Prediction of glycemic index among high-sugar, low-starch foods

A weighted mean of the glycemic index (GI) values of the constituent sugars of a non-starchy fruit is known to give a rough estimate of the GI of that fruit. Previously observed GI values (GI(ob)) were, on average, lower than the calculated GI of the sugar mixture (GI(sm)) for nine acidic fruits (pH of 3.24-4.17) and tended to exceed the GI(sm) for six near-neutral non-sta rchy foods (pH < 5.33). A formula for predicting GI fr om GI(sm) and food p H was developed, and it accounted for 69% of the sum of squares for the 15 GI(ob) values. A model that proposed that organic acids and their acidic an ions slow gastric emptying and thereby lower GI was developed, and it was f ound to account for 57% of the GI(ob) sum of squares. The substances respon sible for lowering GI in acid fruits and the mechanisms of their action rem ain to be identified.