Anti-inflammatory diet may reduce disease activity in rheumatoid arthritis

A proposed anti-inflammatory diet provides positive effects on disease activity in patients with rheumatoid arthritis (RA), a study has shown.

“[W]e did not obtain significant, clinically relevant reductions in Disease Activity Score in 28 joints (DAS28) or its separate components with a portfolio diet containing food items with suggested anti-inflammatory properties compared with a diet nutritionally similar to a typical Swedish diet,” the researchers said. “However, improvements during the intervention period as well as differences between end results of the two diet periods were significant in unadjusted analyses.”

Fifty RA patients were randomized to an intervention diet containing suggested anti-inflammatory foods rich in n–3 fatty acids, fibre, antioxidants, and probiotics or a control diet similar to the general dietary intake in Sweden for 10 weeks. Participants switched diet after a 4-month washout period. Food equivalent to ∼50 percent of energy requirements was delivered weekly to their homes. For the remaining meals, they were urged to eat the same type of foods as those provided during each diet.

No significant difference was found in the primary outcome of change in DAS28-Erythrocyte Sedimentation Rate (ESR) between the intervention and control periods (p=0.116) in the main analysis—a linear mixed ANCOVA model including 47 participants who completed ≥1 diet period. [Am J Clin Nutr 2020;111:1203-1213]

In unadjusted analyses, however, DAS28-ESR significantly decreased during the intervention period and was markedly lower after the intervention than after the control period in participants completing both periods (n=44; median, 3.05, interquartile range [IQR], 2.41–3.79 vs median, 3.27, IQR, 2.69–4.28; p=0.04, Wilcoxon’s Signed Rank test). Moreover, there were no substantial differences seen in the components of DAS28-ESR (tender and swollen joints, ESR, and visual analogue scale for general health).

“The anti-inflammatory diet used in this crossover trial is similar to the Mediterranean diet used in [a parallel trial by] Sköldstam et al, and based on unadjusted analyses, the obtained results are consistent: a reduced DAS28 during the intervention period and a larger reduction than during the control period,” the researchers said. [Ann Rheum Dis 2003;62:208-214]

“During our intervention period, we achieved a median reduction of 0.42 units in DAS28, whereas Sköldstam et al achieved a reduction of 0.56 units. However, disease activity before intervention was higher in Sköldstam et al: 4.4 [vs] 3.4 in our study,” they added.

One component that differentiates the portfolio diet in the current study from a Mediterranean diet is probiotics. RA patients tend to have a less diverse microbiota composition compared with healthy individuals, and probiotics can amend the intestinal microbiota as well as downregulate immune response, according to the researchers. [Front Med 2018;5:349; Int J Rheum Dis 2014;17:519-527]

Clinical studies in the past used several strains of probiotics to improve symptoms in RA patients and showed conflicting results. Some studies reported a decline in disease activity with Lactobacillus casei, alone or together with Lactobacillus acidophilus and Bifidobacterium bifidum. [Int J Rheum Dis 2014;17:519-527; BMC Complement Altern Med 2010;10:1; Med Sci Monit 2011;17:CR347-354; Int J Rheum Dis 2016;19:869-79]

“However, it is not possible to compare [the anti-inflammatory diet in RA] with this research because the strains used differ,” the researchers noted.

“Additional studies are needed to determine whether this diet can induce relevant improvements in RA disease activity,” they added.