Introduction: Systemic inflammation is a key contributor to the pathogenesis of chronic diseases, including cardiovascular disease (CVD), type 2 diabetes mellitus (T2DM), and cancer. Elevated markers such as C-reactive protein (CRP) and interleukin-6 (IL-6) are associated with increased risk of these diseases. Dietary fiber has been linked to reduced inflammation through its impact on gut microbiota and production of anti-inflammatory short-chain fatty acids (SCFAs). However, prospective data on this relationship are limited. Methods: A prospective observational study was conducted with 200 participants aged 25–65, of whom 183 completed the study (91.5% retention). Dietary fiber intake was assessed bi-weekly using 24-hour recalls and categorized into tertiles: low (<12 g/day), moderate (12–25 g/day), and high (>25 g/day). Fasting blood samples were collected at baseline and every two months to measure CRP and IL-6 levels using high-sensitivity assays. Linear mixed-effects models evaluated the association between fiber intake and changes in inflammatory markers, adjusting for age, sex, BMI, and physical activity. Results: Participants in the high fiber intake group exhibited the largest reductions in CRP (-1.3 ± 0.7 mg/L) and IL-6 (-1.2 ± 0.6 pg/mL), compared to moderate (-0.8 ± 0.6 mg/L and -0.6 ± 0.5 pg/mL, respectively) and low intake groups (+0.2 ± 0.5 mg/L and +0.3 ± 0.4 pg/mL, respectively). Changes were statistically significant (p<0.001). Reductions were more pronounced in participants with overweight or obesity. Conclusion: Higher dietary fiber intake was associated with significant reductions in systemic inflammation, highlighting its potential as a cost-effective intervention for mitigating chronic disease risk. Public health strategies should prioritize increasing dietary fiber consumption to improve population health outcomes.

Systemic inflammation is a key contributor to the pathogenesis of chronic diseases,