C URRENT O PINION The glycemic index issue Jennie Brand-Miller a and Anette E. Buyken b Purpose of review In recent years, many of the concerns surrounding the glycemic index have been addressed by methodological studies and clinical trials comparing diets carefully matched for other nutrients. These findings are reviewed together with new observational evidence for the role of the dietary glycemic index in the etiology of cardiovascular disease. Recent findings The determination and classification of the glycemic index of a food product is now standardized by the International Standards Organization. Systematic studies using isoenergetic single and mixed meals have shown that glycemic index and/or glycemic load are stronger predictors of postprandial glycemia and insulinemia than carbohydrate content alone. In overweight individuals, a diet that combined modestly higher protein and lower glycemic index carbohydrates was the most effective diet for prevention of weight regain. New observational studies have reported increased risks of coronary heart disease associated with higher intakes of carbohydrates from high glycemic index foods. Epidemiological evidence has emerged linking dietary glycemic index to visceral fat and inflammatory disease mortality. Summary There is growing recognition that replacing saturated fat with refined, high glycemic index carbohydrates increases postprandial glycemia and may be detrimental for weight control and predisposition to cardiovascular and inflammatory disease. In contrast, low glycemic index carbohydrates reduce risk. Keywords cardiovascular disease, glycemic index, glycemic load, postprandial glycemia, weight INTRODUCTION In the past 2 years, macronutrient advice for the prevention of cardiovascular disease has undergone a remarkable transition [1,2]. This follows the realiz- ation that the efficacy of reducing saturated fat intake largely depends on which foods are substituted [3]. Replacing saturated fat with carbohydrates (the con- ventional low-fat diet) is not effective, unless the quality of the carbohydrate as defined by markers such as the glycemic index is also specified [4 && ]. The glycemic index compares the glycemic nature of the carbohydrates in different foods with that of a refer- ence food. Although postprandial glycemia is tightly controlled in healthy individuals, the rapid digestion and absorption of high glycemic index foods or meals challenges homeostatic mechanisms, particularly b-cell function. Recent prospective observational studies and clinical trials suggest that diets with a high glycemic index or high glycemic load (glycemic load ¼ glycemic index  carbohydrate content) com- promise weight control and cause oxidative stress and inflammatory responses in susceptible individ- uals. In contrast, low glycemic index carbohydrates appear to reduce risk. VALIDITY OF THE GLYCEMIC INDEX AS A PREDICTOR OF POSTPRANDIAL GLYCEMIA OR INSULINEMIA Despite three decades of research, the glycemic index is still contentious, primarily because of con- cerns relating to methodology and extrapolation to mixed meals. However, the determination of the glycemic index in vivo is now the subject of an international standard [5 & ] which member countries are obliged to adopt. Bao et al. [6 & ] systematically studied postprandial glycemia and insulinemia after consumption of 121 single foods in 1000 kJ portions a School of Molecular Bioscience and Boden Institute of Obesity, Nutri- tion and Exercise, University of Sydney, Sydney, New South Wales, Australia and b Research Institute of Child Nutrition, Rheinische Friedrich-Wilhelms-Universita ¨ t Bonn, Dortmund, Germany Correspondence to Professor Jennie C. Brand-Miller, Boden Institute of Obesity, Nutrition & Exercise, Biochemistry Building, G08, The University of Sydney, New South Wales, 2006, Australia. Tel: +61 2 9351 3759; fax: +61 2 9351 6022; e-mail: jennie.brandmiller@sydney.edu.au Curr Opin Lipidol 2012, 23:62–67 DOI:10.1097/MOL.0b013e32834ec705 62 www.co-lipidology.com Volume 23  Number 1  February 2012 REVIEW