Glycemic response and fiber content of some foods

The proposed mechanisms for the action of dietary fiber (DF) on the glycemic response suggest a nonlinear relationship between glycemic index (GI) and DF content. This relationship was analyzed by using the newly reported total DF (TDF) values, assuming a nonlinear regression curve. The empirical equation obtained was Y = 19.9X-0.322. Similar regression curves were also obtained for soluble DF (SDF) and insoluble DF (IDF). The two regression curves indicated that the correlation coefficient between observed GI and GI calculated from the IDF regression curve (-0.781) was virtually identical to that for SDF (-0.780), but a given content (eg, 5% vs available carbohydrate) of SDF gave a lower GI (39) than did IDF (48). This stronger dependency of GI on SDF suggests a major function of SDF in the TDF hypoglycemic effect. From the regression curve of GI vs TDF, we propose a supplemental GI to predict the glycemic response to foods with no published GI.