Assessing beans as a source of intrinsic fiber on satiety in men and women with metabolic syndrome

Dietary fiber is well-known for its satiety inducing properties. Adding fibers to mixed dishes is one way to increase fiber intake. However, adding fibers to foods versus including foods inherently containing fiber may reveal differing effects on satiety. The present study aimed to explore the satiety effects of adding fiber to a mixed meal versus using beans (Phaseolus vulgaris) as a source of intrinsic fiber in the meal. In this pilot study, 12 men and women with metabolic syndrome were randomly assigned to eat three standard meals in a crossover design on three different occasions that contained either no added fiber (control (NF)), extrinsic or added fiber (AF), or whole black beans as the source of intrinsic fiber (BN). Meals were matched for energy and macronutrient composition. Five hour postprandial subjective satiety was measured along with blood glucose, insulin, and the GI hormones, cholecystokinin (CCK) and peptide tyrosine tyrosine (PYY3-36). All meals induced fullness to a similar degree; however, the AF meal suppressed prospective consumption (F2,187 = 9.05, P = 0.0002) compared to the BN or NF meals. The NF meal tended to result in more satisfaction than the BN meal (F2,187 = 5.91, P = 0.003). The BN meal produced significantly higher postprandial CCK concentrations compared to the AF (F2,187 = 6.82, P = 0.001) and NF meals (F2,187 = 6.82, P = 0.002). Similar findings were observed for PYY3-36 response for BN > AF meal (F2,170 = 9.11, P < 0.0001). Postprandial insulin was significantly reduced after the BN meal, compared to the NF (F2,187 = 22.36, P < 0.0001) meal. These findings suggest that incorporating whole black beans into a meal has acute beneficial metabolic and GI hormone responses in adults with metabolic syndrome and are preferred over adding equivalent amounts of fiber from a supplement.