I believe no one diet works equally for every single individual with Autoimmune conditions. For some, a plant-based diet reduces symptoms, for others like Jordan B. Peterson, and his daughter (I believe she suffered from RA) a purely meat-based diet reduced all of their symptoms. Personally, I struggle with Hashimotos, Ankylosing Spondylitis and Crohn's Disease and have to stay away from sugary foods, alcohol and caffeine or else one of the conditions will flare up. Any type of meat is fine for me however.

Some meats like chicken do cause flare ups for auto immune people because the chickens diets are full of crap food yes. Pork also causes a lot of people in these communities issues.

Cows on the other hand just eat grass or plain grains ... and have 7 stomachs filtering and cleaning their food.