Sodium and potassium intake in rheumatoid arthritis: a systematic review of clinical studies with implications for disease-related outcomes

Rheumatoid arthritis (RA) is characterized by immune-mediated inflammation resulting in excess cardiovascular disease (CVD) risk. Increased sodium, decreased potassium intake and their ratio have been acknowledged as CVD risk modifiers, while pathophysiological studies suggest a role in autoimmunity and inflammation. We aimed to review in a systematic manner the literature regarding the effects of dietary sodium, potassium intake and their ratio, on cardiovascular and disease-related outcomes in patients with RA. We performed a systematic literature search in Medline and Cochrane. Our research concluded to 1,283 patients (8 studies). Although not all studies coincide, most agree that increased dietary sodium and reduced dietary potassium intake are adversely associated with disease related (rheumatic and immunologic) outcomes. The ratio between sodium and potassium emerges a potential indicator of autoimmunity state that needs to be further balanced. Only 4 studies reported associations with cardiovascular outcomes in RA, particularly hypertension, although not consistently and none with hard CVD endpoints. These findings support that interventions promoting a poor in sodium and rich in potassium diet in RA may have beneficial effects in terms of autoimmunity regulation, suppression of inflammation and improvement in cardiovascular health.