Relationship between dietary fiber content and composition in foods and the glycemic index.

The dietary fiber content and composition of 25 foods were related to their glycemic index (GI) to see whether the individual components of dietary fiber, specifically soluble fiber, would provide a better predictive capability of the glycemic response than their total dietary fiber content. Total dietary fiber was significantly related to GI (r = 0.461, p less than 0.05). Soluble fiber was not significantly related to GI (r = 0.308), and uronic acids in insoluble fiber were most closely related to GI (r = 0.584, p less than 0.01). Multiple-regression analysis showed that more variation of GI was explained by uronic acids in insoluble fiber (34%) than by total dietary fiber alone (21%, p = 0.05). The combination of pentoses, hexoses, and uronic acids in soluble and insoluble fiber explained only 50% of GI variability. In determining the potential metabolic effects of diet, physiologic assessment of foods is a useful supplement to chemical analysis of their dietary fiber content and composition.