" Then there are two new twists. First, it appears that one autoimmune disease, called ankylosing spondylitis, produces antibodies to a gut bacterium called Klebsiella pneumoniae. Conversely, a different autoimmune disease called rheumatoid arthritis produces antibodies to a second gut bacterium called Proteus mirabilis. Now, this might not seem that earth-shattering, but recent work has shown that the refined carbohydrates in processed food feed those two bacteria in particular, and that carbohydrate restriction improves both of these diseases. Indeed, a low-sugar, high-fiber Mediterranean diet has been shown to be efficacious at prevention and treatment of rheumatoid arthritis. Furthermore, introduction of fiber to the diet appears to improve asthma (frequently an autoimmune disease), likely by improving gut function and reducing inflammation. "

― Robert H. Lustig , Metabolical: The Lure and the Lies of Processed Food, Nutrition, and Modern Medicine