If there is a subject more rife with bad science than that of human nutrition, I don't know what it would be. It seems that every year there is another fad diet, based on unproven theory and void of any semblance of scientific evidence. Of course, the reason that these schemes come along is because people want to live long and healthy lives, and my introductory chemistry students have lots of questions related to their own nutrition. "The China Study" is a book that I can recommend to them. It is based on a lifetime of research by Colin Campbell of Cornell University. He was head of an international group of researchers that studied the eating habits of people in different cultures and their health consequences. As the title implies, the largest and most convincing of these was a study of 6500 Chinese persons of both sexes, from 65 "counties" of China. The range of lifestyles was very large, from urban to rural, and their diets also represented a much larger range of foods than is found in American or European populations. Why is it that the incidence of obesity, diabetes, cancer, and heart disease is very high in our population and very low in countries that have far "poorer" diets? The "bottom line" of this thoroughly-documented study is essentially that animal protein is not good for us - even milk, "the perfect food".My students (and me!) may not relish the change to a vegetarian diet, but it is difficult to refute the mass of evidence in "The China Study".