It is defined as the incremental area under the 2-h blood glucose curve following ingestion of 50 g available CHO as a percentage of the corresponding area following an equivalent amount of CHO from a standard reference product (glucose or white bread).66 Typical blood glucose and plasma insulin responses to HGI and LGI breakfasts are displayed graphically in Fig. 1. Values for GI range from 1 to 100 and CHOs can be classified as high (≥70), moderate (56–69) or low (≤55). Foods classified as HGI include refined-grain products, white bread and potato, whereas LGI foods include whole-grain

products, legumes Temsirolimus and fruits. Numerous published tables now contain GI values for a variety of foods, including the international tables of glycaemic index.67 As the extent of postprandial glycaemia depends on both the GI and the amount of CHO consumed, the glycaemic load (GL) was later proposed to provide an indication of the total glycaemic effect of the diet and is calculated as the product of the

GI and total PLX-4720 research buy dietary CHO divided by 100.68 Critically, the consumption of mixed meals composed of commonly consumed foods more closely reflects “real world” situations than assessing single CHO-containing foods. The GI of mixed meals can be predicted from the GI values of the component CHO foods. The weighted mean of the individual GI values is based on the percentage of the total meal CHO provided by each food

and the predicted response is strongly correlated with the actual glucose response.69 and 70 Various food factors influence the GI of CHO-containing foods, which are affected by the method of preparation, processing, variety, origin, maturation, and degree of ripeness.71 and 72 The term “available carbohydrate” represents parts of the CHO that can be digested and absorbed, excluding dietary fibre. The type of monosaccharide affects the GI, with fructose having a relatively low GI compared with glucose, although it should be noted that diets high in fructose have been implicated in insulin resistance.64 and 71 The ratio of amylose/amylopectin in starch is another important factor; the branched amylopectin is more rapidly digested than the unbranched amylose and results in a higher GI.73 The macronutrient content of foods also affects the GI, with protein TCL and fat reducing the glycaemic response.74, 75 and 76 Although soluble fibre may lower the GI,66 and 77 controversy generally surrounds the effect of dietary fibre on GI.72 Glycaemic and insulinaemic responses to consumed CHO are generally well related.70 However, in certain foods, although the GI can predict the glucose response to a meal it does not necessarily predict the insulin response.72 The unexpectedly high insulinaemic index of milk78 may be important when considering postprandial metabolism following breakfasts typically containing milk.