Associations of blood Omega-3 fatty acid, inflammatory markers, and lung function in UK biobank participants with inflammatory bowel disease

Background Blood omega-3 fatty acids have been linked to inflammatory markers and lung function, but their effects in participants with inflammatory bowel disease (IBD) remain unclear. Objective This study aimed to investigate inflammatory markers in the relationship between blood omega-3 fatty acids and lung function in IBD participants and subtypes. Design, setting and patients A total of 497,134 UK Biobank participants were screened, and 3340 participants with IBD were included in the analysis. Exposures and outcomes Participants were classified into quintiles based on blood omega-3 fatty acid levels (% of total fatty acids), with Q1 as the reference. Linear regression compared inflammatory markers across quintiles. We then examined how inflammatory markers might link omega-3 levels to lung function. Results IBD participants, particularly those with Crohn's disease, showed stronger reductions in inflammatory biomarkers—white blood cells, basophils, neutrophils, neutrophil-to-lymphocyte ratios, and C-reactive protein (CRP) ( p < 0.001)—at higher omega-3 levels. CRP and neutrophils were potential mediators between omega-3 levels and lung function (FEV₁ and FVC). A 1 % increase in omega-3 levels reduced CRP by 0.27 mg/L and neutrophils by 0.07 × 10⁹ cells/L, corresponding to reductions of 10.88 mL in FEV₁ and 12.36 mL in FVC for CRP, and 38.20 mL in FEV₁ and 39.36 mL in FVC for neutrophils. Mediation analysis showed that CRP and neutrophils accounted for 21 % ( p = 0.01) and 18 % ( p = 0.02) of the FEV1 effect, and 22 % ( p = 0.049) and 16 % ( p = 0.049) of the FVC effect, respectively. Conclusions Higher omega-3 fatty acid levels were associated with reduced inflammatory biomarkers, which may also be associated with lung health in individuals with IBD, particularly those with Crohn's disease. Future studies should investigate additional immune mediators, including cytokines and chemokine.