The threshold for satiating effectiveness of psyllium in a nutrient base.
A combination of psyllium fiber with nutrients in a commercially available wafer (Fiberall-Ciba Consumer Pharmaceutical) was evaluated for its effectiveness in reducing food intake and appetite. Each of 15 nonobese healthy women received no wafers and four different amounts (39, 104, 169, and 234 kcal) of the fiber wafer with water, in a ratio of 13 kcal (and 0.565 g psyllium) wafer per 41.67 g water, 30 minutes prior to a test meal of macaroni and beef, on nonconsecutive days. Intake of the test meal and hunger ratings were both significantly reduced after intake of the two largest wafer amounts (169 and 234 kcal, respectively), in comparison with the two smaller amounts and none at all. The reduction produced by the largest amount compared to none at all was 122 kcal (about half the energy of the amount given). There were no significant differences in intake and hunger ratings among the two smaller amounts and none at all. Thus the threshold for intake reduction by this product with water lies between 104 and 169 kcal. Methodologically, this work underscores the importance of testing the satiating effects of foods at multiple levels before conclusions are drawn about their satiating effectiveness, and suggests that the threshold for significant reduction should be considered as a measure of the product's satiating effectiveness. The relative contributions of the nutrients, the fiber, and the water to the satiating effect still need to be determined.