Dietary glycaemic index: a review of the physiological mechanisms and observed health impacts

Carbohydrates (CHOs) are the most important energy source in human diets and are often classified by their molecular size as sugar, oligosaccharides, polysaccharides, and polyols (hydrogenated CHOs). However, the relevance of this structural classification has been questioned and interest in an alternative property of CHOs has grown. The glycaemic index (GI) is a contribution of Jenkins and co-workers in 1981 to classify CHO containing foods according to their impacts on the body¿s postprandial glycaemic response. GI is defined as ¿The incremental area under the 2-hour blood glucose response curve of a test food containing 50 g of glycaemic (available) CHOs expressed as the percentage of the response to the same amount of glycaemic CHOs from a standard food (either white bread or glucose) taken by the same subject¿. Although white bread and glucose both give valid values, glucose may be the preferred control because of its stable composition. When, for any reason, white bread is used as reference, the obtained GI value needs to be divided by 1.4 to get the GI value contrast to glucose