The effects of the Mediterranean diet on rheumatoid arthritis prevention and treatment: a systematic review of human prospective studies

Background: Rheumatoid arthritis (RA) is a progressive autoimmune disease characterised by severely swollen and painful joints and presently its treatment is only symptomatic and lifelong pharmacotherapies ares often required with substantial side effects. Frequently, sufferers turn to dietary interventions such as Mediterranean diet (MD) to help manage their disease. The MD is characterised by a high intake of fruits and vegetables, moderate intake of dairy and fish, and low consumption of red meat. The aim of the present study was to systematically review and discuss the effects of MD on the prevention and treatment of RA. Methods: A systematic review was undertaken following the PRISMA guidelines, using four electronic databases (PubMed, Scopus, CINAHL and the Cochrane Database of Systematic Reviews). A search strategy was formulated to select randomised controlled trials (RCTs), controlled clinical trials (CCTs), prospective cohort studies, and nested case-control studies, investigating the effects of the MD on the development and management of RA in humans. Outcome measures included results of pain score Visual Analogue Scale (VAS), Physical Function Index (HAQ) and Disease Activity Index (DAS28). Results: In total, 1080 studies published up until September 2016 were identified, with four papers (two intervention and two prospective) meeting the inclusion criteria. Two intervention studies reported a significant improvement in pain VAS when compared with the control (p<0.05) and a decrease in HAQ score for the MD group (p<0.05). Additionally two studies, reported a significant reduction in the DAS28 score for the MD group (p<0.05). Included prospective studies both reported no significant association between the MD and risk of developing RA amongst their individuals, but clinical trials showed promising results for sufferers’ life quality. Conclusion: There is currently insufficient evidence to support the use of the MD for the prevention of RA. Nevertheless, MD in conjunction with medical interventions has demonstrated beneficial effects in reducing pain and increasing physical function in RA affected individuals.