Oxylipin serum profile changes in response to an open-label anti-inflammatory dietary intervention

Oxylipins are bioactive lipids involved in inflammation. This study evaluated how a 2-week anti-inflammatory diet (ITIS, omega-3/omega-6 ratio of 1:1.5) affects plasma oxylipin profiles in patients with active Rheumatoid Arthritis (RA).

In an open-label pilot trial, 20 RA patients (≥3 tender and ≥3 swollen joints) followed the ITIS diet. Targeted lipidomics by mass spectrometry was used to quantify oxylipins. Patients were classified as responders or non-responders based on ≥50 % pain reduction (Pain-50). Dietary intake was assessed through diet scores, and statistical analyses were performed using RStudio.

Participants were predominantly female (90 %) with an average age of 57.1. At baseline, responders consumed more walnuts (p = 0.08), almond milk (p = 0.06), avocado (p = 0.04), and quinoa (p = 0.05), and fewer burgers (p = 0.02). No differences in diet adherence were observed between groups. Baseline oxylipin levels did not differ significantly. However, after the intervention, six oxylipins-5-HETE, 11,12-diHETrE, 14,15-diHETrE, 19,20-DiHDPA, 9-oxo-ODE, and 14,15-EET-differed significantly between responders and non-responders. Notably, oxylipins derived from both arachidonic acid (omega-6) and eicosapentaenoic acid (omega-3) decreased significantly after the diet (p = 0.0006 and p = 0.01, respectively).

The anti-inflammatory diet modified circulating levels of both pro- and anti-inflammatory oxylipins. These changes varied by pain response, suggesting that diet can influence inflammatory pathways in RA. Further studies are warranted to clarify the mechanisms linking dietary changes, oxylipin modulation, and clinical outcomes.

NCT04999683.