Proposed Anti-Inflammatory Diet Reduces Inflammation in Compliant, Weight-Stable Patients with Rheumatoid Arthritis in a Randomized Controlled Crossover Trial

Abstract

Background: It is unclear to what extent adjuvant dietary intervention can influence inflammation in rheumatoid arthritis (RA).

Objectives: The objective was to assess the effects of dietary manipulation on inflammation in patients with RA.

Methods: In a crossover design, participants [n = 50, 78% females, median BMI (in kg/m2) 27, median age 63 y] were randomly assigned to begin with either a 10-wk portfolio diet of proposed anti-inflammatory foods (i.e., a high intake of fatty fish, whole grains, fruits, nuts, and berries) or a control diet resembling a Western diet with a 4-mo washout in between. This report evaluates the secondary outcome markers of inflammation among participants with stable medication. Analyses were performed using a linear mixed ANCOVA model.

Results: There were no significant effects on CRP or ESR in the group as a whole. In those with high compliance (n = 29), changes in ESR within the intervention diet period differed significantly compared with changes within the control diet period (mean: -5.490; 95% CI: -10.310, -0.669; P = 0.027). During the intervention diet period, there were lowered serum concentrations of C-X-C motif ligand 1 (CXCL1) (mean: -0.268; 95% CI: -0.452, -0.084;P = 0.006), CXCL5 (mean: -0.278; 95% CI: -0.530, -0.026 P = 0.031), CXCL6 (mean: -0.251; 95% CI: -0.433, -0.069; P = 0.009), and tumor necrosis factor ligand superfamily member 14 (TNFSF14) (mean: -0.139; 95% CI: -0.275, -0.002; P = 0.047) compared with changes within the control diet period.

Conclusion: A proposed anti-inflammatory diet likely reduced systemic inflammation, as indicated by a decreased ESR in those who completed the study with high compliance (n = 29). These findings warrant further studies to validate our results, and to evaluate the clinical relevance of changes in CXCL1, CXCL5, CXCL6, and TNFSF14 in patients with RA.

Keywords: Rheumatoid arthritis; Western diet; anti-inflammatory diet; biomarkers of inflammation; diet intervention; inflammation.

FIGURE 1

Flow chart of subject recruitment reported according to CONSORT. CRP and ESR was quantified in all participants’ samples. Quantifying relative concentrations of inflammation-related proteins in serum samples in the multiplex assay was done only if samples had been handled according to the strictest protocol and in participants whose samples were available from all visits. Participants with new or discontinued DMARD or glucocorticoid treatment were excluded from analyses, and only those who completed both diet periods with high compliance were selected for a sensitivity analysis. CRP, C-reactive protein; DMARD, disease modifying ant-rheumatic drug, ESR, erythrocyte sedimentation rate.

FIGURE 2

Changes in concentrations of inflammation-related proteins within and between dietary periods measured in participants completing at least one diet period who did not discontinue or start any new disease modifying anti-rheumatic drug or glucocorticoid therapy, n = 26. Black colored lines denotes P < 0.05. Concentrations are presented in an arbitrary, semiquantitative log2 scale that is valid for comparison of relative concentrations between different time points within individuals, analyzed using a linear mixed model with period, treatment, BMI, and baseline value as fixed effects and subject as random effect. See Supplemental Table 1 for abbreviations. ¹Analyzed and presented on a log10 scale in order to comply with model assumptions.