Abstract P280: Greater Dietary Fiber Consumption is Associated with Lower Insulin Resistance and Blood Pressure in Adolescents

Abstract

Introduction: Greater dietary fiber intake has shown cardiometabolic benefits in adults. Previously, we have shown that dietary fiber intake is inversely associated with adiposity and inflammation in youth. However, evidence of the relations of fiber intake to insulin resistance and blood pressure in adolescents is lacking. Hypothesis: We hypothesized that greater daily dietary fiber intake would be associated with lower insulin resistance and blood pressure. Additionally, insulin resistance may mediate the relationship between fiber intake and blood pressure. Methods: Seven hundred and sixty-six Southeastern US adolescents from age 14 to 18 were recruited (50.3% females; 49.2% African-Americans). Diet was assessed via four to seven independent 24-hour recalls. Seated systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured five times at 1 minute intervals after 10 minute rest and the last three measurements were averaged. Percent body fat (%BF) was measured by dual-energy x-ray absorptiometry. Fasting blood samples were measured for fasting glucose and fasting insulin. Homeostatic Model Assessment for insulin resistance (HOMA-IR) was then calculated. Results: Multiple linear regressions with bootstrapping, adjusting for age, sex, race, Tanner stage, %BF, and energy intake, revealed that dietary total fiber intake was negatively associated with HOMA-IR, SBP, and DBP (standardized β = -0.22, β = -0.09, and β = -0.12; all p < 0.05). Subcategorizing fiber into soluble and insoluble fiber revealed that both types were negatively associated with HOMA-IR ( p < 0.01). However, only soluble fiber intake was negatively associated with both SBP and DBP (all p < 0.01). No significant race and gender interactions with fiber were identified. Furthermore, a mediation test identified HOMA-IR as a mediator between soluble fiber intake and SBP and DBP (95% CI: -0.34; -0.04; 95% CI: -0.15; -0.01 respectively). Conclusions: Our data suggest that greater consumption of fiber may reduce insulin resistance and blood pressure in adolescents. Furthermore, insulin resistance may mediate the relationship between soluble fiber intake and blood pressure.