Prediction of glycemic index for starchy foods.

Associations between published values for glycemic index (GI) and chemical components were examined by regression analysis in 18 starchy foods. Independent variables were the amounts of protein, fat, phytic acid, and total dietary fiber (TDF) present in food portions containing 50 g available carbohydrate. GI was similarly and significantly correlated (P < 0.05) with TDF, protein, and phytate. When foods were considered as comprising two groups, legumes and others (grains and tubers), food category accounted for as large a fraction of variability in GI as did regression analysis with food components in the undivided sample. Most correlations between GI and components reverted toward zero when calculated only for the legumes or the "others" group. Evidence is cited that the method of preparing foods and the characteristics of starch and starch granules are more important in predicting GI among starchy food than is the content of any of these four food components.