Background Rheumatoid arthritis (RA) is a chronic, inflammatory, autoimmune disease that may affect many aspects of patients' life. Patients with RA seem to be interested in alternative and complementary treatments such as managing their eating habits, which may help them to gain a sense of control over their disease. However, the role of nutrition in the management of RA remains unclear.
Objectives The aim of this study was to review and to describe current studies of nutritional interventions used in the management of RA.
Methods A systematic search was conducted using the medical databases MEDLINE (via PubMed) and EMBASE as well as backward citation tracking. Searches were limited to articles in English, published from January 2003 to January 2014. Two authors independently selected studies for inclusion and assessed methodological quality using Critical Appraisal Skills Programme (CASP) checklists.
Results Our search strategy yielded 19 randomized, placebo-controlled clinical trials including 3 crossover trials. Firstly, 9 trials investigated the role of n-3 and/or n-6 fatty acids. Four trials indicated that dietary supplementation with n-3 fatty acids (>3g/day) improved disease activity in patients with RA in terms of pain intensity, grip strength, duration of morning stiffness and physical functioning. However, 4 trials did not show superior clinical benefit of daily n-3 fatty acids supplementation with moderate or high doses as compared to placebo. Moreover, 2 trials found that a diet low in n-6 fatty acids decreased CRP levels or the numbers of tender and swollen joints. In contrast, another trial found that n-6 fatty acids supplementation resulted in a reduction of DAS28, pain and morning stiffness. Secondly, 8 trials investigated other nutrient supplementation. Specific supplements such as probiotics, pyridoxine, antioxidants, glucosamine and plant-derived polysaccharide were reported not to have any clinical benefit in patients with RA. One single study evaluated the supplementation with potassium in patients with RA. When associated with a sodium-restricted diet, this supplementation was shown to reduce pain. Lastly, 2 trials evaluated diet therapies. Evidence was found for a reduction in inflammatory activity by adjusting to a Mediterranean or a calorie restriction diet. However, these diets were difficult to comply with and maintain in the long-term.
Conclusions Supplementation of n-3 fatty acids, a low n-6 fatty acids intake and some diet therapies appeared to have a positive effect in patients with RA. However, most nutritional interventions cannot be effectively and safely recommended for the management of RA due to the limited number of trials, the inconsistencies between trials and the limits of applicability in patients' daily life. The current evidence suggests that some supplements and suitable diet therapies may warrant further investigation.
Disclosure of Interest None declared