Possible roles of diet in the etiology of rheumatoid arthritis: A systematic review

Background: There is a growing interest in the possible role of diet in the prevention of rheumatoid arthritis (RA). However, the evidence for diet having a role in the etiology of RA is inconsistent, sometimes conflicting. Objective: To critically appraise the literature to pool the results of studies to clarify the relation between diet risk and RA. Methods: We performed a systematic review using guideline-recommended methodology to evaluate the association between pre-illness diet or diet pattern and the risk of subsequent RA diagnosis. Results: A total of 25 studies met the inclusion criteria. They include 13 cohort studies, 10 case-control studies and 2 nested case-control studies, with a total of 1279810 participants. There were new evidences of a protective effect of long term consumption of alcohol. High sodium intake was associated with an increased risk of RA. Fish intake has consistently been shown to have no effect on the development of RA. Mediterranean diet pattern, Vitamin D intake, and the consumption of long-chain omega-3 acids were not associated with an increased/ decreased risk of RA in every two studies. There were non-statistically significant association between RA and sugar-sweetened soda, red meat, vegetable and fruits in each single study. The association between coffee, tea and RA was consistent, and here exists an inverse relationship between olive oil and RA. Due to the heterogeneity of study designs and analyses, the results could not be pooled. Conclusion: The results of this SR indicate that alcohol consumption and sodium intake may be associated with RA risk, especially evidence from recent studies. Because of some discordant results, the debate continues on whether some other dietary intakes increase or decrease RA risk.