Adherence to a Mediterranean diet is associated with modest improvements in disease activity and quality of life in individuals with rheumatoid arthritis, but these associations may be confounded by concurrent lifestyle changes such as increased physical activity or improved overall diet quality, and no clear association between Mediterranean diet adherence and rheumatoid arthritis risk has been established.

Eating a Mediterranean diet increases fiber and healthy fats, which feed good gut bacteria that produce molecules that strengthen the gut lining and calm the immune system. This prevents harmful bacterial parts from leaking into the blood and triggering joint inflammation. The diet also reduces molecules that activate aggressive immune cells and increases molecules that promote calming immune cells, leading to less swelling and pain in the joints.