The glycemic index: methodology and use.

The glycemic index concept owes much to the dietary fiber hypothesis that fiber would reduce the rate of nutrient absorption and increase the value of carbohydrate foods in the maintenance of health and treatment of disease. However, properties and components of food other than its fiber content contribute to the glycemic and endocrine responses postprandially. The aim of the glycemic index classification of foods was therefore to assist in the physiological classification of carbohydrate foods which, it was hoped, would be of relevance in the prevention and treatment of chronic diseases such as diabetes. Over the past two decades low glycemic index diets have been reported to improve glycemic control in diabetic subjects, to reduce serum lipids in hyperlipidemic subjects and possibly to aid in weight control. In large cohort studies, low glycemic index or glycemic load diets (glycemic index multiplied by total carbohydrate) have also been associated with higher levels of high-density lipoprotein cholesterol, reduced C-reactive protein concentrations and with a decreased risk of developing diabetes and cardiovascular disease. More recently, some case-control and cohort studies have also found positive associations between the dietary glycemic index and the risk of colon, breast and other cancers. While the glycemic index concept continues to be debated and there remain inconsistencies in the data, sufficient positive findings have emerged to suggest that the glycemic index is an aspect of diet of potential importance in the treatment and prevention of chronic diseases.