Beyond current fibre recommendations: associations of high dietary fibre intake with inflammation and lipid profile in US adults (NHANES 2015–2018)

Current fibre recommendations are based on historical data and may underestimate the intake required for optimal cardiometabolic protection. We examined whether fibre intakes exceeding current guidelines are associated with additional improvements in inflammation and lipid metabolism. We analysed data from 7,008 adults (≥20 years) from the NHANES 2015-2018 with 24-h dietary recall and biomarker data (CRP, total cholesterol [TC], LDL, HDL, triglycerides [TG]). Fibre intake was expressed relative to recommendations from the Institute of Medicine (IOM) and the Academy of Nutrition and Dietetics (AND), and associations with biomarkers were assessed using multivariable regression models. Higher fibre intake was consistently associated with lower CRP concentrations, with the greatest reductions observed at intakes >150% of the IOM recommendation (>55.7 g/day; 95% CI: 48.6-56.7). Among men, both TC and LDL cholesterol decreased significantly at intakes >150% of IOM values (>69.8 g/day; 95% CI: 64.2-75.4). Triglycerides were significantly lower when fibre intake exceeded AND recommendations (>41.0 g/day; 95% CI: 32.6-49.5). No clear associations were observed for HDL cholesterol. The associations found in this study make us consider the possibility that the benefits of fibre on systemic inflammation and lipid profile may extend beyond current recommended levels. Public health guidelines may need to reconsider fibre targets to better reflect condition-specific benefits rather than minimum thresholds for adequacy should this hypothesis be duly proven by future longitudinal studies.