Glucose and Insulin Responses to a New Zero-Energy Fiber Source

Objective: Consumption of a number of soluble fiber sources reduces glucose and insulin responses in humans. These fibers provide some available energy. Z-trim, a completely insoluble, noncaloric fiber/fat replacer produced from grain, was developed by ARS scientist George Inglett but until this report had not been tested in humans. The objective was to test the effects of consumption of various doses of this new fiber on glucose and insulin responses in humans.

Design: Men and women (12 each) matched for age and body mass index (41 years, BMI 27) were given glucose or glucose with three levels of fiber in a Latin-square design. Blood samples were obtained before and 30, 60, 120 and 180 minutes after solutions containing glucose alone (1 g/kg body weight) and glucose plus 0.08, 0.17 and 0.33 g/kg body weight of Z-trim were consumed. Plasma glucose, insulin and glucagon were determined by enzyme or radioimmunoassays. A repeated-measures analysis of variance was conducted.

Results: Glucose responses were lower for women than for men (p = 0.02) regardless of the test solution. At 30 minutes, glucose levels of men were 0.7–1.1 mmol/L lower after the two higher levels of fiber than after glucose alone. Insulin peak responses were delayed by high amounts of Z-trim. Fasting and response levels of glucagon were higher (p < 0.002) in women than in men. The decline in glucagon usually seen after a glucose load was moderated by the addition of fiber.

Conclusion: Although high levels of this new fiber may beneficially affect glucose metabolism of middle-aged people, it is less effective than soluble fiber.