In vitro and animal models to predict the glycemic index value of carbohydrate-containing foods

Glycemic index (GI) value is an important factor determining the postprandial glycemic response of available carbohydrate in our daily foods. Ideally, it should be determined by feeding foods to healthy human, while this is not always ethically, technically and financially possible especially with a large number of testing foods. Thus, many in vitro and animal models have been developed to predict GI values in human. In this review, the definition of GI related concepts is introduced, followed by reviewing the advantages and limitations of current in vitro and animal models in predicting food GI values. The animal models are especially focused. Generally, in vitro digestion models appear to be reliable estimates of food GI values. However, due to difficulties in standardizing in vitro experimental conditions among different laboratories, many correlation equations have been proposed to predict GI values. This is potentially confusing for the food industry in order to develop food products with low GI values. Animal models are more physiologically relevant to human subjects over in vitro digestion models. However, it may involve ethical issues when applying animal models solely for the GI prediction purpose. In addition, there is currently the lack of correlation analysis between predicted GI values from animal models with those from human studies to support that animal models are reliable indicators of food GI values. The information summarized could help developing an optimal method for a high throughput screening of carbohydrate ingredients for low GI values.