Effects of n-3 fatty acids on serum interleukin-6, tumour necrosis factor-alpha and soluble tumour necrosis factor receptor p55 in active rheumatoid arthritis.

We investigated the effects of a low n-6 fatty acid (FA) diet supplemented with fish oil on serum pro-inflammatory cytokine concentrations and clinical variables in patients with active rheumatoid arthritis (RA). Sixty patients were randomly assigned to receive a diet low in n-6 FAs and n-3 FAs supplement (fish oil group), a diet low in n-6 FAs and placebo (placebo group), or no special diet or intervention (control group). Serum cytokines and clinical and biochemical variables were evaluated at baseline and various timepoints. At week 18 the fish oil group had significant reductions in linoleic acid, C-reactive protein (CRP) and soluble tumour necrosis factor receptor p55 (sTNF-R p55), and significant elevations in eicosapentaenoic acid and docosahexaenoic acid compared with baseline. There were no significant differences in the clinical variables between the three groups. At week 24 there were significant reductions in interleukin-6 and TNF-alpha in the fish oil and placebo groups. Supplementation with n-3 FA and a low n-6 FA intake decreased serum sTNF-R p55 and CRP levels in patients with RA.