No effect of added β-glucan or of fructooligosaccharide on appetite or energy intake

BACKGROUND: An increase in gastrointestinal viscosity or colonic fermentation is suggested to improve appetite control and reduce food intake. It has been proposed that β-glucan and fructooligosaccharide (FOS) are food ingredients that increase gastrointestinal viscosity and colonic fermentation, but the results are inconclusive. OBJECTIVE: The objective was to test the effect of FOS, β-glucan, or a combination thereof on appetite ratings and food intake over 2 consecutive days. DESIGN: In a 4-way balanced-order, crossover, double-blind design, 21 healthy volunteers [mean body mass index (in kg/m²) 25.9] consumed a meal-replacement bar at 0900 and an ad libitum lunch at 1300 on 2 consecutive days. On day 1 only, the subjects consumed a second (identical) bar at 1700 and a fixed snack at 1900. The control bar contained 0.3 g β-glucan from 6.8 g oats (control), and the 3 equicaloric test bars contained an additional 0.9 g β-glucan (from 8.0 g barley), 8 g FOS, or 0.9 g β-glucan + 8 g FOS. Appetite scores and subsequent ad libitum test meal intakes were measured. Viscosities in response to bar consumption were determined under simulated gastric conditions. The results were analyzed by analysis of covariance. RESULTS: The addition of β-glucan, FOS, or a combination thereof did not affect appetite ratings or food intake, although the addition of β-glucan to the bar doubled gastric viscosity (841 compared with 351 mPa · s). CONCLUSIONS: Consumption of β-glucan, FOS, or a combination thereof in meal-replacement bars at the levels tested for 2 consecutive days does not improve appetite control. Efficacy may have improved if the consumption period was longer, if the content of β-glucan was greater, or if a form of β-glucan that generates even higher gastric viscosity was consumed. This trial was registered at clinicaltrials.gov as NCT00776256.