The body attacks itself. That's what happens with autoimmune disease.
The most common and researched diseases that fall under the umbrella of autoimmune are:
MS, rheumatoid arthritis, lupus, Type 1 Diabetes, Crohn's disease, Parkinson's, and IBD.
What all these diseases have in common is internal mutiny;
The immune system is complex. T. Colin Campbell compares it to a military network where the white blood cells are the soldiers. Recruitment of these soldiers occurs in the bone marrow, where stem cells are produced. Some are immediately sent out to be useful elsewhere in the body (B cells), while some remain in training for a while and then travel to the thymus where they develop into specialists (T cells). These specialized soldiers seek out other cells in, for example, the spleen and lymph nodes. At these points, the cells prepare their strategy and organize themselves to tackle intruders.
The invaders are protein molecules called antigens. They can be viruses or bacteria, for example, and they all have a unique composition of amino acids (the building blocks of proteins).
To attack such an antigen, the immune system creates a mirror protein—a kind of template—and then goes to work neutralizing the invader with custom-produced antibodies. The next time such an invader presents itself, it is immediately recognized and, thanks to the template, can be eliminated immediately.
IBD is short for Inflammatory Bowel Disease.
Campbell, T.C., Campbell, T. M. The China Study. BenBella Books. Texas, USA. 2016. p. 176-177
Mistakes
Unfortunately, the immune system mistake the body's own molecules for invaders.
Some proteins aren't completely broken down, and fragments enter the bloodstream; these fragments are identified as invaders, and a mold is immediately created to neutralize them. This initiates an autoimmune process that renders many cells harmless (destroys them). Cow's milk is a food source that often contains large amounts of these so-called invader proteins. This can lead to Type 1 diabetes; in this case, the β-cells are neutralized (destroyed).
MS (Multiple Sclerosis) is an autoimmune disease in which the central nervous system becomes chaotic; signals to and from the nervous system are no longer properly coordinated. The cause: the myelin is destroyed. Myelin is the insulating sheath around the end (axon) of a neuron (nerve cell). Connective tissue replaces myelin, and when this hardens, sclerosis (tissue hardening) occurs. It is a progressive disease that confines people to wheelchairs or beds and often results in early death.
Dr. Swank and other researchers discovered back in the last century that people who consumed more dairy products were more likely to develop MS. Furthermore, Dr. Swank was able to demonstrate that people with an early diagnosis of MS who followed a diet very low in saturated fats were able to significantly slow their disease progression. 95% of his study group (n=144, t=34 years) were able to live for over 30 years with mild symptoms! 80% of the group who followed a standard diet (high in saturated fats) died!
After Swank, many more studies have been conducted (in various countries) that have reached the same conclusions:
Butcher J. The distribution of multiple sclerosis in relation to the dairy industry and milk consumption. N Z Med J. 1976 Jun 23;83(566):427-30.
Swank RL, Dugan BB. Effect of low saturated fat diet in early and late cases of multiple sclerosis. Lancet. 1990 Jul 7;336(8706):37-9.
Dip, JB. “The distribution of multiple sclerosis in relation to the dairy industry and milk consumption.” New Zealand Med. J. 83 (1976): 427-430
Agranoff BW., and Goldberg D. “Diet and the geographical distribution of multiple sclerosis.” Lancet 2(7888) November 2 1974 ; 1061-1066
Malosse D, Perron H, Sasco A. et al. “Correlation between milk and dairy product consumption and multiple sclerosis prevalence: a worldwide study.” Neuroepidemiology 11(1992): 304-312