Association between dietary inflammatory index, empirical dietary inflammatory patterns and the risk of Long COVID: a prospective cohort study

BACKGROUND: Inflammatory responses and immune dysregulation are considered core mechanisms of Long COVID. Given that diet can modulate systemic inflammation, we evaluated the associations between two indices reflecting dietary inflammatory potential-the Dietary Inflammatory Index (DII) and the Empirical Dietary Inflammatory Pattern (EDIP)-and the risk of Long COVID in a prospective cohort of 69,070 participants from the UK Biobank. METHOD: The DII and EDIP were calculated and categorized into quartiles based on Dietary information obtained from the Oxford WebQ online system. Outcome information was obtained from hospital admission records (HESIN, ICD-10) linked to the UK Biobank. Cox proportional hazards models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI). Restricted cubic splines were employed to evaluate the nonlinearity. RESULTS: After full adjustment, the highest EDIP quartile (most pro-inflammatory) was associated with increased Long COVID risk (HR = 1.15, 95% CI: 1.08-1.22, p < 0.001), with no significant association for DII. Yet, both indices demonstrated significant associations with risks for specific organ system conditions-particularly affecting the cardiovascular, gastrointestinal, kidney, and mental health systems-among the 10 predefined categories. Both indices showed significant non-linear associations with Long COVID risk (p for nonlinearity < 0.05), with a U-shaped pattern for DII and a J-shaped pattern for EDIP. CONCLUSION: In this prospective observational study, a pro-inflammatory dietary pattern was associated with a higher risk of Long COVID-related outcomes and multi-organ sequelae. These findings suggest that dietary inflammatory potential may be relevant to post-COVID-19 health and warrant further investigation as a potentially modifiable factor.