Soybeans, for one, contain protease inhibitor, a powerful anti-cancer compound. You won't find it in useful quantities in animal food. Kidney Stones and Gallstones. Aggravated by animal foods. Vegetarians tend to be thinner than meat-eaters, and studies contain it.
Obesity is considered by many doctors to be a disease in itself.
The condition of the intestinal flora is critical to overall health. Animal products putrefy in the colon. Animal products uniformly have longer transit times. Food from animals contain their waste, including adrenaline, uric and lactic acid, etc. This causes excess nitrogen in the blood that creates a host of long-term health problems.