Without a doubt, sugar, the oil and fat in fried foods, artificial
additives, human-made trans fatty acids found in junk food, and the
excessive amount of refined carbohydrates found in white rice, white
bread, and pasta cause health problems, while non-dietary factors harm
us, too. Stress, a lack of sleep, smoking tobacco, chemical pollution,
and a lack of exercise can wreak havoc on the body. However, since animal flesh and the things that come out of animals are always toxic, the main factors for disease development will always be animal protein, casein, cholesterol, the excessive amount of fat found in all animal products, and the 2-9 percent of naturally-occurring trans-fatty acids found in meat and dairy.
Concerning cancer:
Even though we're all born with cancer cells, the cells won't
"activate" and turn deadly unless they are "expressed". So, preemptively
amputating one's breasts
(mastectomy), or taking some other drastic action, will NOT prevent
cancer development if the cell "activators" are still present. Since
cancer thrives in the acidic environment that animal protein creates, it
is essential to eat plant-based foods exclusively, and control the non-dietary factors to the best of your ability. Check out this 2014 University of Southern California study which clearly indicts animal protein as a deadly toxin.
A 2013 Loma Linda University study confirms that vegans have the lowest cancer rates, while the American Journal of Clinical Nutrition (AJCN) proves that dairy increases the risk of prostate cancer. (A UCSF study of 27,000 men also showed an 81-percent increased risk of prostate cancer from consuming 2.5 eggs per week.) Another AJCN study shows that children who consume high levels of dairy products have close to three times the risk of developing colorectal cancer in adulthood, while a study of 60,000 women reveals that those who had four servings of dairy daily had twice the risk of ovarian cancer. The Lancet also reports that dairy, especially yogurt, will increase the risk of ovarian cancer. In the documentary Forks Over Knives, Dr. John McDougall mocks the medical community for NOT recommending veganism as the best way to prevent, treat or cure cancer.
Dairy also contributes to many other health problems, from acne, asthma and allergies to Crohn's disease, ear infections and diabetes, just to name a few.