Adherence to a Mediterranean diet is associated with reduced disease activity, lower levels of inflammatory markers, and improved physical function in individuals with rheumatoid arthritis, with these effects potentially mediated by alterations in gut microbiota composition and a reduction in pro-inflammatory bacterial taxa such as Prevotella.

Eating a Mediterranean diet feeds beneficial gut bacteria that make butyrate, a compound that strengthens the gut lining and stops harmful immune cells from forming. This prevents bacterial toxins from leaking into the blood and triggering joint inflammation. The gut bacteria also calm down the immune system by increasing protective cells and reducing the ones that attack joints.