In short, it is about the multiple health benefits of consuming plant-based foods, and the largely unappreciated health dangers of consuming animal-based foods, including all types of meat, dairy and eggs.
T. Colin Campbell, Thomas M. Campbell (II.) (2006). “The China Study: The Most Comprehensive Study of Nutrition Ever Conducted and the Startling Implications for Diet, Weight Loss and Long-term Health”, p.21, BenBella Books