DEAR DR. BLONZ: I wanted your take on what I consider to be a very important book on diet and nutrition. It is called "The China Study," and it is based on 40 years of research in nutrition by professor T. Colin Campbell. He has identified the main cause of the major diseases - animal protein. I would be interested in your opinion of what it says. - M.S., San Diego, Calif.

DEAR M.S.: I am familiar with the work of professor Campbell and the population studies that comprised the Oxford-Cornell-China project. This work was a major addition to the scientific literature, and contains studies on the relationship between diet and disease in China. A solid relationship was found between the incidence of major disease and the addition of animal protein in the Chinese diet. These findings, along with background information on the science of nutrition and the interplay of science, business and politics, are summarized in Campbell's "The China Study" (Benbella Books, 2005).

The research from China was primarily epidemiological research, the type that gathers information on factors associated with observed patterns of disease. Typical of findings from these types of studies might be: "People who eat more (or less) of food component A are at a higher (or lower) risk of developing disease B." It is correctly pointed out in the book that this type of research can't tell us whether food component A is the actual cause of disease B. In the China studies, however, data linking negative effects with the addition of animal protein were quite consistent.

Unlike China, we in the West lay out the welcome mat for heart disease, cancer, obesity and diabetes with our food and lifestyle choices. But the human body needs a well-rounded plant-based diet combined with an active lifestyle whether a person lives in China or in the West.

With a greater selection of whole foods you tend to eat foods grown under different conditions. Aside from their vitamins and minerals, each whole food offers naturally occurring compounds needed by the plant to survive. By contrast, foods of animal origin have few of these defenses, as the animal relies on different skills to survive.

Professor Campbell's book pushes a vegetarian-only position, but meat and other animal-based foods can be a part of the picture, as there is no evidence that the only healthful approach is the vegetarian one. Findings would suggest, though, that animal protein should be part of the supporting cast and not the star.

All this said, I recommend "The China Study." It presents its information in a very approachable way, and professor Campbell provides valuable perspectives on the intrigues of science. Vegetarianism has much going for it, and whether you support all the book's conclusions or not, you will learn much from the read.