only from a concern for heart disease and came about as a result of reading Esselstyn’s work.
The work is extensively footnoted and traces many of the nutritional recommendations back to earlier works going back to the mid 19th century (and, indeed, back to Hippocrates!).
If this topic interests you at all, and if you are reading this you are likely part of the affluent western society, then I think you would be well served to adopt a plant based diet and to better understand all of the reasons for doing so, do read the work by the Campbells, father and son.