Please read this:
The China Study: Fact or Fallacy?
Denise Minger has analysed the data on which Campbell based his book The China Study in which, to quote wikipedia, the authors conclude:
that diets high in animal protein (including casein in cow's milk) are strongly linked to diseases such as heart disease, cancer, and Type 2 diabetes.Denise has gone back to the data and analysed it herself......and the conclusions are a bit different from those that Campbell arrived at.
In sum, “The China Study” is a compelling collection of carefully chosen data. Unfortunately for both health seekers and the scientific community, Campbell appears to exclude relevant information when it indicts plant foods as causative of disease, or when it shows potential benefits for animal products. This presents readers with a strongly misleading interpretation of the original China Study data, as well as a slanted perspective of nutritional research from other arenas (including some that Campbell himself conducted).
Please read the original and check out Stephan, Kurt, Richard and Robb - each with an excellent analysis.
Something that both Kurt and Stephan pick up on is that while animal food is apparently not a problem wheat is.
UPDATE - Campbell responded to Denise's critique......but Denise has taken his response apart again with great precisions.