Total, Insoluble, and Soluble Dietary Fiber Intake and Insulin Resistance and Blood Pressure in Adolescents

BACKGROUND/OBJECTIVES: To evaluate sex and race differences in fiber intakes, which are understudied in adolescents, and to investigate whether low insoluble and soluble fiber intakes would be associated with higher risk for insulin resistance and blood pressure (BP). SUBJECTS/METHODS: A total of 754 black and white adolescents, 14 to 18 years old (49.2% blacks; 50.3% female) were previously recruited in Augusta, Georgia, the US between 2001 to 2005. Diet was assessed with four to seven independent 24-hour dietary recalls. RESULTS: The average daily consumption of total, insoluble, and soluble fiber were 10.9, 6.7, and 4.0g, respectively. Only two adolescents met their daily fiber intake recommendation. Adjusted multiple linear regressions revealed that increasing dietary fiber intake from current averages to recommendation levels (12g to 38g in the male and 9.9g to 25g in the female), were associated with predicted decreases of 5.4 and 3.0 mg/dL fasting glucose, 7.0 and 5.0 mg/dL fasting insulin, 1.6 and 1.1 HOMA-IR, 6.3 and 3.7 mmHg SBP, and 5.2 and 3.0 mmHg DBP in the males and females, respectively (all p < 0.05). Furthermore, both insoluble and soluble fiber intakes were inversely associated with fasting insulin and HOMA-IR (p <0.05); whereas only soluble fiber intake was found to be associated with BP (p <0.05). CONCLUSIONS: Fiber consumption in adolescents is far below daily-recommended levels across all sex and race groups. Lower fiber intake of all types is associated with higher insulin level. Fiber Intake at recommendation levels may be associated with significant cardiometabolic benefits.